Thursday, September 22, 2022

You can't beat a resonant dipole antenna

I'm a big fan of the Off Centre Fed Dipole. With a 4:1 balun and two lengths of wire you get multiple bands with good resonance. Recently I put up a dipole cut for 40m and could switch between the OCFD and the 40m dipole and it was clear that the dipole performed better.

The weather has been cold here but spring has arrived and I took down the OCFD and replaced it with a dipole cut for 80m. Resonance looks pretty good, if a bit narrow.


I used this dipole on the weekly Macedon Ranges Amateur Radio club net and other stations commented on how good, and improved, my signal was.

The antenna support tree has lots of space to hang baluns so I've now put up dipoles cut for 40m and 20m.


It's quite an effort tuning these antennas. Hoisting up, measuring, trimming, hoisting... but in the end I've got each of the antennas resonant in their bands. 

I use plastic egg insulators and fold the wire ends back and hold them in place with cable ties. This makes it easy to adjust the lengths as required for tuning.

The dead tree is a very handy support.


Getting lines over high branches can be a challenge. Dallas, VK3EB, was a great help with his big squid pole. I've also used a drone and most recently an arborist's throw weight.

Tonight I'm trying out 20m by running WSPR and performance seems excellent.


So far my antennas are all facing East-West and I think the next step is to have some dipoles facing North-South.

I was talking with Stephen, VK2BLQ, about all this and he said "you can't beat a resonant dipole".

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