Adding a Reflector to an M4 Super-4-Bay provides Front/Back and Front/Rear Ratios in excess of 18 dB.
Charts for two difference M4 sizes are provided here:
Compare to M4 without Reflector:
Note that Hi-VHF Gain is only 3.5 dBi....but SWR is Good. When adding mclapp's Double Angle Reflector Hi-VHF Gain increases to about 9 dBi....but SWR becomes Excessively high....that can cut into that Gain improvement by increasing the Noise Figure (reduced Sensitivity).
F/B Ratio is difference between Gain directly FORWARD (90-deg Azimuth in Charts) and Gain directly opposite (270-deg).
F/R Ratio is difference between Gain directly FORWARD (90-deg Azimuth in Charts) and highest Gain Lobe in the Rearward Sector.
BTW: You'll also see initial results for the Free-Form 4-Bay (FF4) improvement to the M4, allowing the Inner and Outer Bowties to have DIFFERENT parameters: I have posted results for the same sized Double Angle Reflector as used in mclapp's M4 (which was as much as 1 dB better on low-mid channels) and will post barely better results for a slightly taller version today...stay tuned over the next week or two when I analyze WIDER Reflectors, which I hope will provide several tenths of a dB (maybe 1 or 2 dB????) improvement:
I'm also working on changing the M4's (or FF4's) Reflector to an entirely different design that will fix the excessive SWR on Hi-VHF when adding a Reflector...but it results in about 3 dB loss of UHF Gain, so you probably have no interest in it....you should use a SEPARATE Hi-VHF Antenna, such as the Hi-VHF Hourglass-Loop with Reflector of your choice:
Or perhaps one of the Hi-VHF Folded Dipole Yagi designs:
http://imageevent.com/holl_ands/yagisEdited by holl_ands - 11/6/13 at 9:22am