FCCライセンス 6月 1 2024 SUBELEMENT T3A SUBELEMENT T3A T3A - Radio wave characteristics: how a radio signal travels, fading, multipath, polarization, wavelength vs absorption; Antenna orientation 1 / 12 T3A12What is the effect of fog and rain on signals in the 10 meter and 6 meter bands? A. Absorption B. There is little effect C. Deflection D. Range increase 2 / 12 T3A11Which region of the atmosphere can refract or bend HF and VHF radio waves? A. The stratosphere B. The troposphere C. The ionosphere D. The mesosphere 3 / 12 T3A10What effect does multi-path propagation have on data transmissions? A. Transmission rates must be increased by a factor equal to the number of separate paths observed B. Transmission rates must be decreased by a factor equal to the number of separate paths observed C. No significant changes will occur if the signals are transmitted using FM D. Error rates are likely to increase 4 / 12 T3A09Which of the following results from the fact that signals propagated by the ionosphere are elliptically polarized? A. Digital modes are unusable B. Either vertically or horizontally polarized antennas may be used for transmission or reception C. FM voice is unusable D. Both the transmitting and receiving antennas must be of the same polarization 5 / 12 T3A08What is a likely cause of irregular fading of signals propagated by the ionosphere? A. Frequency shift due to Faraday rotation B. Interference from thunderstorms C. Intermodulation distortion D. Random combining of signals arriving via different paths 6 / 12 T3A07What weather condition might decrease range at microwave frequencies? A. High winds B. Low barometric pressure C. Precipitation D. Colder temperatures 7 / 12 T3A06What is the meaning of the term “picket fencing”? A. Alternating transmissions during a net operation B. Rapid flutter on mobile signals due to multipath propagation C. A type of ground system used with vertical antennas D. Local vs long-distance communications 8 / 12 T3A05When using a directional antenna, how might your station be able to communicate with a distant repeater if buildings or obstructions are blocking the direct line of sight path? A. Change from vertical to horizontal polarization B. Try to find a path that reflects signals to the repeater C. Try the long path D. Increase the antenna SWR 9 / 12 T3A04What happens when antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization? A. The modulation sidebands might become inverted B. Received signal strength is reduced C. Signals have an echo effect D. Nothing significant will happen 10 / 12 T3A03What antenna polarization is normally used for long-distance CW and SSB contacts on the VHF and UHF bands? A. Right-hand circular B. Left-hand circular C. Horizontal D. Vertical 11 / 12 T3A02What is the effect of vegetation on UHF and microwave signals? A. Knife-edge diffraction B. Absorption C. Amplification D. Polarization rotation 12 / 12 T3A01Why do VHF signal strengths sometimes vary greatly when the antenna is moved only a few feet? A. The signal path encounters different concentrations of water vapor B. VHF ionospheric propagation is very sensitive to path length C. Multipath propagation cancels or reinforces signals D. All these choices are correct Your score isThe average score is 25% 0% Restart quiz Ed 0 コメント
