Tri-Band HF Vertical

Living on a small-holding does have it’s advantages when it comes to putting up antennas for amateur radio. My general purpose long-wire antenna has served me very well but it struggles to get much in the way of DX. I have therefore decided to build a ground plane vertical antenna for the 20, 15 and 10m bands and hopefully reach a few trans-atlantic stations.

Vertical antennas are very popular antennas on the HF bands and with their low angle of radiation are supposed to be ideal for DX work. I’m going to use an old military Clansman 5.5m fibre glass mast kit that I got off E-Bay for £40 and add separate 1/4 wave radiators in parallel with the single feed point. The crucial thing about ground plane antennas is that you have to have loads of radials to make them effective. As I have a sizeable field out the back I will lay down 50 1/4 wave radials and see what happens.

The radial plate is from Antenna-Engineering and saves a lot of work building one. I’ve laid a concrete slab with a short steel scaffold pole to support the mast.

The radials are buried just under the grass and luckily the ground was soft so the work did not take as long as thought.

I’ve added a choke balun at the base of the antenna to reduce feed-line radiation. Using my antenna analyser the elements are tuned and trimmed. With the set up as is I am able to get an SWR of about 1.8 on all bands, acceptable I think. The impedance is about 90 Ohms, quite abit higher than I had imagined and I guess this must be due to the balun.

Here’s the complete antenna:

 You can see the elements running down the side. Another view from the field. I just hope the sheep don’t chew the guys!

After a few final adjustments it was ready to try out on the airwaves. I sent out a few CQ calls out on 20m and within a few minutes worked VE1VEI in Nova Scotia, Canada. Well, you know what they say, the proof of the pudding……!

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