Hi-VHF & UHF COMBO CM4228HD with Holl_ands Horizontal Harness (HHH) Mod and various other Modifications Re-Optimized to improve SWR in Hi-VHF Band, using nikiml's Python Optimization Scripts and EVAL Function to Calculate "Best" Performance.
There are significant Hi-VHF improvements over AS-SHIPPED CM4228HD version plus HHH [Jun2014 Version]: 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. Hi-VHF Raw Gain = 4.3 to 12.9 dBi and SWR (300-ohms) = 14.2 to 9.8 to 61.9 is Excessive. For details: http://imageevent.com/holl_ands/multibay/8bayrefl/newcm4228hdwithhollandshorizharness
Four Alternatives were considered. Overall, (d) was BEST with (c) NEXT BEST, with significant reduction in Hi-VHF F/B Ratio. Version (b) was also Very Good, except for DEEP DIP in Hi-VHF F/R Ratio on Ch10/11:
Detailed Dimensional Drawings for HHH Versions are at bottom of this Webpage. Note that CM's Original PCB (Printed Circuit Board) Balun is UHF-ONLY and MUST BE REPLACED with a conventional, cylindrical 300:75-ohm Transformer Balun, which passes both Hi-VHF and UHF.
a) Re-Optimize HHH Dimensions as well as Tine Separation (TS), because it's easy for user to change:
UNSTABLE and VERY BAD ANYWAY....so will NOT Post.
====================================== b) Re-Optimize HHH Dimensions as well as Tine Separation (TS) and Reflector-to-Bowtie Separation (RS):
Good Overall Performance, except for Deep DIP in Hi-VHF F/R Ratio Performance on Ch10/11: UHF Raw Gain = 15.2 dBi +/- 0.2 dB, F/B & F/R Ratio Minimum = 18.6 dB and SWR (300-ohms) Under 2.1. Hi-VHF Raw Gain = 8 dBi +/- 1 dB, F/B & F/R Ratio Minimum = 5.6 dB and SWR (300-ohms) Under 1.6. Hi-VHF F/B & F/R Ratios = 13.6 to 20 dB EXCEPT on Ch10 they dive to only 5.6 dB.
====================================== c) Re-Optimize HHH Dimensions as well as Tine Separation (TS), Reflector-to-Bowtie Separation (RS) and Wider Reflector Rod Width (+/- Yrod):
UHF Raw Gain Slightly Better than other Versions and Hi-VHF Raw Gain is Second Best: UHF Raw Gain = 15.5 dBi +/- 0.8 dB, F/B & F/R Ratio Minimum = 17.5 dB and SWR (300-ohms) Under 2.1. Hi-VHF Raw Gain = 8.5 dBi +/- 0.5 dB, F/B & F/R Ratio Minimum = 11.7 dB [Moderate] and SWR (300-ohms) Under 1.3.
====================================== d) Re-Optimize HHH Dimensions as well as Tine Separation (TS), Reflector-to-Bowtie Separation (RS) and Overall Reflector Rod Length (+/- Yrod) for ALTERNATING Reflector Rods:
UHF Raw Gain Slightly Better than other Versions and Hi-VHF Raw Gain and F/R Ratio are BEST: UHF Raw Gain = 15.4 dBi +/- 0.6 dB, F/B & F/R Ratio Minimum = 17.0 dB and SWR (300-ohms) Under 2.7. Hi-VHF Raw Gain = 8.6 dBi +/- 0.3 dB, F/B & F/R Ratio Minimum = 17.5 dB [Very Good] and SWR (300-ohms) Under 1.7.
UPDATE (19Mar2017): Uploaded Performance Comparison Charts, incl. Minor Updates to TS+RS Version uploaded earlier, New Images and HHH Dimensional Drawings for two "BEST" Hi-VHF + UHF Versions.
UPDATE (20Mar2017): Uploaded Dimensional Drawing for Alt(b).
Date(s): 5 Feb 2017. Album by holl_ands. 1 - 28 of 28 Total. 2513 Visits.
enlarge 228KB, 1024x696 1 H+U CM4228HD+HHH Alternatives Compared UHF Raw Gain
