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LF: Re: Loading Coils/g2ajv/Roger

To: [email protected]
Subject: LF: Re: Loading Coils/g2ajv/Roger
From: "jannsen" <[email protected]>
Date: Fri, 19 Jan 2001 23:20:49 +0100
References: <000901c08247$aeaaec60$5103883e@default>
Reply-to: [email protected]
Sender: <[email protected]>
MAL HAMILTON schrieb:


.........................
The loading coil is not just a matching device, it is also a primary source
of vector potential and it is the vector potential, rather than its
offspring, the magnetic and electric fields, which is the fundamental
source of electromagnetic radiation.  It is therefore advantageous to place
the coil upright at the base of the antenna.  Furthermore, as a large
component of the vector potential is locally concentrated in this region,
it may be possible to gain a few dBs by placing an aluminium or copper
plate, somewhat larger than the diameter of the solenoid, a few centimetres
under the solenoid, insulated from the earth but it may be connected
directly to the TX ground terminal.  (It reflects the vector potental
instead of allowing it to be absorbed in the terrain, but DON'T stand on
the plate to adjust the solenoid whilst running at full power !!!).
.................................
73,  Roger, G2AJV.

Hello Roger es all,
thats it! Some 20 years ago I got the out of fashion equipment of an lf-transmitt-test-T-antenna from Pinneberg (DCF49). the plate u mentioned has been saved in my vy big junk-box until I myself built a T-antenna some month ago. isolated 40-m-radials (orignaly 80 radials in Pinneberg) increased its effect. the loading-coil 40cm in diameter was centre-positioned. u may have a look: qsl.net/dj8wx/00010.html, picture "messung.jpg" (possi u can not see it, if u use an other browser than internet explorer because my html-writing is not as good as it should be!).
BTW. ..... DON`T stand on the plate .......:
don`t stand on the radials too! whilst I keyed the tx outomatically measuring the fieldstrength outdoors far from the antenna I observed my chickens in the garden doing some uncontrolled somersaults. I do not use the T-antenna anymore. qso`s with OH were not possi. nowadays I got LWs of C-shortened lambd/4 length erected and qso with OH is no broblem anymore.

regards
Uwe/dj8wx



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