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Hot Find: The Gray-Hoverman HDTV OTA Antenna

post #1 of 27
Thread Starter 
Found this on Canada's Digital Home Forum. Sounds like a great DIY project for a "better than commercial" antenna.

http://www.digitalhome.ca/content/view/2462/206/
post #2 of 27
Today the Gray Hoverman build-it-yourself antenna has been improved yet again, this time with a huge jump in VHF-HI gain to make it an excellent post-transition broadband OTA antenna for channels 7 to 51.

http://www.digitalhome.ca/forum/showthread.php?t=81982
post #3 of 27
I just built one of these designs as well. it works very well and is extremly cheap/ easy to make!
post #4 of 27
Quote:
Originally Posted by stampeder View Post

Today the Gray Hoverman build-it-yourself antenna has been improved yet again, this time with a huge jump in VHF-HI gain to make it an excellent post-transition broadband OTA antenna for channels 7 to 51.

http://www.digitalhome.ca/forum/showthread.php?t=81982

Hey stampeder,

Sorry for being slow here... But, is the direct link to the new version with high vhf + uhf capabilities?

thanks.
post #5 of 27
The Gray Hoverman design is based on the Hoverman patents but we are waaaaay past that into a range of performance that beats any comparable commercial antenna (the SBGH smokes the CM4221, the DBGH smokes the CM4228) and any other DIY antenna project of similar requirements.
Code:
Gain Figures For Similar Antennas

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

14      10      11.2    12.5    11      14.24   14.34
19      12      11.6    13.7    12      14.74   17.17
27      14      11.7    14.5    13.5    14.61   17.83
35      15.7    10.9    14.4    14.2    14.75   18.26
43      15.7    11.1    12      15      15.30   16.53
52      15      11.7    10.5    16      15.03    8.92*
60      14      11.7    10      16.6      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 made by Winegard (data from HDTVPrimer)
* DB-8 is 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 for Channel 51 (antenna not designed for 52 and higher)

The announcement I made earlier today is about a new variant of the SBGH and DBGH antennas that also get great VHF-HI gain. It isn't on this table.
post #6 of 27
Quote:
Originally Posted by IDRick View Post

Hey stampeder,

Sorry for being slow here... But, is the direct link to the new version with high vhf + uhf capabilities?

thanks.

No problem, IDRick, I should have posted that you can find the parts and cut list as well as the latest threads here:

http://www.digitalhome.ca/forum/forumdisplay.php?f=186
post #7 of 27
Thanks stampeder, very interesting!
post #8 of 27
Quote:
Originally Posted by stampeder View Post

The Gray Hoverman design is based on the Hoverman patents but we are waaaaay past that into a range of performance that beats any comparable commercial antenna (the SBGH smokes the CM4221, the DBGH smokes the CM4228) and any other DIY antenna project of similar requirements.[code]Gain Figures For Similar Antennas

The resized 4 bay and 8 bay DIY antennas are of comparable gain if not 1 db more than the GH and DBGH on UHF with a wider band width and 1 - 5 db more across the VHF-HI even including the recent VHF-HI improvements to the GH.
post #9 of 27
Mclapp, are your gain measurements in dBi or dBd?

Thanks, Rick
post #10 of 27
IDRick,
The computer modeled stuff is in dbi net gain

Here is an excel chart with some numbers for some computer modeled DIY collinear antennas, there is a early design GH in the chart which has been improved upon a few db since I made this chart but those numbers have been posted earlier in this thread. http://www.frontiernet.net/~mclapp/A...re11-23-08.xls

The GH is a really great design, the driven element is easy to build and pretty forgiving. The new VHF-HI computer modeled performance is yet to be proven in the real world but sounds good. To say it beats all designs especially when it's based on computer modeling and comparisons to published manufacturer data which we have no real idea how it was measured is a bit mis-leading.

I know from my semi controlled field testing that the computer models are good for a base line but the as built performance doesn't follow the computer modeling exactly and usually the peaks and valleys in the gain curves are shifted by different amounts depending on the quality of workmanship and materials used in the build.
post #11 of 27
Mclapp, I was thinking of this plot (see attached). The units are labeled as dBd. This graph represents your field testing of various designs, correct? I like this one because the 10" by 9.5" mclapp with a 4 inch reflector spacing is included...

Thanks!
LL
post #12 of 27
Quote:
Originally Posted by IDRick View Post

Mclapp, I was thinking of this plot (see attached). The units are labeled as dBd. This graph represents your field testing of various designs, correct? I like this one because the 10" by 9.5" mclapp with a 4 inch reflector spacing is included...

Thanks!

That chart was in dbd since it was the result of field testing where I used a series of folded dipoles as reference points. Keep in mind that the GH in that test was a generation 1 design with the narrower feed point and a split screen reflector. Computer models show the gh-10 and others to be 1-3 db better depending on frequency than the gen 1 design, I didn't have a newer version to test so that's what I used.

