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post #96 of (permalink) Old 2009-01-09, 08:22 PM
stampeder
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Join Date: Jan 2005
Posts: 24,879
CM's quoted gain figures converted to dBi for comparison

Here's what the comparison looks like if we assume that the CM4228HD numbers are in dBd units and convert them to dBi units:
Code:
Gain Figures For Similar Antennas

Channel  4228   4228HD  PR-8800  DB-8    GH10    DBGH

14      10.00   13.35   12.50   11.00   14.24   14.34
19      12.00   13.75   13.70   12.00   14.74   17.17
27      14.00   13.85   14.50   13.50   14.61   17.83
35      15.50   13.15   14.40   14.20   14.75   18.26
43      15.70   13.25   12.00   15.00   15.30   16.53
52      15.00   13.85   10.50   16.00   15.03    8.92*
60      14.00   13.85   10.00   16.60      NA      NA
Notes:
  • CM4228 is the original Channel Master 8-bay bowtie reflector (data from HDTVPrimer)
  • CM4228HD is the new Channel Master 8-bay bowtie reflector
  • PR-8800 is an 8-bay bowtie reflector made by Winegard (data from HDTVPrimer)
  • DB-8 is an 8-bay bowtie reflector made by Antennas Direct (data from HDTVPrimer)
  • GH10 is a Single Bay Gray Hoverman Gold Standard (data from j3d)
  • DBGH is a Double Bay Gray Hoverman(data from 300ohm)
  • * is the listed gain on Channel 51 (antenna not designed for 52 and higher)
So if Channel Master's quoted gain figures are in dBd, when we convert to dBi their new 4228HD is still outclassed by all the other antennas in the chart in most of the UHF spectrum. It is not a bad antenna; it is just an also-ran.

Here's a comparison of VHF-HI performance between the original CM4228 and the CM4228HD:
Code:
Channel         4228(dBi)       4228HD(dBi)

 7              2               6.75
 9              6               7.45
11              7               6.85
13              7               5.55

Last edited by stampeder; 2009-01-10 at 01:08 PM.
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