The reason that you probably will never see an antenna like this for scanner frequencies is that its design would not be easy to implement for all the bands needed for scanners in one antenna. As a CB antenna it only had to cover a small chunk of spectrum around 27Mhz. I don't know how well this antenna actually worked. I think like a lot of antennas made for CB in the day it was a gimmick. If you want high gain directional performance with a scanner, get a log periodic and a TV rotor. This antenna really didn't use parasitic elements. Instead, you varied the phase relationship of the three vertical half waves to create a directional pattern. I can envision a system for scanning that would use computer control of the phasing network based on the direction of the signal and optimize for maximum gain. No one would try to build such a thing and no scanner has the capability to control it, but hey it's a thought.
