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Discussion Starter · #1 ·
All gain figures are Net Gain in dBi, which is the default standard for computer design and modeling software.
Code:
Code:
Gain Figures For Similar Large-Sized UHF Antennas

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

14      10.00   13.15   12.50   11.00   14.34   14.93
19      12.00   13.75   13.70   12.00   17.17   15.63[B]^[/B]
27      14.00   13.85   14.50   13.50   17.83   16.40[B]^[/B]
35      15.50   13.05   14.40   14.20   18.26   16.77[B]^[/B]
43      15.70   13.25   12.00   15.00   16.53   17.07[B]^[/B]
52      15.00   13.85   10.50   16.00    8.92[B]*[/B]  17.25
60      14.00   13.85   10.00   16.60      NA   16.07
Notes:
  • CM4228 is the original Channel Master 8-bay bowtie reflector (data from HDTVPrimer site)
  • CM4228HD is the new Channel Master 8-bay bowtie reflector (data provided by CM to videobruce - a DHC member. Assumed to have been in dBd)
  • PR-8800 is an 8-bay bowtie reflector made by Winegard (data from HDTVPrimer site)
  • DB-8 is an 8-bay bowtie reflector made by Antennas Direct (data from HDTVPrimer site)
  • DBGH is a Double Bay Gray Hoverman (data from 300ohm - a DHC member)
  • * is the listed gain on Channel 51 (antenna not designed for 52 and higher)
  • M-8 is a DIY 8-bay 52x40 5 inch space angled Reflector & Elements 17in 450 ohm feed (data from mclapp - a DHC member)
  • ^ is the listed gain on the next highest channel since tables did not match all channels

The new Channel Master 4228HD is 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. The two Do-It-Yourself antennas (the DBGH and the M-8) are clearly in a league of their own.
 

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Discussion Starter · #2 ·
All gain figures are Net Gain in dBi, which is the default standard for computer design and modeling software.
Code:
Code:
Gain Figures For Similar Medium-Sized UHF Antennas

Channel  4221   4221HD  PR-4400  DB-4    SBGH    M-4

14       9.50   13.05    9.00    5.00   14.24    9.87
19      10.50   12.75   10.00    7.50   14.74   13.52[B]^[/B]
27      11.50   12.45   11.00   10.25   14.61   14.91[B]^[/B]
35      13.00   13.55   12.00   11.40   14.75   15.91[B]^[/B]
43      13.50   15.05   12.50   12.10   15.30   16.75[B]^[/B]
52      14.20   13.75   13.00   12.85   15.03   16.21
60      15.00   15.15   14.00   13.20     NA[B]*[/B]   13.85
Notes:
  • CM4221 is the original Channel Master 4-bay bowtie reflector (data from HDTVPrimer site)
  • CM4221HD is the new Channel Master 4-bay bowtie reflector (data provided by CM to videobruce - a DHC member. Assumed to have been in dBd)
  • PR-4400 is a 4-bay bowtie reflector made by Winegard (data from HDTVPrimer site)
  • DB-4 is a 4-bay bowtie reflector made by Antennas Direct (data from HDTVPrimer site)
  • SBGH is a Single Bay Gray Hoverman Gold Standard (GH10 data from j3d - a DHC member)
  • * antenna not designed for 52 and higher
  • M-4 is a DIY 4 Bay 40x44 14 inch Reflector spacing fwd ele & refl (data from mclapp - a DHC member)
  • ^ is the listed gain on the next highest channel since tables did not match all channels

As you can see, the SBGH takes the lower range handily, and the DIY 4-bay by mclapp easily pulls away in the mid to high range.
 

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Quote:
Originally Posted by stampeder /forum/post/15572579


All gain figures are Net Gain in dBi, which is the default standard for computer design and modeling software.
Code:
Code:
Gain Figures For Similar Medium-Sized UHF Antennas

