Deck 16: Microwaves and Lasers

Question 1

An apparatus whose theory of operation is based upon motion of electrons under the influence of combined E field and H field is known as a(n):

A) TWT oscillator.
B) Gunn oscillator.
C) Magnetron oscillator.
D) Klystron oscillator.

Answer 1

C

Question 2

The purpose of the low-loss dielectric material (radome) used to cover the dish is:

A) for protection.
B) for maintenance of internal pressure.
C) to improve performance.
D) A and B

Answer 2

D

Question 3

Parametric amplifiers that have pump frequencies that are double the signal frequency are operating in the:

A) quantum mode
B) nondegenerate mode.
C) superconductive mode.
D) degenerate mode.

Answer 3

D

Question 4

Which of the following is not an application of a ferrite?

A) isolator
B) oscillator
C) attenuator
D) Faraday rotation

Question 5

Which of the following is similar to an IMPATT diode?

A) TRAPATT diode
B) Baritt diode
C) Gunn diode
D) tunnel diode

Question 6

Degenerate mode parametric amplifiers operate with pump frequencies:

A) two times the signal frequency.
B) other than two times signal frequency.
C) equal to zero.
D) same as signal frequency.

Question 7

Above 5 GHz, which device offers greater performance?

A) silicon FETs
B) GaAs FETs
C) bipolars
D) none of the above

Question 8

Calculate the power gain of a microwave dish antenna with a 6 meter mouth diameter when used at 5 GHz.

A) 47.8 dB
B) 27.8 dB
C) 55.6 dB
D) 95.6 dB

Question 9

Which microwave oscillator is becoming obsolete due to its large size and the complex, costly sources of dc required for its operation?

A) Klystron oscillator
B) Gunn oscillator
C) a traveling wave tube oscillator (TWT)
D) Magnetron oscillator

Question 10

Which of the following is also known as a backward-wave oscillator (BWO)?

A) Klystron oscillator.
B) Magnetron oscillator.
C) TWT oscillator.
D) Gunn oscillator.

Question 11

The model of a RF capacitor shows that the capacitor is:

A) resistive
B) inductive
C) capacitive
D) all of the above

Question 12

What material is most useful in the design of masers for low-noise microwave amplification?

A) ruby
B) manganese
C) gallium arsendide
D) ammonia

Question 13

Which of the following is not a vacuum tube?

A) Gunn oscillator
B) Klystron oscillator
C) Magnetron oscillator
D) traveling wave tube (TWT) oscillator
E) all of the above

Question 14

A transphasor is:

A) an optical switch.
B) a fiber optic amplifier.
C) a type of maser.
D) all of the above.

Question 15

A microwave semiconductor that is typically used as T/R switches in RF transceivers operating above 100 MHz is the:

A) Gunn diode.
B) IMPATT diode.
C) GaAs FET transistor.
D) P-I-N diode.

Question 16

Which microwave oscillator is widely used in microwave ovens?

A) Magnetron oscillator
B) Gunn oscillator
C) a traveling wave tube oscillator (TWT)
D) Klystron oscillator

Question 17

Why are microwave antennas characterized by high gain and high directivity?

A) because there is no need for omnidirectional antennas since all microwave links are point-to-point
B) microwave transmitters are very limited in their output power
C) since device noise is greater at these frequencies, receivers require larger input signals.
D) because of the short wavelengths involved, the physical sizes required are enough for designs not practical at lower frequencies.
E) all of the above

Question 18

Special ferrites that are typically used as RF chokes are called:

A) isolators.
B) beads.
C) yigs.
D) circulators.