I thought it would be a useful experiment to make up a 23cm groundplane antenna. There is a useful guide at https://vk1nam.wordpress.com/2017/06/24/23cm-14-wave-ground-plane-antenna/
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.