[opendtv] Re: '50s Gray-Hoverman TV antenna design

  • From: Richard Hollandsworth <holl_ands@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Sun, 6 Sep 2009 15:36:57 -0700 (PDT)

 Gain for the CM4221 4-Bay Bowtie is very broadband....BUT the Gain on Ch52-69 
is quite high,
at the expense of very low Gain on Ch14.  It also isn't all that good for 
Hi-VHF Ch7-13.

Recently, I found that Ken Nist's analysis (cm4221a.ez posted on HDTVPRimer) 
predicted
considerably more loss on Ch14 than my analysis using actual CM4221 
measurements on an old antenna.
Did Nist's measurements come off a different antenna????  Hard to say, since it 
is obvious he simply
took ONE-HALF of the cm4228a.ez 8-Bay model:
http://www.hdtvprimer.com/antennas/comparing.html

mclapp has analyzed a range of LARGER 4-Bay Bowtie antennas in order to improve 
performance
over the New UHF Band (Ch14-51), with moderate (or more) reduction on Ch52-69, 
as the size increases.

I just completed a comparison of mclapp's M4 (9.5x9.0) Super-4-Bay vs the 
(Actual) CM4221, found
under "Multi-Bay Antennas", along with comparisons of the M4, CM4221 and the 
notorious
UTube/MakeTV 4-Bay antenna with NO Reflectors:
http://imageevent.com/holl_ands
You can also see the Hoverman (per original Patent & w mods) and one of the 
better COMBO
Hi-VHF/UHF Grey-Hoverman designs with multiple NAROD (Not a Reflector or a 
Director)
resonators added to improve not only UHF but especially Hi-VHF performance....
and Chireix and Chireix-Mesny....and a bunch of Hi-VHF antennas....

Super-4-Bays, Super-8-Bays, Grey-Hoverman and other designs are being carefully 
designed to
extend UHF performance into the Hi-VHF band, as is discussed here:
http://www.digitalhome.ca/forum/forumdisplay.php?f=186
The "Area 51" thread has some especially interesting high-gain Diamond (e.g. 
Fracarro type), VQUAD,
Chireix (precursor to Hoverman) and Chireix-Mesny Arrays....

holl_ands

===================================================
--- On Thu, 9/3/09, Manfredi, Albert E <albert.e.manfredi@xxxxxxxxxx> wrote:

From: Manfredi, Albert E <albert.e.manfredi@xxxxxxxxxx>
Subject: [opendtv] Re: '50s Gray-Hoverman TV antenna design
To: opendtv@xxxxxxxxxxxxx
Date: Thursday, September 3, 2009, 12:14 PM

Cliff Benham wrote:

> Today, there is a great need for small, high gain TV
> antennas to receive OTA digital transmissions.
>
> An interesting UHF TV antenna design from the '50s is
> the Gray-Hoverman design.  A friend in FL built a
> single bay version of this with wire and a length of
> 1 x 4 inch wood without the reflector. It can be scaled
> to work at VHF.
>
> More information:

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

> Or, Google Gray-Hoverman.
>
> The antenna is installed in the vertical plane instead
> of being installed like a traditional horizontally
> mounted TV antenna.

Cliff, when I saw this, I thought "looks awfully similar to the Antennas
Direct DB4 or Channel Master 4221." And sure enough, check out the
performance comparison:

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

One thing to keep in mind, though, is that the Gray-Hoverman was retuned
for UHF channels only up to 51 or so, whereas the Channel Master 4221 is
evidently still set up through Ch 83. So just push the Channel master
curve a little to the left to see how a retuned design might compare.

The Antennas Direct DB4 is spec'ed out to Ch 69. So its curve may be
closer to that of the Gray-Hoverman.

Bert
 



      

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