A parabolic dish antenna has a conical beam 2º wide. The

A parabolic dish antenna has a conical beam 2º wide. The directivity of the antenna is approximately—

Here conical beamwidth is given so we assume that the parabolic reflector is of circular type so we have relation of BWFN and D & λ as follows

BWFN =	140λ
BWFN =	D

where,
D = diameter
λ = wavelength

2 =	140λ
2 =	D

so we got here,

D	= 70
λ	= 70

we have directivity = ∏²		D		²	= 9.86		D		²
		λ					λ

10 logD_i = 10 log		9.86		D		²		= 46.8 ≈ 50 dB
				λ