SDR antennas

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JimTailor

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I've been experimenting with SDR# and SDRUno using both the SDR Play and the RTL SDR v3 with both a scanner type discone antenna and a 15' vertical. No matter which combination of hardware and software I use the scanner antenna performs better than the vertical on SW frequencies much to my surprise. Seems to pull in more stations and definitely has lower noise.I also plan to try a horizontal long wire (75' or so) when the weather permits strung roughly north to south about 12-15 feet above ground. Would a balun help reduce noise on either the vertical or horizontal? Would an earth ground help on either? All suggestions welcome.
 

jonwienke

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There's no way to answer the question without construction details of your vertical. Preferably photos.
 

ka3jjz

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Just so we get this out of the way, we have dedicated forums for antennas for scanners and VHF (and higher) receivers here...

https://forums.radioreference.com/scanner-receiver-antennas/

and for HF antennas...

https://forums.radioreference.com/receive-antennas-below-30mhz/

As for your antenna question, at least for HF, it very well might. The RTL-SDR has got absolutely no real shielding or front end filters (I'll get to that in a moment), so you will want a coax fed antenna like the PAR end-fed. And don't go too long on the wire - if you are near a major city, chances are you are going to overload the RTL because there's very little front end filtering on those things. You may end up needing to put in a filter in the line to knock out the AM (or FM, it's hard to know which will end up causing the most trouble - it could even be both).

Keep the coax as far away from your computer setup as possible to avoid coupling noise from those components (they can be very noisy) into the SDR. This is discussed a little in the above forum under the common mode thread.

Mike
 

JimTailor

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SDR antenna

Thanks for the replies. I will go to the antenna forums but, just for the record, the vertical is an 1 1/4" aluminum pole connected to the center conductor of coax into the receiver. I'm not in a large city. The nearest FM transmitter is about 5 miles away but there's an AM broadcasting at 1450 about 2 miles away.So I'll keep that in mind.
 

M105

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Thanks for the replies. I will go to the antenna forums but, just for the record, the vertical is an 1 1/4" aluminum pole connected to the center conductor of coax into the receiver. I'm not in a large city. The nearest FM transmitter is about 5 miles away but there's an AM broadcasting at 1450 about 2 miles away.So I'll keep that in mind.
A vertical like this usually does work better with a good ground system. At a minimum drive an 8 ft ground rod directly under it and tie the coax shield to it. That said, my experience with SWL is use a long wire or better yet put up a dipole for 75-80 meters. My 75m dipole used for ham radio works great as a general purpose SWL antenna.
 

ka3jjz

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Re the 75m dipole - the RTL SDR the OP is using is almost certain to overload with that kind of antenna, especially since he has a MW station only 2 miles away. Most of these little SDR sticks have next to nothing insofar as front end filtering is concerned.

Mike
 

M105

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Re the 75m dipole - the RTL SDR the OP is using is almost certain to overload with that kind of antenna, especially since he has a MW station only 2 miles away. Most of these little SDR sticks have next to nothing insofar as front end filtering is concerned.

Mike
Good advice. I have no experience with HF on an SDR stick as I just use them for VHF/UHF listening.
 
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