[Antennas] Unity Gain Rephrased Question

Wed Jun 23 21:46:11 EDT 2004

On Wed, Jun 23, 2004 at 05:59:01PM -0400, A10382 wrote:
> Want to start a 'hot' tread or burn up a net? Just start a conversation
> about one of the hot topics. And "ANTENNA GAIN" is about as hot as any
> other.

<snip>
>> When comparing horizontal antennas (wire dipoles, yagis, multi-element
> 'beams', log periodic, 'zepps', etc.), 'gain' again is comparative and
> is usually referenced to the 'standard' 1/2wl horizontal wire dipole.
> Unfortunately, there are two environments for this:
> 1) a 1/2wl horizontal dipole mounted 1/2wl high over 'average' ground
> (normally slightly moist earth)
> 2) a 1/2wl horizontal dipole mounted in free space (the isotropic
> sphere).

The pattern of a dipole in free space is NOT isotropic, but is toroidal
in shape (a donut with the dipole running through the hole). Its peak
gain is 2.1 dB relative to an isotropic pattern (which is not physically
realizable, but is easy to visualize and has obvious mathematical
significance).
73, Bob N7XY