GM4ULS ham radio station

a QRM-free zone!

The ‘Snake’ Antenna

Posted by gm4uls on June 27, 2012

[This is an edited version of an article I wrote several years ago at my old QTH, so some of the information is out-of-date. I’ll see about making it a permanent page here on the web site.]

I only have a small garden so putting up major HF antennas presents problems, particularly for the longer wavelengths such as Top Band [160m]. A solution was suggested to me one day, during a contact on 12m, by Bill K1ZFE – and it was one which surprised me greatly – the “Snake” antenna! A description follows.

It is not a “miracle antenna”, though some people might say it’s a miracle that it works at all. Some operators swear by it; other operators swear at it! But it does work, albeit via an ATU, and with the availability of propagation.

How is it made?
Mine is a top band Snake, made from 42 metres of 75 Ohm television coax. It doesn’t have to be TV coax, and it doesn’t have to be 75Ω – it can be any coax you happen to have lying around, or whatever is available at the local hardware store. At the tip, the core must be connected to the braid. It is then a good idea to make the join weatherproof. At the “shack end”, connect a PL259 plug, but leave a gap of about an eight of an inch in the braid – the braid should therefore be isolated from the chassis of the ATU. As much of the coax as possible should be outside; I put my spare ATU on a desk by the window, and simply throw the coax outside, leaving only about two feet of it indoors. The coax can then be run ANYWHERE ! The antenna is called the Snake because it can be laid on the ground – it does not have to be straight, but can be left in a series of serpentine Ss! That’s right – a totally ground-mounted antenna! I am not kidding!

How does it perform?
Well, like I said, it’s not a miracle antenna. On receive it does attenuate the wanted signal somewhat, but – here’s the advantage – it attenuates background noise more, and so it has a good signal-to-noise ratio. For this reason it has been reasonably well-known as an antenna for SWLs, and I can say personally that I have heard fine signals on 160m from stations all over Europe, well into Russia. As for 2-way QSOs, well my QTH is near Perth in central eastern Scotland, and I had regular contact with GM4WZD on the Isle of Skye, right over on the other side of the country. I have also worked stations in Ireland, and down as far as G4PC in southern England, and over to LA0HK [though that is a tribute to his incredible “antenna farm”, I would say]. At least it has enabled an amateur with a small garden to be QRV on top band, and that’s saying something.

Will it work on other bands?
Well, a Snake ought to be usable on any higher frequency than the one it was cut for. I use mine to monitor the 5MHz spot frequencies [UK amateurs’ NVIS experiment], for example. During the first few days of using my snake, and taking the opportunity of the CQWW, I worked around Europe on 40m. Likewise on 20m, plus across the Atlantic to the USA. Likewise on 17m, plus the Azores, USA and Australia. Likewise on 15m, plus Turkey, Asian Russia, USA, and Canada.

What else is it useful for?
Have you ever wanted to take an HF station on vacation, and was the rest of the family less than enthusiastic about the luggage space that all the tackle would take? Well, the Snake Antenna is simply a modest roll of coax. Stop anywhere, lay it out straight on a roadside field or across the picnic site. Run it along a hedge or drape it over the branches of some trees – whatever works for you! – and see what it will do. It’s better than being QRT for a couple of weeks!


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