Alan Melia wrote:
I have been grappling with the idea that I need to know how good (or how
bad!) my antenna is on reception. After several months of listening and
slight changes I know it isn't good enough...but how do I know if I have
built a better one or improved it?
I use the simple method of monitoring LF beacons close to the
136kHz band, notably the DCF beacon on 138.82 and the Greek
RTTY just below 136kHz. The German one is remarkably stable on
ground wave, but has a useful sky wave component after dark. The
Greek signal is almost completely sky wave (it is audible
sometimes all day) but has a stable maximum strength on most
days.
These give a practical measure of how good the antenna is at a
distance which is really what is required.
Of course, if it is purely receiving you are interested in, the signal
to noise is more important than simple signal strength, but I can
also measure the relative noise level on the S meter (when local
QRM generators are off - an increasingly rare occurrence).
As a 'ball park' figure, DCF should be several tens of dB over 9 and
the Greek RTTY should be S9 (at night) for a noise reading of less
than S3.
Mike, G3XDV (IO91VT)
http://www.dennison.demon.co.uk/activity.htm
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