New CM4228HD (8" Whiskers x 8" Spacing) with Hollands Horizontal Harness (HHH) replacing the Original Harness analyzed using 4nec2. Dimensions of HHH OPTIMIZED using nikiml's Python Control Scripts were the WIDTH of the Feedline and X-Axis SEPARATION from the Center of the Bowties, similar to 2x2 4-Bay (H4) as well as the Vertically Stacked 4-Bay Antenna designs.
Optimized Dimensions: Xh = - 2.60-in = Separation between Feedlines and Center of Bowties. Diagonal Wire Lengths, Harness to Feedline = 3.18-in (Top-Left & Bottom-Right) AND = 2.84-in (Bottom-Left & Top-Right). Yinner = 10.80-in = Y-Axis Distance from Harness to INNER Bowtie Feedline (Top-Left & Bottom-Right). Youter = 10.85-in = Y-Axis Distance from Harness to OUTER Bowtie Feedline (Bottom-Left & Top-Right).
[Since difference of +/- 1/8-inch won't make much difference in performance, can round Harness Wire Half-Lengths to 8.75-in and Diagonal Wire Lengths to 3.0-in, demonstrating there was no need for separate SYmbols.]
UHF Raw Gain = 15.0 to 14.9 to 16.5 dBi, F/B & F/R Ratio Min = 19.1 dB and SWR (300-ohms) Under 2.3. These are significant improvements over the AS-SHIPPED CM4228HD version.
Hi-VHF Raw Gain = 4.3 to 12.9 dBi and SWR (300-ohms) = 14.2 to 9.8 to 61.9 is Excessive.
PS: Views with Reflector Removed are included to facilitate seeing the HHH. Note that Optimizer determined Harness Wire Lengths, rather than constraining them to be 1/2 the Bay Separation, as presumed in some OTHER HHH designs.
===================================================== Parametric Sweeps (Calculate/Start Optimizer in 4nec2) were used to investigate sensitivity to changes in HHH Dimensions (see Images 44+).
Raw Gain and SWR were very insensitive to changes in either Gap, Xh, Youter=Yinner or Rharn with only a few tenths of change to SWR and only a few tenths of a dB change to F/B & F/R Ratios over the fairly wide range of HHH dimensions tested.
===================================================== ERRATA (12Jul2014): Typo found in above text (HHH Diagram showed correct values). Yinner = Youter = 10.8+ inches (NOT 8.8-in).
EDIT (12JUL2014): Added Parametric Sweeps to investigate HHH sensitivity to changes.
EDIT (5Apr2016): Added missing (2.84") Dimension for Upper Left Short Diagonal Wire in HHD Dimensional Drawing.
EDIT (20Mar2017): Added Tine Separation to HHH Dimensional Drawing. Added "UHF" to Labels to emphasize that THIS HHH Version was Optimized for UHF-ONLY, to differentiate from newer Hi-VHF/UHF HHH's.
EDIT (3Apr2017): Added Elevation Pattern Charts showing NULL at about 40-45 degrees.
Date(s): 26 May 2014. Album by holl_ands. 1 - 47 of 47 Total. 4636 Visits.
enlarge 206KB, 1024x1015 1 CM4228HD with UHF Hollands Horiz Harness 3D View
enlarge 270KB, 1024x817 2 CM4228HD with UHF Hollands Horiz Harness Front View [1 large square = 5-inches]
enlarge 74KB, 288x1024 3 CM4228HD with UHF Hollands Horiz Harness Top View [1 large square = 5-inches]
enlarge 175KB, 1024x675 4 CM4228HD with UHF Hollands Horiz Harness UHF Raw Gain = 15.0 to 14.9 to 16.5 dBi UHF F/B & F/R Minimum = 19.1 dB
enlarge 184KB, 1024x675 5 CM4228HD with UHF Hollands Horiz Harness UHF SWR (300-ohms) Under 2.3
Great Work ! I am going to try it as I get CH 25 RF 572-578 Mhz and Ch 38 620-626 Mhz breaking up mostly. Hope the increased gain with the UHF Only Harness solves my problem. I also intend to use a N1201SA Vector Impedance Meter to see the impedance. I have a feeling it is 150 Ohms rather then 300 OHms in said case two quarter wave RG63 125 Ohm Coax (accounting for Velocity Factor) will make a 2:1 Balun or I will use a CM0089 Balun that I have. - Howard | www.fcc1.biz, Mon, 11 Mar 2019 4:24PM
Great stuff here, holl_ands. Thanks for sharing it with folks! Lots of *great* work here!!!! - Intheswamp | www.beeweather.com, Wed, 18 Oct 2017 3:50PM