"Buck" wrote in message
...
On Sun, 03 Apr 2005 22:46:05 GMT, Jim - NN7K
wrote:

This got me thinking (a dangerous thing when comes
to concepts)! When discussing an Isotropic, as an
object that radiates equally well- in ALL DIRECTIONS,
does this also include all PLANES, as well? Horizontal
Vertical, how about Left-Hand , or Right-hand Circular ?
Linear Circular? or, does polarization even enter into
the situation (it being an infinatly small point source)?
Not trying to be smart- Just not the best educated bloke
on the block, and never seen it disgussed.

Thanks, es 73, Jim NN7K

Isn't gain something that comes about by reshaping and polarizing that
isotropic radiation?

Buck

--
73 for now
Buck
N4PGW

Re-shaping, yes. Polarization, no. Gain is defined by power radiated through
a unit area, or power density. It doesn't matter which way the E-field
vector is pointing at any given instant.

A good physical analogy is to think of a circular baloon. If you squeeze the
baloon, it will distort from circular. The narrower parts will be "nulls",
and the bulges will be directed energy, or "gain". The tough part of antenna
design is getting those bulges to point where you want them. For instance,
if you want GPS reception, you want good performance roughly from horizon to
horizon, and no nulls overhead. But if you want to talk with other hams on a
hike, very few of them will be located 15,000 feet overhead, so you can
optimize your antenna to not waste power vertically. Indeed, the best
pattern for this work is a squashed-down to the horizon, equi-azimuth
pattern.


Ed
WB6WSN