Which of the following factors determine the characteristic impedance of a parallel conductor feed line?
AThe distance between the centers of the conductors and the radius of the conductors
general pool
Subelement G9 question review
All 46 official questions with the exact winning phrase marked.
What is the relationship between high standing wave ratio (SWR) and transmission line loss?
BHigh SWR increases loss in a lossy transmission line
What is the nominal characteristic impedance of “window line” transmission line?
D450 ohms
What causes reflected power at an antenna’s feed point?
CA difference between feed line impedance and antenna feed point impedance
How does the attenuation of coaxial cable change with increasing frequency?
BAttenuation increases
In what units is RF feed line loss usually expressed?
DDecibels per 100 feet
What must be done to prevent standing waves on a feed line connected to an antenna?
DThe antenna feed point impedance must be matched to the characteristic impedance of the feed line
If the SWR on an antenna feed line is 5:1, and a matching network at the transmitter end of the feed line is adjusted to present a 1:1 SWR to the transmitter, what is the resulting SWR on the feed line?
B5:1
What standing wave ratio results from connecting a 50-ohm feed line to a 200-ohm resistive load?
A4:1
What standing wave ratio results from connecting a 50-ohm feed line to a 10-ohm resistive load?
D5:1
What is the effect of transmission line loss on SWR measured at the input to the line?
AHigher loss reduces SWR measured at the input to the line
What is a characteristic of a random-wire HF antenna connected directly to the transmitter?
BStation equipment may carry significant RF current
Which of the following is a common way to adjust the feed point impedance of an elevated quarter-wave ground-plane vertical antenna to be approximately 50 ohms?
BSlope the radials downward
Which of the following best describes the radiation pattern of a quarter-wave ground-plane vertical antenna?
DOmnidirectional in azimuth
What is the radiation pattern of a dipole antenna in free space in a plane containing the conductor?
AIt is a figure-eight at right angles to the antenna
How does antenna height affect the azimuthal radiation pattern of a horizontal dipole HF antenna at elevation angles higher than about 45 degrees?
CIf the antenna is less than 1/2 wavelength high, the azimuthal pattern is almost omnidirectional
Where should the radial wires of a ground-mounted vertical antenna system be placed?
COn the surface or buried a few inches below the ground
How does the feed point impedance of a horizontal 1/2 wave dipole antenna change as the antenna height is reduced to 1/10 wavelength above ground?
BIt steadily decreases
How does the feed point impedance of a 1/2 wave dipole change as the feed point is moved from the center toward the ends?
AIt steadily increases
Which of the following is an advantage of using a horizontally polarized as compared to a vertically polarized HF antenna?
ALower ground losses
What is the approximate length for a 1/2 wave dipole antenna cut for 14.250 MHz?
D33 feet
What is the approximate length for a 1/2 wave dipole antenna cut for 3.550 MHz?
C132 feet
What is the approximate length for a 1/4 wave monopole antenna cut for 28.5 MHz?
A8 feet
Which of the following would increase the bandwidth of a Yagi antenna?
ALarger-diameter elements
What is the approximate length of the driven element of a Yagi antenna?
B1/2 wavelength
How do the lengths of a three-element Yagi reflector and director compare to that of the driven element?
AThe reflector is longer, and the director is shorter
How does antenna gain in dBi compare to gain stated in dBd for the same antenna?
BGain in dBi is 2.15 dB higher
What is the primary effect of increasing boom length and adding directors to a Yagi antenna?
AGain increases
What does “front-to-back ratio” mean in reference to a Yagi antenna?
CThe power radiated in the major lobe compared to that in the opposite direction
What is meant by the “main lobe” of a directive antenna?
DThe direction of maximum radiated field strength from the antenna
In free space, how does the gain of two three-element, horizontally polarized Yagi antennas spaced vertically 1/2 wavelength apart typically compare to the gain of a single three-element Yagi?
BApproximately 3 dB higher
Which of the following can be adjusted to optimize forward gain, front-to-back ratio, or SWR bandwidth of a Yagi antenna?
DAll these choices are correct
What is a beta or hairpin match?
AA shorted transmission line stub placed at the feed point of a Yagi antenna to provide impedance matching
Which of the following is a characteristic of using a gamma match with a Yagi antenna?
AIt does not require the driven element to be insulated from the boom
Which of the following antenna types will be most effective as a near vertical incidence skywave (NVIS) antenna for short-skip communications on 40 meters during the day?
AA horizontal dipole placed between 1/10 and 1/4 wavelength above the ground
What is the feed point impedance of an end-fed half-wave antenna?
DVery high
In which direction is the maximum radiation from a VHF/UHF “halo” antenna?
COmnidirectional in the plane of the halo
What is the primary function of antenna traps?
ATo enable multiband operation
What is an advantage of vertically stacking horizontally polarized Yagi antennas?
DIt narrows the main lobe in elevation
Which of the following is an advantage of a log-periodic antenna?
AWide bandwidth
Which of the following describes a log-periodic antenna?
AElement length and spacing vary logarithmically along the boom
How does a “screwdriver” mobile antenna adjust its feed point impedance?
BBy varying the base loading inductance
What is the primary use of a Beverage antenna?
ADirectional receiving for MF and low HF bands
In which direction or directions does an electrically small loop (less than 1/10 wavelength in circumference) have nulls in its radiation pattern?
BBroadside to the loop
Which of the following is a disadvantage of multiband antennas?
DThey have poor harmonic rejection
What is the common name of a dipole with a single central support?
AInverted V