Topband: Evaluating Rx antennas with Spectran
Luis Mansutti IV3PRK
luisprk at tin.it
Wed Mar 15 09:47:26 EST 2006
I wonder if anyone has ever tried to evaluate his receiving antennas with
the method fully described by W3EEE with a talk given at the RSGB HF
Convention in November 2003 http://www.hifidelity.com/w3eee/rsgbtalk.html
By means of a FFT audio frequency spectrum analyzer "Spectran" it is
possible to "see" and separate several BC carriers on the same channel, and
identify them after knowing their direction and power.
After normalizing the readings taken on an ominidirectional antenna it
should be possible to build an azimut plot with the comparative readings
with the target Rx antenna as shown in the interesting W3EEE work.
It should be possible to see if a 3 dB improvement on an End-fire Pennants
configuration, calculated with EZNEC, is confirmed "in the real world" !
But could those BC audio frequency carriers, taken during the day on the
ground wave, be really reliable?
Here is my problem: I am unbable to get stable readings, as they are
continously moving up and down on Spectran.... where am I wrong?
(Not found enough explanations on the several Spectran settings!).
My Rx antennas are working OK as switching between Pennants, (or the K9AY
loop or rotating the Flag), I can substitute on the "radio" one AM station
with another on the same channel and see the S-meter variation, but I can't
get a meaningful audio frequency variation on Spectran.
I hope to get an help from the wisdom on this Reflector !
73 Luis IV3PRK
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