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Hobbyists Create GPLed DIY Super TV Antenna
Freshly Exhumed writes "Retired and hobbyist antenna engineers working together in the Digital Home forums have taken an obscure 1950s UHF TV antenna called the Hoverman [PDF] and subjected the design to modern software-based computer modeling in hopes of optimizing its middling performance. The result: the new Gray-Hoverman antenna is more powerful than similar commercially manufactured consumer antennas in every category, sometimes by whopping amounts. Best thing yet: they've released the design, diagrams, and schematics under the GPLv3 so that we can roll our own! Quoth one of the testers, a former U.S. Government antenna engineer: 'Boy, this antenna is hot... This antenna is a vast, and I mean REALLY VAST improvement over anything I have used.' The home thread of the Gray-Hoverman development gives the background of their great work."
Just a few years ago I thought broadcast TV and "rabbit ears" were pretty much gone forever. Now, broadcast TV is often the best quality high-def signal available. What makes broadcast relevant again is having the Internet to compliment it. With cable TV you get something like 120 channels, which is both too many to flip through, yet not enough to get whatever you want whenever you want it. I think a great combination in the future will be Broadcast TV for shows with huge audiences (like football and network news) plus Internet for pre-recorded stuff people want on demand.
The main reason the original Hoverman died out was that the bandwidth was not enough to cover the UHF (Ch 14-83) spectrum. This new variant appears to mainly improve on it by shifting its limited bandwidth down. The difference nowadays is that with the 700 and 800 Mhz bands removed from the spectrum used for TV, the basic Hoverman design DOES have the bandwidth to cover it, at least starting next year for "in-core" channels in the US.
Maybe they should do some software-based computer modeling of their webserver...
What doesn't kill you only delays the inevitable
I will be living in a new duplex soon in Bloomington, IN where I can receive the nearby PBS station, WTIU quite easily, but apart from that the nearest stations are all serving Indianapolis. That's around 50 miles away, so I am wondering if an antenna like this would make it possible to receive several more stations. Keep in mind that I need reception to be very good or excellent...we a matter of months away from the analogue switch-off now.
I have seen various antennas capable of pulling stations from a good distance away, maybe 20 miles or more, but depending on weather and other factors they can come in pretty fuzzy. When NTSC's gone I want a solution that will work. Has anyone here played with antennas like these? I couldn't really find anything that gave the approximate range on the site.
Take off every sig. For great justice.
This is a specific variation of the Hoverman antenna. The first original achievement is the specific design, which would be enough justification for an article on its own. I'm not an expert on the history of antenna design so I can't vouch for that.
The second and more important achievement is that the designers tried to verify the design of this antenna analytically using relatively new methods. The computational power needed to do this didn't emerge until after this kind of small antenna was no longer in vogue. As you probably know, about half of what hams say about antennas and interference is "black magic." The kind of hands-on techie who turns into a ham tends to be more like MacGuyver and less like Bertrand Russell.
Why would the existence of antenna design as a discipline imply that no new designs are possible?
The server is Slashdotted, so I can't find out what legal protection this new antenna has. I hope it has some protection against cheap knockoffs. Most people aren't going to want to build this themselves, and will want to buy a factory-made version.
The Hoverman-Gray is described as "GPLed". If that's the only legal protection it has, then I predict a lot of cheap knockoffs that don't work very well. Some trademark protection (with free licenses for anybody who agrees to follow the spec) would be nice.
Wow, this new concept of wireless TV might just take off!
They are auctioning off the frequencies used by 18 UTF channels, leaving 38. Most HDTV programming is delivered by UTF.
For years, the aliens that land in Area 51 have had to make do with cheap, low-grade bobble antennae sticking out of their heads, which is very disconcerting when they run for Congress. The job of a Government antenna engineer is to design antenna that better blend in with the Congressmen's hairstyles, pointed ears, etc. This is why you don't see them any more.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
...but this is obviously impossible. Nobody creates something new, then gives it away for free, that's why we need copyrights.
Or could that tired old argument just possibly be wrong?
No tyrant thrives when every subject says no.
