Key Topic 93: Antennas & Waveguides

Question 1

3-93O1: How does the gain of a parabolic dish antenna change when the operating frequency is doubled?

A. Gain does not change.
B. Gain is multiplied by 0.707.
C. Gain increases 6 dB.
D. Gain increases 3 dB.

Answer 1

C. Gain increases 6 dB.

Question 2

3-93O2: What type of antenna or pickup device is used to extract the RADAR signal from the wave guide?

A. J-hook.
B. K-hook.
C. Folded dipole.
D. Circulator.

Answer 2

A. J-hook.

Question 3

3-93O3: What happens to the beamwidth of an antenna as the gain is increased? The beamwidth:

A. Increases geometrically as the gain is increased.
B. Increases arithmetically as the gain is increased.
C. Is essentially unaffected by the gain of the antenna.
D. Decreases as the gain is increased.

Answer 3

D. Decreases as the gain is increased.

Question 4

3-93O4: A common shipboard RADAR antenna is the:

A. Slotted array.
B. Dipole.
C. Stacked Yagi.
D. Vertical Marconi.

Answer 4

A. Slotted array.

Question 5

3-93O5: Conductance takes place in a waveguide:

A. By interelectron delay.
B. Through electrostatic field reluctance.
C. In the same manner as a transmission line.
D. Through electromagnetic and electrostatic fields in the walls of the waveguide.

Answer 5

D. Through electromagnetic and electrostatic fields in the walls of the waveguide.

Question 6

3-93O6: To couple energy into and out of a waveguide use:

A. Wide copper sheeting.
B. A thin piece of wire as an antenna.
C. An LC circuit.
D. Capacitive coupling.

Answer 6

B. A thin piece of wire as an antenna.