Hi all,
Since a while i'm now comparing RX results between two omnidirrectional
E field antennas. One of them is active (similar to the PA0RDT antenna),
the other one is a T antenna, resonanted to the frequency of interest
and matched to 50 Ohm... (So the T antenna could be used for
transmitting). The small active antenna is inside a plastic tube, so
(charged!) raindrops do not fall on the probe directly. The charge can
flow to ground through the weak conducting water layer (probably in the
range of 1E8 Ohm?).During rain i saw that the "QRN" was significantly
higher on the T antenna.
So, could it be a better idea to use an active antenna (with a limited
large signal capability and a non-perfect linearity!) instead of a
"real" or "traditional" band-selective T antenna? Maybe worth to compare
the results on a stereo RX ;-) I my imagination i see the active antenna
with an umbrella to protect from rain (charged drops, |q| > 0). As
higher the distance between probe and umbrella, the better the noise
reduction and the lower the signal loss?
Time to build and test the performance of an active E field probe
consuming 5V/1mA...
Just some thoughts...
73, Stefan
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