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Jim,
Its very hard to estimate / guestimate
may be move the decimal point, one place to the left , g4jnt
beacon at 311Kmt is showing round 10 db up on your signal at 243Kmt
at the same time of day , If I am right the power
feed on wspr is -6db of the ral pulse/psk , making power feed
25 watts
Similar power / similar distance / very similar
bearing , 10 db less , possibly 0.025 % ? ..... its all
smoke and mirrors , perhaps a little more smoke with wspr
?
G ..
Sent: Sunday, November 08, 2009 3:19 PM
Subject: LF: Losses due to ant in tree?
Hi All,
The vertical 5m section of my
inverted L runs up into the branches of a silver birch tree. The wire goes
over a large bough at 5m or so and then comes out of the branches for some 22m
down to a 4m high pole attached to the garage.
Has anyone a guesstimation of the
losses in signal caused by running the wire through the
tree?
Using vertload and tophat2 I
calculate the antenna to be around 0.25% efficient but this assumes it is in
free space. Can anyone suggest a figure for the additional loss due to
tree heating!
The vertical element is actually
sloping at about 20 degree from the tree down to the loading coil. The
length is nearer 6metres but the vertical height over ground at the bough is
about 5m.
(Santa may be bringing me a set of
swaged poles with which to build mark 2, well away from the silver
birch!)
With best
regards
Jim
Dr. James Cowburn
G7NKS
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