Question

Which of the following is not used for aperture blocking?

(a) Reducing size of sub-reflector

(b) Offset feed system

(c) High directive feed

(d) Reducing spillover

This question was addressed to me in an interview.

I'm obligated to ask this question of Aperture Blockage in chapter Reflector Antenna of Antennas

Answer 1

The correct choice is (c) High directive feed

To explain: A high directive feed means a large feed. It partially shadows the primary reflector and becomes an obstacle for blockage. Aperture blocking can be avoided by reducing size of sub-reflector, thereby spillover and by using Offset feed system.