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nephelai

nephelai

Antenna performance is measured in dBi (the antennas gain/loss over a theoretical isotropic antenna)

dBd (the antennas gain/loss over a dipole antenna)
dBi = dBd + 2.15
dBd = dBi – 2.15

jack c

jack c

8.6 + 2.15 =10.75

jack c

jack c

dBd (decibels related to dipole antenna) is a measure of the gain of an antenna system relative to a dipole antenna at radio frequency.

The dBd specification is based on the decibel, a logarithmic measure of relative power. Suppose an antenna A produces an electromagnetic field of intensity IA microwatts per square meter (µW/m2) in its favored direction at a point located a defined distance away. Also, suppose a half-wave dipole antenna D produces an electromagnetic field of intensity ID µW/m2 in its favored direction at the same distance. Then the gain G of antenna A, in dBd, is:

G = 10 log10 (IA / ID)

A dipole antenna has a gain of 0 dBd. An isotropic radiator has a gain of -2.15 dBd.