UHF+Hi-VHF HFF8, a Horizontal Stack of 2 ea Free-Form 4-Bays (FF4) with Double Angle Reflectors (each 48" H x 36" W using 2x2-in Grid) were analyzed using 4nec2, presuming they are driven separately. FF4 dimensions are sameas found for the Optimized version with a Variable Double Angle Reflector.
Here the usual Horizontal Stacking approach is used, with Equal Length Coax to a (ZERO LOSS) RF Combiner.
Initially, 4nec2 Parameter Sweep plotted Raw Gain versus Horizontal Stacking Distance. Since SWR plots were always excellent across the UHF Band, they are not shown here.
Performance was slightly "Better" at THREE notable Stacking Distances: 34.821-inches (NO GAP, Continuous Reflector), 35-inches (Metal-to-Metal about 1/4-inch) and 51-inches, which are analyzed below. There were notable Stacking Distances further out, but none were particularly "Better".
Although the differences are only a few tenths of a dB, Stack Distance = 51-inches was just a bit "Better", esp. Hi-VHF, than at 35-inches. The wider Separation may also be slightly "Better" at combating Multipath Fading due to the reduction in Statistical Correlation between the two Antenna signals. The "NO GAP between Reflector" alternative was slightly worse.
=========================================== a) Horizontal Stacking Distance (4-Bay Center-to-Center) = 34.821 inches (NO GAP between Reflectors).
UHF Raw Gain = 17.2 to 19.7 dBi, F/B & F/R Ratio Minimum = 16.4 dB & SWR (300-ohms) under 2.1. Hi-VHF Raw Gain = 10.4 to 9.9 to 10.3 dBi, F/R & F/B Ratio Min = 16.4 dB, although SWR (300-ohms) under 20 dB is EXCESSIVE, which may or may NOT be an issue in any particular situation.
=========================================== b) Horizontal Stacking Distance (4-Bay Center-to-Center) = 35-inches (0.18-in GAP between Reflectors).
UHF Raw Gain = 17.3 to 20.1 dBi, F/B & F/R Ratio Minimum = 15.8 dB & SWR (300-ohms) under 2.1. Hi-VHF Raw Gain = 10.5 to 11.7 to 11.9 dBi, F/R Ratio = 11.6 to 14.9 dB, although SWR (300-ohms) = 24 to 15 dB is EXCESSIVE, which may or may NOT be an issue in any particular situation.
=========================================== c) Horizontal Stacking Distance (4-Bay Center-to-Center) = 51-inches (16.18-in GAP between Reflectors).
UHF Raw Gain = 17.6 to 20.3 dBi, F/B & F/R Ratio Minimum = 14.2 dB and SWR (300-ohms) under 2.1. Hi-VHF Raw Gain = 13.5 to 11.4 dBi, F/R Ratio = 9 to 19 dB, although SWR (300-ohms) = 29 to 22 dB is EXCESSIVE, which may or may NOT be an issue in any particular situation.
Date(s): 3 Jun 2014. Album by holl_ands. 1 - 69 of 69 Total. 3598 Visits.
enlarge 163KB, 1024x675 1 Horiz-Stack FF4 + VDAR (48" x 36") Raw Gain vs Stack Distance at 470 MHz For Stack Distance = 35 to 75 inches
enlarge 170KB, 1024x675 2 Horiz-Stack FF4 + VDAR (48" x 36") Raw Gain vs Stack Distance at 584 MHz For Stack Distance = 35 to 75 inches
enlarge 169KB, 1024x675 3 Horiz-Stack FF4 + VDAR (48" x 36") Raw Gain vs Stack Distance at 698 MHz For Stack Distance = 35 to 75 inches
enlarge 162KB, 1024x675 4 Horiz-Stack FF4 + VDAR (48" x 36") Raw Gain vs Stack Distance at 470 MHz For Stack Distance = 75 to 115 inches
enlarge 163KB, 1024x675 5 Horiz-Stack FF4 + VDAR (48" x 36") Raw Gain vs Stack Distance at 584 MHz For Stack Distance = 75 to 115 inches
enlarge 167KB, 1024x675 6 Horiz-Stack FF4 + VDAR (48" x 36") Raw Gain vs Stack Distance at 698 MHz For Stack Distance = 75 to 115 inches
enlarge 293KB, 897x1024 7 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Front View [1 large square = 5 inches]
enlarge 351KB, 1024x761 8 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Front View [1 large square = 5 inches]
enlarge 89KB, 250x1024 9 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Top View [1 large square = 5 inches]
enlarge 194KB, 1024x675 10 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) UHF Raw Gain = 17.2 to 19.7 dBi UHF F/B & F/R Ratio Minimum = 16.4 dB
enlarge 180KB, 1024x675 11 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) UHF SWR (300-ohms) Under 2.1
enlarge 227KB, 1024x675 12 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) UHF Impedance
enlarge 314KB, 1024x1024 13 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Azimuthal Pattern at 470 MHz
enlarge 316KB, 1024x1024 14 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Azimuthal Pattern at 530 MHz
enlarge 319KB, 1024x1024 15 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Azimuthal Pattern at 590 MHz
enlarge 323KB, 1024x1024 16 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Azimuthal Pattern at 650 MHz
enlarge 323KB, 1024x1024 17 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Azimuthal Pattern at 698 MHz
enlarge 321KB, 1024x1024 18 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Azimuthal Pattern at 758 MHz
enlarge 322KB, 1024x1024 19 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Azimuthal Pattern at 806 MHz
enlarge 168KB, 791x1024 20 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) 4nec2 File
enlarge 103KB, 336x1024 21 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Side View [1 large square = 5 inches]
enlarge 182KB, 1024x675 22 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Hi-VHF Raw Gain = 10.4 to 9.9 to 10.3 dBi Hi-VHF F/R Ratio Minimum = 16.2 dB
enlarge 187KB, 1024x675 23 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Hi-VHF SWR (300-ohms) Under 20
enlarge 219KB, 1024x675 24 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Hi-VHF Impedance
enlarge 323KB, 1024x1024 25 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Azimuthal Pattern at 174 MHz
enlarge 318KB, 1024x1024 26 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Azimuthal Pattern at 198 MHz
enlarge 316KB, 1024x1024 27 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 34.821 inches (NO GAP) Azimuthal Pattern at 216 MHz
enlarge 250KB, 794x1024 28 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 35 inches 3D View
enlarge 358KB, 1024x759 29 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 35 inches Front View [1 large square = 5 inches]
enlarge 88KB, 254x1024 30 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 35 inches Top View [1 large square = 5 inches]
enlarge 185KB, 1024x675 31 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 35 inches UHF Raw Gain = 17.3 to 20.1 dBi UHF F/B & F/R Ratio Minimum = 15.8 dB
enlarge 104KB, 327x1024 42 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 35 inches Side View [1 large square = 5 inches]
enlarge 171KB, 1024x675 43 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 35 inches Hi-VHF Raw Gain = 10.5 to 11.7 to 11.9 dBi Hi-VHF F/R Ratio = 11.6 to 14.9 dB
enlarge 102KB, 321x1024 63 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 51 inches Side View [1 large square = 5 inches]
enlarge 180KB, 1024x675 64 Horiz-Stack FF4 + VDAR (48" x 36") Stack Distance = 51 inches Hi-VHF Raw Gain = 13.5 to 11.4 dBi Hi-VHF F/R Ratio = 9 to 19 dB