I don't know if it would be fair to just add 1 - 3 db to the field test numbers to represent the newer generation GH. What I've learned while doing field testing about the difference between computer modeled numbers and field testing would steer me away from that, but I'm sure that the numbers would be higher.

If you take the excel sheet computer generated numbers and the field test numbers you will see what I mean about slight differences in the gain curves.
post #13 of 27
Quote:
Originally Posted by IDRick View Post

Mclapp, I was thinking of this plot (see attached). The units are labeled as dBd. This graph represents your field testing of various designs, correct? I like this one because the 10" by 9.5" mclapp with a 4 inch reflector spacing is included...

Thanks!

A little off topic, but what surprised me was how well the Winegard 4 bay was across the band. You never hear anyone raving about that compared to 4221 or DB4, but those tests look impressive.
post #14 of 27
Quote:
Originally Posted by Piggie View Post

A little off topic, but what surprised me was how well the Winegard 4 bay was across the band. You never hear anyone raving about that compared to 4221 or DB4, but those tests look impressive.

The HDTV Primer modeling shows the actual 4-bay Winegard (which I think has 8" elements, not 8.5", but I could be wrong) as being about 1dB inferior to the CM4221 across the band.
post #15 of 27
Quote:
Originally Posted by Piggie View Post

A little off topic, but what surprised me was how well the Winegard 4 bay was across the band. You never hear anyone raving about that compared to 4221 or DB4, but those tests look impressive.

If you're looking at the field test data that I published, the Winegard style antennas were not made by winegard but were DIY antennas rescaled and modified off of the winegard design. They use flat metal elements like winegard does instead of whiskers. It would be interesting to see how an actual winegard pr4400 would perform under those same conditions.

I probably shouldn't have named them that way on the chart but thats what I called it for my own use when I did the testing. I should have probably called it a flat element 4 bay or something like I did in other tests.

Yes we're a bit off topic but I wanted to clear that up so no one was mis-lead
post #16 of 27
mclapp my apologies for not being up to date on your data. We haven't seen you much on the other forum lately, but in all cases accurate data is essential and I will do my best to integrate your results into comparisons.

Which set of data would you prefer that I use (chart, text file, NEC file, etc.)?
post #17 of 27
Quote:
Originally Posted by stampeder View Post

mclapp my apologies for not being up to date on your data. We haven't seen you much on the other forum lately, but in all cases accurate data is essential and I will do my best to integrate your results into comparisons.

Which set of data would you prefer that I use (chart, text file, NEC file, etc.)?

The only data I have that would be the same as what you are using now would be the excel spread sheet data I posted earlier in this thread. It has the computer modeled net gain data which is the same type of data as you use for the GH and HDTV primer commercial antenna comparisions.

I'm there almost every day I try to only throw my 2 cents in if I got something.
post #18 of 27
Quote:
Originally Posted by mclapp View Post

Yes we're a bit off topic but I wanted to clear that up so no one was mis-lead

When you answered I realized it was not as far off topic as I thought. Had I not asked I would have walked away thinking you found something I didn't know about their commercial antenna. Thanks for clarifying.
post #19 of 27
Quote:
Originally Posted by mclapp View Post

The only data I have that would be the same as what you are using now would be the excel spread sheet data I posted earlier in this thread. It has the computer modeled net gain data which is the same type of data as you use for the GH and HDTV primer commercial antenna comparisions.

Got it - thanks! I'll work on an updated comparison asap.
post #20 of 27
I built the original SBGH for indoor test purposes, except with 32” wide foil reflector. I modified it later with a .1 inch reflector gap and 95mm center array separation. (The .1 was controllable since it was glued to cardboard supports.) The first version had wood for element support and connections, and a front vertical center wood member for the wood support attachments. The second version eliminated the front vertical member and the supports were placed on plastic. The new version also had Plexiglas for washers except for the feed point. Heads of the bolts were placed outward and nut/washers on the back side.

Guess what? Performance went down. Just trying to figure out why! The 32” is a change from the 30” specified but the 44 to 95mm change is about a 2" increase and it was 32” before the change also. So should reflector be wider than 30”. Are the array and reflector gap changes additive? I have checked the foil gap and it is not touching.

The second build is not even as good an antenna as my Winegard PR-4400. The performance was worst on analog and on most digital stations except for channel 33. I could tell it had a narrow beam width and had to be aimed very accurately to get anything. Probably something else, but initially I saw a vertical line in the picture that I had not seen before. I tried it with two different balun’s one of them being the original one, but no change.

So what to do? Back up and punt? Quit on it? Get Cable? Turn on the radio! I was going to try to build and outdoor DBGH but that’s on hold till I can get a good SBGH somehow!

