I received the question that you see in the Title today (from Chris, KJ7I), and realized its a great Blog topic. Thank you Chris! Lets start with how the antenna works:
These are wonderful animated EZNec plots that are featured on Dan, AC6LA’s phenominal web site: https://www.ac6la.com/
The reason I searched for EZNec plots for the UrbanBeam is that I did not really believe the specs when I first saw them. Like others I have heard on the air – I also thought it was some weird “bastardized” Moxon, and I figured it was nothing more than a fancy rotatable dipole on all but maybe 20M. I can say FOR SURE – with on the air testing that it is indeed a 2 element yagi on 20 – 6M and a rotatable dipole on 40 and 30M. This makes it (IMHO) the most innovative antenna I have ever seen or used. It performs to SteppIR specs, and I congratulate them for a superbly engineered product. I had the 2 element SteppIR yagi years ago – and I can say from experience that this antenna does not feel like a compromise at all – regardless of specs.
Here is a list of when I would recommend such an antenna up “only” 30-ish feet (if you can get the antenna up 40′ or more that would make it excellent on 30 – 6M and quite decent on 40M):
When would I NOT recommend such a system:
For my goals and where I am in ham radio – I wanted as few antennas up with as few guy ropes and large antennas up possible. But I still wanted to jump in the occasional pileup – and I also have a “Plan B” for when Bouvet and Glorioso are activated and when this antenna might be a bit low on 40 – 20M. My DX Engineering DV-40-P phased array will be what gets me those last two (Plan B), and if being in my bowl doesn’t cut the mustard – I can run over to W6NV’s QTH (Plan C).
That’s it – hope this helps!