The Space Age is a period encompassing the activities related to the Space Race, space exploration, space technology, and the cultural developments influenced by these events. The Space Age began with the development of several technologies that culminated with the launch of Sputnik 1 by the Soviet Union. This was the world's first artificial satellite, orbiting the Earth in 98.1 minutes and weighing in at 83 kg. The launch of Sputnik 1 ushered a new era of political, scientific and technological achievements that became known as the Space Age. The Space Age was characterized by rapid development of new technology in a close race mostly between the United States and the Soviet Union. The Space Age brought the first human spaceflight during the Vostok programme and reached its peak with the Apollo program which captured the imagination of much of the world's population. The landing of Apollo 11 was an event watched by over 500 million people around the world and is widely recognized as one of the defining moments of the 20th century. Since then and with the end of the space race due to the dissolution of the Soviet Union, public attention has largely moved to other areas.


How long does did it take for the Sputnik 1 to orbit the earth?


How many people watched the Apollo 11 landing?


What types of control are considered when labeling a country with the perjorative "51st state" label?

The phrase "51st state" can be used in a positive sense, meaning that a region or territory is so aligned, supportive, and conducive with the United States, that it is like a U.S. state. It can also be used in a pejorative sense, meaning an area or region is perceived to be under excessive American cultural or military influence or control. In various countries around the world, people who believe their local or national culture has become too Americanized sometimes use the term "51st state" in reference to their own countries.


Sometimes, when a country refers to themselves as the 51st state, what has happened to their culture?


What reasoning would cause a country to be referred to as the "51st state" in a positive way?


What is a positive connotation of the label "51st state"?


What is a reason for one negative connotation of the term?


If a country refers to themselves as the "51st state" after cultural changes, what can we assume has changed?


What does Article IV, Section three of the US Constitution outline?

Under Article IV, Section Three of the United States Constitution, which outlines the relationship among the states, Congress has the power to admit new states to the union. The states are required to give "full faith and credit" to the acts of each other's legislatures and courts, which is generally held to include the recognition of legal contracts, marriages, and criminal judgments. The states are guaranteed military and civil defense by the federal government, which is also obliged by Article IV, Section Four, to "guarantee to every state in this union a republican form of government".


Article IV, Section Three of th United States Constitution gives Congress the power to do what?


What does the states' requirement to give "full faith and credit" help recognize?


What are all states guaranteed by the federal government?


What does Article 4, Section 4 guarantee?


What part of the US Constitution outlines the relationship among the states?


What does the concept of "full faith and credit" protect?


Article IV, Section Three allows Congress to do what?


What is guaranteed to the states by the federal government?


What country has been regarded as a potential new addition to the United States?

Puerto Rico has been discussed as a potential 51st state of the United States. In a 2012 status referendum a majority of voters, 54%, expressed dissatisfaction with the current political relationship. In a separate question, 61% of voters supported statehood (excluding the 26% of voters who left this question blank). On December 11, 2012, Puerto Rico's legislature resolved to request that the President and the U.S. Congress act on the results, end the current form of territorial status and begin the process of admitting Puerto Rico to the Union as a state.


What percentage of voters expressed dissatisfaction with their current political relationship?


What percentage of voters supported statehood?


When did Puerto Rico resolve to request that the United States act on these results?


What would be an ideal reaction from the United States, according to Puerto Rico?


What territory has been suggested as a new addition to the United States?


What percentages of voters expressed unhappiness with the current political relationship between the U.S. and Puerto Rico?


When did the legislature of Puerto Rico request that they be considered for statehood?


How long has Puerto Rico had representation in Congress?

Since 1898, Puerto Rico has had limited representation in the Congress in the form of a Resident Commissioner, a nonvoting delegate. The 110th Congress returned the Commissioner's power to vote in the Committee of the Whole, but not on matters where the vote would represent a decisive participation. Puerto Rico has elections on the United States presidential primary or caucus of the Democratic Party and the Republican Party to select delegates to the respective parties' national conventions although presidential electors are not granted on the Electoral College. As American citizens, Puerto Ricans can vote in U.S. presidential elections, provided they reside in one of the 50 states or the District of Columbia and not in Puerto Rico itself.


Which Congress gave the commissioner the power to vote?


What is the commissioner not allowed to vote on?


What types of taxes do Puerto Ricans pay?

Residents of Puerto Rico pay U.S. federal taxes: import/export taxes, federal commodity taxes, social security taxes, therefore contributing to the American Government. Most Puerto Rico residents do not pay federal income tax but do pay federal payroll taxes (Social Security and Medicare). However, federal employees, those who do business with the federal government, Puerto Rico–based corporations that intend to send funds to the U.S. and others do pay federal income taxes. Puerto Ricans may enlist in the U.S. military. Puerto Ricans have participated in all American wars since 1898; 52 Puerto Ricans had been killed in the Iraq War and War in Afghanistan by November 2012.


What makes up the federal taxes Puerto Rican citizens pay?


How many Puerto Ricans have died in the Iraq War and War in Afghanistan?


In the aftermath of which war was the U.S. granted Puerto Rico?

Puerto Rico has been under U.S. sovereignty for over a century when it was ceded to the U.S. by Spain following the end of the Spanish–American War, and Puerto Ricans have been U.S. citizens since 1917. The island's ultimate status has not been determined as of 2012[update], its residents do not have voting representation in their federal government. Puerto Rico has limited representation in the U.S. Congress in the form of a Resident Commissioner, a delegate with limited no voting rights. Like the states, Puerto Rico has self-rule, a republican form of government organized pursuant to a constitution adopted by its people, and a bill of rights.


What country handed over Puerto Rico to the US?


How long have Puerto Ricans been U.S. citizens?


What form of government do the Puerto Ricans have?


How was the Puerto Rican constitution brought about?

This constitution was created when the U.S. Congress directed local government to organize a constitutional convention to write the Puerto Rico Constitution in 1951. The acceptance of that constitution by Puerto Rico's electorate, the U.S. Congress, and the U.S. president occurred in 1952. In addition, the rights, privileges and immunities attendant to United States citizens are "respected in Puerto Rico to the same extent as though Puerto Rico were a state of the union" through the express extension of the Privileges and Immunities Clause of the U.S. Constitution by the U.S. Congress in 1948.


When was the Puerto Rican constitution written?


When was the constitution accepted by the electorate, U.S. Congress, and U.S. President?


What clause gives Puerto Rican citizens the same rights as US citizens?


How is Puerto Rico designated in its constitution?

Puerto Rico is designated in its constitution as the "Commonwealth of Puerto Rico". The Constitution of Puerto Rico which became effective in 1952 adopted the name of Estado Libre Asociado (literally translated as "Free Associated State"), officially translated into English as Commonwealth, for its body politic. The island is under the jurisdiction of the Territorial Clause of the U.S. Constitution, which has led to doubts about the finality of the Commonwealth status for Puerto Rico. In addition, all people born in Puerto Rico become citizens of the U.S. at birth (under provisions of the Jones–Shafroth Act in 1917), but citizens residing in Puerto Rico cannot vote for president nor for full members of either house of Congress. Statehood would grant island residents full voting rights at the Federal level. The Puerto Rico Democracy Act (H.R. 2499) was approved on April 29, 2010, by the United States House of Representatives 223–169, but was not approved by the Senate before the end of the 111th Congress. It would have provided for a federally sanctioned self-determination process for the people of Puerto Rico. This act would provide for referendums to be held in Puerto Rico to determine the island's ultimate political status. It had also been introduced in 2007.


What act was approved on April 29th, 2010?


What is the island under jurisdiction of?


What percentage of voters rejected the status of territory?

In November 2012, a referendum resulted in 54 percent of respondents voting to reject the current status under the territorial clause of the U.S. Constitution, while a second question resulted in 61 percent of voters identifying statehood as the preferred alternative to the current territorial status. The 2012 referendum was by far the most successful referendum for statehood advocates and support for statehood has risen in each successive popular referendum. However, more than one in four voters abstained from answering the question on the preferred alternative status. Statehood opponents have argued that the statehood option garnered only 45 percent of the votes if abstentions are included. If abstentions are considered, the result of the referendum is much closer to 44 percent for statehood, a number that falls under the 50 percent majority mark.


What percentage of voters preferred statehood?


What percentage of voters abstained from voting on a preferred alternative status?


What argument do those opposing statehood use?


What newspaper suggested that Congress would ignore Puerto Rico's referendum?

The Washington Post, The New York Times and the Boston Herald have published opinion pieces expressing support for the statehood of Puerto Rico. On November 8, 2012, Washington, D.C. newspaper The Hill published an article saying that Congress will likely ignore the results of the referendum due to the circumstances behind the votes. and U.S. Congressman Luis Gutiérrez U.S. Congresswoman Nydia Velázquez, both of Puerto Rican ancestry, agreed with the The Hill 's statements. Shortly after the results were published Puerto Rico-born U.S. Congressman José Enrique Serrano commented "I was particularly impressed with the outcome of the 'status' referendum in Puerto Rico. A majority of those voting signaled the desire to change the current territorial status. In a second question an even larger majority asked to become a state. This is an earthquake in Puerto Rican politics. It will demand the attention of Congress, and a definitive answer to the Puerto Rican request for change. This is a history-making moment where voters asked to move forward."


What newspapers have published opinion pieces expressing support for Puerto Rico's statehood?


What Congress members agreed with the Hill's assesment?


What politicians pushed for statehood for Puerto Rico?

