RE: LF: Antenna tests

["Rik Strobbe" <rik.strobbe@fys.kuleuven.ac.be>]

Hi Hugh and Gary,

If you have a 136kHz TX it's rather easy : measure the antenna current
and the TX output voltage, R = U/I. The calculated R is the total loss
resistance + radiation resistance, but the last is far less than 1 Ohm so
you can ignore it. If you want to know the ground loss (or better said
environmental losses) you have to subtract the loss in the loading
coil.
An more direct resistance measurement can be done using a Wheatstone
bridge or something similar
 ("antenna analyzer"), have a look here for some
construction ideas :
http://home4.swipnet.se/~w-41522/bridge/bridge.html
http://www.lwca.org/library/articles/k0lr/lfanalyz/lfanalyz.htm
http://www.lwca.org/library/articles/k0lr/lfanalyz/mfj259.htm
http://www.geocities.com/df8zr/zx.html
Some interesting reading on ground loss at G3NYK's webpage :
http://www.alan.melia.btinternet.co.uk/aelossbr.htm

73, Rik  ON7YD

At 21:43 12/12/2002 +0000, you wrote:

Hi Hugh,
 
Not a dumb question if you don't know the answer.
 
I would also like to know how to measure the earth resistance or series loss resistance of my antenna when it is finally completed and also what it tells us about the system.
 
73
 
Gary  G4WGT

-----Original Message-----

From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of g6tmk

Sent: 12 December 2002 16:29

To: rsgb_lf_group@blacksheep.org

Subject: Re: LF: Antenna tests

Hi Dick and group,

Please forgive the dumb question ...

 

Dick wrote:

I measured the earth resistance at my station several times this year:

On the dry day of 6 April it was 21 ohm...

 
 
 
How did you measure the resistance ?
 
 
73
Hugh M0WYE