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Hardware Hacking Media Television

Hobbyists Create GPLed DIY Super TV Antenna 185

Posted by ScuttleMonkey from the what-open-source-can-do dept.
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."
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Hobbyists Create GPLed DIY Super TV Antenna More

Hobbyists Create GPLed DIY Super TV Antenna

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  • Comment removed based on user account deletion

    • Re:How is this different than what hams have done? (Score:5, Insightful)

      by Anonymous Coward on Friday March 14, 2008 @04:52PM (#22755222)
      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 traditional way to design antennas is pretty old and relies on some pretty straight forward theory that has been around for a long time. All you need for a computer is s slide rule.

      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/ [otago.ac.nz] are using genetic algorithms link

    • Re: (Score:3, Informative)

      by NateTech ( 50881 )
      The ARRL Antenna Manual [arrl.org] is probably one of the longest-standing references for antenna and feedline theory.

  • Renewed niche for broadcast TV? (Score:5, Interesting)

    by timeOday ( 582209 ) on Friday March 14, 2008 @04:41PM (#22755130)
    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.

    • Re:Renewed niche for broadcast TV? (Score:5, Funny)

      by noidentity ( 188756 ) on Friday March 14, 2008 @05:36PM (#22755546)

      What makes broadcast relevant again is having the Internet to compliment it.

      The Internet loves to compliment things. Why yesterday, it was complimenting me on how well I was using its bandwidth.

    • Re:Renewed niche for broadcast TV? (Score:5, Interesting)

      by darjen ( 879890 ) on Friday March 14, 2008 @05:51PM (#22755620)
      Personally, I don't even bother paying for cable TV anymore. I have an early gen hdtv (at least 3 years old) that I use with a cheapo Radio Shack HD antenna. Gets me all the local HD channels. Before that I was paying an arm and a leg for HDTV from Time Warner. I also downgraded my internet to first tier, so now I pay only $15/month for that. Huge difference and great pictures. If I really want to watch something I can download it, but usually Netflix fills the gap for me. The time you speak of in the future is pretty much here for me.

    • Re: (Score:2)

      by SIGBUS ( 8236 )
      One thing that has received rather little attention is that DTV broadcasts can contain multiple subchannels. For instance, in Chicago, the local PBS affiliate (WTTW) has four DTV subchannels: one 720p HD that's dedicated exclusively to HD programming, along with their regular SD channel, and two extra SD channels.

      Unfortunately, they're the only Chicago station that's really taking advantage of this capability. I'd love to see ABC run ESPN on a subchannel, but that'll probably never happen unless enough peop
    • The future? Dude... the future must've begun in 2004.

  • Bandwidth (Score:5, Informative)

    by russotto ( 537200 ) on Friday March 14, 2008 @04:41PM (#22755140) Journal
    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.

  • model a better server (Score:5, Funny)

    by SoupGuru ( 723634 ) on Friday March 14, 2008 @04:41PM (#22755142)
    Maybe they should do some software-based computer modeling of their webserver...
    • Nah. Thats the normal /. Standing Wave coming into play.
      It sweeps all in its path like a Tsunami.
      Then after a period of total anihilation,
      things start recovering.

      Sounds Familiar eh?

      • Re: (Score:2)

        by Anpheus ( 908711 )
        Between your odd sentence structure and capitalization, I would like to remind you that when you say things like "sounds familiar, eh?" you should probably keep the reference you're making vague, subtle, clever, witty, or ironic. Not blatantly obvious.

        Because saying "sounds familiar" after using the word tsunami makes it a little obvious.

        Also, I think standing wave doesn't mean what you think it means.
  • I don't know what a "U.S. Government antenna engineer" is - but I want that job!

    • Re:I want that job! (Score:5, Funny)

      by jd ( 1658 ) <`imipak' `at' `yahoo.com'> on Friday March 14, 2008 @05:03PM (#22755300) Homepage Journal
      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.
    • I was essentially a Gov't Antenna Engineer for ~2.5 years. It isn't everything it's cut out to be. You do learn all the interesting uses that antennas are put to and the wide variety out there.