You've been watching the teletubbies, haven't you :o)
Open Source Drum Kit, LPLC deve board - mjhdesigns.com
Performance and Designs, Schematics, and Diagrams to follow as they become available.
Gray-Hoverman Antenna | Performance | Designs, Schematics, And Diagrams | Join the Digital Forum Discussion
The Gray-Hoverman Antenna For UHF Television Reception
March 13, 2008
This project is dedicated to Doyt R. Hoverman (b.1913), the man who created and did the early work on the Hoverman antenna at a time when antenna modeling programs did not exist. His work would have been entirely created and improved by field testing, trial and error, and with a great amount of calculation without the benefit of electronic devices. Without his efforts, our work would not have been. Doyt Hoverman passed away in December, 1989 at Van Wert, Ohio, USA.
First, A Bit About The Original Hoverman Antenna
Doyt R. Hoverman's original design for a television antenna was granted US patents #2918672 on 22 Dec 1959 and #3148371 on 8 Sept 1964, which expired in 1979 and 1984 respectively. To view them, click on this link and then simply enter the patent number mentioned above to retrieve each.
In his patent applications, Hoverman describes two designs with 4 rod reflectors, full wavelength and co-linear half-wavelength reflectors, with the second design using the following specifications:
* Driven array = 56" dual segments with 8 subsections of 7" (same as the first design)
* Reflector spacing = 3.5"
* Full Wavelength Reflectors:
o Top and bottom = 29"
o The two middle = 24"
* Half Wavelength Co-Linear Reflectors
o Top and bottom = 14"
o The two middle = 10"
The above dimensions are for reception of UHF channels ranging from 14 to 35, as claimed in the patent. He gives design equations for shifting the range, and suggests 35-58 and 58-83, although the range 58-83 is not applicable now as UHF TV channels in North America only go to 69, and after 2009 will only go to 51.
The original Hoverman antenna design did not have a reflector and used a driven array of 56" segments with eight zig-zag 7" sub-elements. The original patent # 2918672 claimed UHF and VHF reception. The modeling results did not find any positive net gain for VHF Low channels 2-6 nor for VHF High channels 7-13.
There is very little information available anywhere on the Hoverman antenna. The only reference to any commercially manufactured Hoverman antennas seems to be in the article (PDF) The Hoverman, VUD Sept 1982, which mentioned a 4 bay Hoverman made by AntennaCraft named the model G-1483 and which was also made for Radio Shack as the model 15-1627, seen in this photo courtesy of tvlurker:
Radio Shack Hoverman
Some of these commercially manufactured Hoverman variants used 7 pairs of collinear rod reflectors. Judging from the AntennaCraft and Radio Shack websites and many Internet searches those Hoverman models do not seem to be currently in manufacture, although it seems that old stock of the AntennaCraft Super-G 1483 is or was available from SummitSource.com.
Recent Research On The Hoverman
Canadian antenna buff Autofils, speculating in an online discussion of Build It Yourself Antennas on the Digital Home web site in early 2008 on the possibility of experimenting with the old Hoverman Antenna design, sought out old sparks, another Canadian antenna enthusiast, who used 4NEC2 computer antenna modelling software to model the original Hoverman design. His research showed that the Hoverman had p
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
What's amusing, (and not in a funny-haha sense, but more in a funny-smell sense), is all the new antennas out there advertising that they're somehow "digital" antennas as if the mode affects antenna performance. I suppose they *could* be optimized for the smaller bandwidth somehow, but that's not how they're being advertised. It's not as if your 17 element beam on the roof is going to suddenly start working worse than an indoor loop-antenna.
Can you be Even More Awesome?!
Even if someone does begin marketing these commercially, I don't see "cheap knock-offs" being a problem. It doesn't cost anything more to manufacture one of these with the correct dimensions (which is pretty much what determines its performance) than to make one with the wrong dimensions. The only thing that would likely make an antenna "cheap" in this sense is purely mechanical - inability to hold up in high winds, or to the sun's UV (I've seen some TV antennas with plastic components that were literally crumbling due to long-term UV exposure).
Check out this antenna: http://uhfhdtvantenna.blogspot.com/
It has gotten some interesting write ups and looks similar in many ways to the new hoverman.