Several days after the referendum, the Resident Commissioner Pedro Pierluisi, Governor Luis Fortuño, and Governor-elect Alejandro García Padilla wrote separate letters to the President of the United States Barack Obama addressing the results of the voting. Pierluisi urged Obama to begin legislation in favor of the statehood of Puerto Rico, in light of its win in the referendum. Fortuño urged him to move the process forward. García Padilla asked him to reject the results because of their ambiguity. The White House stance related to the November 2012 plebiscite was that the results were clear, the people of Puerto Rico want the issue of status resolved, and a majority chose statehood in the second question. Former White House director of Hispanic media stated, "Now it is time for Congress to act and the administration will work with them on that effort, so that the people of Puerto Rico can determine their own future."


What politician fought against statehood for Puerto Rico?


How did these politicians voice their concerns?


On May 15, 2013, Resident Commissioner Pierluisi introduced H.R. 2000 to Congress to "set forth the process for Puerto Rico to be admitted as a state of the Union," asking for Congress to vote on ratifying Puerto Rico as the 51st state. On February 12, 2014, Senator Martin Heinrich introduced a bill in the US Senate. The bill would require a binding referendum to be held in Puerto Rico asking whether the territory wants to be admitted as a state. In the event of a yes vote, the president would be asked to submit legislation to Congress to admit Puerto Rico as a state.


What did Senator Heinrich's bill require?


What would happen in the event of a yes vote in this referendum?


Who considered the implications of the definition of the seat of government in the Constitution?

Washington, D.C. is often mentioned as a candidate for statehood. In Federalist No. 43 of The Federalist Papers, James Madison considered the implications of the definition of the "seat of government" found in the United States Constitution. Although he noted potential conflicts of interest, and the need for a "municipal legislature for local purposes," Madison did not address the district's role in national voting. Legal scholars disagree on whether a simple act of Congress can admit the District as a state, due to its status as the seat of government of the United States, which Article I, Section 8 of the Constitution requires to be under the exclusive jurisdiction of Congress; depending on the interpretation of this text, admission of the full District as a state may require a Constitutional amendment, which is much more difficult to enact. However, the Constitution does not set a minimum size for the District. Its size has already changed once before, when Virginia reclaimed the portion of the District south of the Potomac. So the constitutional requirement for a federal district can be satisfied by reducing its size to the small central core of government buildings and monuments, giving the rest of the territory to the new state.


Where are these ideas located in the Federalist Papers?


What limits does the constitution have for the size of Washington, D.C.?


What caused the size of Washington, D.C. to change?


What Revolutionary War motto have Washington, D.C. statehood supporters modified and used?

Washington, D.C. residents who support the statehood movement sometimes use a shortened version of the Revolutionary War protest motto "No taxation without representation", omitting the initial "No", denoting their lack of Congressional representation; the phrase is now printed on newly issued Washington, D.C. license plates (although a driver may choose to have the Washington, D.C. website address instead). President Bill Clinton's presidential limousine had the "Taxation without representation" license plate late in his term, while President George W. Bush had the vehicle's plates changed shortly after beginning his term in office. President Barack Obama had the license plates changed back to the protest style at the beginning of his second term.


In what way has the phrase been spread wide?


When did Obama have the protest plates put on his Presidential limousine?


What party carried the position of D.C. Statehood?

This position was carried by the D.C. Statehood Party, a political party; it has since merged with the local Green Party affiliate to form the D.C. Statehood Green Party. The nearest this movement ever came to success was in 1978, when Congress passed the District of Columbia Voting Rights Amendment. Two years later in 1980, local citizens passed an initiative calling for a constitutional convention for a new state. In 1982, voters ratified the constitution of the state, which was to be called New Columbia. The drive for statehood stalled in 1985, however, when the Washington, D.C. Voting Rights Amendment failed because not enough states ratified the amendment within the seven-year span specified.


What party did the D.C. Statehood Party merge when?


When did the movement get closest to success?


What would be the new name of the D.C. State?


When did the drive for statehood falter?


What is another likely country for statehood?

Other less likely contenders are Guam and the United States Virgin Islands, both of which are unincorporated organized territories of the United States. Also, the Northern Mariana Islands and American Samoa, an unorganized, unincorporated territory, could both attempt to gain statehood. Some proposals call for the Virgin Islands to be admitted with Puerto Rico as one state (often known as the proposed "Commonwealth of Prusvi", for Puerto Rico/U.S. Virgin Islands, or as "Puerto Virgo"), and for the amalgamation of U.S. territories or former territories in the Pacific Ocean, in the manner of the "Greater Hawaii" concept of the 1960s. Guam and the Northern Mariana Islands would be admitted as one state, along with Palau, the Federated States of Micronesia, and the Marshall Islands (although these latter three entities are now separate sovereign nations, which have Compact of Free Association relationships with the United States). Such a state would have a population of 412,381 (slightly lower than Wyoming's population) and a land area of 911.82 square miles (2,361.6 km2) (slightly smaller than Rhode Island). American Samoa could possibly be part of such a state, increasing the population to 467,900 and the area to 988.65 square miles (2,560.6 km2). Radio Australia, in late May 2008, issued signs of Guam and the Northern Mariana Islands becoming one again and becoming the 51st state.


What entity reported on Guam and the Northern Mariana Islands becoming one again?


What country had small grassroots movement for US Statehood?

The Philippines has had small grassroots movements for U.S. statehood. Originally part of the platform of the Progressive Party, then known as the Federalista Party, the party dropped it in 1907, which coincided with the name change. As recently as 2004, the concept of the Philippines becoming a U.S. state has been part of a political platform in the Philippines. Supporters of this movement include Filipinos who believe that the quality of life in the Philippines would be higher and that there would be less poverty there if the Philippines were an American state or territory. Supporters also include Filipinos that had fought as members of the United States Armed Forces in various wars during the Commonwealth period.


What party used to be known as the Federalista Party?


What was the most recent year of the Phillipines pushing for statehood?


What is another connotation for the 51st state label?

In Canada, "the 51st state" is a phrase generally used in such a way as to imply that if a certain political course is taken, Canada's destiny will be as little more than a part of the United States. Examples include the Canada-United States Free Trade Agreement in 1988, the debate over the creation of a common defense perimeter, and as a potential consequence of not adopting proposals intended to resolve the issue of Quebec sovereignty, the Charlottetown Accord in 1992 and the Clarity Act in 1999.


When was the Canada-US Free Trade Agreement enacted?


When was the Charlottetown Accord signed?


When did the Clarity Act go into effect?


Who suggested that the Free Trade Agreement amounted to an American takeover of Canada?

The phrase is usually used in local political debates, in polemic writing or in private conversations. It is rarely used by politicians themselves in a public context, although at certain times in Canadian history political parties have used other similarly loaded imagery. In the 1988 federal election, the Liberals asserted that the proposed Free Trade Agreement amounted to an American takeover of Canada—notably, the party ran an ad in which Progressive Conservative (PC) strategists, upon the adoption of the agreement, slowly erased the Canada-U.S. border from a desktop map of North America. Within days, however, the PCs responded with an ad which featured the border being drawn back on with a permanent marker, as an announcer intoned "Here's where we draw the line."


The implication has historical basis and dates to the breakup of British America during the American Revolution. The colonies that had confederated to form the United States invaded Canada (at the time a term referring specifically to the modern-day provinces of Quebec and Ontario, which had only been in British hands since 1763) at least twice, neither time succeeding in taking control of the territory. The first invasion was during the Revolution, under the assumption that French-speaking Canadians' presumed hostility towards British colonial rule combined with the Franco-American alliance would make them natural allies to the American cause; the Continental Army successfully recruited two Canadian regiments for the invasion. That invasion's failure forced the members of those regiments into exile, and they settled mostly in upstate New York. The Articles of Confederation, written during the Revolution, included a provision for Canada to join the United States, should they ever decide to do so, without needing to seek U.S. permission as other states would. The United States again invaded Canada during the War of 1812, but this effort was made more difficult due to the large number of Loyalist Americans that had fled to what is now Ontario and still resisted joining the republic. The Hunter Patriots in the 1830s and the Fenian raids after the American Civil War were private attacks on Canada from the U.S. Several U.S. politicians in the 19th century also spoke in favour of annexing Canada.


What did several US politicians suggest doing in the 19th century?


When were the last days of the Dominion of Newfoundland?

In the late 1940s, during the last days of the Dominion of Newfoundland (at the time a dominion-dependency in the Commonwealth and independent of Canada), there was mainstream support, although not majority, for Newfoundland to form an economic union with the United States, thanks to the efforts of the Economic Union Party and significant U.S. investment in Newfoundland stemming from the U.S.-British alliance in World War II. The movement ultimately failed when, in a 1948 referendum, voters narrowly chose to confederate with Canada (the Economic Union Party supported an independent "responsible government" that they would then push toward their goals).


What did the Economic Union Party support?


What was the result of the 1948 referendum?


What does Canada being referred to as the 51st state in a positive way mean in the US, generally?

In the United States, the term "the 51st state" when applied to Canada can serve to highlight the similarities and close relationship between the United States and Canada. Sometimes the term is used disparagingly, intended to deride Canada as an unimportant neighbor. In the Quebec general election, 1989, the political party Parti 51 ran 11 candidates on a platform of Quebec seceding from Canada to join the United States (with its leader, André Perron, claiming Quebec could not survive as an independent nation). The party attracted just 3,846 votes across the province, 0.11% of the total votes cast. In comparison, the other parties in favour of sovereignty of Quebec in that election got 40.16% (PQ) and 1.22% (NPDQ).


