On Mar 23, 1:56*pm, Art Unwin wrote:
On Mar 23, 12:13*pm, Tim Shoppa wrote:



On Mar 22, 9:24*pm, "Joel Koltner"
wrote:

I know that many people think G3LHZ is a little bit off his rocker, but out of
curiosity... what he suggests on slide 15 hehttp://frrl.files.wordpress.com/2009...ts-of-small-an...
- is that a valid approach to measuring antenna efficiency? -- Use a thermal
camera to note how much an antenna heats up with a given input power, find out
how much DC power it required to heat it to the same temperature (the
antenna's loss), and -- poof! -- antenna efficiency = (input power-loss)/input
power?

What are the significant loss mechanisms that he's not accounting for? *(He
claims his matching network isn't getting at all hot.)

With some feedlines and frequencies, feedline radiation can become an
issue. For example, using 4" ladder line at UHF.

I think his method, especially for physically compact antennas and
feed systems which tend to have very low radiation resistance at HF
frequencies, is a great check on theoretical calculations. There has
to be a meeting point between mathematical models/NEC and reality and
he is working at one such point. There are of course other points too
(e.g. near field and far field measurements).

Tim.

I can't see how the external fields come into it! * That would
automatically be within the two vectors that supply acceleration, this
would be measure by the skin depth created by the displacement
current. The accelleration of charge is a constant dependent on the
conductor used. Where the particle goes when acceleration stops i.e.
after leaving the boundary is of no consequence.This would be seen in
the oscillation losses of the radiator
in the same way as with a pendulum

If you dont understand external fields then you dont understand
Maxwell's equations at all. Maxwell is all about fields. This pretty
much means you havent had a clue about anything you have ever said
about antennas.

Jimmie