Question

Which of the following best describes the condition for Maximum effective aperture?

(a) Load impedance must be equal to the antenna impedance

(b) Load impedance must be equal complex conjugate to the antenna impedance

(c) Receiver power should be minimum

(d) Transmitter power should be minimum

The question was asked in an interview.

This interesting question is from Effective Aperture topic in chapter Antenna Parameters of Antennas

Answer 1

The correct answer is (b) Load impedance must be equal complex conjugate to the antenna impedance

Easy explanation: Foe effective aperture to be maximum, the receiver power should be maximum. Maximum power transfer states that the maximum received power is obtained when the impedance of network matches with the complex conjugate of the load impedance. Hence, Load impedance must be equal to the complex conjugate of the antenna impedance.