  • on that topic... (Score:3, Interesting)

    by eobanb ( 823187 ) on Friday March 14, 2008 @04:46PM (#22755176) Homepage
    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.
    • Comment removed based on user account deletion

      • Re:on that topic... (Score:5, Insightful)

        by Chris Pimlott ( 16212 ) on Friday March 14, 2008 @07:41PM (#22756508)

        Why not just download whatever you want to watch? Granted, I watch little television (usually just "Human Giant", "Lost" and "Prison Break"), but I can generally get a torrent for them from Mininova or The Pirate Bay. Maybe we should rejoice that with the Internet people are no longer slaves to the idiot box, and while we all want some mindless entertainment TV isn't worth going through too much effort for.

        Why not just download whatever you want to watch?
        Well, one reason might be that it is technically illegal...
        • Comment removed based on user account deletion

        • Re: (Score:3, Interesting)

          by powerlord ( 28156 )

          Why not just download whatever you want to watch?

          Well, one reason might be that it is technically illegal...

          Well that is only partially true.

          The GPs comment of:

          ... but I can generally get a torrent for them from Mininova or The Pirate Bay

          IS an illegal method.

          On the other hand, considering how fast new programming show up on iTunes and AmazonUnbox (not mentioning Hulu yet, since it isn't "Download" per se), there ARE often legal ways to down movies and television programming.

          In the past when I've had my cab

      • Re: (Score:3, Insightful)

        by witherstaff ( 713820 )
        Having been in the ISP field I have seen too many DMCA notices to not say - watch out for torrents. You can still get served simply because your IP is of the torrents in use.

        With that said, I'd suggest a good usenet service - avoid giganews - and a usenet tracker like newzbin.com. You can even SSL usenet nowadays. Safer, easier, and pretty darn easy. Of course, this is /., so you should already know about the wonders of usenet...

    • Re: (Score:3, Insightful)

      by Hatta ( 162192 )
      The only good broadcast TV is on PBS anyway, don't worry about it.
    • Is the independent station once broadcasting on channel 4 still in service? Their antenna tower was in Trafalgar, IN, which should be close enough to receive, given reasonable terrain.
    • but apart from that the nearest stations are all serving Indianapolis.

      I have been using a UHF yagi for quite a while. They are broad enough to pick up the lower UHF just fine and have a narrow beamwidth. If the stations you want to pick up are all clustered on a far hilltop, I have had great luck line of sight at 85 miles. Finding a UHF only yagi is a little hard, or build your own. The ARRL Antenna handbook is a great place to start.

      Here is a great article on fringe area UHF reception including some ext
    • up high in the clear with a good low-loss feedline. When I was a kid, we lived in the sticks. The nearest UHF channel was about 35 miles away. We got good reception from that as well as two stations that were about 50 miles away by having a 4 element bowtie antenna that was on a 30 foot guyed mast on top of a two story house. I figure 60 feet up. That was back in the days when the TVs used tubes!

      Try not to use the cheap old flat 300 ohm twinlead. It's pretty lossy at UHF frequencies. If you can get foam

  • For non DIYers (Score:3, Insightful)

    by fm6 ( 162816 ) on Friday March 14, 2008 @04:54PM (#22755244) Homepage Journal
    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.

    • Re: (Score:2)

      by Nimey ( 114278 )
      RTFS, dude. It says what you want to know right in the middle.

      • Re: (Score:3, Insightful)

        by fm6 ( 162816 )
        Read the post you're replying to, dude. I did notice that it was GPLed.

        GPL protects the plans. It doesn't stop me from selling old coathangers and calling them "Gray-Hoverman antennas." For that, you need trademark protection.

    • Re: (Score:2)

      by geekoid ( 135745 )
      If it doesn't work well, wouldn't that mean it wasn't built to the spec, and thus not be the same device?

      • Re: (Score:2)

        by fm6 ( 162816 )
        Yes it does. But if the name of the device isn't protected, then there's nothing to prevent every ripoff artist from building a sub-spec device and selling it as the real thing. Since these are always cheaper, they have a way of driving the real device off the market and giving it an undeserved reputation for being a POS.

    • Won't be a problem (Score:3, Informative)

      by pestie ( 141370 )
      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 c

      • Re: (Score:3, Interesting)

        by Mr. Roadkill ( 731328 )
        I'm no lawyer, and my understanding may be wrong. If it is, please tell me - I might be worried about nothing.

