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Excessive modulation.
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An increase in output power.
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Correct AnswerA detuned antenna coupler.
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Low power from the transmitter.
Which of the following could cause a high standing wave ratio on a transmission line?
A detuned antenna coupler.
The antenna coupler, found at the feed point, helps to match the antenna to the impedance of the transmitter. The HF spectrum of an antenna is extended, since without the coupler an antenna will be functional on a much smaller range of frequencies. Detuned antenna tends also to work on much smaller frequency range, especially in the lower frequency band.
For more information, please see EEEGUIDE site for the article Antenna Coupling:
Also see SGC World site for the article Tuner Vs. Coupler
And, from W8JI site, the article Detuning Towers
Reference: Antenna specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES
Since applicable regulations are in a number of places, please use CTRL-F and search on the word "antenna" to look up applicable regulations.
Also, please see Antenna-Theory site for the in-depth info on Antenna Types.
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Correct AnswerKnowing the radiation resistance makes it possible to match impedances for maximum power transfer.
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Knowing the radiation resistance makes it possible to measure the near-field radiation density from transmitting antenna.
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The value of the radiation resistance represents the front-to-side ratio of the antenna.
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The value of the radiation resistance represents the front-to-back ratio of the antenna.
Why is the value of the radiation resistance of an antenna important?
Knowing the radiation resistance makes it possible to match impedances for maximum power transfer.
Matching impedance facilitates ability to transfer maximum power from transmitter through the antenna.
If there is no match, especially if the antenna has a higher impedance, then some of the power will be reflected back to the transmitter, and then the transmitter will adjust to lower level of power transmission so that no reflection will occur.
For more information, please see the Electronics Notes site well-illustrated article called Antenna Feed Impedance
For more details, please see Electronics Tutorials site for the article Maximum Power Transfer
For overview, please see Wikipedia's article Radiation resistance
Reference: Antenna specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES
Since applicable regulations are in a number of places, please use CTRL-F and search on the word "antenna" to look up applicable regulations.
Also, please see Antenna-Theory site for the in-depth info on Antenna Types.
Last edited by markadlerdallas. Register to edit
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Circulator.
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Wave trap.
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Multiplexer.
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Correct AnswerIsolator.
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:
Isolator.
This device is placed between a source of power and processor of a signal to protect the processing device.
For more information, please see Wikipedia's article Isolator (microwave)
Also, see Electronics Notes site for the article RF / Microwave Circulator / Isolator Basics
And, Military Aerospace Electronics site for the article What are RF Isolators and RF Circulators?
Reference: Antenna specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES
Also, please see Antenna-Theory site for the in-depth info on Antenna Types.
Since applicable regulations are in a number of places, please use CTRL-F and search on the word "antenna" to look up applicable regulations.
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Correct AnswerIt may be used for multiband operation.
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It has high directivity in the high-frequency bands.
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It has high gain.
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It minimizes harmonic radiation.
What is an advantage of using a trap antenna?
It may be used for multiband operation.
You can use the antenna trap to change the effective frequency of the antenna by changing its length. Then, the inner portion of the antenna can be used for a different frequency.
See Electronics Notes site for the article Trap Dipole for Multi-band HF Operation
Also, for a great list of resources, please see the ARRL site HF Trap Antennas
Reference: Antenna specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES
Since applicable regulations are in a number of places, please use CTRL-F and search on the word "antenna" to look up applicable regulations.
Also, please see Antenna-Theory site for the in-depth info on Antenna Types.
Last edited by markadlerdallas. Register to edit
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Losses in the antenna elements and feed line.
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The specific impedance of the antenna.
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The resistance in the trap coils to received signals.
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Correct AnswerAn equivalent resistance that would dissipate the same amount of power as that radiated from an antenna.
What is meant by the term radiation resistance of an antenna?
An equivalent resistance that would dissipate the same amount of power as that radiated from an antenna.
Matching impedance facilitates ability to transfer maximum power from transmitter through the antenna.
If there is no match, especially if the antenna has a higher impedance, then some of the power will be reflected back to the transmitter, and then the transmitter will adjust to lower level of power transmission so that no reflection will occur.
For more information, please see the Electronics Notes site well-illustrated article called Antenna Feed Impedance
For more details, please see Electronics Tutorials site for the article Maximum Power Transfer
For overview, please see Wikipedia's article Radiation resistance
Reference: Antenna specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES
Since applicable regulations are in a number of places, please use CTRL-F and search on the word "antenna" to look up applicable regulations.
Also, please see Antenna-Theory site for the in-depth info on Antenna Types.
Last edited by markadlerdallas. Register to edit
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Antenna length divided by the number of elements.
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Correct AnswerThe frequency range over which an antenna can be expected to perform well.
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The angle between the half-power radiation points.
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The angle formed between two imaginary lines drawn through the ends of the elements.
What is meant by the term antenna bandwidth?
The frequency range over which an antenna can be expected to perform well.
From sammylandler:
Antenna bandwidth is the frequency range over which an antenna can be expected to perform well. Some antennas have a wider bandwidth than others.
When an antenna has narrow bandwidth, this doesn't necessarily mean that the antenna won't work, but it does mean that it will have a harder time working on the frequencies that a wideband antenna would be able to handle.
A good example of a wideband antenna found on Wikipedia's site is the Log-periodic antenna
See the Antenna Theory site for the article Bandwidth
Reference: Antenna specifications and use are listed in the Code of Federal Regulations, Title 47 Chapter I Subchapter D
Part 80 - STATIONS IN THE MARITIME SERVICES
Since applicable regulations are in a number of places, please use CTRL-F and search on the word "antenna" to look up applicable regulations.
Also, please see Antenna-Theory site for the in-depth info on Antenna Types.
Last edited by markadlerdallas. Register to edit
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