The latter half of December 2025 had me playing around with the 2-meter J-pole some more, starting with replacing the crushed copper tubing feed clamps with more durable ones made from brass strip.
But for some reason, the resonant frequency was much too high no matter how I adjusted the clamps, so I started playing around with capacitive hats.
My experimentation eventually led me to making hats that look kind of like flower petals, as that's what I saw when looking around online at the time.
I spent much of December of 2025 playing around with alternative feed points and adjusting the resonant frequency with variable capacitors across the feed point.
One thing I kept seeing was a strange SWR spike at about 50 MHz, which I still can't explain to this day. Maybe the balcony railing was resonating?
I also tried a resonant stub to see if that would do anything interesting, but the SWR spike remained.
DD8SF wondered if the autotransformer was hitting resonance, but that occurred at around 69 MHz.
While this experimentation didn't really pan out thanks to that weird SWR spike, don't think I'm done with this dipole! There's more experimentation to follow.
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.
Since my Yaesu FT-991a radio isn't able to operate on the 1.25-meter band, I spent some time looking for solutions to getting onto said band. This led me to the Q5 Signal L22-28HPtransverter, which maps 10-meter on the radio side to 1.25-meter on the antenna side.
But since I didn't have an appropriate antenna for 1.25-meters, this also prompted experimentation into loops of proper sizes (which also included more playing around with 70cm).
At this point, I'm not sure why I started playing around with alternate feed point designs, but here are photos of what I ended up with.
It was at this point where I was starting to get strange readings with the Amazon Special SMA to SMA coaxial line I'd been using, so I finally built a new line using LL-240 coax and higher quality connectors.
The exterior maintenance on our building finally completed in early November of 2025, which meant that I could put a new pair of 6-meter dipole legs made from even thicker copper pipe out.
After cutting it down to a suitable length for the 6-meter band, I started playing around with capacitive hats for the first time
This also prompted playing around with autotransformer baluns some more.
Still stuck inside in October of 2025, I started playing around with ways to get onto the 2-meter band, starting with halo antennas.
Since the initial feed proved not durable enough, I built a better one out of box section PVC that is still my go-to to this day.
I started having a lot of trouble getting reliable and repeatable results with this gamma match, which I only later realized was because the aluminum hoops were painted, and paint obviously wouldn't conduct electricity. That also explained why I was having a bear of a time getting any solder to stick.
In the meantime, with the issues with the gamma match, I decided to switch to a “plain” feed instead.
While this did prove to be a somewhat viable antenna, the feed point impedance was far too low.
The low feed point impedance prompted me to go to the same style of twin coax impedance match that I'd used for the 6-meter dipole.
That all sounds great, right? Well, the signal and audio quality were garbage because I'd cheaped out and used Amazon RG-6 instead of coax of higher quality. That certainly taught me a lesson, and I'd go for LMR-240-75 cable for 75 ohms in the future.
When I finally got my amateur radio technician license in June of 2025, I pursued the steep discount that newly-licensed hams get on the Explorer QRZ-1 radio, which included any accessories I wanted.
The first time I used it was later the same month, when I walked around Everett, Washington while my wife was at her motorcycle permit course. I tried joining a net without having thought to configure my radio for the repeater offset, so nobody could hear me. To this day, I never forget to do so because I felt so dumb back then!
Continuing on from my earlier UHF exploits, my next 70cm antenna was made from brass tubing with the same Mix 61 bead balun.
However, I eventually cut it too short as I worked on getting its resonant frequency up.
DD8SF and I thought that the issue was the feed point design, so I switched to something much simpler: brass tubing soldered onto knurled nuts that could easily be screwed onto and off studs at the feed point.
This design also was my first real foray into telescoping legs.
I also did some experimentation with traps and a fan dipole, neither of which really panned out.
The last thing I tried was a super chunky pair of aluminum tubes, targeting maximum bandwidth. DD8SF said that it was far too large for what the NanoVNA was showing, but we later determined that the issue had to do with a metallic coating on the windowpane.
Since I was stuck doing antenna stuff indoors in September of 2025, I decided to start playing around with UHF stuff, starting with this antenna, which didn't quite work:
I then tried a toroid feed, which I now know isn't suitable for 70cm because coils tend to start resonating before even hitting that band.
I still went with it anyway, though!
Since coils really aren't suitable for this band, I ended up switching to a Mix 61 bead balun instead, but the resulting impedance wasn't good, most likely because of the surroundings:
And just for fun, I threw together a basic dipole using a pair of Red Bull cans with the same bead balun, which ended up faring about the same
Even though none of those worked well enough for my taste, I didn't give up there! Tune in next time for more UHF shenanigans.
As mentioned in my previous post, I was forced to bring my antennas indoors while our balcony was resurfaced, repainted, cleaned, etc. That was no problem for the 2-meter J-pole, which I simply had to adjust.
But my 6-meter dipole needed a new feed after being mounted.
That need prompted experimentation with autotransformers and loading coils, and while it did result in a usable antenna eventually, anytime I wanted to transmit, it caused my PC's keyboard and mouse to become unresponsive!
