Term
Antennas
Key Topic 63: Antenna Theory
3-63J1 Which of the following could cause a high standing wave ratio on a transmission line?
A. Excessive modulation.
B. An increase in output power.
C. A detuned antenna coupler.
D. Low power from the transmitter. |
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Definition
| C. A detuned antenna coupler. |
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Term
Antennas
Key Topic 63: Antenna Theory
3-63J2 Why is the value of the radiation resistance of an antenna important?
A. Knowing the radiation resistance makes it possible to match impedances for maximum power transfer.
B. Knowing the radiation resistance makes it possible to measure the near-field radiation density from transmitting antenna.
C. The value of the radiation resistance represents the front-to-side ratio of the antenna.
D. The value of the radiation resistance represents the front-to-back ratio of the antenna. |
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Definition
| A. Knowing the radiation resistance makes it possible to match impedances for maximum power transfer. |
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Term
Antennas
Key Topic 63: Antenna Theory
3-63J3 A radio frequency device that allows RF energy to pass through in one direction with very little loss but absorbs RF power in the opposite direction is a:
A. Circulator.
B. Wave trap.
C. Multiplexer.
D. Isolator. |
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Definition
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Term
Antennas
Key Topic 63: Antenna Theory
3-63J4 What is an advantage of using a trap antenna?
`B. It has high directivity in the high-frequency bands.
C. It has high gain.
D. It minimizes harmonic radiation. |
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Definition
| A. It may be used for multiband operation. |
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Term
Antennas
Key Topic 63: Antenna Theory
3-63J5 What is meant by the term radiation resistance of an antenna?
A. Losses in the antenna elements and feed line.
B. The specific impedance of the antenna.
C. The resistance in the trap coils to received signals.
D. An equivalent resistance that would dissipate the same amount of power as that radiated from an antenna. |
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Definition
| D. An equivalent resistance that would dissipate the same amount of power as that radiated from an antenna. |
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Term
Antennas
Key Topic 63: Antenna Theory
3-63J6 What is meant by the term antenna bandwidth?
A. Antenna length divided by the number of elements.
B. The frequency range over which an antenna can be expected to perform well.
C. The angle between the half-power radiation points.
D. The angle formed between two imaginary lines drawn through the ends of the elements. |
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Definition
| B. The frequency range over which an antenna can be expected to perform well. |
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Term
Antennas
Key Topic 64: Voltage, Current and Power Relationships
3-64J1 What is the current flowing through a 52 ohm line with an input of 1,872 watts?
A. 0.06 amps.
B. 6 amps.
C. 28.7 amps.
D. 144 amps. |
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Definition
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Term
Antennas
Key Topic 64: Voltage, Current and Power Relationships
3-64J2 The voltage produced in a receiving antenna is:
A. Out of phase with the current if connected properly.
B. Out of phase with the current if cut to 1/3 wavelength.
C. Variable depending on the station’s SWR.
D. Always proportional to the received field strength. |
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Definition
| D. Always proportional to the received field strength. |
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Term
Antennas
Key Topic 64: Voltage, Current and Power Relationships
3-64J3 Which of the following represents the best standing wave ratio (SWR)?
A. 1:1.
B. 1:1.5.
C. 1:3.
D. 1:4. |
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Definition
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Term
Antennas
Key Topic 64: Voltage, Current and Power Relationships
3-64J4 At the ends of a half-wave antenna, what values of current and voltage exist compared to the remainder of the antenna?
A. Equal voltage and current.
B. Minimum voltage and maximum current.
C. Maximum voltage and minimum current.
D. Minimum voltage and minimum current. |
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Definition
| C. Maximum voltage and minimum current. |
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Term
Antennas
Key Topic 64: Voltage, Current and Power Relationships
3-64J5 An antenna radiates a primary signal of 500 watts output. If there is a 2nd harmonic output of 0.5 watt, what attenuation of the 2nd harmonic has occurred?
A. 10 dB.
B. 30 dB.
C. 40 dB.
D. 50 dB. |
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Definition
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Term
Antennas
Key Topic 64: Voltage, Current and Power Relationships
3-64J6 There is an improper impedance match between a 30 watt transmitter and the antenna, with 5 watts reflected. How much power is actually radiated?
A. 35 watts.
B. 30 watts.
C. 25 watts.
D. 20 watts. |
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Definition
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Term
Antennas
Key Topic 65: Frequency and Bandwidth
3-65J1 A vertical 1/4 wave antenna receives signals:
A. In the microwave band.
B. In one vertical direction.
C. In one horizontal direction.
D. Equally from all horizontal directions. |
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Definition
| D. Equally from all horizontal directions. |
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Term
Antennas
Key Topic 65: Frequency and Bandwidth
3-65J2 The resonant frequency of a Hertz antenna can be lowered by:
A. Lowering the frequency of the transmitter.
B. Placing an inductance in series with the antenna.
C. Placing a condenser in series with the antenna.
D. Placing a resistor in series with the antenna. |
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Definition
| B. Placing an inductance in series with the antenna. |
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Term
Antennas
Key Topic 65: Frequency and Bandwidth
3-65J3 An excited 1/2 wavelength antenna produces:
A. Residual fields.
B. An electro-magnetic field only.
C. Both electro-magnetic and electro-static fields.
D. An electro-flux field sometimes. |
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Definition
| C. Both electro-magnetic and electro-static fields. |
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Term
Antennas
Key Topic 65: Frequency and Bandwidth
3-65J4 To increase the resonant frequency of a 1/4 wavelength antenna:
A. Add a capacitor in series.
B. Lower capacitor value.
C. Cut antenna.
D. Add an inductor. |
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Definition
A. Add a capacitor in series.
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Term
Antennas
Key Topic 65: Frequency and Bandwidth
3-65J5 What happens to the bandwidth of an antenna as it is shortened through the use of loading coils?
