SWL longwire antenna

Useful information regarding antennas for SDR products.
Umanyar
Posts: 6
Joined: Sat Mar 26, 2016 1:43 am

SWL longwire antenna

Postby Umanyar » Sat Apr 16, 2016 10:33 pm

I am trying to get more mileage out of my RSP for SWL. I was wondering if anyone has had any experience with the following SWL antennas?

1. alpha delta's DX-SWL
2. Par electronics EF-SWL

It would be great if anyone has these antenna's specifically or something similar rigged up with the RSP, would be wondering how effective these antennas are.


Thank you
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CaptainNemo
Posts: 114
Joined: Mon Jan 05, 2015 1:22 pm
Location: Genoa - Italy

Re: SWL longwire antenna

Postby CaptainNemo » Sun Apr 17, 2016 2:33 pm

I suppose my DIY random wire is
Umanyar wrote:...something similar...
to EF-SWL.
It is a 10meters piece of wire with a 9:1 toroidal transformer and a coax feed line of 25 meters
Despite this long feed line I have no attenuation problem with RSP.
Also I used 75ohm tv-sat coax and F connectors and -- again -- despite impedance mismatch
with RSP there is signal to sell.
This antenna is rigged on the roof (at 25 meters over sea level). Due to security constraint the antenna is rigged
only 2-3meters over the roof (I was not allowed to use longer poles).

Considering all the above limitations, this is my only antenna from 300k to 30M, and I have a lot of fun with it.
I've copied near all kind of tx (NDB, HAM, MWARA, VOLMET, HFDL, SLB, CODAR, OTHR, BC, COASTAL STATIONS, UTILITY, etc. etc. etc.).

Bye
Gio
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Umanyar
Posts: 6
Joined: Sat Mar 26, 2016 1:43 am

Re: SWL longwire antenna

Postby Umanyar » Mon Apr 18, 2016 5:39 am

This is good news. Happy to hear a similar wire has so much success with the RSP. Thanks for the feedback.
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sdjack
Posts: 4
Joined: Mon Apr 18, 2016 10:13 pm

Re: SWL longwire antenna

Postby sdjack » Mon Apr 18, 2016 10:17 pm

I have very good results with a mini whip, up from 10khz.
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rgood123
Posts: 15
Joined: Fri Dec 18, 2015 9:55 pm

Re: SWL longwire antenna

Postby rgood123 » Wed Apr 20, 2016 11:39 pm

HI to all.
This homemade longwire antenna works great it improved my reception on 80meters to 10meters " 20 OVER " on my sdrplay.
and very inexpensive to construct.
Good Luck
Attachments
BALUN with two longwires.jpg
BALUN with two longwires.jpg (17.96 KiB) Viewed 8145 times
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CaptainNemo
Posts: 114
Joined: Mon Jan 05, 2015 1:22 pm
Location: Genoa - Italy

Re: SWL longwire antenna

Postby CaptainNemo » Thu Apr 21, 2016 10:45 am

Hi rgood123, you gave me a good idea to experiment!!!
(My diy balun primary winding has one end connected to the random wire and the other end is grounded to the metal pole -- this is the mostly reported schematic in the net).
Gio
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PA2EM
Posts: 3
Joined: Fri Apr 29, 2016 7:24 pm

Re: SWL longwire antenna

Postby PA2EM » Fri Apr 29, 2016 7:39 pm

I hope future models will include a 9:1 un-un (balun) and a longwire connection (in addition to the SMA). It enables using any wire for reception up to 50mHz. http://m0ukd.com/homebrew/baluns-and-ununs/91-magnetic-longwire-balun-unun/

With the same set up, you could ad three wire terminals: 1:4 1:9 1:16 to give more length / band flexibility
http://www.radioamatoripeligni.it/i6ibe/pdf/balun9a1.pdf

For reception only these can be made much smaller. You can buy a cheap small external one:

http://www.ebay.com/itm/100K-50MHz-RTL-SDR-Supporting-long-Antenna-9-1-Impedance-Transformer-Balun-BNC-/172153360141?hash=item281523cf0d:g:S3IAAOSwEK9W~fST
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n6dnm
Posts: 1
Joined: Wed Jun 01, 2016 10:37 pm

Re: SWL longwire antenna

Postby n6dnm » Wed Jun 01, 2016 10:49 pm

Thanks rgood123!!! Sometimes simple approach is the best one. I have tried quite a few combinations before - with folded dipole, center fed, simple long wire (single) with 1:1 and 9:1 UnUns - this one comes out the cleanest and stations that i could only sense now come in low but clean. For me it was not 20 fold improvement, but quite significant one - let's just say noise floor dropped from S4 to S1 and strong signals have improved by a few S's. Thanks again and can't wait how far i can get listening.
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CaptainNemo
Posts: 114
Joined: Mon Jan 05, 2015 1:22 pm
Location: Genoa - Italy

Re: SWL longwire antenna

Postby CaptainNemo » Tue Jun 07, 2016 11:54 am

The "configuration" proposed by rgood123 has a name?
There is some documentation available in internet?
Thanks in advance.
Gio.
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rgood123
Posts: 15
Joined: Fri Dec 18, 2015 9:55 pm

Re: SWL longwire antenna

Postby rgood123 » Thu Jun 09, 2016 4:01 pm

A dipole antenna with 90 degree radials to each other,I believe is called a Quadrant antenna.
Don't known much about the design.
I can say it works well.
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