81 lines
3.4 KiB
Markdown
81 lines
3.4 KiB
Markdown
G9D – Specialized antenna types and applications
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- [[G9D01]] (A)
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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? #card
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- A. A horizontal dipole placed between 1/10 and 1/4 wavelength above the ground
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- B. A vertical antenna placed between 1/4 and 1/2 wavelength above the ground
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- C. A horizontal dipole placed at approximately 1/2 wavelength above the ground
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- D. A vertical dipole placed at approximately 1/2 wavelength above the ground
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- [[G9D02]] (D)
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What is the feed point impedance of an end-fed half-wave antenna? #card
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- A. Very low
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- B. Approximately 50 ohms
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- C. Approximately 300 ohms
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- D. Very high
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- [[G9D03]] (C)
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In which direction is the maximum radiation from a VHF/UHF “halo” antenna? #card
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- A. Broadside to the plane of the halo
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- B. Opposite the feed point
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- C. Omnidirectional in the plane of the halo
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- D. On the same side as the feed point
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- [[G9D04]] (A)
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What is the primary function of antenna traps? #card
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- A. To enable multiband operation
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- B. To notch spurious frequencies
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- C. To provide balanced feed point impedance
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- D. To prevent out-of-band operation
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- [[G9D05]] (D)
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What is an advantage of vertically stacking horizontally polarized Yagi antennas? #card
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- A. It allows quick selection of vertical or horizontal polarization
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- B. It allows simultaneous vertical and horizontal polarization
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- C. It narrows the main lobe in azimuth
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- D. It narrows the main lobe in elevation
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- [[G9D06]] (A)
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Which of the following is an advantage of a log-periodic antenna? #card
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- A. Wide bandwidth
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- B. Higher gain per element than a Yagi antenna
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- C. Harmonic suppression
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- D. Polarization diversity
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- [[G9D07]] (A)
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Which of the following describes a log-periodic antenna? #card
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- A. Element length and spacing vary logarithmically along the boom
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- B. Impedance varies periodically as a function of frequency
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- C. Gain varies logarithmically as a function of frequency
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- D. SWR varies periodically as a function of boom length
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- [[G9D08]] (B)
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How does a “screwdriver” mobile antenna adjust its feed point impedance? #card
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- A. By varying its body capacitance
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- B. By varying the base loading inductance
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- C. By extending and retracting the whip
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- D. By deploying a capacitance hat
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- [[G9D09]] (A)
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What is the primary use of a Beverage antenna? #card
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- A. Directional receiving for MF and low HF bands
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- B. Directional transmitting for low HF bands
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- C. Portable direction finding at higher HF frequencies
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- D. Portable direction finding at lower HF frequencies
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- [[G9D10]] (B)
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In which direction or directions does an electrically small loop (less than 1/10 wavelength in circumference) have nulls in its radiation pattern? #card
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- A. In the plane of the loop
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- B. Broadside to the loop
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- C. Broadside and in the plane of the loop
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- D. Electrically small loops are omnidirectional
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- [[G9D11]] (D)
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Which of the following is a disadvantage of multiband antennas? #card
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- A. They present low impedance on all design frequencies
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- B. They must be used with an antenna tuner
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- C. They must be fed with open wire line
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- D. They have poor harmonic rejection
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- [[G9D12]] (A)
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What is the common name of a dipole with a single central support? #card
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- A. Inverted V
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- B. Inverted L
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- C. Sloper
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- D. Lazy H
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- [[G9D13]] Question Removed (section not renumbered)
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SUBELEMENT G0 – ELECTRICAL AND RF SAFETY [2 Exam Questions – 2 Groups]
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