ZS6BKW – an Optimised G5RV multi-band wire antenna
I’ve been playing with aerials again (can’t be studying ALL the time) and as I usually do have come around to putting up as much wire as I can and feeding it with 300 ohm ribbon.
I tried the G5RV (in the days before I had an antenna analyser) and didn’t like it much – can’t quite remember why but (from memory) it wasn’t that easy to tune. This corresponds to what I’ve found on the net – the G5RV was never intended as an all-band antenna, however by making it just a bit shorter you can match it easily on lots of bands.
It was derived by Brian Austin ZS6BKW (now G0GSF) and will match most of the HF band excluding 10 & 21MHz.
Have a look at these two articles from Sprat (the journal of the GQRP Club – http://www.gqrp.com):
Martin G3UKV trying it out (with Antenna Analyser results):
ZS6BKW Antenna Revisited (from Sprat #129)
A more extensive article by its designer G0GSF/ZS6BKW, on the rational behind the antenna design:
ZS6BKW revisits his G5RV variant and describes its evolution
Sometime I’ll publish my measurements, but for now, these should give you something to work with …
Giovanni – ZL2BOI
Hi,
I use one of these antennas. It proved to be much better than a normal G5RV. I have also tried a 60m dia loop and various verticals, but the measured performance of the ZS6BKW was either better or in the worst case equal to the other antennas. Too many antenna recomendations are not based on fact, so don’t believe everything you read. G5RV’s seem to have a bad reputation, so you’ll get better signal reports if you say you are using a open wire fed doublet !
The key things to watch when constructing the antenna are:-
get the length of 450 ohm open feeder correct. The velocity factor of the stuff I used was not as advertised. I measured it with an antenna analyser and cut it to the correct length.
Use a good 1:1 balun at the end of the 450 ohm feeder. This drastically reduces the receive noise level on 160m and 80m. Note that a few turns of coax do not make an effective balun. You need plenty of ferrite.
See http://www.geocities.com/martin_ehrenfried/HFantennas.pdf
I’m now working on a remote switching box to strap the feeders together for transmit on 160m. Tests proved that this gave a 20dB improvement over the antenna running in it’s balanced configuration on this band.
Regards,
Martin