What is Effective Antenna Aperture?
What is Effective Antenna Aperture?
Effective antenna aperture can be considered as the area from which the antenna receives electromagnetic radiation which is having the same polarization as the antenna. It can be considered as a measure of how effective the antenna is in receiving power of electromagnetic radiation. Effective antenna aperture can be defined as the area oriented perpendicular to the direction of the incoming electromagnetic wave which would have the same amount of power from that wave which is produced in the antenna on receiving it.
This means that if p is the power density of the incident wave in Watts/m2 and Pt the power available at the antenna terminals to the receiver, then, Pt = p x Ae, where Ae is the effective antenna aperture. The effective antenna aperture is proportional to the square of the wavelength and the gain of the antenna. The formula for calculating the effective antenna aperture if the gain of the antenna is known is: Ae = (λ2/4π) x G, where λ is the wavelength and G the gain of the antenna as its linear value and not dB.
Antennas with large effective apertures are considered as high gain antennas or beam antennas. They are very sensitive to radio waves coming from the preferred direction compared to radio waves coming from other directions, which are considered as interference. On the transmitting side, most of their power is radiated in the same direction, while radiation in other directions are minimized.