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Nomograph

for the antenna gain of a symmetrical parabolic antenna

Figure 1: Preview of the nomograph

Nomograph for the antenna gain
of a symmetrical parabolic antenna

This nomograph is used to determine an antenna gain of a symmetrical parabolic antenna from the data of a frequency (or wavelength λ) and the diameter d of the antenna (alternatively in meters or in feet.) The nomograph is based on the approximation:

G = 20log(d/λ) + 9.94 dB - 10log(η) (1)

The example describes a satellite receiving antenna with a frequency range of 10.7 to 12.75 GHz and a diameter of 80 cm. For more oval reflectors of offset antennas, use the smaller dimension.

However, the nomogram can only consider two variables. Therefore, the efficiency η is assumed to be equal to 1 and must be corrected as follows:

Please print out the nomogram as an individual image.