Just for your info the SBGH and the PR-4400 is both getting VHF-hi stations fine here. But they are local and have super strong signals.
post #21 of 27
Quote:
Originally Posted by abutterf View Post

Found this on Canada's Digital Home Forum. Sounds like a great DIY project for a "better than commercial" antenna.
http://www.digitalhome.ca/content/view/2462/206/

i'm glad u made note of this antenna project, abutterf....i found that forum last year and made a very simple 'indoor for attic mount' version of it (using no reflector elements or screen, just 2 coat hanger wires, a small piece of wood and a $2 '75 to 300 ohm' matching transformer)....it works great from inside my attic and it feeds 4 tv's in my house with no amplifier! i was amazed! and all my digital signals are well above the minimum needed for my dtv converter boxes except for one dtv station on vhf channel 3...it does work for this channel but just barely ....but thats ok because they are moving to a vhf high band channel in june, which i think will work well then....

it does not work very well on analog tv signals tho....mostly because of ghosting/multipath problems but that seems to have zero effect on the digital signals.....and thats all that counts since most analog will be gone by june...

i mentioned it here on avs months ago in a few posts i made on different threads but no one had any questions or made any comments about it whatsoever so i figured no one was interested...

i am only about 10 miles from most of my local tv station transmitters (one uhf is 33 miles away and it comes in well too) but i am guessing this antenna would work well in an attic (or out-of-sight in a closet, under a couch, behind a cabinet, etc) for most people up to maybe 15 or even 20 miles away....

heres what i did if anyone wants to try to make one for themselves ...theres a link to a pic of this antenna to show u what youre trying to create....its not my pic but what i built is identical to this pic...its very easy to make >

http://www.avsforum.com/avs-vb/showt...=#post15077171
post #22 of 27
Quote:
Originally Posted by pm3839 View Post

i mentioned it here on avs months ago in a few posts i made on different threads but no one had any questions or made any comments about it whatsoever so i figured no one was interested...

I've happened upon several postings about the GH antenna, and it sounds like it beats most other UHF designs. However, there seems to be some disagreement about the spacing of the active elements, and there has also been talk about some tweaks to increase VHF reception, so I've been kind of playing the waiting game to see how things shake out.

I'm not much of a do it yourselfer, so I don't want to have to build several versions to find out which one is best. Also, Antennacraft is supposed to be coming out with a new GH design soon, so I've also been curious to see what they come up with and how much it costs.

I guess the thing that's been holding me back the most is the fact that I haven't seen any mounting strategies that appeal to me for the homemade GH. I mean the antenna design itself is cool, but you are kind of left on your own to come up with a way to mount it that works for you. What I would like to find is a plan for a free standing indoor mount that includes the VHF tweaks, but I haven't found it yet, so I wait.
post #23 of 27
pm3839
Quote:


i mentioned it here on avs months ago in a few posts i made on different threads but no one had any questions or made any comments about it whatsoever so i figured no one was interested...

Just because we don't post an answer right away doesn't mean we are not interested. Your post adds to the knowledge bank.
What we really like to sink our teeth in is a new answer to an old problem or the challenge of a new problem.
post #24 of 27
300 ohm: I could use some help on selecting the best gray hoverman from all the choices. From what i seen, the original with about 95mm center spread of the array and .2 inch screen reflector gap or the array for the gen2 rev 2 Gh10 array with a screen reflector gives the best gain. The rod reflector Z axis offsets looks like they would too difficult to build. Have some 3/8 rods form an old antenna but guess I will use 1 by 2 grid.
Which of these is the best? Is there a gain curve comparing these?

Now looking at building an outdoor SB and DB for local and fringe reception. Appreciate the help.

mclapp: I was noting my PR4400 phasing line. They look like they are within a 1/4" of metal for the whole length. Wonder how they get away with this and it sure seems to be a good antenna. I looked carefully at your 10 by 9.5 design. Good work!
post #25 of 27
Quote:
Originally Posted by Rick313 View Post

... Antennacraft is supposed to be coming out with a new GH design soon, so I've also been curious to see what they come up with and how much it costs.

Hey, Rick: You really don't need to wait for the U4500. AC has been making them exclusively for Summit Source:

G1483

Stacked G1483

Super G 1483
post #26 of 27
Quote:
Originally Posted by Don_M View Post

You really don't need to wait for the U4500.

Yeah, I know. I've thought about ordering the G1483, but I am curious to see what, if any, improvements are incorporated into the U4500. I wish they would at least publish the specs.
post #27 of 27
Quote:
Originally Posted by pittmanthomas View Post

mclapp: I was noting my PR4400 phasing line. They look like they are within a 1/4" of metal for the whole length. Wonder how they get away with this and it sure seems to be a good antenna. I looked carefully at your 10 by 9.5 design. Good work!

Thanks, I modeled the phase lines as close as 1/2" to a metal back bone and it showed only minor interaction didn't try any closer. I've made some antennas with the flat elements like the PR4400 with good success they seem to have better band width on VHF-hi than the whisker style.

I wonder if anyone has tested near by metal objects with the G-H antenna. I built a G-H with a metal pole going right up the middle between the elements and split screen reflector and it worked well. I ran a computer model of it before I built it and it showed that it should be OK.
For construction purposes it might be interesting to know how close a metal support could be to the driven elements of a G-H.
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