What is a negative connotation of the term?


How man votes did Parti 51 attract in 1989?


What did the other parties receive that year?


When did Panama have the US-ruled Canal Zone Territory?

Due to geographical proximity of the Central American countries to the U.S. which has powerful military, economic, and political influences, there were several movements and proposals by the United States during the 19th and 20th centuries to annex some or all of the Central American republics (Costa Rica, El Salvador, Guatemala, Honduras with the formerly British-ruled Bay Islands, Nicaragua, Panama which had the U.S.-ruled Canal Zone territory from 1903 to 1979, and formerly British Honduras or Belize since 1981). However, the U.S. never acted on these proposals from some U.S. politicians; some of which were never delivered or considered seriously. In 2001, El Salvador adopted the U.S. dollar as its currency, while Panama has used it for decades due to its ties to the Canal Zone.


When did El Salvador adopt the US Dollar as its currency?


When did the British Honduras become Belize?


Cuba, like many Spanish territories, wanted to break free from Spain. A pro-independence movement in Cuba was supported by the U.S., and Cuban guerrilla leaders wanted annexation to the United States, but Cuban revolutionary leader José Martí called for Cuban nationhood. When the U.S. battleship Maine sank in Havana Harbor, the U.S. blamed Spain and the Spanish–American War broke out in 1898. After the U.S. won, Spain relinquished claim of sovereignty over territories, including Cuba. The U.S. administered Cuba as a protectorate until 1902. Several decades later in 1959, the corrupt Cuban government of U.S.-backed Fulgencio Batista was overthrown by Fidel Castro. Castro installed a Marxist–Leninist government allied with the Soviet Union, which has been in power ever since.


What battleship sunk in the Havana Harbor?


When did Fidel Castro overthrow the Cuban government?


Why is Israel referred to as the 51st state?

Several websites assert that Israel is the 51st state due to the annual funding and defense support it receives from the United States. An example of this concept can be found in 2003 when Martine Rothblatt published a book called Two Stars for Peace that argued for the addition of Israel and the Palestinian territories surrounding it as the 51st state in the Union. The American State of Canaan, is a book published by Prof. Alfred de Grazia, political science and sociologist, in March 2009, proposing the creation of the 51st and 52nd states from Israel and the Palestinian territories.


What book did Martine Rothblatt publish?


Who wrote the book The American State of Canaan?


When did Artcle 3 of the Treaty of San Francisco come into effect?

In Article 3 of the Treaty of San Francisco between the Allied Powers and Japan, which came into force in April 1952, the U.S. put the outlying islands of the Ryukyus, including the island of Okinawa—home to over 1 million Okinawans related to the Japanese—and the Bonin Islands, the Volcano Islands, and Iwo Jima into U.S. trusteeship. All these trusteeships were slowly returned to Japanese rule. Okinawa was returned on May 15, 1972, but the U.S. stations troops in the island's bases as a defense for Japan.


How many people lived on the island of Okinawa?


When did the 51st State Party attempt to register in New Zealand?

In 2010 there was an attempt to register a 51st State Party with the New Zealand Electoral Commission. The party advocates New Zealand becoming the 51st state of the United States of America. The party's secretary is Paulus Telfer, a former Christchurch mayoral candidate. On February 5, 2010, the party applied to register a logo with the Electoral Commission. The logo – a US flag with 51 stars – was rejected by the Electoral Commission on the grounds that it was likely to cause confusion or mislead electors. As of 2014[update], the party remains unregistered and cannot appear on a ballot.


Who is the secretary of the 51st State Party?


What does the 51st State Party advocate?


Can people in New Zealand vote for the 51st State Party?


Albania has often been called the 51st state for its perceived strongly pro-American positions, mainly because of the United States' policies towards it. In reference to President George W. Bush's 2007 European tour, Edi Rama, Tirana's mayor and leader of the opposition Socialists, said: "Albania is for sure the most pro-American country in Europe, maybe even in the world ... Nowhere else can you find such respect and hospitality for the President of the United States. Even in Michigan, he wouldn't be as welcome." At the time of ex-Secretary of State James Baker's visit in 1992, there was even a move to hold a referendum declaring the country as the 51st American state. In addition to Albania, Kosovo which is predominately Albanian is seen as a 51st state due to the heavily presence and influence of the United States. The US has had troops and the largest base outside US territory, Camp Bondsteel in the territory since 1999.


Who said that Albania is the most pro-American country in Europe?


When did James Baker visit Albania as Secretary of State?


What is the name of the largest US military base outside of US territory?


During World War II, when Denmark was occupied by Nazi Germany, the United States briefly controlled Greenland for battlefields and protection. In 1946, the United States offered to buy Greenland from Denmark for $100 million ($1.2 billion today) but Denmark refused to sell it. Several politicians and others have in recent years argued that Greenland could hypothetically be in a better financial situation as a part of the United States; for instance mentioned by professor Gudmundur Alfredsson at University of Akureyri in 2014. One of the actual reasons behind US interest in Greenland could be the vast natural resources of the island. According to Wikileaks, the U.S. appears to be highly interested in investing in the resource base of the island and in tapping the vast expected hydrocarbons off the Greenlandic coast.


How much did the US offer to pay for Greenland?


What university is professor Gudmundur Alfredssson from?


What is one reason the US would be interested in Greenland?


What had been Poland's stance towards the US, historically?

Poland has historically been staunchly pro-American, dating back to General Tadeusz Kościuszko and Casimir Pulaski's involvement in the American Revolution. This pro-American stance was reinforced following favorable American intervention in World War I (leading to the creation of an independent Poland) and the Cold War (culminating in a Polish state independent of Soviet influence). Poland contributed a large force to the "Coalition of the Willing" in Iraq. A quote referring to Poland as "the 51st state" has been attributed to James Pavitt, then Central Intelligence Agency Deputy Director for Operations, especially in connection to extraordinary rendition.


What led to the creation of an independent Poland?


What did Poland contribute to the "Coalition of the Willing"?


How many members did the Party of Reconstruction in Sicily have in 1944?

The Party of Reconstruction in Sicily, which claimed 40,000 members in 1944, campaigned for Sicily to be admitted as a U.S. state. This party was one of several Sicilian separatist movements active after the downfall of Italian Fascism. Sicilians felt neglected or underrepresented by the Italian government after the annexation of 1861 that ended the rule of the Kingdom of the Two Sicilies based in Naples. The large population of Sicilians in America and the American-led Allied invasion of Sicily in July–August 1943 may have contributed to the sentiment.


What did the Party of Reconstruction in Sicily campaign for?


When did the annexation of Sicily by Italy happen?


When did the Allied invasion of Sicily occur?


What are the four categories of terra nullius?

There are four categories of terra nullius, land that is unclaimed by any state: the small unclaimed territory of Bir Tawil between Egypt and Sudan, Antarctica, the oceans, and celestial bodies such as the Moon or Mars. In the last three of these, international treaties (the Antarctic Treaty, the United Nations Convention on the Law of the Sea, and the Outer Space Treaty respectively) prevent colonization and potential statehood of any of these uninhabited (and, given current technology, not permanently inhabitable) territories.


What three treaties exist for unclaimed lands?


What device is able to change electric powerinto radio waves and also do the reverse?

An antenna (plural antennae or antennas), or aerial, is an electrical device which converts electric power into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver. In transmission, a radio transmitter supplies an electric current oscillating at radio frequency (i.e. a high frequency alternating current (AC)) to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of an electromagnetic wave in order to produce a tiny voltage at its terminals, that is applied to a receiver to be amplified.


What device is often used in conjuntion with the antenna?


What process associated with antennas produces a high frequency alternating current?


When does an antenna catch electromagnetic waves?


What is frequently used to connect elements to the receiver?

Typically an antenna consists of an arrangement of metallic conductors (elements), electrically connected (often through a transmission line) to the receiver or transmitter. An oscillating current of electrons forced through the antenna by a transmitter will create an oscillating magnetic field around the antenna elements, while the charge of the electrons also creates an oscillating electric field along the elements. These time-varying fields radiate away from the antenna into space as a moving transverse electromagnetic field wave. Conversely, during reception, the oscillating electric and magnetic fields of an incoming radio wave exert force on the electrons in the antenna elements, causing them to move back and forth, creating oscillating currents in the antenna.


During transmission does the electric field wave move closer to the antenna?


What particles are pushed through the antenna by a transmitter?


During what process would electrons be vacillating in the antenna?


What is an acceptable synonym for antenna?

The words antenna (plural: antennas in US English, although both "antennas" and "antennae" are used in International English) and aerial are used interchangeably. Occasionally the term "aerial" is used to mean a wire antenna. However, note the important international technical journal, the IEEE Transactions on Antennas and Propagation. In the United Kingdom and other areas where British English is used, the term aerial is sometimes used although 'antenna' has been universal in professional use for many years.


What can sometimes be meant by the term aerial specifically?


What is one way of referring to more than one antenna?


What is the most widely accepted term for an electrical device that converts electric power into radio waves?


Who is most associated with the emergence of the word antenna?

