While it's not the original Gray Hoverman Antenna design on the web, Dr. John E. Davis (aka j3d) has done his fair share to advance the state of the art in this particular antenna design.

Through numerical methods, he has developed a series of models that specify optimized antennas for the post-transition UHF Spectrum, using various numbers of reflectors (The GH4, pictured here, uses four mirrored pairs of aluminum reflectors.)



He has also developed a few 'gapless' Gray Hoverman antennas, where the reflectors in the back of the antenna are unbroken. The one antenna I've physically built is a poorly executed version of one of these antennas, with 12 quarter inch diameter aluminum rods reflecting onto a pair of 6 gauge copper antenna elements.