A. It is increased.
B. It is decreased.
C. No change occurs.
D. It becomes flat. |
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Definition
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Term
Antennas
Key Topic 65: Frequency and Bandwidth
3-65J6 To lengthen an antenna electrically, add a:
A. Coil.
B. Resistor.
C. Battery.
D. Conduit. |
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Definition
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Term
Antennas
Key Topic 66: Transmission Lines
3-66J1 What is the meaning of the term velocity factor of a transmission line?
A. The ratio of the characteristic impedance of the line to the terminating impedance.
B. The velocity of the wave on the transmission line divided by the velocity of light in a vacuum.
C. The velocity of the wave on the transmission line multiplied by the velocity of light in a vacuum.
D. The index of shielding for coaxial cable. |
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Definition
| B. The velocity of the wave on the transmission line divided by the velocity of light in a vacuum. |
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Term
Antennas
Key Topic 66: Transmission Lines
3-66J2 What determines the velocity factor in a transmission line?
A. The termination impedance.
B. The line length.
C. Dielectrics in the line.
D. The center conductor resistivity. |
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Definition
C. Dielectrics in the line.
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Term
Antennas
Key Topic 66: Transmission Lines
3-66J3 Nitrogen is placed in transmission lines to:
A. Improve the “skin-effect” of microwaves.
B. Reduce arcing in the line.
C. Reduce the standing wave ratio of the line.
D. Prevent moisture from entering the line. |
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Definition
| D. Prevent moisture from entering the line. |
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Term
Antennas
Key Topic 66: Transmission Lines
3-66J4 A perfect (no loss) coaxial cable has 7 dB of reflected power when the input is 5 watts. What is the output of the transmission line?
A. 1 watt.
B. 1.25 watts.
C. 2.5 watts.
D. 5 watts. |
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Definition
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Term
Antennas
Key Topic 66: Transmission Lines
3-66J5 Referred to the fundamental frequency, a shorted stub line attached to the transmission line to absorb even harmonics could have a wavelength of:
A. 1.41 wavelength.
B. 1/2 wavelength.
C. 1/4 wavelength.
D. 1/6 wavelength. |
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Definition
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Term
Antennas
Key Topic 66: Transmission Lines
3-66J6 If a transmission line has a power loss of 6 dB per 100 feet, what is the power at the feed point to the antenna at the end of a 200 foot transmission line fed by a 100 watt transmitter?
A. 70 watts.
B. 50 watts.
C. 25 watts.
D. 6 watts. |
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Definition
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Term
Antennas
Key Topic 67: Effective Radiated Power
3-67J1 What is the effective radiated power of a repeater with 50 watts transmitter power output, 4 dB feedline loss, 3 dB duplexer and circulator loss, and 6 dB antenna gain?
A. 158 watts.
B. 39.7 watts.
C. 251 watts.
D. 69.9 watts. |
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Definition
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Term
Antennas
Key Topic 67: Effective Radiated Power
3-67J2 What is the effective radiated power of a repeater with 75 watts transmitter power output, 4 dB feedline loss, 3 dB duplexer and circulator loss, and 10 dB antenna gain?
A. 600 watts.
B. 75 watts.
C. 18.75 watts.
D. 150watts. |
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Definition
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Term
Antennas
Key Topic 67: Effective Radiated Power
3-67J3 What is the effective radiated power of a repeater with 75 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 6 dB antenna gain?
A. 37.6 watts.
B. 237 watts.
C. 150 watts.
D. 23.7 watts. |
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Definition
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Term
Antennas
Key Topic 67: Effective Radiated Power
3-67J4 What is the effective radiated power of a repeater with 100 watts transmitter power output, 4 dB feedline loss, 3 dB duplexer and circulator loss, and 7 dB antenna gain?
A. 631 watts.
B. 400 watts.
C. 25 watts.
D. 100 watts. |
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Definition
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Term
Antennas
Key Topic 67: Effective Radiated Power
3-67J5 What is the effective radiated power of a repeater with 100 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 10 dB antenna gain?
A. 126 watts.
B. 800 watts.
C. 12.5 watts.
D. 1260 watts. |
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Definition
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Term
Antennas
Key Topic 67: Effective Radiated Power
3-67J6 What is the effective radiated power of a repeater with 50 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 7 dB antenna gain?
A. 300 watts.
B. 315 watts.
C. 31.5 watts.
D. 69.9 watts. |
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Definition
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