The origin of the word antenna relative to wireless apparatus is attributed to Italian radio pioneer Guglielmo Marconi. In the summer of 1895, Marconi began testing his wireless system outdoors on his father's estate near Bologna and soon began to experiment with long wire "aerials". Marconi discovered that by raising the "aerial" wire above the ground and connecting the other side of his transmitter to ground, the transmission range was increased. Soon he was able to transmit signals over a hill, a distance of approximately 2.4 kilometres (1.5 mi). In Italian a tent pole is known as l'antenna centrale, and the pole with the wire was simply called l'antenna. Until then wireless radiating transmitting and receiving elements were known simply as aerials or terminals.


When did experimentation with electromagnetic waves begin?


What is a way to increase the strength of a radio transmission?


How far was Marconi able to get his signal to go using this technique?


What is essential for the mating of the elements that create radio waves?

Antennas are required by any radio receiver or transmitter to couple its electrical connection to the electromagnetic field. Radio waves are electromagnetic waves which carry signals through the air (or through space) at the speed of light with almost no transmission loss. Radio transmitters and receivers are used to convey signals (information) in systems including broadcast (audio) radio, television, mobile telephones, Wi-Fi (WLAN) data networks, trunk lines and point-to-point communications links (telephone, data networks), satellite links, many remote controlled devices such as garage door openers, and wireless remote sensors, among many others. Radio waves are also used directly for measurements in technologies including radar, GPS, and radio astronomy. In each and every case, the transmitters and receivers involved require antennas, although these are sometimes hidden (such as the antenna inside an AM radio or inside a laptop computer equipped with Wi-Fi).


How fast are signals produced by antenna transmitted?


What is one system that uses electromagnetic waves?


What mobile locator and direction finder technology takes advantage of radio waves?


What often inconspicuous part of a laptop computer allows for internet usage?


What is the main element of an omnidirectional antenna?

One example of omnidirectional antennas is the very common vertical antenna or whip antenna consisting of a metal rod (often, but not always, a quarter of a wavelength long). A dipole antenna is similar but consists of two such conductors extending in opposite directions, with a total length that is often, but not always, a half of a wavelength long. Dipoles are typically oriented horizontally in which case they are weakly directional: signals are reasonably well radiated toward or received from all directions with the exception of the direction along the conductor itself; this region is called the antenna blind cone or null.


What type of antenna would most likely be a half a wavelength long?


In which direction would you expect to find a dipole?


What is meant by the area where signals cannot be accepted well along the conductor?


Both the vertical and dipole antennas are simple in construction and relatively inexpensive. The dipole antenna, which is the basis for most antenna designs, is a balanced component, with equal but opposite voltages and currents applied at its two terminals through a balanced transmission line (or to a coaxial transmission line through a so-called balun). The vertical antenna, on the other hand, is a monopole antenna. It is typically connected to the inner conductor of a coaxial transmission line (or a matching network); the shield of the transmission line is connected to ground. In this way, the ground (or any large conductive surface) plays the role of the second conductor of a dipole, thereby forming a complete circuit. Since monopole antennas rely on a conductive ground, a so-called grounding structure may be employed to provide a better ground contact to the earth or which itself acts as a ground plane to perform that function regardless of (or in absence of) an actual contact with the earth.


What is the foundation most often used when creating new antenna models?


What category do vertical antennas fall under?


What is used to close the circuit of a dipole antenna?


What are different designs aimed at increasing?

Antennas more complex than the dipole or vertical designs are usually intended to increase the directivity and consequently the gain of the antenna. This can be accomplished in many different ways leading to a plethora of antenna designs. The vast majority of designs are fed with a balanced line (unlike a monopole antenna) and are based on the dipole antenna with additional components (or elements) which increase its directionality. Antenna "gain" in this instance describes the concentration of radiated power into a particular solid angle of space, as opposed to the spherically uniform radiation of the ideal radiator. The increased power in the desired direction is at the expense of that in the undesired directions. Power is conserved, and there is no net power increase over that delivered from the power source (the transmitter.)


What is different from a monopole antenna with most other antenna types?


Gain when referring to an antenna refers to what about radiated power?


Where is the power that is distributed originating from?


How many antenna would make up a phased array?

For instance, a phased array consists of two or more simple antennas which are connected together through an electrical network. This often involves a number of parallel dipole antennas with a certain spacing. Depending on the relative phase introduced by the network, the same combination of dipole antennas can operate as a "broadside array" (directional normal to a line connecting the elements) or as an "end-fire array" (directional along the line connecting the elements). Antenna arrays may employ any basic (omnidirectional or weakly directional) antenna type, such as dipole, loop or slot antennas. These elements are often identical.


What determines if the antenna creates a broadside array or an end fire array?


What are the two standard antenna types?


How are antennas oriented when arranged with specific spacing?


What type of antenna formation is made up of multiple dipole elements of varying lengths?

However a log-periodic dipole array consists of a number of dipole elements of different lengths in order to obtain a somewhat directional antenna having an extremely wide bandwidth: these are frequently used for television reception in fringe areas. The dipole antennas composing it are all considered "active elements" since they are all electrically connected together (and to the transmission line). On the other hand, a superficially similar dipole array, the Yagi-Uda Antenna (or simply "Yagi"), has only one dipole element with an electrical connection; the other so-called parasitic elements interact with the electromagnetic field in order to realize a fairly directional antenna but one which is limited to a rather narrow bandwidth. The Yagi antenna has similar looking parasitic dipole elements but which act differently due to their somewhat different lengths. There may be a number of so-called "directors" in front of the active element in the direction of propagation, and usually a single (but possibly more) "reflector" on the opposite side of the active element.


What is the benefit of this formation type?


What is a variation of this antenna type?


What is the main application of these set ups?


For radio broadcast that one would hear in their car what type of towers are used?

At low frequencies (such as AM broadcast), arrays of vertical towers are used to achieve directionality and they will occupy large areas of land. For reception, a long Beverage antenna can have significant directivity. For non directional portable use, a short vertical antenna or small loop antenna works well, with the main design challenge being that of impedance matching. With a vertical antenna a loading coil at the base of the antenna may be employed to cancel the reactive component of impedance; small loop antennas are tuned with parallel capacitors for this purpose.


If one wished to take an antenna to different locations, which type would be best?


What is a problem one might encounter when using a portable antenna?


What is mainly responsible for the connection of the antenna to its end destinations?

An antenna lead-in is the transmission line (or feed line) which connects the antenna to a transmitter or receiver. The antenna feed may refer to all components connecting the antenna to the transmitter or receiver, such as an impedance matching network in addition to the transmission line. In a so-called aperture antenna, such as a horn or parabolic dish, the "feed" may also refer to a basic antenna inside the entire system (normally at the focus of the parabolic dish or at the throat of a horn) which could be considered the one active element in that antenna system. A microwave antenna may also be fed directly from a waveguide in place of a (conductive) transmission line.


What is the group of elements used to join the elements of an antenna?


What are the type of antennas used with satellite television called?


What can be used in place of a standard transmission line?


Monopole antennas consist of what element?

Monopole antennas consist of a single radiating element such as a metal rod, often mounted over a conducting surface, a ground plane. One side of the feedline from the receiver or transmitter is connected to the rod, and the other side to the ground plane, which may be the Earth. The most common form is the quarter-wave monopole which is one-quarter of a wavelength long and has a gain of 5.12 dBi when mounted over a ground plane. Monopoles have an omnidirectional radiation pattern, so they are used for broad coverage of an area, and have vertical polarization. The ground waves used for broadcasting at low frequencies must be vertically polarized, so large vertical monopole antennas are used for broadcasting in the MF, LF, and VLF bands. Small monopoles are used as nondirectional antennas on portable radios in the HF, VHF, and UHF bands.


What is the most widley used antenna class?

The most widely used class of antenna, a dipole antenna consists of two symmetrical radiators such as metal rods or wires, with one side of the balanced feedline from the transmitter or receiver attached to each. A horizontal dipole radiates in two lobes perpendicular to the antenna's axis. A half-wave dipole the most common type, has two collinear elements each a quarter wavelength long and a gain of 2.15 dBi. Used individually as low gain antennas, dipoles are also used as driven elements in many more complicated higher gain types of antennas.


What radiates two lobes perpendicular to the antennas axis?


Besides low gain antennas, what is also used as driven elements in complicated higher gain types of antennas?


How much gain does a half-wave dipole have?


What must be true of the antenna and transmission medium for the repiprocity rule to apply ?

A necessary condition for the aforementioned reciprocity property is that the materials in the antenna and transmission medium are linear and reciprocal. Reciprocal (or bilateral) means that the material has the same response to an electric current or magnetic field in one direction, as it has to the field or current in the opposite direction. Most materials used in antennas meet these conditions, but some microwave antennas use high-tech components such as isolators and circulators, made of nonreciprocal materials such as ferrite. These can be used to give the antenna a different behavior on receiving than it has on transmitting, which can be useful in applications like radar.


What is one material that does not have this quality?


How can the lack of this quality be used in an everyday way?


What is called when the direction of the elctrical current does not make a difference to the current?


How could one deide what type of antenna is nedded for a project?

Antennas are characterized by a number of performance measures which a user would be concerned with in selecting or designing an antenna for a particular application. Chief among these relate to the directional characteristics (as depicted in the antenna's radiation pattern) and the resulting gain. Even in omnidirectional (or weakly directional) antennas, the gain can often be increased by concentrating more of its power in the horizontal directions, sacrificing power radiated toward the sky and ground. The antenna's power gain (or simply "gain") also takes into account the antenna's efficiency, and is often the primary figure of merit.


