Contest Recaps

Transmit antennas for a 160M contest

Contesting on Top Band is one of the more difficult challenges in ham radio. The band is quite amazing – situated just above the AM broadcast band, you can make DX and cross-continent contacts all night long. From where I am in British Columbia, for example, it’s usually no problem to work across North America during the hours of darkness.

The challenge is the long wavelength – it is “160 meters” after all – which requires a lot of antenna. A half-wavelength dipole for 160M would be 265 feet long!

Clearly, not everyone can string up even a low dipole over that length. Now, also consider that to be effective as a DX antenna, that dipole should be at least a quarter wave above ground and preferably a half-wavelength in the air – so 130 to 260 feet or more off the ground. Again, who has that kind of space and height?

Not me, that’s for sure.

Fortunately, there are workarounds and many contesters run loaded verticals or low-ish inverted-Vees – long but only needing one tall center support. An inverted-Vee provides horizontal and some vertical polarization.

Perhaps the most popular 160M antenna is the Inverted-L. That’s what I use. Take 135 feet of wire (a bit longer is even better, but will need some reactance tuned out by placing a capacitor in series at the feedpoint). Run the wire vertically as tall as you can go, then run the rest of the wire horizontally as far out as you can support it. Radials on the ground, or elevated radials (in my case) provide the counterpoise.

The inverted-L here needs a little tuning in the shack when I move up beyond the CW portion of the band — say, above 1.830Mhz.

My inverted-L for 160M goes up about 70 feet, and out to the east about another 70 feet. I have four 135-foot-long elevated radial wires suspended about five feet off the ground. It works for getting out a signal but is quite noisy for receiving.

160M transmit antenna improvement projects at VA7ST:

  • Radials on ground… About 11 years ago, I laid out 12 radials on the ground and fed the inverted-L over those. It was a much better antenna than the current elevated radial version. (Read my report from that 2010 CQ 160M CW experience).

    Sadly, the ground chemistry in my yard, which has centuries of decomposed pine needles in the soil, ate through the aluminum fence wire radials in about six months, leaving nothing more than thousands of little bits of wire in the grass.

    Lesson learned – don’t use bare wire for on-ground radials in this part of the country. I have prepared a dozen or so 50-foot PVC-jacketed wire radials which I will deploy this summer and see if I can recover the inverted-L’s former glory, before trying a folded counterpoise system.

  • Folded counterpoise… I have on hand a K2AV FCP feedpoint isolation box to create a folded counterpoise (FCP) system to replace the four quarter-wave elevated radials. I’ll tackle that project this summer (2021) after the on-ground radial experiment, and let you know how it goes.

I could outline many other options for Top Band transmitting antennas, but others have already done that. A great online resource is TopBandHams.com – they’ve published a page with illustrations and basic dimensions for 22 wire antennas for the 160M band.

That’s it for transmit antennas on the low bands. For receiving, read Hearing through the noise.

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