Article: 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.

Question: What has vertical polarization?
Ans: Monopoles


Article: Starting in mid-June 1944, Iwo Jima came under sustained aerial bombardment and naval artillery fire. However, Kuribayashi's hidden guns and defenses survived the constant bombardment virtually unscathed. On 19 February 1945, some 30,000 men of the 3rd, 4th, and 5th Marine Divisions landed on the southeast coast of Iwo, just under Mount Suribachi; where most of the island's defenses were concentrated. For some time, they did not come under fire. This was part of Kuribayashi's plan to hold fire until the landing beaches were full. As soon as the Marines pushed inland to a line of enemy bunkers, they came under devastating machine gun and artillery fire which cut down many of the men. By the end of the day, the Marines reached the west coast of the island, but their losses were appalling; almost 2,000 men killed or wounded.

Question: What was the name of the mountain on Iwo Jima?
Ans: Mount Suribachi


Article: Urban AC is a form of AC music geared towards adult African-American audiences, and therefore, the artists that are played on these stations are most often black, such as Des'ree, whose album I Ain't Movin' was massively popular amongst both African American audience as well as the wider national audience.

Question: What is the ethnicity of artists commonly played on urban adult contemporary radio?
Ans: black


Article: Current circulating in one antenna generally induces a voltage across the feedpoint of nearby antennas or antenna elements. The mathematics presented below are useful in analyzing the electrical behaviour of antenna arrays, where the properties of the individual array elements (such as half wave dipoles) are already known. If those elements were widely separated and driven in a certain amplitude and phase, then each would act independently as that element is known to. However, because of the mutual interaction between their electric and magnetic fields due to proximity, the currents in each element are not simply a function of the applied voltage (according to its driving point impedance), but depend on the currents in the other nearby elements. Note that this now is a near field phenomenon which could not be properly accounted for using the Friis transmission equation for instance.

Question: What cause mutual interactions between the elements electric and magnetic fields?
Ans:
proximity