3.5 KiB
3.5 KiB
T9A – Antennas: vertical and horizontal polarization, concept of antenna gain, definition and types of beam antennas, antenna loading, common portable and mobile antennas, relationships between resonant length and frequency, dipole pattern
- T9A01 (C)
What is a beam antenna? #card
- A. An antenna built from aluminum I-beams
- B. An omnidirectional antenna invented by Clarence Beam
- C. An antenna that concentrates signals in one direction
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D. An antenna that reverses the phase of received signals
- T9A02 (A)
Which of the following describes a type of antenna loading? #card
- A. Electrically lengthening by inserting inductors in radiating elements
- B. Inserting a resistor in the radiating portion of the antenna to make it resonant
- C. Installing a spring in the base of a mobile vertical antenna to make it more flexible
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D. Strengthening the radiating elements of a beam antenna to better resist wind damage
- T9A03 (B)
Which of the following describes a simple dipole oriented parallel to Earth's surface? #card
- A. A ground-wave antenna
- B. A horizontally polarized antenna
- C. A travelling-wave antenna
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D. A vertically polarized antenna
- T9A04 (A)
What is a disadvantage of the short, flexible antenna supplied with most handheld radio transceivers, compared to a full-sized quarter-wave antenna? #card
- A. It has low efficiency
- B. It transmits only circularly polarized signals
- C. It is mechanically fragile
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D. All these choices are correct
- T9A05 (C)
Which of the following increases the resonant frequency of a dipole antenna? #card
- A. Lengthening it
- B. Inserting coils in series with radiating wires
- C. Shortening it
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D. Adding capacitive loading to the ends of the radiating wires
- T9A06 (D)
Which of the following types of antenna offers the greatest gain? #card
- A. 5/8 wave vertical
- B. Isotropic
- C. J pole
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D. Yagi
- T9A07 (A)
What is a disadvantage of using a handheld VHF transceiver with a flexible antenna inside a vehicle? #card
- A. Signal strength is reduced due to the shielding effect of the vehicle
- B. The bandwidth of the antenna will decrease, increasing SWR
- C. The SWR might decrease, decreasing the signal strength
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D. All these choices are correct
- T9A08 (C)
What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz? #card
- A. 112
- B. 50
- C. 19
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D. 12
- T9A09 (C)
What is the approximate length, in inches, of a half-wavelength 6 meter dipole antenna? #card
- A. 6
- B. 50
- C. 112
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D. 236
- T9A10 (D)
In which direction does a half-wave dipole antenna radiate the strongest signal? #card
- A. Equally in all directions
- B. Off the ends of the antenna
- C. In the direction of the feed line
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D. Broadside to the antenna
- T9A11 (C)
What is antenna gain? #card
- A. The additional power that is added to the transmitter power
- B. The additional power that is required in the antenna when transmitting on a higher frequency
- C. The increase in signal strength in a specified direction compared to a reference antenna
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D. The increase in impedance on receive or transmit compared to a reference antenna
- T9A12 (A)
What is an advantage of a 5/8 wavelength whip antenna for VHF or UHF mobile service? #card
- A. It has more gain than a 1/4-wavelength antenna
- B. It radiates at a very high angle
- C. It eliminates distortion caused by reflected signals
- D. It has 10 times the power gain of a 1/4 wavelength whip