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On Wednesday, October 22, 2014 5:09:16 PM UTC-5, Fred McKenzie wrote:
In article ,
Helmut Wabnig [email protected] --- -.dotat wrote:

Somebody wrote:

If 10 watts is delivered to a short antenna, where does it go if it is
not
radiated just as well as 10 watts delivered to a long antenna?


Make it 100 Watts, make it 1000 Watts,

Transmit for 5 minutes, then switch off and measure temperature.

Is the short antenna hotter?

W.-

Yes. I use a Hustler mobile antenna with resonators for each band.
After transmitting 100 Watts, the resonator coils become hot to the
touch. It seems to be worse on the lower bands with larger resonators.

Fred
K4DII

# I consider that part of the matching network though.
# If you were to apply the same power to a non loaded same length
# whip alone, and the matching were before the whip, IE: a tuner, the
# whip would change temp very little, while the heat would build
#in the tuner inductor. With the loaded antenna, the inductor is part
# of the antenna, instead of in the tuner, and that part will get
# warmer. But the whip above it, and the mast below it if center
# loaded, will stay fairly cool.

I use a 14 foot whip over a good ground plane on 10-30 meters. Matching is
in the shack, with coax feed to the antenna. I tune for maximum RF current
at the base of the whip.

The matching network can get hot, but the whip itself has very low
resistance. I consider I^2 R loss to be negligible.