Channel  4221   4221HD  PR-4400  DB-4    SBGH    M-4

14       9.50   13.05    9.00    5.00   14.24    9.87
19      10.50   12.75   10.00    7.50   14.74   13.52[B]^[/B]
27      11.50   12.45   11.00   10.25   14.61   14.91[B]^[/B]
35      13.00   13.55   12.00   11.40   14.75   15.91[B]^[/B]
43      13.50   15.05   12.50   12.10   15.30   16.75[B]^[/B]
52      14.20   13.75   13.00   12.85   15.03   16.21
60      15.00   15.15   14.00   13.20     NA[B]*[/B]   13.85
Notes:
  • CM4221 is the original Channel Master 4-bay bowtie reflector (data from HDTVPrimer site)
  • CM4221HD is the new Channel Master 4-bay bowtie reflector (data provided by CM to videobruce - a DHC member. Assumed to have been in dBd)
  • PR-4400 is a 4-bay bowtie reflector made by Winegard (data from HDTVPrimer site)
  • DB-4 is a 4-bay bowtie reflector made by Antennas Direct (data from HDTVPrimer site)
  • SBGH is a Single Bay Gray Hoverman Gold Standard (GH10 data from j3d - a DHC member)
  • * antenna not designed for 52 and higher
  • M-4 is a DIY 4 Bay 40x44 14 inch Reflector spacing fwd ele & refl (data from mclapp - a DHC member)
  • ^ is the listed gain on the next highest channel since tables did not match all channels

As you can see, the SBGH takes the lower range handily, and the DIY 4-bay by mclapp easily pulls away in the mid to high range.

None of your conclusions are not accurate.


The HDTVprimer data is dBd (not dBi). See link below.

http://www.hdtvprimer.com/ANTENNAS/comparing.html


dBd refers to the antenna gain with respect to a reference dipole antenna. A reference dipole antenna is defined to have 2.15 dBi of gain. So converting between dBi and dBd is as simple as adding or subtracting 2.15 according to these formulas:


* dBi = dBd + 2.15

* dBd = dBi - 2.15


Therefore 2.15 dB needs to be added to the antenna data form HDTVprimer.
 

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Quote:
Originally Posted by serndipity /forum/post/15586565


None of your conclusions are not accurate.


The HDTVprimer data is dBd (not dBi). See link below.

http://www.hdtvprimer.com/ANTENNAS/comparing.html


dBd refers to the antenna gain with respect to a reference dipole antenna. A reference dipole antenna is defined to have 2.15 dBi of gain. So converting between dBi and dBd is as simple as adding or subtracting 2.15 according to these formulas:


* dBi = dBd + 2.15

* dBd = dBi - 2.15


Therefore 2.15 dB needs to be added to the antenna data form HDTVprimer.

The HDTVprimer data chart shows "both" dBd & dBi. The left side is dBi, & the right side is dBd.
 

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Discussion Starter · #5 ·
Thanks for clarifying that, Digital Rules. I think he just misread things.
All of the data is in dBi, serndipity.


I also want to clarify that the antenna names M-4 and M-8 were made up by me to describe antennas designed by mclapp (a 4-bay bowtie reflector and an 8-bay, respectively) so if you're looking for info on how to build them you need to go to the How To Build A UHF Antenna thread:

http://www.avsforum.com/avs-vb/showthread.php?t=798265
 

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Stampeder,


It would be interesting to see antenna size specs (length and span width), f/b, and beam width on the various antennas.


Best,


Rick
 

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Discussion Starter · #7 ·
For comparison with a Corner Reflector Yagi here are the numbers on the Antennas Direct 91XG (data from HDTVPrimer site):
Code:
Code:
Channel     Net Gain dBi

14              11.50
19              12.00
27              13.40
35              14.40
43              14.95
52              15.60
60              16.60
You can see that the two Large DIY antennas (DBGH and M-8) smoke the 91XG, while the Small DIY antennas (SBGH and M-4) are equal or better to it. The 91XG fares well against the commercial Large-Sized antennas, but unfortunately it's strongest reception is on the channels that will be disappearing after the digital transition.
 

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Discussion Starter · #8 ·

Quote:
Originally Posted by IDRick /forum/post/0


It would be interesting to see antenna size specs (length and span width), f/b, and beam width on the various antennas.

The SBGH is comparable in size to the commerical 4-bay bowtie reflectors shown on the chart so it will fit in an attic if needed. The DBGH is really two SBGH's stacked (with some important differences) so size-wise it is definitely too large for an attic and is meant for fringe to deepest fringe reception up on a roof or tower.


All the measurement specs for the Generation 1 GH antennas are shown here:

http://www.digitalhome.ca/ota/superantenna/


The newer GH variants are works in progress but you can see their latest progress over at digitalhome.ca in the Antenna Research and Development forum.


The reflector sized of the M-4 and M-8 antennas are shown on the charts in the Notes sections. I don't have much other size Info on the mclapp antennas, but that can be found in the How To Build A UHF Antenna thread here at AVS.


cheers
 
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