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Roger
We have gone beyond the few watts and uW stage and should
now be thinking about Kilowatts and at least mWatts erp.
Several hundred watts and balloons or kites must be the
next stage with the intention of having two way QSO'S at reasonable
speeds.
G3KEV
----- Original Message -----
Sent: Friday, March 18, 2011 2:09
PM
Subject: LF: Loop TX antennas at
VLF?
Just wondering if anyone has done the maths to work out what
sort of ERP could be expected at 8.97kHz with, say, 100W to a smallish loop
antenna in the garden?
It would certainly avoid the need for very very
large matching coils and may be easier to engineer than a Marconi. Even an
efficiency of -80dB would allow 1uW ERP and, judging by results from G3XIZ
with around 2uW, this could be useful with long stable carrier transmissions
of several hours. Most of us could run a loop with an area of 100sq m. with
thickish wire in our gardens. A loop might also be more practical for portable
operations perhaps with a triangle with one high support.
Certainly my
own results with WSPR at 136 and 500kHz with just a few watts and quite thin
wire and around 80sq m loop area were encouraging. Mind you, 9kHz is very much
lower than 136kHz, so the radiation resistance would be tiny I assume.
73s
Roger G3XBM
--
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G3XBM GQRP
1678 ISWL G11088
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