        Suppose the hypothetical AntennaCorp(TM), who have tons of design and manufacturing experience, choose to implement this design in a commercial product. They build good gear, not the cheapest but the quality is second-to-none and they've got some patented manufacturing processes and parts like the design of their baluns and mounting hardware.

        For obvious reasons, they want to protect their commercial
    • You can't copyright a useful physical object. There is not, and has never been, copyright protection for antennas, circuits, or anything like that. The only protection available is patents.

      This project has released their drawings and other artifacts under an open license. Unlike useful objects, drawings are automatically copyrighted by their creators, therefore a license is necessary to allow their full use by the community.
      • On the contrary, licenses are not required for copyrighted works. They are only required to distribute or copy them. The license is to allow us to modify, change, and redistribute the works.

        They could also have rendered the works into the public domain.

      • Re: (Score:2)

        by fm6 ( 162816 )
        Who said anything about a copyright?
    • 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.

      I would think the whole purpose of a GPL'ed design is to encourage "cheap knockoffs" i.e. competitition, so it will be less expensive for any of us to purchase. Now, it is certainly possible for one "knockoff" to be a lower quality than another, and even fraudulently claim to be one of these antennas but actually be something else, but in the end p

      • Re: (Score:2)

        by fm6 ( 162816 )

        but in the end product reviews and trusted brand names should sort it out

        Right, because the big brand names never sell crap.

        If anybody can sell a piece of wire and call it a "Gray-Hoverman antenna" then they'll do so. Competition is fine, but most of the big manufacturers compete on price, period. If you're not careful to restrict who can claim they're selling your invention, not only does the cheap crap own the marketplace, but it destroys the reputation for the real thing. That's why we have trademarks.

      • One other thing I wonder about is the following. Suppose a manufacturer makes an improvement to the design. This could be anything from a way to lighten the frame with the same strength to a cheaper-to-build design for a joint. Normally such incremental improvements would either be internal trade secrets or would be patented. Would the GPLed nature of the design prevent either of these from happening, so that any such incremental improvement to the design would be have to be made public and available to

    • Re: (Score:3, Insightful)

      by Jeff DeMaagd ( 2015 )
      It seems like Creative Commons non-commercial license should have been used if protecting their design was their intent.

      As they aren't trying to sell the antenna, its plans or the knowledge, I don't know if trademarks would do any good. Even if trademarks are enforced, does it really matter? People see "TV antenna" on the box and that's all they need to know. Heck, I didn't know there were proper names for specific antenna shapes until I got interested in playing with WiFi antennas. The general public i

  • Wireless TV! (Score:4, Funny)

    by frieza79 ( 947618 ) on Friday March 14, 2008 @04:56PM (#22755254)
    Wow, this new concept of wireless TV might just take off!

  • I'm sorry... (Score:3, Funny)

    by cloakable ( 885764 ) on Friday March 14, 2008 @05:04PM (#22755314)
    ...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?
  • Seriously, geeks will be geeks and find something to homebrew... But what's next? An open source buggy whip? A Franklin stove built using a Beowulf cluster of Commodore 64's to optimize the burning and thermodynamic characteristics?
    • I have trouble seeing why this is so important. Of course, since the site is slashdotted, I can't find out any gain numbers. This business of experimenting with antennas is very old hat, as is NEC.

    • Re: (Score:2)

      by geekoid ( 135745 )
      Yes, no one uses antennas for anything anymore~

      You fail in the imagination dept.
      • Maybe you've noticed that over the air TV broadcasts are essentially coming to an end in a few years?

        Or maybe you're too stupid to realize that performing extreme optimizations on one specific antenna design means jack point shit for other antennas?

        • Re:Next up: The open source buggy whip! (Score:4, Insightful)

          by evilviper ( 135110 ) on Saturday March 15, 2008 @02:11AM (#22758102) Journal

          Maybe you've noticed that over the air TV broadcasts are essentially coming to an end in a few years?

          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.

  • In an age of cable and satellite everything, it's often assumed that antennas are a thing of the past, or are limited to cheap Chinese rabbit ears.

    Think again. While living in Appalachian Kentucky we found that the Radio Shack FM antenna on the roof did an amazing job of pulling in radio stations. Some times the old tech is the best tech.

