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: Defensive Counterair (DCA) is defined as "all the defensive measures designed to detect, identify, intercept, and destroy or negate enemy forces attempting to penetrate or attack through friendly airspace" (JP 1-02). A major goal of DCA operations, in concert with OCA operations, is to provide an area from which forces can operate, secure from air and missile threats. The DCA mission comprises both active and passive defense measures. Active defense is "the employment of limited offensive action and counterattacks to deny a contested area or position to the enemy" (JP 1-02). It includes both ballistic missile defense and air breathing threat defense, and encompasses point defense, area defense, and high value airborne asset defense. Passive defense is "measures taken to reduce the probability of and to minimize the effects of damage caused by hostile action without the intention of taking the initiative" (JP 1-02). It includes detection and warning; chemical, biological, radiological, and nuclear defense; camouflage, concealment, and deception; hardening; reconstitution; dispersion; redundancy; and mobility, counter-measures, and stealth.

Question: What does the abbreviation DCA stand for? 
Ans: Defensive Counterair


Article: Due to recording mastering and manufacturing limitations, both high and low frequencies were removed from the first recorded signals by various formulae. With low frequencies, the stylus must swing a long way from side to side, requiring the groove to be wide, taking up more space and limiting the playing time of the record. At high frequencies, hiss, pops, and ticks are significant. These problems can be reduced by using equalization to an agreed standard. During recording the amplitude of low frequencies is reduced, thus reducing the groove width required, and the amplitude at high frequencies is increased. The playback equipment boosts bass and cuts treble so as to restore the tonal balance in the original signal; this also reduces the high frequency noise. Thus more music will fit on the record, and noise is reduced.

Question: What kinds of unwanted sounds are often heard at high frequencies?
Ans: hiss, pops, and ticks


Article: According to CIA World Factbook, the people of Republic of the Congo are largely a mix of Catholics (33.1%), Awakening Lutherans (22.3%) and other Protestants (19.9%). Followers of Islam make up 1.6%, and this is primarily due to an influx of foreign workers into the urban centers.

Question: What portion of the Congolese population is Protestant?
Ans:
19.9%