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[TowerTalk] Re: KT34 XA

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Subject: [TowerTalk] Re: KT34 XA
From: (Roderick M. Fitz-Randolph)
Date: Tue, 25 Nov 1997 23:04:36 -0600
>Does anybody knows the take off angle of a KT34XA ?
>It's 13m above sandy ground.
>Thanks and 73 de F3PZ,
Claude, the take-off angle will depend a great deal on the
conductivity of the ground.  Let me offer an example.  While
living in Tucson, Arizona (where the soil is rather sandy and
not very conductive when dry) I noticed that I could hear and
work DX from Europe when the band conditions were OK - AND THE
SOIL WAS DRY.  When it rained, however, and the soil became
conductive, the DX from Europe disappeared!  And it stayed
disappeared for at least 3 days - until the soil dried.  We were
finally able to figure out what was happening: the virtual ground
level was very low (below the actual ground level) when the sandy
soil was dry.  When the soil was wet from rain, the distance
between the virtual ground and the antenna became much less,
thereby effectively placing the antenna closer to the rf ground
and the angle of take-off was much higher and I couldn't reach
the European DX!  I noticed this phenomena over a more than 2
year period.  It was consistent.

If your soil was perfectly conducting, the angles of your
take-off at 13 meters above the ground would be:

   20 meters: approximately 20 degrees

   15 meters: approximately 14-15 degrees

   10 meters: approximately 11-12 degrees with a minor lobe
              at 37 degrees (about 10 dB down from major lobe.

In actuality, with the sandy soil being dry and a poor conductor,
the angles should be lower.

This information was gleaned from the Antenna Terrain software
named TA.

Good luck,

Rod, N5HV

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