RadCom Basics May 2022, Edition 28

RadCom Basics 21 dipole, to ensure the antenna would work as well as it could with low power. This was followed by another for my 40/30m inverted-V dipole, basically two half-wave dipoles with each half of each dipole slop- ing downwards. The antenna only required one mast and one coaxial cable.The balun is a compromise for both bands – details can be found in G3LDO’s book. And only recently, I was kindly presented with a 1965 RSGB Bulle - tin article on how important a balun is to the inverted-V! When I’m operational again at this location, I’ll also fit a coiled balun at ground level with any co- axial fed antenna to help with any potential common mode currents before they get into the shack. You may get away with not fitting any balun when feeding your bal- anced antenna, but if you recognise any of the symptoms illustrated or highlighted, it might pay to install one. What it won’t do is transform a poorly located antenna into a super performing one! References Books (all still available from the RSGB shop at time of writing): Foundation Licence Manual. Alan Betts, G0HIQ, Building Successful HF Antennas. Peter Dodd, G3LDO HF Antennas for all locations. Les Moxon, G6XN RadCom articles: Antennas. May 2022. Mike Parkin, G0JMI HF choke baluns. March 2022. Andy Nehan, G4HUE Easily made HF balun.May 2017.Tony Preedy, G3LNP Further reading: [1] Coaxial cable https://en.wikipedia. org/wiki/Coaxial_cable [2] Skin effect https://en.wikipedia. org/wiki/Skin_effect [3] Common mode current https:// en.wikipedia.org/wiki/Common_ mode_current