Hello Paul,
For your information, today I have tested a ´low noise vertical´.
This is a 50 mm diameter and 3.30 meter long aluminium pole.
The capacitance is 47 pf.
Using a transformer of 80 turns primary and 8 turns secondary on a high mu
toroid the output
as measured with a PERSEUS SDR on the carrier of a local NDB on 399.5 kHz is
-97 dBm. The
output on my standard mini-whip mounted 4 meter high is -81 dBm. The output is
low, but not
completely useless, depending on the amount of local noise it picks up. At my
location the
signal to noise ratio is 10 dB worse as on my mini-whip antenna.
The K9AY is an excellent antenna and if you have the space, I should go for it.
I do prefer an omnidirectional antenna as at LF you never know the exact path
of arrival.
I am not only interested in receiving amateur radio signals but also hunt
NDB's, NAVTEX and
DGPS stations. NDB's and DGPS stations from Canada are received here every day,
Summer
included.
73,
Roelof, pa0rdt
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