What would most likely be the main concern in making this decision?


How would you distribute power to allow for a greater gain?


What is often the most imprtant crediting factor of antennas?


Which antenna type would be best for a project requiring a specific frequency?

Resonant antennas are expected to be used around a particular resonant frequency; an antenna must therefore be built or ordered to match the frequency range of the intended application. A particular antenna design will present a particular feedpoint impedance. While this may affect the choice of an antenna, an antenna's impedance can also be adapted to the desired impedance level of a system using a matching network while maintaining the other characteristics (except for a possible loss of efficiency).


How could an antenna be made to coordinate with the needed frequency?


What factor would result in a desired feedback independence?


If you were unable to choose the antenna you wanted how could you still achieve this result?


What is the essential difference in radio waves transmitted by an antenna?

An antenna transmits and receives radio waves with a particular polarization which can be reoriented by tilting the axis of the antenna in many (but not all) cases. The physical size of an antenna is often a practical issue, particularly at lower frequencies (longer wavelengths). Highly directional antennas need to be significantly larger than the wavelength. Resonant antennas usually use a linear conductor (or element), or pair of such elements, each of which is about a quarter of the wavelength in length (an odd multiple of quarter wavelengths will also be resonant). Antennas that are required to be small compared to the wavelength sacrifice efficiency and cannot be very directional. Fortunately at higher frequencies (UHF, microwaves) trading off performance to obtain a smaller physical size is usually not required.


How can this be adjusted more easily than changing antenna types?


When might the size of an antenna cause an issue?


What size antenna would not be good when the antenna needs to be directional?


There is a relationship between the size of the antenna and the size of the wavelength with what antenna type?


What particle's migration does the resonance principle rely on?

The majority of antenna designs are based on the resonance principle. This relies on the behaviour of moving electrons, which reflect off surfaces where the dielectric constant changes, in a fashion similar to the way light reflects when optical properties change. In these designs, the reflective surface is created by the end of a conductor, normally a thin metal wire or rod, which in the simplest case has a feed point at one end where it is connected to a transmission line. The conductor, or element, is aligned with the electrical field of the desired signal, normally meaning it is perpendicular to the line from the antenna to the source (or receiver in the case of a broadcast antenna).


What is the basis for the way most antennas are developed?


What type of surface is formed by the tip of a conductor?


How would you place the conductor in relation to the signal you wished to obtain?


What part of the radio signal creates voltage?

The radio signal's electrical component induces a voltage in the conductor. This causes an electrical current to begin flowing in the direction of the signal's instantaneous field. When the resulting current reaches the end of the conductor, it reflects, which is equivalent to a 180 degree change in phase. If the conductor is 1⁄4 of a wavelength long, current from the feed point will undergo 90 degree phase change by the time it reaches the end of the conductor, reflect through 180 degrees, and then another 90 degrees as it travels back. That means it has undergone a total 360 degree phase change, returning it to the original signal. The current in the element thus adds to the current being created from the source at that instant. This process creates a standing wave in the conductor, with the maximum current at the feed.


What would the electric current always gravitate to?


What is the outcome when a curren is reflected>


What amount of phase change would return a signal to its originial state?


The ordinary half-wave dipole is probably the most widely used antenna design. This consists of two 1⁄4-wavelength elements arranged end-to-end, and lying along essentially the same axis (or collinear), each feeding one side of a two-conductor transmission wire. The physical arrangement of the two elements places them 180 degrees out of phase, which means that at any given instant one of the elements is driving current into the transmission line while the other is pulling it out. The monopole antenna is essentially one half of the half-wave dipole, a single 1⁄4-wavelength element with the other side connected to ground or an equivalent ground plane (or counterpoise). Monopoles, which are one-half the size of a dipole, are common for long-wavelength radio signals where a dipole would be impractically large. Another common design is the folded dipole, which is essentially two dipoles placed side-by-side and connected at their ends to make a single one-wavelength antenna.


What is the current usually beng put into it or pulled out of?


Elements in a half wave dipole and on an identical axis are said to be what?


What antenna type is a portion of the half wave dipole?


What popular type combines more that one antenna?


What frequency are antennas normally designed to be?

The standing wave forms with this desired pattern at the design frequency, f0, and antennas are normally designed to be this size. However, feeding that element with 3f0 (whose wavelength is 1⁄3 that of f0) will also lead to a standing wave pattern. Thus, an antenna element is also resonant when its length is 3⁄4 of a wavelength. This is true for all odd multiples of 1⁄4 wavelength. This allows some flexibility of design in terms of antenna lengths and feed points. Antennas used in such a fashion are known to be harmonically operated.


What can be added to f0 to create a standing wave pattern?


What multiple is essential for wavelengths?


How are waves which are used in the ways discussed controlled?


How do quarter wave elements act in relation to a series relevant electrical element?

The quarter-wave elements imitate a series-resonant electrical element due to the standing wave present along the conductor. At the resonant frequency, the standing wave has a current peak and voltage node (minimum) at the feed. In electrical terms, this means the element has minimum reactance, generating the maximum current for minimum voltage. This is the ideal situation, because it produces the maximum output for the minimum input, producing the highest possible efficiency. Contrary to an ideal (lossless) series-resonant circuit, a finite resistance remains (corresponding to the relatively small voltage at the feed-point) due to the antenna's radiation resistance as well as any actual electrical losses.


How would you describe a current that has maximum efficiency?


What could be the best possible output versus input ratio?


For use with more than one channel changes are made to increase what property?

It is possible to use the impedance matching concepts to construct vertical antennas substantially shorter than the 1⁄4 wavelength at which the antenna is resonant. By adding an inductance in series with the antenna, a so-called loading coil, the capacitive reactance of this antenna can be cancelled leaving a pure resistance which can then be matched to the transmission line. Sometimes the resulting resonant frequency of such a system (antenna plus matching network) is described using the construct of electrical length and the use of a shorter antenna at a lower frequency than its resonant frequency is termed electrical lengthening.


What could be coupled with an antenna to form pure resistance?


What element would this pure resistance be coupled with?


What phrase describes the process of purposely using a lower standing antenna at a less than peak frequency?


If your were unable to match the source frequency with the design frequency of the antenna what could you use?

The end result is that the resonant antenna will efficiently feed a signal into the transmission line only when the source signal's frequency is close to that of the design frequency of the antenna, or one of the resonant multiples. This makes resonant antenna designs inherently narrowband, and they are most commonly used with a single target signal. They are particularly common on radar systems, where the same antenna is used for both broadcast and reception, or for radio and television broadcasts, where the antenna is working with a single frequency. They are less commonly used for reception where multiple channels are present, in which case additional modifications are used to increase the bandwidth, or entirely different antenna designs are used.


What is the most common application of resonant antennas?


What antenna setup type is generally used for TV viewing?


What accounts for the geometry involved in the use of an antenna?

The amount of signal received from a distant transmission source is essentially geometric in nature due to the inverse square law, and this leads to the concept of effective area. This measures the performance of an antenna by comparing the amount of power it generates to the amount of power in the original signal, measured in terms of the signal's power density in Watts per square metre. A half-wave dipole has an effective area of 0.13 2. If more performance is needed, one cannot simply make the antenna larger. Although this would intercept more energy from the signal, due to the considerations above, it would decrease the output significantly due to it moving away from the resonant length. In roles where higher performance is needed, designers often use multiple elements combined together.


How is the compactness of the signal measured?


What type of project would call for more than one element used together?


What is a half wave dipole need to be coupled with in most instances?

Returning to the basic concept of current flows in a conductor, consider what happens if a half-wave dipole is not connected to a feed point, but instead shorted out. Electrically this forms a single 1⁄2-wavelength element. But the overall current pattern is the same; the current will be zero at the two ends, and reach a maximum in the center. Thus signals near the design frequency will continue to create a standing wave pattern. Any varying electrical current, like the standing wave in the element, will radiate a signal. In this case, aside from resistive losses in the element, the rebroadcast signal will be significantly similar to the original signal in both magnitude and shape. If this element is placed so its signal reaches the main dipole in-phase, it will reinforce the original signal, and increase the current in the dipole. Elements used in this way are known as passive elements.


What part of the current is usually strongest?


Element used to provide support to the original signal are called?


What can take advantage of these elements to add more gain?

A Yagi-Uda array uses passive elements to greatly increase gain. It is built along a support boom that is pointed toward the signal, and thus sees no induced signal and does not contribute to the antenna's operation. The end closer to the source is referred to as the front. Near the rear is a single active element, typically a half-wave dipole or folded dipole. Passive elements are arranged in front (directors) and behind (reflectors) the active element along the boom. The Yagi has the inherent quality that it becomes increasingly directional, and thus has higher gain, as the number of elements increases. However, this also makes it increasingly sensitive to changes in frequency; if the signal frequency changes, not only does the active element receive less energy directly, but all of the passive elements adding to that signal also decrease their output as well and their signals no longer reach the active element in-phase.


Does this device improve the operation of the antenna?


What is the name for passive elements nearer to the source of the signal?


Adding more elements to a Yagi-Uda would have what effect?


What can be paired with transmission lines to create phases that would support output?

It is also possible to use multiple active elements and combine them together with transmission lines to produce a similar system where the phases add up to reinforce the output. The antenna array and very similar reflective array antenna consist of multiple elements, often half-wave dipoles, spaced out on a plane and wired together with transmission lines with specific phase lengths to produce a single in-phase signal at the output. The log-periodic antenna is a more complex design that uses multiple in-line elements similar in appearance to the Yagi-Uda but using transmission lines between the elements to produce the output.


