(Q). A parabolic antenna having a circular mouth is to have a gain of 1000 at the wavelength of 10 cm. Estimate the diameter of the mouth and the half-power beamwidth of the antenna.

λ = 10 cm = 0.1m

G_p = 1000

G_p = 6 (D/ λ)^2

D/ λ = √( G_p /6)

D = √ (1000/6)*0.1

D = 1.29 m

and HPBW = 1/2 *(BWFN)

=1/2*140 λ/D

= 1/2*140*0.1/1.29

= 5.426^O