Question

BWFN of a paraboloid antenna with circular aperture assuming feed is isotropic is ____

(a) \(\frac{140λ}{d} \)

(b) \(\frac{115λ}{d} \)

(c) \(\frac{58λ}{d} \)

(d) \(\frac{40λ}{d} \)

This question was addressed to me by my school principal while I was bunking the class.

I want to ask this question from Parabolic Reflector Antenna in portion Reflector Antenna of Antennas

Answer 1

Right option is (a) \(\frac{140λ}{d} \)

Easy explanation: A paraboloid antenna with a circular aperture has

BWFN (Beam width between two first nulls) =  \(\frac{140λ}{d}, \) (d is diameter of circular aperture)

For a rectangular aperture \(BWFN =\frac{115λ}{L}, \) (L is length of rectangular aperture).