70cm Dual Quad
Here's an antenna project that I just finished today! It's a 70cm dual quad/beam loop made from annealed copper tubing.
I had a bear of a time trimming and tuning it, mostly because I went down the nasty “too focused to eat” kind of rabbit hole as I worked on it. I was placing the reflector far too close to the driven element to get proper gain, all because it provided a good feed point impedance. I eventually ended up with elements that were too small, too, so I had to solder extensions back on in order to restore their size. Despite all that, though, it works!
I have it pointed at Capitol Hill here in Seattle, since that's where the main amateur radio towers that I can see from here are.
This project also involved building the feed point in the little blue enclosure, which went through a few revisions as I went from targeting a dipole to targeting the loop shown here. And during the trimming and tuning of said loop, an earlier incarnation's internal solder joint broke, so I had to rebuild it to what's shown here. Oh, and this was the first time I've ever used a panel mount N connector, which is more suitable for UHF than “UHF” connectors, albeit with an adapter on the coax line for now.
Reflector Placement
After discussing reflector spacing with DD8SF, he sent me this from the Rothammels Antenna Book:
This was proof enough that I had been working with the reflector far too close to the driven element earlier today, and that the final spacing I ended up with at 0.15λ was good enough for my use.