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I can tune my antenna and get S9 +20 noise on 75 meters, then I detune it and the noise floor lowers and I hear signals.

I use 40 meter dipole for receive on 160 meters, not resonant.

I agree resonant antennas do make a difference, but not that important for SWL, hell my little 20" antenna on my truck receives real well and it is no where near resonant from 500 kHz up to 108 mhz.

( Copy and paste from link you posted)
RE: Resonant Listening Antennas -- Why?
by AA4PB on April 8, 2013 Mail this to a friend!
Receiving is all about signal to noise ratio. If most of the noise is generated outside of the receiver (as it is on most HF bands) then matching the antenna system to the receiver increases the signal and the noise by the same amount so you have no change in the signal to noise ratio. Thats why the mismatched random wire works so well on HF receivers and impedance match is not so important in that case.

Thanks for the link. interesting reading especially the magnetic loop antennas.
To resonant or not to resonant??

<blockquote data-quote="wavrider" data-source="post: 563812" data-attributes="member: 9893">I can tune my antenna and get S9 +20 noise on 75 meters, then I detune it and the noise floor lowers and I hear signals.I use 40 meter dipole for receive on 160 meters, not resonant.I agree resonant antennas do make a difference, but not that important for SWL, hell my little 20&quot; antenna on my truck receives real well and it is no where near resonant from 500 kHz up to 108 mhz.( Copy and paste from link you posted)RE: Resonant Listening Antennas -- Why? by <a href="http://www.eham.net/user/profile/AA4PB" target="_blank">AA4PB</a> on April 8, 2013 <a href="http://www.eham.net/forums/mailto/1?id=218077" target="_blank"> Mail this to a friend!</a>Receiving is all about signal to noise ratio. If most of the noise is generated outside of the receiver (as it is on most HF bands) then matching the antenna system to the receiver increases the signal and the noise by the same amount so you have no change in the signal to noise ratio. Thats why the mismatched random wire works so well on HF receivers and impedance match is not so important in that case.&nbsp;Thanks for the link. interesting reading especially the magnetic loop antennas.To resonant or not to resonant??</blockquote>

[QUOTE="wavrider, post: 563812, member: 9893"] I can tune my antenna and get S9 +20 noise on 75 meters, then I detune it and the noise floor lowers and I hear signals. I use 40 meter dipole for receive on 160 meters, not resonant. I agree resonant antennas do make a difference, but not that important for SWL, hell my little 20" antenna on my truck receives real well and it is no where near resonant from 500 kHz up to 108 mhz. ( Copy and paste from link you posted) [B]RE: Resonant Listening Antennas -- Why?[/B] by [URL='http://www.eham.net/user/profile/AA4PB'][U]AA4PB[/U][/URL] on April 8, 2013 [URL='http://www.eham.net/forums/mailto/1?id=218077'][U] Mail this to a friend![/U][/URL] Receiving is all about signal to noise ratio. If most of the noise is generated outside of the receiver (as it is on most HF bands) then matching the antenna system to the receiver increases the signal and the noise by the same amount so you have no change in the signal to noise ratio. Thats why the mismatched random wire works so well on HF receivers and impedance match is not so important in that case. Thanks for the link. interesting reading especially the magnetic loop antennas. To resonant or not to resonant?? [/QUOTE]

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