FCC Commercial Element 8 pool, section 15

Subelement B

Transmitting Systems

Section 15

TR - ATR - Circulators - Directional Couplers-1

815B1

The ferrite material in a circulator is used as a(an):

A.
Electric switch.
B.
Saturated reactor.
C.
Loading element.
Correct Answer
D.
Phase shifter.

815B1

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815B2

In a circular resonant cavity with flat ends, the E-field and the H-field form with specific relationships. The:

A.
E-lines are parallel to the top and bottom walls.
Correct Answer
B.
E-lines are perpendicular to the end walls.
C.
H-lines are perpendicular to the side walls.
D.
H-lines are circular to the end walls.

815B2

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815B3

A ferrite circulator is most commonly used in what portion of a RADAR system?

A.
The antenna.
B.
The modulator.
Correct Answer
C.
The duplexer.
D.
The receiver.

815B3

A ferrite circulator is most commonly used in the duplexer portion of a RADAR system.

The duplexer is a device that allows the sharing of a single antenna between the transmitter and receiver in a RADAR system. It enables the transmission of high-power pulses from the transmitter while providing isolation to protect the receiver from the transmitted energy.

A ferrite circulator is a key component within the duplexer. It utilizes the unique properties of ferrite material to control the flow of RF signals. The ferrite circulator facilitates the separation of the transmitted and received signals, ensuring that the high-power transmitted pulse is directed towards the antenna while allowing the weaker echo signals from the target to be received by the receiver.

The circulator accomplishes this by utilizing the non-reciprocal properties of ferrite material, which allow signals to flow in a specific direction while isolating the other ports. This ensures that the transmitted power is effectively directed towards the antenna and prevents it from reaching the receiver.

Mnemonic: "Duplexer Defender"

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815B4

A circulator provides what function in the RF section of a RADAR system?

Correct Answer
A.
It replaces the TR cell and functions as a duplexer.
B.
It cools the magnetron by forcing a flow of circulating air.
C.
It permits tests to be made to the thyristors while in use.
D.
It transmits antenna position to the indicator during operation.

815B4

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815B5

A directional coupler has an attenuation of -30 db. A measurement of 100 milliwatts at the coupler indicates the power of the line is:

A.
10 watts.
Correct Answer
B.
100 watts.
C.
1,000 watts.
D.
10,000 watts.

815B5

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815B6

What is the purpose or function of the RADAR duplexer/circulator?

Correct Answer
A.
An electronic switch that allows the use of one antenna for both transmission and reception.
B.
A coupling device that is used in the transition from a rectangular waveguide to a circular waveguide.
C.
A modified length of waveguide used to sample a portion of the transmitted energy for testing purposes.
D.
A dual section coupling device that allows the use of a magnetron as a transmitter.

815B6

A Duplexer is a “switch” that you can use to connect an antenna to two components. KD9TIP

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