KR4CYF

With a fresh Ham Radio license on my wall alongside a printout of the US Amateur Radio Bands, and the woodshop shed likely to become my ham shack, I now had plenty of time to consider what antenna to erect at home.

Constraints

I moved my temporary dipole (roughly cut for the 20m band) to the side of the shed and continued listening in, but knew I would want coverage for a number of the HF bands and that I needed to get higher off the ground in order to usefully transmit – received wisdom is that below a half-wavelength becomes less useful for distance communication due to the angle of radiation, and for how much power is absorbed by the ground. But thankfully all the math and models somewhat wash out against the reality of hanging things from trees and roofs, knowing I was not constructing a huge mast, I would be able to get between 8-15m up in the air, and that would dictate whether the 80m or 10m bands were primarily usable for me for near or far communication. I paced off distances between all the clear paths to trees that intersected my shed, which also gave me some length constraints, though good options for dipoles for 20m, 40m, perhaps 80m.

Fan Dipole

So many acronymns and names were thrown my way for multi-band antenna designs – G5RV, EFHW, Zep, Fan Dipole. Without a transceiver or other peripheral testing equipment to evaluate and the ease of 50-ohm impedance, I decided to start with an expansion of my wire dipole to a fan dipole for both 40m (and hopefully 15m) and 20m based on this design which gave good confidence for spacing the wires and connections. After a few days getting a crude pulley mounted in opposing trees and constructing the central PVC support and coax terminations, I was once again rewarded with “works on the first time” listening in to contacts on new wavelengths and further afield – now more often I might even hear both sides of a conversation! Perhaps irrelevantly I also added a 1:1 choke balun to the coax feedline based on this page, 12T on FT-240-43.

End-fed Half-Wire

In keeping to exploring cheap self-built options, and wanting to try portable operation in the future, I'd be likely to use an EFHW tossed up temporarily in a tree. To experiment with this, I'd ordered the basic parts for a low-wattage 49:1 unun (toroid, capacitor) along with the coax connectors I needed for the dipole. Some winding of wire and point-to-point soldering and it all fit in a tic-tac container. So next I threw another line up in a further tree and lifted a 137ft length of wire to an inverted vee (about 12m at the high point, 3m at either end) kinda perpendicular to the fan dipole. This antenna added 80m to my listening, and was reasonably effective on 40m and 20m as well for some comparison between the two antennas.

Time to decide on a real radio next!