Hi Gerry
Yes you can add capacitance - I suggest two equal value capacitors, one
at each side of the feed-point. (Not sure exactly what you mean by the
"baseline wire" I'm afraid) I did a rough NEC model, and came up with
X=481 Ohms at 3.6 MHz. This suggests about 92 pF total is required, so
two 180pF capacitors (they are effectively in series) should be the
right sort of size (not knowing the layout of the loop, my model was
very approximate, so probably off by a factor of 2 either way).
The best would be if you have access to an antenna analyzer to measure
the actual reactance X at the feedpoint, then calculate total C from
C = 1 / (2 pi f X)
Each capacitor should be double this.
73 es GL
Andrew ZS6AAA
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Geert Hofman
Sent: 10 October 2006 08:26 AM
To: towertalk@contesting.com
Subject: [TowerTalk] Delta loop too long
Have set up a delta loop during weekend, based on available posts and
masts.
Delta resonates at 3.150 MHz (is indeed around 95 m in circumference) ,
but want it to resonate at 3.550 MHz . Of course I can cut about 10
meter off, but will give me some mechanical problems.
So is there any electrical way of shortening (add capacitance ) and if
so can it be done in the baseline wire ? I assume to preserve symmetry,
will need to do it at two ends...
Feedpoint is in a corner.
Thanks
Gerry - ON4IG - OQ5A
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