I’ve been investigating putting some antennas outside and not getting very far. So I got a 2m ‘big wheel’ antenna off a trader on eBay. Plan A was to build my own but, being lazy I purchased a Wimo one. I’ve just installed this in the loft, directly above the shack so no issues of distancing (!) and it is a lot bigger than I had pictured. I now need to crawl under the thing to get to the fan dipole and other less important things such as the plumbing feeding the shower… hmmm.
Anyway, it all went together without much struggle and the NanoVNA shows a decent low SWR across the 2m band. I’ve had to rearrange stuff so the 4m dipole is now where the 2m one was and had to be rotated 90 degrees so is now roughly north-south.
Initial PSK Reporter results from the big wheel – note both the 2 and 4m antennas are fed from transverters from the transverter store in the Ukraine – showed 2m FT8 results of -14db into Cornwall and -10db into Cork plus a decent spread, and 4m picked up in south Wales so no worse than before. Of course, all these reports will probably be from stations with far better antennas than me, but hey.
The next task is to build a halo for 4m. I have some metal on order for that and other projects, like a 4m ground plane so I can do vertical as well as horizontal.
All still in the loft of course. One day these will be outside getting wet…
Using some 2mm copper wire from a supplier on eBay plus a N-type female socket the construction was fairly simple. Using the dimensions given above plus a bit for fiddle room I soldered the vertical element to the centre conductor of the socket. For the radials, given it was copper wire I decided to press my jewellers anvil to work and flattened the end of each element sufficiently to drill a 2.5mm hole. Using 2.5mm bolts each was secured to the respective mounting hole in the socket, and then the excess thread was cut off with a Dremel.
Bringing it all indoors – the heavy stuff like drills and hammers live in the workshop – I calibrated my NanoVNA and gave the new antenna a go. It was a bit off but then each element was too long. Trimming each gave a fairly flat SWR where I wanted it. Well, almost, but near enough to stop cutting bits off!
But does it work? Yes, I can open up GB3WC from the shack holding the antenna up inside the window. It’s about two S-points down on the Yagi, or anyway two of whatever the divisions are on the signal strength meter on the FT2D. Surprisingly I can get into the repeater with the antenna on the desk, albeit only coming alway up the signal strength bar and very hissy. It was the same when sitting the antenna in an old bottle as a support – at that altitude there are a lot of houses and trees between us and the repeater.
For a bit of copper wire and a socket it was a fun little thing to make. I actually planned to make a collinear and may still, but this was nice and simple and quick.