During the last couple of days I've been making a half square antenna for 30 metres. I had a listen on it today and it does seem to work as well as they say they should. I was listening on 40 metres and some Russian stations did seem to be quite loud and clear, and on 17 metres, even though the antenna was miles away from resonance a station in the US was the best and strongest I've heard for years, maybe be was blowing smoke with a killowatt, I don't know.
Now my question before I go out and buy some more wire. Would it be possible to make a smaller version for 20 metres, have it suspended within the 30 metre antenna and use the same feedpoint and feeder and would it work properly ?
Can someone remind me, well, it's a bit late now really because I've made the antenna, but when cutting the wire using the formula's 492/F Mhz and 240/ F Mhz should the lengths be increased or reduced by 5% if the wire is plastic covered.? My excuse for forgetting is old age.
I'm going to have a listen on 30 metres in a few minutes I hope the Chinese radar's gone away.