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 holl_ands | Home > Multi-Bay Bowtie Antennas > UHF 8-Bay Bowtie with Reflector > 
CM-4228a (Nist) If RF Combiner Mod
Old CM-4228 8-Bay Bowtie analyzed with 4nec2 with an RF Combiner Mod replacing the original Feedline between left & right bays.
Ken Nist's CM4228a.ez.nec file was modified, replacing the Feedline with a simple SOURCE wire at the center feedpoint on each 4-Bay stack.
This required the use of TWO "EX Cards" vice the usual one EX.  For SWR & Impedance measurements, one of the EX Cards must be disabled.

There is very little Net Gain difference up thru Ch51, considering AT LEAST an additional 0.5 dB loss in a typical RF Combiner, although the
RF Combiner Mod does provide 1 to 3 dB higher Raw Gain on the lowest channels and 1-3 dB more on the highest.
Even better performance should be expected when applied to larger, Super-Sized 8-Bay antennas as the Max Gain moves to a lower frequency.

If one of the Baluns is REVERSED, a DUAL BEAM pattern results, with each beam about 2.4-2.8 dB lower than a single beam and a NULL in between.

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.]
Date(s): 27 Mar 2010. Album by holl_ands. 1 - 22 of 22 Total. 928 Visits.
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CM-4228 8-Bay Bowtie - 3D View
RF Combiner Mod replaces Original Feedline.


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COMPARISONS - UHF Raw and Net Gain:
CM4228 w Combiner Mod, CM4228a Nist File,
mclapp M4 4-Bay (9.5x9.0) w 2" BowSwp & DblAnglRefl,
Kosmic SuperQuad (9.75x9.5 w 2" BowSwp & SnglAnglRefl.


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COMPARISONS - UHF F/R & F/B Ratios:
CM4228 w Combiner Mod, CM4228a Nist File,
mclapp M4 4-Bay (9.5x9.0) w 2" BowSwp & DblAnglRefl,
Kosmic SuperQuad (9.75x9.5 w 2" BowSwp & SnglAnglRefl.


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CM-4228 8-Bay Bowtie - Front View
RF Combiner Mod replaces Original Feedline.


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CM-4228 8-Bay Bowtie - Top View
RF Combiner Mod replaces Original Feedline.


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CM-4228 8-Bay Bowtie - Side View
RF Combiner Mod replaces Original Feedline.


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CM-4228 8-Bay Bowtie - UHF Raw Gain
RF Combiner Mod replaces Original Feedline.

NOTE: 4nec2 must have BOTH EX Cards enabled
to measure Gain, F/B and F/R.


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CM-4228 8-Bay Bowtie - UHF SWR (300-ohm)
RF Combiner Mod replaces Original Feedline.

NOTE: 4nec2 must have only ONE of the two EX Cards
enabled to measure SWR.


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CM-4228 8-Bay Bowtie - UHF Impedance
RF Combiner Mod replaces Original Feedline.

NOTE: 4nec2 must have only ONE of the two EX Cards
enabled to measure Impedance.


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CM-4228 8-Bay Bowtie - UHF Pattern at 470 MHz
RF Combiner Mod replaces Original Feedline


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CM-4228 8-Bay Bowtie - UHF Pattern at 584 MHz
RF Combiner Mod replaces Original Feedline.


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CM-4228 8-Bay Bowtie - UHF Pattern at 698 MHz
RF Combiner Mod replaces Original Feedline.


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CM-4228 8-Bay Bowtie - UHF Pattern at 470 MHz
RF Combiner Mod replaces Original Feedline.

Dual Beams (2.8 dB lower) when one Balun is REVERSED.


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CM-4228 8-Bay Bowtie - UHF Pattern at 584 MHz
RF Combiner Mod replaces Original Feedline.

Dual Beams (2.6 dB lower) when one Balun is REVERSED.


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CM-4228 8-Bay Bowtie - UHF Pattern at 698 MHz
RF Combiner Mod replaces Original Feedline.

Dual Beams (2.4 dB lower) when one Balun is REVERSED.


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CM-4228 8-Bay Bowtie - Hi-VHF Raw FORWARD Gain
RF Combiner Mod replaces Original Feedline.

NOTE: 4nec2 must have BOTH EX Cards enabled
to measure Gain, F/B and F/R.


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CM-4228 8-Bay Bowtie - Hi-VHF SWR (300-ohm)
RF Combiner Mod replaces Original Feedline.

NOTE: 4nec2 must have only ONE of the two EX Cards
enabled to measure SWR.


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CM-4228 8-Bay Bowtie - HiHF Pattern at 174 MHz
RF Combiner Mod replaces Original Feedline.


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CM-4228 8-Bay Bowtie - HiHF Pattern at 186 MHz
RF Combiner Mod replaces Original Feedline.


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CM-4228 8-Bay Bowtie - HiHF Pattern at 199.5 MHz
RF Combiner Mod replaces Original Feedline.


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CM-4228 8-Bay Bowtie - HiHF Pattern at 216 MHz
RF Combiner Mod replaces Original Feedline.


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DOC22
CM-4228 8-Bay Bowtie - 4nec2 File
RF Combiner Mod replaces Original Feedline.


 
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