Convert gain to effective aperture
Compute Effective Aperture
An antenna has a gain of 3 dB. Calculate the antenna's effective aperture when used to capture an electromagnetic wave with a wavelength of 10 cm.
a = gain2aperture(3,0.1)
a = 0.0016
GdB — Antenna gains
scalar | N-element real-valued vector
Antenna gains, specified as a scalar or as an N-element
real-valued vector. If
GdB is a vector, each element of
GdB corresponds to the effective aperture of the
same element in the output argument
A. See Gain and Effective Aperture for a discussion of aperture and
gain. Units are in dBi.
lambda — Wavelength of the incident electromagnetic wave
Wavelength of the incident electromagnetic wave, specified as a positive scalar. The wavelength of an electromagnetic wave is the ratio of the wave propagation speed to the frequency. Units are in meters.
A — Antenna effective aperture
positive scalar |
N-element vector of positive values
Antenna effective aperture, returned as a positive scalar or as an
N-element vector of positive values. The elements of
A represent the effective apertures for the
corresponding elements of
GdB. The size of
A equals the size of
Gain and Effective Aperture
The effective aperture describes how much energy is captured by an antenna from an incident electromagnetic plane wave. The effective area of the antenna and is not the same as the actual physical area. The array gain of an antenna G is related to its effective aperture Ae by:
where λ is the wavelength of the incident electromagnetic wave. For a fixed wavelength, the antenna gain is proportional to the effective aperture. For a fixed effective aperture, the antenna gain is inversely proportional to the square of the wavelength.
The gain expressed in dBi (GdB) is
The effective antenna aperture can be derived from the gain in dB using
 Skolnik, M. Introduction to Radar Systems, 3rd Ed. New York: McGraw-Hill, 2001.
 Richards, M. Fundamentals of Radar Signal Processing, New York: McGraw-Hill, 2005.
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