Installing a Long Wire antenna

Today I decided to pull down my 20m dipole and replace it with a long wire antenna. The reason for this was so I could work the 80m band in addition to the normal HF bands I was currently working.

Some time ago I printed out a table by AA8AF which he called the End Fed Antenna Length Study as I was sure it would come in handy one day. Well that day has come. It was based on the work by G3CCB that was published in “The Antenna File”. The aim was to determine the length of an end fed antenna suitable for the 40, 30, 20 and 15m bands, steering clear of the high impedance half wave points.

The table I saved pointed out a few good lengths, and I chose the one that covered all the bands from 80 to 10m. The ideal length, the table said, was 15m or 10m.
I settled for 15m.

Now everything I had read about end fed antennae suggested that a balun is needed at the transceiver end of the wire. Better still, mount the balun outside the shack to keep RF out, most experts said.

Now I happen to have an LDG RBA-4:1 Balun, which is a voltage balun. I also have the spec sheet which says a long wire is basically an elevated wire at least a half-wavelenght long at the lowest frequency to be used. As a general rule, the higher the better and the longer the better, it pointed out.

Performance will also depend in large part on the quality of the ground connection. It should be connected to a counterpoise or ground for best results.

My balun is mounted outside the shack above the front door and just below the antenna mast on the roof. This would be ideal for the long wire, so up it went.

The LDG balun is fed with coax on the input side and the long wire and ground connect to binding posts on the other side.

The LDG balun is fed with coax on the input side and the long wire and ground connect to binding posts on the other side.

I connected the far end of the long wire to a ceramic insulator and a palm tree, then connected a length of wire to a copper ground stake and headed into the shack to see if it would tune up on all bands.

It did and I was delighted.

My first qso was with Sergei DL1DGS in Germany on 20m CW. Then I worked John VK4WID in Toowoomba on 40m.

At least I know the thing works. It is a bit noisier than I am used to but the day was one of the hottest on record for this time of year at 37C. Maybe the bands were just plain noisy. I’ll try another day to be sure.

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2 thoughts on “Installing a Long Wire antenna

  1. You might be interested in some of the regenerative radio designs I have done.
    The one that I think is all round best is the TriStar design:
    http://theradioboard.com/rb/viewtopic.php?f=4&t=5257

    I don’t know if you do any programming but I have devised a very good numerical optimization algorithm recently:
    http://www.freebasic.net/forum/viewtopic.php?f=8&t=22090

    I actually wrote a numerical optimizer for LTSpice about a year ago called EvoSpice but I didn’t get the basic support from anyone at all to develop it further. Well, that’s just too bad.

    Long wire antennas are better for regenerative receivers because they are typically high impedance. I don’t know how you could efficiently transform 50 Ohms to 100k+ if you used a conventional antenna. It would be interesting to figure out what the optimum antenna design for a regen would be for say one of the amateur bands.

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