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 holl_ands | Home > Multi-Bay Bowtie Antennas > UHF 8-Bay Bowtie with Reflector > 
CM4228HD with UHF Hollands Horiz Harness
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. 3994 Visits.
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CM4228HD with UHF Hollands Horiz Harness
3D View


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CM4228HD with UHF Hollands Horiz Harness
Front View
[1 large square = 5-inches]


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CM4228HD with UHF Hollands Horiz Harness
Top View
[1 large square = 5-inches]


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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


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CM4228HD with UHF Hollands Horiz Harness
UHF SWR (300-ohms) Under 2.3


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CM4228HD with UHF Hollands Horiz Harness
UHF Impedance


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CM4228HD with UHF Hollands Horiz Harness
Azimuthal Pattern at 470 MHz


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CM4228HD with UHF Hollands Horiz Harness
Azimuthal Pattern at 530 MHz


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CM4228HD with UHF Hollands Horiz Harness
Azimuthal Pattern at 590 MHz


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CM4228HD with UHF Hollands Horiz Harness
Azimuthal Pattern at 650 MHz


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CM4228HD with UHF Hollands Horiz Harness
Azimuthal Pattern at 698 MHz


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CM4228HD with UHF Hollands Horiz Harness
Azimuthal Pattern at 806 MHz


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CM4228HD with UHF Hollands Horiz Harness
Elevation Pattern at 470 MHz


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CM4228HD with UHF Hollands Horiz Harness
Elevation Pattern at 530 MHz


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CM4228HD with UHF Hollands Horiz Harness
Elevation Pattern at 590 MHz


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CM4228HD with UHF Hollands Horiz Harness
Elevation Pattern at 650 MHz


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CM4228HD with UHF Hollands Horiz Harness
Elevation Pattern at 698 MHz


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CM4228HD with UHF Hollands Horiz Harness
Elevation Pattern at 806 MHz


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Compare 8-Bay Antennas:
CM4228HD As Shipped
CM4228HD with RF Combiner Mod
CM4228HD with UHF Hollands Horizontal Harness


Enlarge Microsoft Word Document 20
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DOC20
UHF CM4228HD with UHF Hollands Horiz Harness
4nec2 File (incl. Python Control Script)


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CM4228HD with UHF Hollands Horiz Harness
Side View
[1 large square = 2.5-inches]


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CM4228HD with UHF Hollands Horiz Harness
Raw Gain, F/B & F/R Ratio vs Tine Separation
Wide Range: Up to 3 dB Variation
Optimizer does NOT choose Max Gain at 470 MHz


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CM4228HD with UHF Hollands Horiz Harness
Raw Gain, F/B & F/R Ratio vs Tine Separation
Mid-Range: Optimizer chose TineSep = 3.87-in


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CM4228HD with UHF Hollands Horiz Harness
Raw Gain, F/B & F/R Ratio vs Tine Separation
Narrow Range: NOTE DISAGREEMENT with Mid-Range View


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CM4228HD with UHF Hollands Horiz Harness
Raw Gain, F/B & F/R Ratio vs Bow Sweep
Wide Range: CM4228HD Model sets BowSwp=0.00


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CM4228HD with UHF Hollands Horiz Harness
Raw Gain, F/B & F/R Ratio vs Bow Sweep
Mid-Range: Over 1 dB Loss away from BowSwp=0.00


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CM4228HD with UHF Hollands Horiz Harness
Raw Gain, F/B & F/R Ratio vs Bow Sweep
Takes only +/- 0.02-in to Lose over 1 dB Raw Gain


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CM4228HD with UHF Hollands Horiz Harness
Hi-VHF Raw Gain = 4.3 to 12.9 dBi
Hi-VHF F/B & F/R: Narrow Dropoff near 196.5 MHz


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CM4228HD with UHF Hollands Horiz Harness
Hi-VHF SWR (300-ohms) = 14.2 to 9.8 to 61.9 is Excessive


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CM4228HD with UHF Hollands Horiz Harness
Hi-VHF Impedance


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CM4228HD with UHF Hollands Horiz Harness
Azimuthal Pattern at 174 MHz


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CM4228HD with UHF Hollands Horiz Harness
Azimuthal Pattern at 196.5 MHz
Bi-Directional over Narrow Freq Range


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CM4228HD with UHF Hollands Horiz Harness
Azimuthal Pattern at 216 MHz


Enlarge Microsoft Word Document 34
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DOC34
Hi-VHF CM4228HD with UHF Hollands Horiz Harness
4nec2 File (incl. Python Control Script)


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CM4228HD with Hollands Horiz Harness
3D View from REAR, with Reflector Removed


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CM4228HD with UHF Hollands Horiz Harness
3D View DETAIL from REAR, with Reflector Removed


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CM4228HD with UHF Hollands Horiz Harness
Front View, with Reflector Removed
[1 large square = 2.5-inches]


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CM4228HD with Hollands Horiz Harness
Top View, with Reflector Removed
[1 large square = 2.5-inches]


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CM4228HD with Hollands Horiz Harness
Side View, with Reflector Removed
[1 large square = 2.5-inches]


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CM4228HD with UHF Hollands Horiz Harness
Parameter Sweep at 470 MHz
Raw Gain vs Separation Between Harness Wires
[Optimum Gap = 2.22-in]


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CM4228HD with UHF Hollands Horiz Harness
Parameter Sweep at 470 MHz
Raw Gain vs Separation of Harness Wires
away from Plane of Bowties
[Optimum Xh = - 2.60-in]


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CM4228HD with UHF Hollands Horiz Harness
Parameter Sweep at 470 MHz
Raw Gain vs Length of Harness Wires
Parallel to Plane of Bowties
[Optimum Youter = Yinner = 10.8-in]


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43
CM4228HD with UHF Hollands Horiz Harness
Parameter Sweep at 470 MHz
SWR vs Separation Between Harness Wires
[Optimum Gap = 2.22-in]


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44
CM4228HD with UHF Hollands Horiz Harness
Parameter Sweep at 470 MHz
SWR vs Separation of Harness Wires
away from Plane of Bowties
[Optimum Xh = - 2.60-in]


Enlarge photo 45
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CM4228HD with UHF Hollands Horiz Harness
Parameter Sweep at 470 MHz
SWR vs Length of Harness Wires
Parallel to Plane of Bowties
[Optimum Youter = Yinner = 10.8-in]


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CM4228HD with UHF Hollands Horiz Harness
Parameter Sweep at 470 MHz
Raw Gain vs Radius of Harness Wires
[Assumed Rharn=Rfeed=0.059-in AWG10]


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CM4228HD with UHF Hollands Horiz Harness
Parameter Sweep at 470 MHz
SWR vs Radius of Harness Wires
[Assumed Rharn=Rfeed=0.059-in AWG10]


 
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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