How does one use a receive only antenna?

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  • Updated 8 months ago
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Now that I have the capability, I am intrigued by the idea of having a receive only antenna.  I am confused, however, how one effectively listens with it.  At least in my experience,  if you have an untuned antenna such as loop or wire, it "doesn't hear that well" unless you use a tuner to peak the signal.  Do you need to use a multiband tuned antenna?  What am I missing?  
Thanks and 73,
Bob WK2Y
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Bob Gerzoff, WK2Y

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Posted 8 months ago

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AH0U

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With my 6700 I use a three element HI-Z receive array... the idea is not to gain stronger signals but to get less noise making the weak signal drand out.... it is a game changer on 160. or 80 meters where I use mine.... it’s all about sugnalbto noise not dB gain which also brings up more noise with the bigger sugnal
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Mike - VE3CKO, Elmer

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AH0U hit it exactly. To give an example, my 160m inverted L has a noise floor of 7.5 S-units on my 6700. When I switch in my 80m double bazooka my noise floor drops to S4. This drop in noise allows me to hear what I can't on the inverted L that picks up a lot more static and neighbourhood RF garbage. Give it a go, you maybe pleasantly surprised. The city lot I live in doesn't allow for any 160m beverage but certainly would love to have two bi-directional beverages. Using one of the two receive antenna inputs, RXA or RXB on the 6700 is an easy way to switch in dedicated receive only antennas where they can never be mistaken as an xmit antenna.
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Ria - N2RJ, Elmer

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Here is the skinny - noise is usually vertically polarized. Since 99% of people can't really put up big and high horizontally polarized antennas on 160 meters (and for most people, 80 meters as well), verticals are more effective for low angle DX on the low bands for most of us. Therefore on 160 and to a lesser extent 80, you need transmit and receive antennas to hear DX and work it. 

My receive antennas (Beverages) are all terrible transmit antennas. They are all very lossy - by design, actually. However they reduce the noise so that I can hear the DX instead. I use them only on low bands and mostly on 160. Sometimes with "diversity" receive along with my inverted L vertically so I can hear fading signals more effectively. 

Generally a good match is not really an issue with a receive antenna. Mine use 75 ohm RG6 cable because it is cheap and loss is not an issue. I use high quality components from DX engineering and also some professional CATV and commercial 75 ohm CCTV fittings for reliability. 

If you want to learn about receive antennas, W8JI has LOTS of useful info. He knows what works and what doesn't.

http://www.w8ji.com/receiving.htm

Trust me, I learned a LOT of stuff from there.

Also pick up a copy of ON4UN low band DXing if you haven't already. Every low band enthusiast should have a copy. 


See you on the low bands.

73
Ria N2RJ
(Edited)
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Ria - N2RJ, Elmer

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BTW, before someone comes along and says, "there are effective verticlly polarized receive antennas too!!!" 

Yes there are. They are usually shorter than 1/4 wave (102" is common for a 4sq on 160). 
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Bob Gerzoff, WK2Y

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Thanks for all the great information and references.  Really appreciate  it. 
Bob