I attended the 2023 Microwave Update conference in Windsor CT on April 14 and 15. This was the first MUD since 2019 and was hosted by the North East Weak Signal Group. I had a lot of fun and learned a ton. This conference focused on developments on the VHF, UHF, and SHF amateur radio bands. These bands go from 50MHz to 300GHz. There were two days of presentations on a wide range of topics. Here are just a few of the presentations that I found interesting.
Dennis Sweeny, WA4LPR, presented his program “INTRFIL: Design and Construction of Round Rod Interdigitated Filters”. This program designs a bandpass filter of the users’ spec, including bandwidth, ripple, and impedance. He showed a few designs that he built and their performance, which closely matches the design. The program outputs can also be used in RF simulators to verify the design. These designs are good for frequencies between 500MHz and 6GHz. As the frequency goes lower the filters get impractical due to size.
Neil Smith, G4DBN, presented “3D printed Gradient Index RF Lenses”. He worked with Rogers to design a 10GHz gradient lens antenna to be 3D printed using their new Radix Printable Dielectric. By varying the infill density, the dielectric constant changes and a lens is created. This allows more complex lenses to be mad compared to previous technology. Currently Rogers doesn’t sell the resin directly, but they have partnered with the 3D printing company Fortify to provide manufacturing of designs. This was one of my favorite presentations and I am excited to see how this technology matures.
Tom Williams, WA1MBA, and Brian Justin, WA1ZMS, both had presentations on making radios for the 47GHz band. They presented the various challenges and tricks to getting up to 47GHz, and how the signal degrades as it’s multiplied. Tom talked about testing his design at various voltages and temperatures. He experienced failures with high temperature and voltage, with operating at either high temperature or high voltage is within spec, the combination caused failures.
Paul Wade, W1GHZ, and Rene Barbeau, VE2UG, presented on Cassegrain antennas for 47, 78, and 122GHz. Cassegrain antennas use a concave and a secondary convex reflector. This makes a high-performance antenna in smaller area. They both made the same antenna, but with Paul making his out of machined aluminum and Rene making his with 3D printed parts and a conductive coating. They then compared the performance. The 3D printed antenna was only a few dB worse in performance, and this was attributed to the roughness of the surface of the feed. Their presentations showed that it is possible to make low-cost antennas with consumer 3D printing rather than needing expensive CNC equipment.
Doug Miller, K6JEY, presented his experience with using mixers to expand the frequency range of spectrum analyzer. He presented multiple low-cost setups to expand lower cost analyzers up to 47GHz.
Greg Bonaguide, WA1VUG, presented “Using a Spectrum Analyzer as a Downconverter for RF Applications”. His presentation goes over using the IF output of a spectrum analyzer as a downconverter for a radio. He goes through possible issues and how to avoid them. This was kind of an opposite to Doug’s presentation. Doug went through expanding low-cost equipment, and Greg went through using high end equipment to expand low cost radios. Greg is a Product Line Manager for Rohde & Schwarz and brought a full set of test equipment for people to use. It was interesting to see and use the R&S equipment.
On Saturday evening there was a banquet with Chip Cohen, W1YW, as the speaker. He is the inventor of Fractal Antennas. He gave an interesting speech about an RF Invisibility Cloak he invented and the importance of ethics in engineering.
Overall, I found all the presentations interesting and learned lots. I met a lot of wicked smart people and learned about new developments in VHF, UHF, and SHF. I hope to be able to attend this conference in the future. You can find all of the presentations and papers here: http://www.microwaveupdate.org/conf2023/2023papers.html. Next year will be in Vancouver, October 3 to 5, 2024.