Actually it's 37 UHF channels, because channel 37 is reserved for radio astronomy. And 2-13 are still available, but 2-6 are not very good for ATSC. So that leaves 44-49 channels.
However, unlike NTSC, ATSC tolerates broadcasting on adjacent channels (other than the gaps at 4-5, 6-7, and 13-14), and is more tolerant of distant stations on the same channel, so it uses the spectrum more efficiently. In the past, you could have no more than 35 channels in any given market, and now you can have at least 40.
#naabhaprzrag, #sverubfr-000, #agi-fcbafberq, negvpyr[pynff*=' negvpyr-ary-'] { qvfcynl: abar !vzcbegnag; }
Oops, I forgot about the "UHF taboo" limitations of channels n+14 and n+15 (and sometimes n-7), due to the way UHF tuners usually do IF. Apparently those are still a problem with ATSC, but less so than with NTSC.
#naabhaprzrag, #sverubfr-000, #agi-fcbafberq, negvpyr[pynff*=' negvpyr-ary-'] { qvfcynl: abar !vzcbegnag; }
So, what about VHF? I realize the majority of DTV broadcasts are UHF, but a few are in the VHF range.
Ugh, it's research time. As I understood it, all VHF is going away. There is some VHF DTV now so studios can get DTV stuff tested and ready for the transition. When the switch is flipped, the analog UHF stations will go away and the VHF DTV stations will move to UHF. Does anybody know for sure? Investing in VHF antenna stuff may be a waste of resources.
Does anyone know the plan? Will there be any VHF DTV after the analog switch-off?
The truth shall set you free!
The bandwidth isn't any smaller, it's still 6 MHz. What has changed is the improved resistance to interference. That allows more stations to fit in the same band, with less spectrum wasted on protecting stations from interference.
Mea navis aericumbens anguillis abundat
See above, these guys know what they're talking about.
But, (obligatory), if you don't trust them, you can always:
1) Hit ctrl-alt-delete twice really fast and you'll unlock article-reply feature!
2) Alter windows to allow article replies by deleting C:/Windows/System32/*.dll
3) Your modem isn't fast enough. Open your computer, remove the modem, and lubricate it with vaseline to help reduce packet friction.
+5, Truth
There are a number of stations broadcasting in VHF DTV presently, and there will be quite a few more post-Feb09 transition. Several VHF stations will retake their VHF frequency for DTV. The biggest reason to go to VHF is that it needs substantially less power to cover a certain number of square miles.
Very few stations, though, will be in the low-VHF ranges (channels 2-6). Ignition noise, lightning, etc, are big problems in low-VHF. Those frequencies covered a lot of ground for the watt, even with more interference in that band. But, the errors are generally too much for digital reception, so there aren't but a dozen or so low-VHF digital transmitters now. I expect that 30 MHz will eventually be repurposed.
But, high-VHF (RF channels 7-13) is probably with us for quite a while.
Modern model-based antenna design is a lot different and a lot more challenging. For example, building a 5-band antenna for a cell phone defies straight forward dipole etc design. People are increasingly doing very different stuff. For example, the guys over at http://www.physics.otago.ac.nz/ are using genetic algorithms linked with an electromagnetic modelling package to design antennas. Some of the shapes look pretty wierd.
Engineering is the art of compromise.
Actually, I've noticed exactly the opposite.
* Many more homes will be able to receive an OTA signal, that previously could not.
* Digital broadcasts will offer perfect reception, eliminating much of the need for cable/sat.
* OTA HDTV will offer the highest quality picture anyone can get.
* OTA ATSC offers the potential for more TV channels than an expensive subscription service (50*6 = 300), in addition to other informational services.
* Rising prices and horrendous support will push people away from cable/satellite.
* Proprietary STBs and feet-dragging on CableCard will push even more people away from cable/sat.
* DVR technology will eliminate the need for syndication, and there the business model for 90% of cable/satellite networks will fail.
* The quality of original programming on cable/satellite networks has dropped SEVERELY, anyhow.
* Pop-up ads on cable/sat networks (largely not found on broadcast) will push even more people away.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
The ARRL Antenna Manual is probably one of the longest-standing references for antenna and feedline theory.
+++OK ATH