What is the most common element used to create a single in phase signal?


What must be precise in order to create this signal at output?


What is a more complicated occurrence of the single in-phase producing antenna?


If you wanted to somehow clone the original signal you could use?

Reflection of the original signal also occurs when it hits an extended conductive surface, in a fashion similar to a mirror. This effect can also be used to increase signal through the use of a reflector, normally placed behind the active element and spaced so the reflected signal reaches the element in-phase. Generally the reflector will remain highly reflective even if it is not solid; gaps less than 1⁄10 generally have little effect on the outcome. For this reason, reflectors often take the form of wire meshes or rows of passive elements, which makes them lighter and less subject to wind. The parabolic reflector is perhaps the best known example of a reflector-based antenna, which has an effective area far greater than the active element alone.


What effect would the use of a reflector have on a signal?


What allowance can be made for gaps without loss of performance?


What is the most recognized type of an antenna that has its basis in reflection?


What magnifies the small radiation resistance of a loop?

Another extreme case of impedance matching occurs when using a small loop antenna (usually, but not always, for receiving) at a relatively low frequency where it appears almost as a pure inductor. Resonating such an inductor with a capacitor at the frequency of operation not only cancels the reactance but greatly magnifies the very small radiation resistance of such a loop.[citation needed] This is implemented in most AM broadcast receivers, with a small ferrite loop antenna resonated by a capacitor which is varied along with the receiver tuning in order to maintain resonance over the AM broadcast band


What is resonated by a capacitor along with the receiver tuning that maintains resonance over the AM broadcast band?


What is used in most AM broadcaster receivers?


When using a small loop antenna at a low frequency, what may occur?


Antenna tuning generally refers to cancellation of any reactance seen at the antenna terminals, leaving only a resistive impedance which might or might not be exactly the desired impedance (that of the transmission line). Although an antenna may be designed to have a purely resistive feedpoint impedance (such as a dipole 97% of a half wavelength long) this might not be exactly true at the frequency that it is eventually used at. In some cases the physical length of the antenna can be "trimmed" to obtain a pure resistance. On the other hand, the addition of a series inductance or parallel capacitance can be used to cancel a residual capacitative or inductive reactance, respectively.


Where does cancellation of any reactance seen?


What can be used to cancel a inductibe reactance or residual capacitative?


What type of antenna has impedance at a specific frequency?

Although a resonant antenna has a purely resistive feed-point impedance at a particular frequency, many (if not most) applications require using an antenna over a range of frequencies. An antenna's bandwidth specifies the range of frequencies over which its performance does not suffer due to a poor impedance match. Also in the case of a Yagi-Uda array, the use of the antenna very far away from its design frequency reduces the antenna's directivity, thus reducing the usable bandwidth regardless of impedance matching.


What term can be used to refer to the usable spectrum of an antennas frequency?


What causes the frequencies outside of the bandwidth to be unusable?


What is lessened by the Yagi-Uda design?


What characteristic of the conductor changes the amount of reactance?

Instead, it is often desired to have an antenna whose impedance does not vary so greatly over a certain bandwidth. It turns out that the amount of reactance seen at the terminals of a resonant antenna when the frequency is shifted, say, by 5%, depends very much on the diameter of the conductor used. A long thin wire used as a half-wave dipole (or quarter wave monopole) will have a reactance significantly greater than the resistive impedance it has at resonance, leading to a poor match and generally unacceptable performance. Making the element using a tube of a diameter perhaps 1/50 of its length, however, results in a reactance at this altered frequency which is not so great, and a much less serious mismatch which will only modestly damage the antenna's net performance. Thus rather thick tubes are typically used for the solid elements of such antennas, including Yagi-Uda arrays.


What characteristic would be better if it were steady?


What would be used to create a half wave or quarter wave dipole?


What type of tubes are generally used for sturdier always of antennas?


What effect do cages have on the spectrum of usable frequencies?

Rather than just using a thick tube, there are similar techniques used to the same effect such as replacing thin wire elements with cages to simulate a thicker element. This widens the bandwidth of the resonance. On the other hand, amateur radio antennas need to operate over several bands which are widely separated from each other. This can often be accomplished simply by connecting resonant elements for the different bands in parallel. Most of the transmitter's power will flow into the resonant element while the others present a high (reactive) impedance and draw little current from the same voltage. A popular solution uses so-called traps consisting of parallel resonant circuits which are strategically placed in breaks along each antenna element. When used at one particular frequency band the trap presents a very high impedance (parallel resonance) effectively truncating the element at that length, making it a proper resonant antenna. At a lower frequency the trap allows the full length of the element to be employed, albeit with a shifted resonant frequency due to the inclusion of the trap's net reactance at that lower frequency.


How could one achieve the task of creating an antenna that can be Used over various bands?


What is an essential for dealing with directing the flow of power?


What is an acknowledgement of the range of possible direction for and antenna?

Gain is a parameter which measures the degree of directivity of the antenna's radiation pattern. A high-gain antenna will radiate most of its power in a particular direction, while a low-gain antenna will radiate over a wider angle. The antenna gain, or power gain of an antenna is defined as the ratio of the intensity (power per unit surface area) radiated by the antenna in the direction of its maximum output, at an arbitrary distance, divided by the intensity radiated at the same distance by a hypothetical isotropic antenna which radiates equal power in all directions. This dimensionless ratio is usually expressed logarithmically in decibels, these units are called "decibels-isotropic" (dBi)


What is another way to refer to an antennas gain?


What type of an antenna would offer the same level of power to each possible destination?


Antennas with higher gain have what positive feature?

High-gain antennas have the advantage of longer range and better signal quality, but must be aimed carefully at the other antenna. An example of a high-gain antenna is a parabolic dish such as a satellite television antenna. Low-gain antennas have shorter range, but the orientation of the antenna is relatively unimportant. An example of a low-gain antenna is the whip antenna found on portable radios and cordless phones. Antenna gain should not be confused with amplifier gain, a separate parameter measuring the increase in signal power due to an amplifying device.


What is a measure of how much efficient is improved by adding a device designed to make something stronger?


Dish network Tv takes example of what type of antenna?


What type of antenna would be best if placement was tricky?


What must the relationship of an antenna and the receiving area be due to reciprocity?

Due to reciprocity (discussed above) the gain of an antenna used for transmitting must be proportional to its effective area when used for receiving. Consider an antenna with no loss, that is, one whose electrical efficiency is 100%. It can be shown that its effective area averaged over all directions must be equal to λ2/4π, the wavelength squared divided by 4π. Gain is defined such that the average gain over all directions for an antenna with 100% electrical efficiency is equal to 1. Therefore, the effective area Aeff in terms of the gain G in a given direction is given by:


what could an antenna with complete electrical efficiency be said to have?


hat could an antenna with complete electrical efficiency be said to have?


A plot of the radiation behaviors of an antenna would show what?

The radiation pattern of an antenna is a plot of the relative field strength of the radio waves emitted by the antenna at different angles. It is typically represented by a three-dimensional graph, or polar plots of the horizontal and vertical cross sections. The pattern of an ideal isotropic antenna, which radiates equally in all directions, would look like a sphere. Many nondirectional antennas, such as monopoles and dipoles, emit equal power in all horizontal directions, with the power dropping off at higher and lower angles; this is called an omnidirectional pattern and when plotted looks like a torus or donut.


What type of pictoral aid is often used to show this?


A sphere shows what type of antennas radiation?


Dipoles are considered to be what antenna type?


What would an omnidirectional antenna look like if plotted?


What is the term that refers to areas where an antennas radiation is zero?

The radiation of many antennas shows a pattern of maxima or "lobes" at various angles, separated by "nulls", angles where the radiation falls to zero. This is because the radio waves emitted by different parts of the antenna typically interfere, causing maxima at angles where the radio waves arrive at distant points in phase, and zero radiation at other angles where the radio waves arrive out of phase. In a directional antenna designed to project radio waves in a particular direction, the lobe in that direction is designed larger than the others and is called the "main lobe". The other lobes usually represent unwanted radiation and are called "sidelobes". The axis through the main lobe is called the "principal axis" or "boresight axis".


What do radio waves do that account for maxima or nulls in an antenna pattern?


If you desired to project radio waves to the south, what part of the antenna would you build larger in that direction?


What is the main distinction of side lobes?


What is one piece that makes up an antenna system?

As an electro-magnetic wave travels through the different parts of the antenna system (radio, feed line, antenna, free space) it may encounter differences in impedance (E/H, V/I, etc.). At each interface, depending on the impedance match, some fraction of the wave's energy will reflect back to the source, forming a standing wave in the feed line. The ratio of maximum power to minimum power in the wave can be measured and is called the standing wave ratio (SWR). A SWR of 1:1 is ideal. A SWR of 1.5:1 is considered to be marginally acceptable in low power applications where power loss is more critical, although an SWR as high as 6:1 may still be usable with the right equipment. Minimizing impedance differences at each interface (impedance matching) will reduce SWR and maximize power transfer through each part of the antenna system.


What is created by a portion of a radio waves energy reversing?


A term that refers to the highs and lows of power in electro magnetic waves is?


Impedance matching makes an important difference in what antenna function?


A measure of the power that is useable and the power absorbed by the terminals?

