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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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.

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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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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.

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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.

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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.

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