Since I got the Xiegu G90 I have been playing around with building suitable antennae for other bands such as 20 and 40m. I was pleased with the results of the coax end fed antenna I build for 10 and 11 so knocked up something similar for 20m. Initially I tried just putting a choke round a ferrite core at the 1/2 wave mark but the analyzer was showing things were way out of whack so removed it and wound an electrical quarter wave of coax around an 8″ plastic core. Instantly showed an SWR low around 13.5mhz and 3 or 4 goes of removing a couple of inches of coax from the top of the coil had an SWR of 1.17 at 14.2mhz. But I had a problem. My 10m pole was not really long enough to keep the coil off the ground! It was difficult to set this antenna up vertically due to the length. At this point I decided it would not work for me and went to work on the 40m dipole. This was also long but a few times of fold the wire back on itself, test, if OK snip off the tail, test again, fold back, test, snip, test…etc etc soon had an SWR of 1.3 : 1 at 7150. Feed point up about 9.5m and ends at 3m off the ground. Easily covered the entire 40m band under 2:1. I am sure if I was to raise the antenna further; and efficiencies improved the SWR curve would be much sharper. For the amount of wire and work to get a resonant 40m antenna in the air this has to be the easiest yet. The wire was plastic coated and quite light but for portable use it should be OK. Not something you want to put up as a “set and forget” antenna by any means. No balun. Just direct feed to coax. Portable. 20w max. Just needs to work. I think I will make something similar for 20m. Simple is always good when out in the woods. And Inverted V’s do work well and they don’t have to be heavy. For a single pole set up I think an inverted V is the simplest, cheapest and possibly most efficient antenna one can make for portable use. It is resonant on one band and that should be the band you are working on.
Join the 40m wires together and could be forced into use on 20m as a quad!
When it stops raining I will be going portable on 40m.