My QTH isn’t great for antennas. I’ve tried a few types but haven’t managed to find one that works for me, especially on the lower bands like 40m and 80m. About 2 years ago I made up a W3EDP antenna using some left over wire and a 4:1 balun. It was noisy and worse than anything else I had kicking about. So back in the box it went.
I thought I’d give it another go as domestic planning permission has been relaxed a bit. There are a few different configurations of the antenna but they follow a similar path. A long, not particularly resonant, antenna made up of a long element and a counterpoise.
In my case I followed the ‘ladder line method‘ where the antenna and counterpoise are as a single piece of ladder line for 17ft and the remainder antenna wire is just normal wire. So it looks like the original Zepp antennas and a little bit like this
The diagram above gives an additional component to the ‘normal’ W3EDP antenna. that is an additional counterpoise. I thought I’d give this a go based on a bit of background reading I did. NC4FB explains his experiences with the normal design and I have to say I had similar experiences. Namely that the swr was quite high and it was not that easy to get it down to usable levels on any of the bands when the antenna was first played with. A good idea to try my own extra’s.
So, test gear is as follows.
Antenna connected to homemade 4:1 balun with some mini 8 coax (about 7m) hanging outside a downstairs window. Antenna raised in a V shape with the balun box at ground level and the antenna supported about 1/3 of the way down on an aluminum mast approximately 8m off the ground. The end of the antenna is resting on the fence at about 1.8m off the ground. Hardly ideal but good for enough for a lash up.
I used a MR100 Antenna analyser. These are cheap and good for indicative measurements. There is also some good free software available to use with you Linux PC (There are probably windows varieties but I didn’t look).
I did 4 tests. Vanilla, i.e. no extra counterpoise. A 32ft counterpoise, A 16ft counterpoise & lastly an 8ft counterpoise. The outputs are below.
So what does this tell us?
Actually that there is a good argument on the face of it to add in an additional counterpoise. The 32ft one has a greater effect on the lower bands and the short on the higher bands. Nothing too contentious here then. So what happens if you connect them all up together.
It does lower the swr but that is probably not the only effect. I think this might need some extra experimentation or at least a bit more digging to see how to improve the antenna for my qth. But for now I’ll sort the lash up out and give it some on air testing.