    • Re:Antennas rule (Score:5, Insightful)

      by zippthorne ( 748122 ) on Friday March 14, 2008 @06:11PM (#22755832) Journal
      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.

      • Re: (Score:3, Insightful)

        by Detritus ( 11846 )
        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.

  • The article (Score:4, Informative)

    by davidwr ( 791652 ) on Friday March 14, 2008 @05:29PM (#22755494) Homepage Journal
    Since it's heavily slashdotted, here is The Gray-Hoverman Antenna For UHF Television Reception [digitalhome.ca] as plain text

    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

    • Re: (Score:2, Informative)

      by davidwr ( 791652 )
      Designs, Schematics, And Diagrams
      http://www.digitalhome.ca/ota/superantenna/design.htm [digitalhome.ca]

      Text only, with Wikipedia Commons links to the designs but not real-world photos.

      Gray-Hoverman Antenna | Performance | Designs, Schematics, And Diagrams | Join the Digital Forum Discussion

      The Gray-Hoverman Antenna Designs, Schematics, And Diagrams
      The Gray-Hoverman antenna designs, schematics, and diagrams on this site are Copyright ©2008 and are free: you can redistribute them and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at our option) any later version.

      These designs, schematics, and diagrams are distributed in the hope that they will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

      For your complete copy of the GNU General Public License to go along with the designs, schematics, and diagrams, see www.gnu.org/licenses/gpl.txt.
      GPLv3

      Single Bay Gray-Hoverman Diagram Original Manuscript, Copyright ©2008:
      SBGH Image:HovermanDimensions.jpg [wikimedia.org]

      Double Bay Gray-Hoverman Diagram Original Manuscript, Copyright ©2008:

      DBGH Image:HovermanDimensions-2.jpg [wikimedia.org]

      Gray-Hoverman Construction Examples

      Photo of PVC-fabricated Double Bay Gray-Hoverman Designed and Built by DogT:

      DBGH Photo

      Photo of Light Weight, Flexible Single Bay Gray-Hoverman Designed and Built by Keo:

      DBGH Photo

      Gray-Hoverman Antenna Introduction
      Digital Home | Digital Forum | Over-the-Air (OTA) Digital Television Discussion Forum
      Copyright ©2008

    • Re: (Score:2, Interesting)

      by davidwr ( 791652 )
      Text of Gray-Hoverman Antenna Performance [digitalhome.ca].

      Sorry, no pictures this time. There are just too many. By tomorrow morning the site should no longer be slashdotted.

      The pictures are graphs showing this gets decent performance from about channels 14-62, with very good performance at about 34-54.

      Gray-Hoverman Antenna | Performance | Designs, Schematics, And Diagrams | Join the Digital Forum Discussion

      Gray-Hoverman Antenna Performance
      Seeing is believing, so let's examine some of the test result diagrams of Gray-Hoverman design variants, paired with similar class commercial-brand competitors for comparison. We've chosen as benchmarks the highly regarded Channel Master 4221 4-Bay Reflector UHF Antenna and its bigger sibling, the 4228 8-Bay Reflector UHF Antenna, which is generally considered to be the best commercially made consumer antenna available for reception in North America.

      As has been mentioned above, the North American spectrum of UHF Television channels will span 14 through 51 in the coming years. Thus, performance on channels above 51 was not deemed to be an important focus of our research and design resources.

      Single Bay Gray-Hoverman (SBGH) vs. Channel Master 4221 4-Bay Reflector UHF Antenna:
      SBGH vs. CM4221
      SBGH vs. CM4221
      SBGH vs. CM4221
      SBGH vs. Several Commercial UHF Antennas:
      SBGH vs. CM4221
      DBGH vs. CM4228:
      DBGH vs. CM4228
      Comparative EZNEC v3 Performance Plots:
      Left to Right: Original Hoverman, SBGH, CM4221
      Comparative Performance Plots
      Comparative EZNEC v3 Polar Plots:
      Comparative Polar Plots
      Comparative Polar Plots
      Comparative Polar Plots
      Comparative Polar Plots

      Next: Get the specifications for the Gray-Hoverman Antenna
      Digital Home | Digital Forum | Over-the-Air (OTA) Digital Television Discussion Forum
      Copyright ©2008

