8-39E: Antenna Systems

Question 1

8-39E1

Slotted waveguide arrays, when fed from one end exhibit:

A. Frequency scan.
B. High VSWR.
C. Poor performance in rain.
D. A narrow elevation beam.

Answer 1

ANSWER A
The slotted waveguide antenna is a popular one for small shipboard RADAR antenna systems. The slots are in-phase radiating openings, similar to a stacked array for narrow horizontal beamwidth. The Slotted array also has low SWR, good performance in rain, and a regular vertical beamwidth, and the slotted waveguide array is said to be frequency scan.

Question 2

8-39E5

How does antenna length affect the horizontal beamwidth of the transmitted signal?

A. The longer the antenna the wider the horizontal beamwidth.
B. The longer the antenna the narrower the horizontal beamwidth.
C. The horizontal beamwidth is not affected by the antenna length.
D. None of the above.

Answer 2

ANSWER B
It is desirable to sharpen the horizontal beamwidth by providing the longest possible antessa array, improving resolution to individual targets.