# Forum

## Isotrpoic Antenna

3 posts by 3 authors in: Forums > CWNA - Enterprise Wi-Fi Admin
Last Post: January 13, 2009:
• Hi All,

Need help for a newbie!

If an isotrpoic antenna existed. Am I right in saying that it would provide zero gain? Thats why all antennas have a certain level of gain as isotropic is only theoretically possible?

regards

aidan

• Hi Avenn,

The wikipedia definition of antenna gain is as follows"Antenna Gain is defined as the ratio of the radiation intensity of an antenna in a given direction to the intensity that would be produced by a hypothetical ideal antenna that radiates equally in all directions (isotropically) and has no losses."

Therefore here we see that antenna gain in itself is nothing but the ratio of the intensity of that antenna in one direction as compared to the intensity of an isotropic antenna in that direction.

So since gain of an antenna is just a relative quantity which has an isotropic antenna as a reference(zero), therefore there is nothing called the gain of a isotropic antenna and thus hypothetically we can say isotropic antenna has zero gain, but that only when comparing to an another antenna.

Hope this helps and does not confuse you anymore.

Kanwal

• An isotropic radiator produces zero gain because it is a reference point. Gain is always in reference to something else.

An isotropic radiator would radiate energy equally efficiently in every direction.

A gain antenna would be one that directs energy in one direction, or along one plane.

An antenna less efficient than an isotropic radiator would be something that is not meant to radiate, but does.

An isotropic radiator is a theoretical ideal, but impractical, antenna.

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