    • Re: (Score:3, Insightful)

      by dfn_deux ( 535506 )
      What this is article is clearly missing is construction directions and a BoM to make replication of their design possible without a background in the field of antenna design/construction. While I'm sure that their design works well for them. I don't see it being very useful to the average garage tinkerer to have this GPL'd without any sort of assembly/construction guidance. For something as fiddly as an antenna things like materials, construction techniques, connector positioning and design can make somethi

      • Re:The article (Score:4, Insightful)

        by Bobartig ( 61456 ) on Friday March 14, 2008 @06:25PM (#22755950)
        Yep. I was going to build to TONIGHT. I have to the tools, and I'm good with DIY projects and tinkering, but I don't know much about antennas. I don't know what metal to use for this, or how this connects to a piece of coax to plug into a tuner. It looks extremely simple, but some critical pieces are missing.

        • Re:The article (Score:4, Informative)

          by phil reed ( 626 ) on Friday March 14, 2008 @07:37PM (#22756476) Homepage
          Pretty much any stiff metal rod or wire will work for the elements. Use whatever's handy. Any metallic screen material will work for the backplane; try window screen or chickenwire. You connect to the center points with 300 ohm twinlead TV wire, then use a standard antenna-to-coax converter (both available at RatShack).

          • Re: (Score:2)

            by adolf ( 21054 )
            Are you sure?

            Last time I toyed with the idea of building an antenna, I was looking at constructing a Yagi (for one particular FM station about 95 miles away). All available information seemed to indicate that the diameter of the elements was not only important, but that different diameters required sometimes vast differences in the overall shape of the antenna.

            Now, of course, this isn't a Yagi.

            But what I really want to know is: Can I make this out of 12-gauge Romex and hang it from the ceiling? Because I

            • Re: (Score:2)

              by adolf ( 21054 )
              And now, I see that the antenna is supposed to be of vertical orientation. Doh! So I'll ask the same question, modified by 90 degrees and an additional quandary:

              Can I build this out of 12-guage Romex and hang it from an inside wall? Can I use that wall's screened metal lath as a reflector? (The other walls in line with the antenna's path are either wooden lath or gypsum -- thankfully, only 1/4 of the computer room serves as a Faraday shield.)

  • Haven't used a UHF antenna in 25 years, so the fact that anyone made one is a miracle in itself. U can make antennas more directional + high gain or less directional + lower gain, but anyone who can actually make antennas better deserves a BluRay player.

    • Re: (Score:2)

      by Detritus ( 11846 )
      You can get good gain in an omnidirectional antenna with a collinear design. The hitch is that it's vertically polarized.
  • Can you hear me now?

    Sorry I couldn't resist...

    Sheldon

  • Very nice work. These antenna designers have the enormous advantage of having antenna simulation software that runs on PCs. It's a problem where intuition isn't good enough, hand calculation involves oversimplification, and repeatable experimental work requires either an RF anechoic chamber or a big flat field in an RF-quiet area where you can transmit on the band in question. Antenna test ranges thus tend to be located in Outer Nowhere, and hams who do antenna development usually go to some isolated pl

  • How the hell do you rotate it? Those pictures looked like all the antennas were mounted on the side of a house. Also, what is its wind load if you put it up on a mast? Would it disintegrate with 60mph winds? As far as the rotation issue goes, rural people need it to orient the antenna's gain towards the station they want, and city people need to rotate it as well to get rid of ghosts caused by large buildings.
    • If you construct it with a pipe down the center, you can rotate it (a metallic pipe would reduce performance by not allowing you to use the split-reflector design, but PVC should work). Wind load would depend mostly on reflector construction.
  • ...which I built after reading through the AVS forums (iirc) on the subject, though it also shows up on lumenlabs forums and several other pages. Google DB4 DIY for hits. Its very directional, gives GREAT results, can be stacked with multiple "bays" and the design is very very similar to this hoverman design, the main difference at a glance is that the zig-zag elements in the hoverman are a single piece, whereas the DB4 style uses individual separate elements. I Built mine from scrap metal window screen as
  • My current antenna stinks, and since there's fears of a recession, I sure as heck won't plunk down for a dish right now :->

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