Efficiency of a transmitting antenna is the ratio of power actually radiated (in all directions) to the power absorbed by the antenna terminals. The power supplied to the antenna terminals which is not radiated is converted into heat. This is usually through loss resistance in the antenna's conductors, but can also be due to dielectric or magnetic core losses in antennas (or antenna systems) using such components. Such loss effectively robs power from the transmitter, requiring a stronger transmitter in order to transmit a signal of a given strength.


What happens to the power that is not absorbed by the antenna?


What would need to be placed into the transmitter to create ten W oh warmth?

For instance, if a transmitter delivers 100 W into an antenna having an efficiency of 80%, then the antenna will radiate 80 W as radio waves and produce 20 W of heat. In order to radiate 100 W of power, one would need to use a transmitter capable of supplying 125 W to the antenna. Note that antenna efficiency is a separate issue from impedance matching, which may also reduce the amount of power radiated using a given transmitter. If an SWR meter reads 150 W of incident power and 50 W of reflected power, that means that 100 W have actually been absorbed by the antenna (ignoring transmission line losses). How much of that power has actually been radiated cannot be directly determined through electrical measurements at (or before) the antenna terminals, but would require (for instance) careful measurement of field strength. Fortunately the loss resistance of antenna conductors such as aluminum rods can be calculated and the efficiency of an antenna using such materials predicted.


What would need to be investigated to determine how much power was radiated?


What factor may play a hand in lessened power from a transmitter?


What can increase the feedpoint impedance of a component?

However loss resistance will generally affect the feedpoint impedance, adding to its resistive (real) component. That resistance will consist of the sum of the radiation resistance Rr and the loss resistance Rloss. If an rms current I is delivered to the terminals of an antenna, then a power of I2Rr will be radiated and a power of I2Rloss will be lost as heat. Therefore, the efficiency of an antenna is equal to Rr / (Rr + Rloss). Of course only the total resistance Rr + Rloss can be directly measured.


The addition of Rr and Rloss equals what?


What equation an determine an antennas effectiveness?


What is the single factor that can be precisely measured?


What is the median level for measuring atmospheric noise?

According to reciprocity, the efficiency of an antenna used as a receiving antenna is identical to the efficiency as defined above. The power that an antenna will deliver to a receiver (with a proper impedance match) is reduced by the same amount. In some receiving applications, the very inefficient antennas may have little impact on performance. At low frequencies, for example, atmospheric or man-made noise can mask antenna inefficiency. For example, CCIR Rep. 258-3 indicates man-made noise in a residential setting at 40 MHz is about 28 dB above the thermal noise floor. Consequently, an antenna with a 20 dB loss (due to inefficiency) would have little impact on system noise performance. The loss within the antenna will affect the intended signal and the noise/interference identically, leading to no reduction in signal to noise ratio (SNR).


In what type of programs would low efficiency antennas not make a difference in effectiveness?


At lesser frequencies what can account for incorrect assumptions about efficiency?


The definition of antenna gain or power gain already includes the effect of the antenna's efficiency. Therefore, if one is trying to radiate a signal toward a receiver using a transmitter of a given power, one need only compare the gain of various antennas rather than considering the efficiency as well. This is likewise true for a receiving antenna at very high (especially microwave) frequencies, where the point is to receive a signal which is strong compared to the receiver's noise temperature. However, in the case of a directional antenna used for receiving signals with the intention of rejecting interference from different directions, one is no longer concerned with the antenna efficiency, as discussed above. In this case, rather than quoting the antenna gain, one would be more concerned with the directive gain which does not include the effect of antenna (in)efficiency. The directive gain of an antenna can be computed from the published gain divided by the antenna's efficiency.


What is used to signal toward a reciever?


Which gain does not iclude the effect of an antenna?


Wats divided by the antennas efficiency?


Small and minimal frequency antennas are know to be what?

This is fortunate, since antennas at lower frequencies which are not rather large (a good fraction of a wavelength in size) are inevitably inefficient (due to the small radiation resistance Rr of small antennas). Most AM broadcast radios (except for car radios) take advantage of this principle by including a small loop antenna for reception which has an extremely poor efficiency. Using such an inefficient antenna at this low frequency (530–1650 kHz) thus has little effect on the receiver's net performance, but simply requires greater amplification by the receiver's electronics. Contrast this tiny component to the massive and very tall towers used at AM broadcast stations for transmitting at the very same frequency, where every percentage point of reduced antenna efficiency entails a substantial cost.


What is added to to increase ability for reception?


How would this antenna rate in the greater scheme of things?


When talking about much larger network what effect can reduced antenna effectiveness have?


How many polarizations will a antenna have when mounted vertically?

The polarization of an antenna refers to the orientation of the electric field (E-plane) of the radio wave with respect to the Earth's surface and is determined by the physical structure of the antenna and by its orientation; note that this designation is totally distinct from the antenna's directionality. Thus, a simple straight wire antenna will have one polarization when mounted vertically, and a different polarization when mounted horizontally. As a transverse wave, the magnetic field of a radio wave is at right angles to that of the electric field, but by convention, talk of an antenna's "polarization" is understood to refer to the direction of the electric field.


What is another name for electric-field?


When is a magnetic fields right angles to a electrical field?


Whats understood in reference of direction of an E-plane?


Reflections generally affect polarization. For radio waves, one important reflector is the ionosphere which can change the wave's polarization. Thus for signals received following reflection by the ionosphere (a skywave), a consistent polarization cannot be expected. For line-of-sight communications or ground wave propagation, horizontally or vertically polarized transmissions generally remain in about the same polarization state at the receiving location. Matching the receiving antenna's polarization to that of the transmitter can make a very substantial difference in received signal strength.


What reflector can change the waves polarization?


What will you be matching with the receiving antenna's polarization?


What stays the same regarding polarization state at the recieving location?


What is the name used for signals recieved following reflection by the ionosphere?


Whats predictable about an antenna's geometry?

Polarization is predictable from an antenna's geometry, although in some cases it is not at all obvious (such as for the quad antenna). An antenna's linear polarization is generally along the direction (as viewed from the receiving location) of the antenna's currents when such a direction can be defined. For instance, a vertical whip antenna or Wi-Fi antenna vertically oriented will transmit and receive in the vertical polarization. Antennas with horizontal elements, such as most rooftop TV antennas in the United States, are horizontally polarized (broadcast TV in the U.S. usually uses horizontal polarization). Even when the antenna system has a vertical orientation, such as an array of horizontal dipole antennas, the polarization is in the horizontal direction corresponding to the current flow. The polarization of a commercial antenna is an essential specification.


The polarization of what antenna is essential specification?


Most rooftop antenna's are polarized in which direction?


What is a more complicated type of polarization from an antenna's geometry?


What are electrical fields projected on to?

Polarization is the sum of the E-plane orientations over time projected onto an imaginary plane perpendicular to the direction of motion of the radio wave. In the most general case, polarization is elliptical, meaning that the polarization of the radio waves varies over time. Two special cases are linear polarization (the ellipse collapses into a line) as we have discussed above, and circular polarization (in which the two axes of the ellipse are equal). In linear polarization the electric field of the radio wave oscillates back and forth along one direction; this can be affected by the mounting of the antenna but usually the desired direction is either horizontal or vertical polarization. In circular polarization, the electric field (and magnetic field) of the radio wave rotates at the radio frequency circularly around the axis of propagation. Circular or elliptically polarized radio waves are designated as right-handed or left-handed using the "thumb in the direction of the propagation" rule. Note that for circular polarization, optical researchers use the opposite right hand rule from the one used by radio engineers.


What is the imagenary plane perpindicular to?


What is the name to describe polarization of radio waves varies over times?


How many directions does the E-plane of the radio waves oscillates back and forth?


What is the best for an recieving antenna for optimum reception?

It is best for the receiving antenna to match the polarization of the transmitted wave for optimum reception. Intermediate matchings will lose some signal strength, but not as much as a complete mismatch. A circularly polarized antenna can be used to equally well match vertical or horizontal linear polarizations. Transmission from a circularly polarized antenna received by a linearly polarized antenna (or vice versa) entails a 3 dB reduction in signal-to-noise ratio as the received power has thereby been cut in half.


What is used to match vertical and horizontal linear polarizations?


A transmission can cause reduction in what?


What requires matching of the empedance to an antenna system?

Maximum power transfer requires matching the impedance of an antenna system (as seen looking into the transmission line) to the complex conjugate of the impedance of the receiver or transmitter. In the case of a transmitter, however, the desired matching impedance might not correspond to the dynamic output impedance of the transmitter as analyzed as a source impedance but rather the design value (typically 50 ohms) required for efficient and safe operation of the transmitting circuitry. The intended impedance is normally resistive but a transmitter (and some receivers) may have additional adjustments to cancel a certain amount of reactance in order to "tweak" the match. When a transmission line is used in between the antenna and the transmitter (or receiver) one generally would like an antenna system whose impedance is resistive and near the characteristic impedance of that transmission line in order to minimize the standing wave ratio (SWR) and the increase in transmission line losses it entails, in addition to supplying a good match at the transmitter or receiver itself.


Why would a transmitter have additional adjustments?


What is the desired design value for transmmiting circuitry?


What can be shorter than 1/4 wavelength long?

