UHF M4 (9.5"x9.0") with Flat Screen Grid Reflector analyzed using 4nec2. Dimensions for Bowties are for mclapp's M4 using AWG8 per his website drawings. There was no attempt was made here (yet) to jointly optimize Bowtie & Reflector dimensions.
Better for HiVHF: 40-in x 40-in Screen Grid (1"x2") Reflector located 16-in behind 4-Bay Bowties, but higher SWR on lowest UHF Channels and Gain on higher UHF channels moves to +/- 25-deg, resulting in reduced Forward Gain. [An improved design should be investigated, reducing these UHF degradations.]
UHF Raw Gain = 13.7 to 14.5 to 9.8 dBi, F/B & F/R Ratio Min = 10.9 dB and SWR (300-ohms) up to 4.5 on Ch14 and under 2.7 on Ch17 and above. Hi-VHF Raw Gain = 8.0 to 7.7 dBi, F/B & F/R Ratio = 13-15 dB and SWR (300-ohms) under 3.2.
ERRATA (27Oct2013): Corrected labels and narrative (charts remain the same). Separation between Reflector and Bowties for the two alternatives is actually 16-in (vice 17-in). When defining nec file names, I overlooked -1 inch offset in the Bowties.
Date(s): 27 Oct 2013. Album by holl_ands. 1 - 21 of 21 Total. 4822 Visits.
enlarge 198KB, 897x1024 1 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) 3D View
enlarge 346KB, 904x1024 2 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Front View [1 large square = 5 inches]
enlarge 145KB, 586x1024 3 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Top View [1 large square = 5 inches]
enlarge 208KB, 1152x686 4 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) UHF Raw Gain = 13.7 to 14.5 to 9.8 dBi UHF F/B & F/R Ratio Minimum = 10.9 dB
enlarge 203KB, 1152x686 5 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) UHF SWR (300-ohms) Under 4.5 and under 2.7 on Ch17 and above.
Excessive on lowest Channels
enlarge 247KB, 1152x686 6 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) UHF Impedance
enlarge 184KB, 1152x686 7 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) UHF Raw Gain = 13.7 to 14.5 to 9.8 dBi UHF F/B & F/R Ratio Minimum = 10.9 dB
enlarge 150KB, 791x1024 8 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) 4nec2 File
enlarge 142KB, 580x1024 9 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Side View [1 large square = 5 inches]
enlarge 303KB, 1024x1024 10 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Azimuthal Pattern at 470 MHz
enlarge 305KB, 1024x1024 11 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Azimuthal Pattern at 530 MHz
enlarge 305KB, 1024x1024 12 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Azimuthal Pattern at 590 MHz
enlarge 305KB, 1024x1024 13 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Azimuthal Pattern at 650 MHz
enlarge 307KB, 1024x1024 14 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Azimuthal Pattern at 698 MHz
enlarge 303KB, 1024x1024 15 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Azimuthal Pattern at 806 MHz
enlarge 179KB, 1152x686 16 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Hi-VHF Raw Gain = 8.0 to 7.7 dBi Hi-VHF F/B & F/R Ratio = 13-15 dB
enlarge 210KB, 1152x686 17 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Hi-VHF SWR (300-ohms) Under 3.2
enlarge 237KB, 1152x686 18 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Hi-VHF SWR Impedance
enlarge 308KB, 1024x1024 19 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Azimuthal Pattern at 174 MHz
enlarge 305KB, 1024x1024 20 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Azimuthal Pattern at 198 MHz
enlarge 306KB, 1024x1024 21 M4 (9.5x9.0) 4-Bay + Grid Refl at 16-in 40-in H x 40-in W Grid Size (1x2) Azimuthal Pattern at 216 MHz
