Question

Which of the following statement is true regarding a Gregorian antenna?

(a) Sub-reflector ellipsoidal lies closer to the focus of the paraboloid

(b) Sub-reflector is a hyperboloid with its convex facing feed

(c) Sub-reflector is an ellipsoidal with its concave facing reflector

(d) Sub-reflector is an ellipsoidal with its concave facing feed

I got this question in an interview for internship.

My doubt is from Aperture Blockage topic in division Reflector Antenna of Antennas

Answer 1

Right option is (c) Sub-reflector is an ellipsoidal with its concave facing reflector

Explanation: Gregorian antenna is a dual reflector antenna having a concave secondary reflector. The secondary reflector also known as sub-reflector is a ellipsoidal. It lies beyond the focus of the paraboloid.