Why do VHF signal strengths sometimes vary greatly when the antenna is moved only a few feet?
CMultipath propagation cancels or reinforces signals
technician pool
Subelement T3 question review
All 35 official questions with the exact winning phrase marked.
How does vegetation affect UHF and microwave signals?
BAbsorbs signals, leading to poor reception of weak signals
What antenna polarization is normally used for long-distance CW and SSB contacts on the VHF and UHF bands?
CHorizontal
What is the effect of antenna cross-polarization over a line-of-sight VHF or UHF path?
BReceived signal strength is reduced
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?
BTry to find a path that reflects signals to the repeater
What is the meaning of the term “picket fencing”?
BRapid flutter on mobile signals due to multipath propagation
What weather condition might decrease range at microwave frequencies?
CPrecipitation
What is a likely cause of irregular fading of signals propagated by the ionosphere?
DRandom combining of signals arriving via different paths
Which of the following results from the fact that signals propagated by the ionosphere are elliptically polarized?
BEither vertically or horizontally polarized antennas may be used for transmission or reception
What effect does multi-path propagation have on data transmissions?
DError rates are likely to increase
Which region of the atmosphere can reflect HF radio waves?
CThe ionosphere
What effect does fog or rain have on 10-meter and 6-meter band signals?
BLittle effect
What is the relationship between the electric and magnetic fields of an electromagnetic wave?
DThey are at right angles
What property of a radio wave defines its polarization?
AThe orientation of the electric field
What are the two components of a radio wave?
CElectric and magnetic fields
What is the velocity of a radio wave traveling through free space?
ASpeed of light
What is the relationship between wavelength and frequency?
BWavelength gets shorter as frequency increases
What is the formula for converting frequency to approximate wavelength in meters?
DWavelength in meters equals 300 divided by frequency in megahertz
In addition to frequency, which of the following is used to identify amateur radio bands?
AThe approximate wavelength in meters
What frequency range is referred to as VHF?
B30 MHz to 300 MHz
What frequency range is referred to as UHF?
D300 to 3000 MHz
What frequency range is referred to as HF?
C3 to 30 MHz
What is the approximate velocity of a radio wave in free space?
B300,000,000 meters per second
Which of these frequencies travels at the highest velocity in free space?
DAll radio frequencies travel at the same velocity
Why are simplex UHF signals rarely heard beyond their radio horizon?
CUHF signals are usually not propagated by the ionosphere
What is a characteristic of HF communication compared with communications on VHF and higher frequencies?
CLong-distance ionospheric propagation is far more common on HF
What is one characteristic of VHF signals received via auroral backscatter?
BThey are distorted, with a characteristic raspy sound
Which of the following types of propagation is most commonly associated with occasional strong signals on the 10-, 6-, and 2-meter bands from beyond the radio horizon?
BSporadic E
Which of the following effects may allow radio signals to travel beyond obstructions between the transmitting and receiving stations?
AKnife-edge diffraction
What type of propagation is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis?
ATropospheric ducting
What band is best suited for communicating via meteor scatter?
B6 meters
What causes tropospheric ducting?
DTemperature inversions in the atmosphere
What is generally the best time for long-distance 10-meter band propagation via the F region?
AFrom dawn to shortly after sunset during periods of high sunspot activity
Which of the following bands may provide long-distance communications via the ionosphere’s F region during the peak of the sunspot cycle?
A6 and 10 meters
Why is the radio horizon for VHF and UHF signals more distant than the visual horizon?
CThe atmosphere refracts radio waves slightly