[TowerTalk] Top hat on mobile usefull?

[Tom Rauch]

> Radiation resistance increases along the length of an
antenna. Higher
> radiation resistance means less current for a given amount
of power.


Not so Gary.

Radiation resistance associated with any particular antenna
is a single value based solely on the radiation from the
antenna system and the net or effective current causing that
radiation. That's the basis of the IRE definition of
radiation resistance.

We shouldn't confuse a useful term like radiation resistance
with a nearly useless parameter that actually is just the
real part of the feed impedance as the feedpoint is moved
around to different parts of the antenna. Doing that will
just confuse us.

Radiation is caused by charge acceleration, and that is why
lower current areas of an antenna contribute less to
radiation than high current areas. It all comes down to
ampere-feet. The greater the ampere-foot product the more
radiation we have from that area.

73 Tom