Why do VHF signal strengths sometimes vary greatly when the antenna is moved only a few feet?

1. A The signal path encounters different concentrations of water vapor
2. B VHF ionospheric propagation is very sensitive to path length
3. C Multipath propagation cancels or reinforces signals
4. D The Doppler effect causes slight frequency shifts which result in changes in signal strength

How does vegetation affect UHF and microwave signals?

1. A Causes knife-edge diffraction, distorting voice peaks
2. B Absorbs signals, leading to poor reception of weak signals
3. C Amplifies signals, improving reception of weak signals
4. D Has no effect

What antenna polarization is normally used for long-distance CW and SSB contacts on the VHF and UHF bands?

1. A Right-hand circular
2. B Left-hand circular
3. C Horizontal
4. D Vertical

What is the effect of antenna cross-polarization over a line-of-sight VHF or UHF path?

1. A Modulation sidebands might become inverted
2. B Received signal strength is reduced
3. C Signals have an echo effect
4. D Nothing significant will happen

When 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?

1. A Change from vertical to horizontal polarization
2. B Try to find a path that reflects signals to the repeater
3. C Try the long path
4. D Increase the antenna SWR

What is the meaning of the term "picket fencing"?

1. A Alternating transmissions during a net operation
2. B Rapid flutter on mobile signals due to multipath propagation
3. C A type of ground system used with vertical antennas
4. D Interference from cable TV in the form of carriers at fixed intervals across the band

What weather condition might decrease range at microwave frequencies?

1. A High winds
2. B Low barometric pressure
3. C Precipitation
4. D Colder temperatures

What is a likely cause of irregular fading of signals propagated by the ionosphere?

1. A Frequency shift due to Faraday rotation
2. B Interference from thunderstorms
3. C Intermodulation distortion
4. D Random combining of signals arriving via different paths

Which of the following results from the fact that signals propagated by the ionosphere are elliptically polarized?

1. A Digital modes are unusable
2. B Either vertically or horizontally polarized antennas may be used for transmission or reception
3. C FM voice is unusable
4. D Both the transmitting and receiving antennas must be of the same polarization

What effect does multi-path propagation have on data transmissions?

1. A Transmission rates must be increased by a factor equal to the number of separate paths observed
2. B Transmission rates must be decreased by a factor equal to the number of separate paths observed
3. C No significant changes will occur if the signals are transmitted using FM
4. D Error rates are likely to increase

Which region of the atmosphere can reflect HF radio waves?

1. A The stratosphere
2. B The troposphere
3. C The ionosphere
4. D The electrosphere

What effect does fog or rain have on 10-meter and 6-meter band signals?

1. A Absorption
2. B Little effect
3. C Deflection
4. D Increased range