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CM4228HD No Reflector + HHH (20 Oct 2015)CM4228HD with NO Reflector and HHH (Holl_ands Horizontal Harness) analyzed using 4nec2,
SAME version as OPTIMIZED earlier with 16 Reflector Rods. Note that HHH "Reflector" improves Forward Gain a bit.
UHF Raw Gain = 11.7 to 13.8 dBi, F/B & F/R Ratio = 1.6 to 0.4 dB and SWR (300-ohms) Under 2.8 (Good).
Hi-VHF Raw Gain = 3.6 to 5.1 dBi, F/B & F/R Ratio = 1.1 to 0.9 dB and SWR (300-ohms) Under 3.0 (a bit High). |
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New CM4228HD 8-Bay - If NO Reflector (28 Aug 2010)New CM4228HD 8-Bay Bowtie Antenna (If NO Relector for Bi-Directional pattern) analyzed using 4nec2.
Measurements taken directly from a newly delivered antenna.
Investigates UHF and Hi-VHF performance if a user decides to remove the Reflector.
A supporting structure would then need to be provided, such as using PVC pipes.
UHF SWR is Good, but Raw Gain is only 6 dBi on Ch14, climbing to about 11 dBi just below Ch51.
Hi-VHF SWR is Excessive, except above Ch10. Hi-VHF Gain is Good, except on Ch10.
NOTE: The Autosegment feature of 4nec2 was used to determine how many wire segments to use when modeling each wire element.
The choice of Autosegment=11 was very critical in getting the CM-4228HD Gain and SWR calculations to work AT ALL.
And small changes to Autosegment resulted in large changes in Hi-VHF Gain & SWR....so Hi-VHF might not be all that accurate. |
| 4527 Visits
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Old CM4228 8-Bay - If NO Reflector (17 Aug2009)Channel Master CM4228 8-Bay Bowtie (If NO Reflector) analyzed using 4nec2.
Ken Nist's cm4228a.ez file was revised, replacing long twinlead feed with a simple SOURCE wire.
Removing Reflector Screen makes it much easier to see antenna structure. |
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