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Low Noise receiving Loop antenna
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November 17th 07, 10:35 PM posted to rec.radio.amateur.antenna
Owen Duffy
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First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Low Noise receiving Loop antenna
Tony Giacometti wrote in news:CpKdnabH6fWF-
:
here are links to the preamps I use
http://www.iceradioproducts.com/reconly.html
NF=1.8dB and Gain=18dB
http://www.isp.ca/ve3nh/kd9sv.htm
Ok, I can't work with specs like "Noise figure is quite low and the
design appears to have no vices." I am not saying it is bad, it just
doesn't say anything meaninful... well to me anyway.
Still no info on the transceiver, but lets guess it has a NF=8dB.
Transceiver + preamp has a NF of 2dB, which suggests an equivalent noise
floor of about -139dBm (2kHz bandwidth).... provided that the preamp
doesn't generate internal noise due to IMD and which would not be
captured in the 1.8dB spec NF.
ITU-R P.372-8 suggests ambient noise on 1.8MHz in Residential locality
should be about -75dBm+AvgAntGain or about -122dBm, so you should get
noticeably more noise (~17dB) from the loop than from a dummy load. That
would mean the configuration should deliver almost as good a S/N ratio as
possible... even though the S meter reading might be shy.
Again, I am talking about the 160m loop alone. You can't diagnose this
easily with the two loops in parallel.
Owen
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