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Date: Mon, 27 Sep 2010 18:24:26 +0100
Message-ID: <AANLkTinsoxgfUWU1o-JxrpVn0fcDhbWDMdO0BhD7gpfV@mail.gmail.com>
From: Roger Lapthorn <rogerlapthorn@gmail.com>
To: rsgb_lf_group@blacksheep.org
DomainKey-Status: good (testing) 
Subject: LF: Loops on TX
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Good to see the reflector back again.

For the last week or so I've been running my vertical "fully in the air" TX
loop (1mm diameter wire, 80m sq area) on both 137 and 500kHz. Now, the
bottom of the loop is laying right on the lawn with no attempt to raise it
off the ground. Weather has been mixed and yesterday it rained all day.
Results on 500kHz suggest it is every bit as good (actually better) than my
top loaded Marconi used last winter with best DX so far with 2mW ERP being
LA3EQ last evening (heavy rain all day and evening). Results on 136kHz with
<20uW ERP have been encouraging too with 6 different WSPR reports out to
148km. I clearly know that improving the wire diameter will improve the ERP
simply as a result of reducing resistive losses. What I'm less clear about
is why people say all of the loop should be raised above the ground.

My questions are these:

   - What additional losses, if any, do I suffer having the loop on the
   ground (even wet ground)? How do these arise?
   - Could I bury the return part of the loop wire in the ground and maybe
   gain a few more square metres of area?
   - Is there anywhere where I can get a simple explanation of loop losses
   due to ground presence and foliage presence?

In the last year a lot of accepted theory/beliefs, for example on earth
electrode antennas, has proved to be questionable and I am wondering if the
"loop must be in the air and away from foliage" is another accepted "fact"
which needs to be questioned.

73s
Roger G3XBM

-- 
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM   GQRP 1678    ISWL G11088

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Good to see the reflector back again.<br><br>For the last week or so I&#39=
;ve been running my vertical &quot;fully in the air&quot; TX loop (1mm dia=
meter wire, 80m sq area) on both 137 and 500kHz. Now, the bottom of the lo=
op is laying right on the lawn with no attempt to raise it off the ground.=
 Weather has been mixed and yesterday it rained all day. Results on 500kHz=
 suggest it is every bit as good (actually better) than my top loaded Marc=
oni used last winter with best DX so far with 2mW ERP being LA3EQ last eve=
ning (heavy rain all day and evening). Results on 136kHz with &lt;20uW ERP=
 have been encouraging too with 6 different WSPR reports out to 148km. I=
 clearly know that improving the wire diameter will improve the ERP=20
simply as a result of reducing resistive losses. What I&#39;m less clear=
=20
about is why people say all of the loop should be raised above the=20
ground.<br><br>My questions are these:<br><ul><li>What additional losses,=
 if any, do I suffer having the loop on the ground (even wet ground)? How=
 do these arise?<br></li><li>Could I bury the return part of the loop wire=
 in the ground and maybe gain a few more square metres of area?</li>
<li>Is there anywhere where I can get a simple explanation of loop losses=
 due to ground presence and foliage presence?</li></ul>In the last year a=
 lot of accepted theory/beliefs, for example on earth electrode antennas,=
 has proved to be questionable and I am wondering if the &quot;loop must=
 be in the air and away from foliage&quot; is another accepted &quot;fact&=
quot; which needs to be questioned.<br>
<br>73s<br>Roger G3XBM<br><br>-- <br><a href=3D"http://g3xbm-qrp.blogspot.=
com/" target=3D"_blank">http://g3xbm-qrp.blogspot.com/</a><br><a href=3D"h=
ttp://www.g3xbm.co.uk" target=3D"_blank">http://www.g3xbm.co.uk</a><br><a=
 href=3D"http://www.youtube.com/user/g3xbm" target=3D"_blank">http://www.y=
outube.com/user/g3xbm</a><br>
G3XBM=A0=A0 GQRP 1678=A0=A0=A0 ISWL G11088<br>

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