Old CM4228 (holl_ands) analyzed using 4nec2 simulation, assuming the Horizontal Interconnect Harness is replace by a pair of Baluns (one to each 4-Bay) which are summed using an RF Combiner Module.
Measurements were obtained directly by holl_ands from an antenna purchased in 2005.
BowLength = 8.0-in, Bowtie Spacing = 8.0-in, Tine Separation = 5.25-in. Approx. AWG10 wire size (0.102" O.D.). Feedline Separation = 1.3-in, with 0.7-in Hop at Crossover. AWG12 wire size (0.088" O.D.). Center of Crossovers 2.1-in from Center of Outer Bowties. Left to Right Bay Separation = 20-in. Screen Reflector (36"H x 40"W), AWG12, 1"H x 2"W Grid. Separation from Bowties = 4.6-in (varies 4.5-4.75-in).
UHF Raw Gain Climbs from 13.5 to 17.5 dBi. UHF SWR is Very Good, although rises to 3.7 on lowest Ch14. Hi-VHF Raw Gain is Very Good (8.9 to 9.3 dBi), however SWR is Excessive except on Ch12 & 13.
NOTE: 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.]
EDIT (29Mar2013): Added ANOMALOUS plots versus Bowtie Tine Separation and Bowtie Forward Sweep, which can frustrate finding an "Optimum" set of dimensions. I believe that this is a 4nec2 Modeling anomaly, rather than inherent in old CM4228 design. It's unlikely Whisker movements of under 0.25-in result in significant Gain changes.
Date(s): 30 Aug 2010. Album by holl_ands. 1 - 23 of 23 Total. 3888 Visits.
enlarge 300KB, 927x1024 1 Old CM4228 (As Built) - 3D View
enlarge 322KB, 1024x807 2 Old CM4228 (As Built) - Front View [1 small box = 1-inch]
enlarge 71KB, 306x1024 3 Old CM4228 (As Built) - Top View [1 small box = 1-inch]
enlarge 147KB, 1024x648 4 Old CM4228 (As Built) UHF Raw Gain Climbs from 13.5 to 17.5 dBi.
enlarge 142KB, 1024x648 5 Old CM4228 (As Built) UHF SWR (300-ohm) is Good, climbing to 3.7 on Ch14.
enlarge 138KB, 1024x648 6 Old CM4228 (As Built) UHF Impedance
enlarge 206KB, 1152x678 7 Old CM4228 8-Bay Bowtie w RF Combiner Mod Raw Gain vs Bowtie Tine Separation HIGHLY ANOMALOUS RESULTS at 470 MHz
enlarge 225KB, 1152x678 8 Old CM4228 8-Bay Bowtie w RF Combiner Mod SWR (300-ohms) vs Bowtie Tine Separation HIGHLY ANOMALOUS RESULTS at 470 MHz
enlarge 264KB, 1152x678 9 Old CM4228 8-Bay Bowtie w RF Combiner Mod Impedance vs Bowtie Tine Separation HIGHLY ANOMALOUS RESULTS at 470 MHz
enlarge 176KB, 1152x678 10 Old CM4228 8-Bay Bowtie w RF Combiner Mod Raw Gain vs Bowtie Forward Sweep NORMAL RESULTS at 470 MHz
enlarge 204KB, 1152x678 11 Old CM4228 8-Bay Bowtie w RF Combiner Mod SWR (300-ohms) vs Bowtie Forward Sweep NORMAL RESULTS at 470 MHz
enlarge 251KB, 1152x678 12 Old CM4228 8-Bay Bowtie w RF Combiner Mod Impedance vs Bowtie Forward Sweep NORMAL RESULTS at 470 MHz
enlarge 302KB, 1024x1024 13 Old CM4228 (As Built) UHF Azimuthal Pattern on 470 MHz
enlarge 307KB, 1024x1024 14 Old CM4228 (As Built) UHF Azimuthal Pattern on 590 MHz
enlarge 307KB, 1024x1024 15 Old CM4228 (As Built) UHF Azimuthal Pattern on 698 MHz
enlarge 132KB, 1024x648 16 Old CM4228 (As Built) Hi-VHF Raw Gain is Very Good, climbing from 8.9 to 9.3 dBi.
enlarge 176KB, 1024x648 17 Old CM4228 (As Built) Hi-VHF SWR (300-ohm) Excessive except on Ch12 & Ch13.
enlarge 148KB, 1024x648 18 Old CM4228 (As Built) Hi-VHF Impedance
enlarge 309KB, 1024x1024 19 Old CM4228 (As Built) Hi-VHF Azimuthal Pattern at 174 MHz
enlarge 309KB, 1024x1024 20 Old CM4228 (As Built) Hi-VHF Azimuthal Pattern at 198 MHz
enlarge 312KB, 1024x1024 21 Old CM4228 (As Built) Hi-VHF Azimuthal Pattern at 216 MHz
enlarge 66KB, 312x1024 22 Old CM4228 (As Built) - Side View [1 small box = 1-inch]
enlarge 137KB, 791x1024 23 Old CM4228 (As Built) 4nec2 File
