T3A - Radio wave characteristics: how a radio signal travels, fading, multipath, polarization, wavelength vs absorption; Antenna orientation 

- [[T3A01]] (C)
Why do VHF signal strengths sometimes vary greatly when the antenna is moved only a few feet? #card
	- 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

- [[T3A02]] (B)
What is the effect of vegetation on UHF and microwave signals? #card
	- A. Knife-edge diffraction
	- B. Absorption
	- C. Amplification
	- D. Polarization rotation

- [[T3A03]] (C)
What antenna polarization is normally used for long-distance CW and SSB contacts on the VHF and UHF bands? #card
	- A. Right-hand circular
	- B. Left-hand circular
	- C. Horizontal
	- D. Vertical

- [[T3A04]] (B)
What happens when antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization? #card
	- A. The modulation sidebands might become inverted
	- B. Received signal strength is reduced
	- C. Signals have an echo effect
	- D. Nothing significant will happen

- [[T3A05]] (B)
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? #card
	- 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

- [[T3A06]] (B)
What is the meaning of the term “picket fencing”? #card
	- 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

- [[T3A07]] (C)
What weather condition might decrease range at microwave frequencies? #card
	- A. High winds
	- B. Low barometric pressure
	- C. Precipitation 
	- D. Colder temperatures

- [[T3A08]] (D)
What is a likely cause of irregular fading of signals propagated by the ionosphere? #card
	- A. Frequency shift due to Faraday rotation
	- B. Interference from thunderstorms
	- C. Intermodulation distortion 
	- D. Random combining of signals arriving via different paths 

- [[T3A09]] (B)
Which of the following results from the fact that signals propagated by the ionosphere are elliptically polarized? #card
	- 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

- [[T3A10]] (D)
What effect does multi-path propagation have on data transmissions? #card
	- 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

- [[T3A11]] (C)
Which region of the atmosphere can refract or bend HF and VHF radio waves? #card
	- A. The stratosphere
	- B. The troposphere
	- C. The ionosphere
	- D. The mesosphere

- [[T3A12]] (B)
What is the effect of fog and rain on signals in the 10 meter and 6 meter bands? #card
	- A. Absorption
	- B. There is little effect
	- C. Deflection
	- D. Range increase