I’ve been exploring antenna designs that can fit on a protest sign. Something which would not be obvious as an antenna if carried about, but which could facilitate communications in the field.
A 70cm antenna could easily fit on a protest sign, but since most of the repeaters near me are 2m, I wanted something in that band. After some research, I learned of the moxon antenna, which is perfect for my use-case.
The linked image isn’t my design, but it’s what I’m building. The longest dimension is just the right size for the cardboard signs sold at my local crafts store. Usually people build this with PVC tubes, wire, or aluminum poles. However, I built a prototype using copper foil tape. Bought from the gardening section at my hardware store, apparently it’s used to keep slugs from climbing a plant pot. I’m hoping that by integrating the copper foil with the design of my sign, it will be relatively stealthy. You could probably hide the coax in a PVC pipe and mount the sign to that.
My shoddy PoC had an SWR of ~2.5 at 145MHz, and I hope to improve it for the final version. Not too shabby, considering how bad some rubber ducky antennae can be.
I’m curious if people know of other compact (maximum dimension) antenna designs that I could test out.
Honestly, my plan is to use it as a minor propaganda tool: Call up a local ham friend for a “radio check”, and “just happen” to mention that there’s a protest going on and nobody is being aggressive, etc. I hear way too many maga guys on the airwaves, I want to do what I can to counter it.
Plus, if the cops do get violent, there’s no downside to having a communication tool that doesn’t rely on big tech or cell phones. One more way to get the word out.
Of course, something like this could be adapted for tools like meshtastic, or used with digital modes in order to coordinate a group.
Cool. Thanks for the explanation.