In some cases this is done in a more extreme manner, not simply to cancel a small amount of residual reactance, but to resonate an antenna whose resonance frequency is quite different from the intended frequency of operation. For instance, a "whip antenna" can be made significantly shorter than 1/4 wavelength long, for practical reasons, and then resonated using a so-called loading coil. This physically large inductor at the base of the antenna has an inductive reactance which is the opposite of the capacitative reactance that such a vertical antenna has at the desired operating frequency. The result is a pure resistance seen at feedpoint of the loading coil; unfortunately that resistance is somewhat lower than would be desired to match commercial coax.[citation needed]


What is the opposite of inductive reactance?


Where is the resistance seen on the loading foil?


What is not adjustable when it comes to a transformer?

So an additional problem beyond canceling the unwanted reactance is of matching the remaining resistive impedance to the characteristic impedance of the transmission line. In principle this can always be done with a transformer, however the turns ratio of a transformer is not adjustable. A general matching network with at least two adjustments can be made to correct both components of impedance. Matching networks using discrete inductors and capacitors will have losses associated with those components, and will have power restrictions when used for transmitting. Avoiding these difficulties, commercial antennas are generally designed with fixed matching elements or feeding strategies to get an approximate match to standard coax, such as 50 or 75 Ohms. Antennas based on the dipole (rather than vertical antennas) should include a balun in between the transmission line and antenna element, which may be integrated into any such matching network.


How many ohms are in are in a standard coax?


A general matching network needs a minimum of how many adjustments to correct all components of impedance?


What is included between the transmission line and the antenna element?


Unlike the above antennas, traveling wave antennas are nonresonant so they have inherently broad bandwidth. They are typically wire antennas multiple wavelengths long, through which the voltage and current waves travel in one direction, instead of bouncing back and forth to form standing waves as in resonant antennas. They have linear polarization (except for the helical antenna). Unidirectional traveling wave antennas are terminated by a resistor at one end equal to the antenna's characteristic resistance, to absorb the waves from one direction. This makes them inefficient as transmitting antennas.


How long are the wire antenna's that the voltage and current waves travel in the same direction?


What are undirectional traveling wave directions terminated by?


What antenna does not have linear polarization?


What is the radiation patter influenced by?

The radiation pattern and even the driving point impedance of an antenna can be influenced by the dielectric constant and especially conductivity of nearby objects. For a terrestrial antenna, the ground is usually one such object of importance. The antenna's height above the ground, as well as the electrical properties (permittivity and conductivity) of the ground, can then be important. Also, in the particular case of a monopole antenna, the ground (or an artificial ground plane) serves as the return connection for the antenna current thus having an additional effect, particularly on the impedance seen by the feed line.


The ground is important for what antenna?


What does the artificial ground plane do for the antenna current?


What is the net quality of the ground dependent of?

The net quality of a ground reflection depends on the topography of the surface. When the irregularities of the surface are much smaller than the wavelength, we are in the regime of specular reflection, and the receiver sees both the real antenna and an image of the antenna under the ground due to reflection. But if the ground has irregularities not small compared to the wavelength, reflections will not be coherent but shifted by random phases. With shorter wavelengths (higher frequencies), this is generally the case.


What is the reason for the receiver seeing both the ral antenna and image of the antenna?


What frequencies is associated with shorter wavelengths?


What is the refractive index of the ground?

The phase of reflection of electromagnetic waves depends on the polarization of the incident wave. Given the larger refractive index of the ground (typically n=2) compared to air (n=1), the phase of horizontally polarized radiation is reversed upon reflection (a phase shift of radians or 180°). On the other hand, the vertical component of the wave's electric field is reflected at grazing angles of incidence approximately in phase. These phase shifts apply as well to a ground modelled as a good electrical conductor.


Besides a ground, what has these phases apply well to?


When an electromagnetic wave strikes a plane surface such as the ground, part of the wave is transmitted into the ground and part of it is reflected, according to the Fresnel coefficients. If the ground is a very good conductor then almost all of the wave is reflected (180° out of phase), whereas a ground modeled as a (lossy) dielectric can absorb a large amount of the wave's power. The power remaining in the reflected wave, and the phase shift upon reflection, strongly depend on the wave's angle of incidence and polarization. The dielectric constant and conductivity (or simply the complex dielectric constant) is dependent on the soil type and is a function of frequency.


Is the ground has a great conductor, how much of the wave will be reflected?


what is reflected and transmitted into the ground when a plane surface is struck?


What depends on the polarization and waves angle?


What is the portion of something that is reached by the radio transmission called?

The effective area or effective aperture of a receiving antenna expresses the portion of the power of a passing electromagnetic wave which it delivers to its terminals, expressed in terms of an equivalent area. For instance, if a radio wave passing a given location has a flux of 1 pW / m2 (10−12 watts per square meter) and an antenna has an effective area of 12 m2, then the antenna would deliver 12 pW of RF power to the receiver (30 microvolts rms at 75 ohms). Since the receiving antenna is not equally sensitive to signals received from all directions, the effective area is a function of the direction to the source.


What effects the function of signals received by an antenna?


What is a measure of the power of an antenna?


How much power will be delivered to the reciever if the antenna has an effective area of 12 m/2?


The properties of a usable radio frequency can be called its?

The bandwidth characteristics of a resonant antenna element can be characterized according to its Q, just as one uses to characterize the sharpness of an L-C resonant circuit. However it is often assumed that there is an advantage in an antenna having a high Q. After all, Q is short for "quality factor" and a low Q typically signifies excessive loss (due to unwanted resistance) in a resonant L-C circuit. However this understanding does not apply to resonant antennas where the resistance involved is the radiation resistance, a desired quantity which removes energy from the resonant element in order to radiate it (the purpose of an antenna, after all!). The Q is a measure of the ratio of reactance to resistance, so with a fixed radiation resistance (an element's radiation resistance is almost independent of its diameter) a greater reactance off-resonance corresponds to the poorer bandwidth of a very thin conductor. The Q of such a narrowband antenna can be as high as 15. On the other hand, a thick element presents less reactance at an off-resonant frequency, and consequently a Q as low as 5. These two antennas will perform equivalently at the resonant frequency, but the second antenna will perform over a bandwidth 3 times as wide as the "hi-Q" antenna consisting of a thin conductor.


What is a measure of the comparison between reactance and resistance?


What is the largest Q that could be achieved with a slimmer band antenna?


What type of element would be used to encounter less reactance?


What can be added to allow for an antenna shorter than the needed height to produce desired results?

For example, at 30 MHz (10 m wavelength) a true resonant 1⁄4-wavelength monopole would be almost 2.5 meters long, and using an antenna only 1.5 meters tall would require the addition of a loading coil. Then it may be said that the coil has lengthened the antenna to achieve an electrical length of 2.5 meters. However, the resulting resistive impedance achieved will be quite a bit lower than the impedance of a resonant monopole, likely requiring further impedance matching. In addition to a lower radiation resistance, the reactance becomes higher as the antenna size is reduced, and the resonant circuit formed by the antenna and the tuning coil has a Q factor that rises and eventually causes the bandwidth of the antenna to be inadequate for the signal being transmitted. This is the major factor that sets the size of antennas at 1 MHz and lower frequencies.


How would the resistive impedance from this scenario compare to if the antenna was the proper height?


The coil has lengthed the antenna to reach how much length electrically?


What is the major thing that sets the size of antennas at lower frequencies?


How big would an antenna be used to with with one m wavelengths?

Consider a half-wave dipole designed to work with signals 1 m wavelength, meaning the antenna would be approximately 50 cm across. If the element has a length-to-diameter ratio of 1000, it will have an inherent resistance of about 63 ohms. Using the appropriate transmission wire or balun, we match that resistance to ensure minimum signal loss. Feeding that antenna with a current of 1 ampere will require 63 volts of RF, and the antenna will radiate 63 watts (ignoring losses) of radio frequency power. Now consider the case when the antenna is fed a signal with a wavelength of 1.25 m; in this case the reflected current would arrive at the feed out-of-phase with the signal, causing the net current to drop while the voltage remains the same. Electrically this appears to be a very high impedance. The antenna and transmission line no longer have the same impedance, and the signal will be reflected back into the antenna, reducing output. This could be addressed by changing the matching system between the antenna and transmission line, but that solution only works well at the new design frequency.


How could the rection of output be adressed by?


What effect occurs when the signal is reflected back into the antenna?


What sort of changes in material would a current reflect?

Recall that a current will reflect when there are changes in the electrical properties of the material. In order to efficiently send the signal into the transmission line, it is important that the transmission line has the same impedance as the elements, otherwise some of the signal will be reflected back into the antenna. This leads to the concept of impedance matching, the design of the overall system of antenna and transmission line so the impedance is as close as possible, thereby reducing these losses. Impedance matching between antennas and transmission lines is commonly handled through the use of a balun, although other solutions are also used in certain roles. An important measure of this basic concept is the standing wave ratio, which measures the magnitude of the reflected signal.


What must match between the transmission line and elements?


What technique is used to prevent unintentional decrease in signal?


How is this process usually used for transmission lines and antennas?


What is used to allow one to control the function of wave fronts moving through an antenna?

An electromagnetic wave refractor in some aperture antennas is a component which due to its shape and position functions to selectively delay or advance portions of the electromagnetic wavefront passing through it. The refractor alters the spatial characteristics of the wave on one side relative to the other side. It can, for instance, bring the wave to a focus or alter the wave front in other ways, generally in order to maximize the directivity of the antenna system. This is the radio equivalent of an optical lens.


What changes the structuak traits of a wave on either side?


What is the main purpose of a refractor?


A refractor can be compared to what type of viewing?