You may recall that I'm trying to build a compact whole-band antenna for 80 meters, and the simulations I've done show some odd results that I'd like to resolve. To that end I've built a scale model that should work for both 10m and 12m. Unfortunately, the scale model doesn't work and it doesn't work in interesting ways. In particular, it looks like the antenna wire wasn't cut to the right length. I've been wondering what mistake I could have made that would give me the results, but I hadn't been able to come up with anything.
I re-measured and cut new wire and added a ground grid (a four-foot square of chicken wire) and it still doesn't work. The way that it appears to not work is interesting, so I'm recording it. The feedpoint impedance is very small. I was expecting about 100 ohms, and it's less than 20 ohms from 24.682 MHz to around 30.508 MHz and at most of the frequencies in the range, it's less than 10 ohms. I also discovered that I needed to disconnect the resonator from the ground plane to get those numbers. The simulations all connected the resonator to the ground plane.
I am attempting to create whole-band antennas for 80m and 160m that will actually fit on my yard. NEC2 says that a particular design will definitely work, but having built a 10/12m scale model of the larger antenna, well, it doesn't work. I'm going to be investigating why. I hope it is because I made a construction error.