On-Axis Gain and Effective Area of a Uniformly Illuminated Aperture Antenna

This text discusses the on-axis gain and effective area of a uniformly illuminated aperture antenna. The on-axis gain is independent of aperture shape, so is the effective area. The on-axis effective area of a uniformly illuminated aperture approximates its physical area.

Questions

• What is the on-axis gain of a uniformly illuminated aperture antenna?
• What is the effective area of a uniformly illuminated aperture antenna?
• How does the on-axis gain and effective area of an aperture antenna relate to its physical area?

Answers

• The on-axis gain of a uniformly illuminated aperture antenna is given by G0,0 = P/(4πr^2), where P is the power transmitted through the aperture, r is the distance to the receiver, and ηff is the free-space wave impedance.
• The effective area of a uniformly illuminated aperture antenna is given by Aeff = (G0,0)^2/(2ηff).
• The on-axis gain and effective area of an aperture antenna approximate its physical area when the aperture is uniformly illuminated.