An antenna in free space receives 2 µW of power when the

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An antenna in free space receives 2 µW of power when the incident electric field is 20 V/m rms. The effective aperture of the antenna is—

1. 0.005 m²
2. 0.05 m²
3. 1.885 m²
4. 3.77 m²

Correct Option: D

P_r =	\|E_rms\|²	A_e
	2η₀

Given η₀ = 120 πΩ, E_rms = 20 V/m,
P_r = 20 × 10^–6 watt
Now,

A_e =	2 × 10⁻⁶ × 2 × 120∏
	20 × 20 × 10⁻⁶

= 3.77 m²