New CM4228HD with simple user mods analyzed using 4nec2.
a) RF Combiner Mod plus Squeeze Bowtie Tine Separation down from 4.75 to 2.0-in, which improved lowest frequency Gain by 0.75 dB compared to just RF Combiner Mod. Minor SWR increase from 3.6 to 3.9.
Charts do NOT include RF Combiner Loss, which is "typically" 0.5 to 1.5+ dB, see: www.antennahacks.com [Back-To-Back Combiner Loss - divide by two.]
###################################################### b) Enclosed Bowties: Vertical Wires interconnect Tips of Whiskers.
Raw Gain on lower channels was significantly improved, at the expense of a large Gain Hole on the upper channels. Hi-VHF performance was unstable, with a large Gain Hole in the middle of the Band and AGT correction problems, so there is considerable uncertainty in the Hi-VHF Gain charts.
Nikiml's Python Optimization Scripts should be run to improve on these imperfect results, finding the "best" Whisker Length, Tine Separation and Bowtie "Shape", whether Indented, Triangle or Pointed ("Outdented?).
Date(s): 6 Jan 2011. Album by holl_ands. 1 - 42 of 42 Total. 4122 Visits.
enlarge 229KB, 1024x976 1 CM4228HD - RF Combiner Mod and Tine Sep.=2-in 3D View
enlarge 275KB, 1024x851 2 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Front View
enlarge 74KB, 291x1024 3 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Top View
enlarge 142KB, 1024x907 4 CM4228HD - RF Combiner Mod and Tine Sep.=2-in UHF Raw Gain Some improvement (14.0 dBi) on lowest Freq
enlarge 161KB, 1024x907 5 CM4228HD - RF Combiner Mod and Tine Sep.=2-in UHF SWR (300-ohms) Under 3.9 Some degradation on lowest Freqs
enlarge 123KB, 1024x816 6 CM4228HD - RF Combiner Mod and Tine Sep.=2-in UHF Impedance
enlarge 265KB, 1024x1024 7 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Azimuthal Pattern at 470 MHz
enlarge 299KB, 1024x1024 8 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Azimuthal Pattern at 530 MHz
enlarge 270KB, 1024x1024 9 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Azimuthal Pattern at 590 MHz
enlarge 272KB, 1024x1024 10 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Azimuthal Pattern at 698 MHz
enlarge 271KB, 1024x1024 11 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Azimuthal Pattern at 758 MHz
enlarge 273KB, 1024x1024 12 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Azimuthal Pattern at 806 MHz
enlarge 134KB, 1024x811 13 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Hi-VHF Raw Gain FORWARD (90-deg)
enlarge 181KB, 1024x799 14 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Hi-VHF SWR (300-ohms) Excessive on Lower Channels
enlarge 148KB, 1024x799 15 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Hi-VHF Impedance
enlarge 301KB, 1024x1024 16 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Azimuthal Pattern at 174 MHz
enlarge 300KB, 1024x1024 17 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Azimuthal Pattern at 198 MHz
enlarge 301KB, 1024x1024 18 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Azimuthal Pattern at 216 MHz
enlarge 44KB, 791x1024 19 CM4228HD - RF Combiner Mod and Tine Sep.=2-in 4nec2 File for UHF Band (Only)
enlarge 48KB, 791x1024 20 CM4228HD - RF Combiner Mod and Tine Sep.=2-in 4nec2 File for Hi-VHF Band (Only)
enlarge 77KB, 316x1024 21 CM4228HD - RF Combiner Mod and Tine Sep.=2-in Side View
enlarge 233KB, 992x1024 22 CM4228HD - Enclosed Bowties 3D View
enlarge 301KB, 1024x899 23 CM4228HD - Enclosed Bowties Front View [1 large square = 5 inches]
enlarge 73KB, 273x1024 24 CM4228HD - Enclosed Bowties Top View [1 large square = 5 inches]
enlarge 207KB, 1152x689 25
enlarge 198KB, 1152x689 26
enlarge 253KB, 1152x689 27
enlarge 296KB, 1024x1024 28
enlarge 296KB, 1024x1024 29
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enlarge 312KB, 1024x1024 33
enlarge 223KB, 1152x689 34
enlarge 209KB, 1152x689 35
enlarge 249KB, 1152x689 36
enlarge 301KB, 1024x1024 37
enlarge 299KB, 1024x1024 38
enlarge 299KB, 1024x1024 39
enlarge 48KB, 791x1024 40 CM4228HD - Enclosed Bowties 4nec2 File for UHF Band (Only)
enlarge 48KB, 791x1024 41 CM4228HD - Enclosed Bowties 4nec2 File for Hi-VHF Band (Only)
enlarge 85KB, 337x1024 42 CM4228HD - Enclosed Bowties Side View [1 large square = 5 inches]
