HDTV antenna that can hang in a window

We can’t wait to give this one a try. We’ve got a DIY HDTV antenna hanging out in the attic which was made from some scrap wood and eight metal coat hangers. It works great but it’s pretty ugly and not everyone has an attic to hide it in (not to mention the signal drop caused by the roof shingles). This is a fractal antenna anchored to some clear plastic so you can just hang it in the window and start picking up the over-the-air channels without much effort.

The pattern was modeled in SketchUp then printed out on two pieces of paper. One piece had it printed on both sides, which makes it easy to glue on a sheet of aluminum foil, then follow the pattern on the opposite side to cut out the important parts. The other template was used as an aligment guide when gluing the foil to the clear plastic. A coaxial adapter was then attached using nuts and machine screws. If you build it, let us know how it comes out!

Comments

  1. Baz says:

    I wonder if running it through a plastic pouch hot laminator work just as well as glueing to a sheet of thin plastic?

  2. Rob says:

    I used a single paperclip to get HD OTA. I get quite a few channels. I think it’s time to upgrade!

  3. No One says:

    Does anyone have any links on the theory and design of fractal antennae? I’d be interested in seeing if a more complex fractal would be helpful or not and whether you could create three or more and make a cylinder of them to get a wider reception area. I had problems with how directional I had to get when using my HDTV antenna before I returned it.

    • echodelta says:

      You must be dealing with different directions and don’t want to get a rotor or just need one of those flying saucer shaped antenna for urban use only. I took one apart and it has crossed bent dipoles. 2 sets, the VHF set would not do TV6 at all. This was before the fractal craze. Nonetheless this omnidirectional antenna is ripe for the fractal design.

  4. Rocco says:

    Just a thought. Instructions suggest double side printing the fractal. One side so you know where to glue other side so you know where to cut. I just realized a single sided print with the aluminum foil attached to the non printed side will as well.

    • GZ says:

      My thought as I was reading this. Might have to try this for the heck of it.

    • HTPC-DIY says:

      @Rocco,

      You could print it just on one side but I found it easier to have the pattern on both sides when using the glue I was using. If you’re using a spray adhesive it doesn’t matter.

      @charles,

      The adhesive on most foil tapes is non-conductive from what I understand. I added a link to the instructions for a copper tape I found with conductive adhesive. It’s not too expensive but aluminum foil is something most people will already have and you don’t have to worry about connections as it’s all one continuous conductor.

  5. tony says:

    I built this and it worked really well when paired with an LNA. http://www.qsl.net/va3rr/hdtv/HDTV.htm

    I used copper tube for the booms, brass rod for the elements, and nylon spacer for keeping the booms separated. Everything was soldered together with a balun at one end.

    There are some handy on-line calculators for building custom LPDA antennas as well. The LPDA works best for rural locations as it is highly directional. Point it at a single urban area where the Tx antennae are located. If you are in a city, a non directional antenna is best.

    Be careful when buying the amplifier. You need a low noise one or some of the lower level signals will get lost in the noise the amplifier introduces. I followed some recommendations over at AVS forum and bought a Winegard. I was more than pleased with the results. The crap Home Depot and Lowes sell is useless. Those are more for increasing the number of cable drops in your house.

    If you are close enough to the source(s), an amp might not be necessary.

    • tony says:

      Just read this at wikipedia:

      “The first fractal ‘antennas’ were, in fact, fractal ‘arrays’, with fractal arrangements of antenna elements, and not recognized initially as having self-similarity as their attribute. Log-periodic antennas are arrays, around since the 1950s (invented by Isbell and DuHamel), that are such fractal arrays”

  6. HTPC-DIY says:

    @Mike,

    Thanks for posting this. It’s an honor to be on hackaday :)

    @Baz,

    Putting the foil between laminated sheets would be a good idea. I wanted to pick up some sheets that could be laminated with an iron but I didn’t want to run out to buy anything special to make it.

  7. rectifier says:

    Really a lovely antenna, but can we just start calling these “UHF antennas?”
    HDTV is no different from any old UHF signal… if you already have a UHF yagi there is no reason to build a “HDTV” antenna…

    This is a neat antenna though and I don’t know much about fractal antennas so it could be a fun build to try out. Any idea on gain figures?

  8. fartface says:

    No! it’s a special HDTV antenna and it’s specially designed for COLOR and STEREO! If you hang it right you can get 5.1 surround sound!

  9. n0lkk says:

    I’m certainly no expert on antennas, but I’m pretty sure a “HDTV antenna” doesn’t exist, just a marketing term like “color TV antenna”. In markets where there are no HDTV broadcasts, and DTV share the airwaves with the reaming low power analog UHF stations it’s simply a TV antenna.No doubt this can improve reception, “fractal antenna is becoming a misused term as well. My opinion based on what little hobbyist level information I can find on fractal antennas Unless a horrible mismatch is created simply putting up random lengths of length and shapes of metal in the air can improve reception. This is a dipole with elements shaped to look like fractal antennas based on images found on the web. Dipoles have a characteristic impedance of around 75 ohms, so the balun used could introduce some signal loss. No doubt this has nulls of the ends of the elements, In UHF TV reception the trick has always been getting lucky enough to get the lobes of the transmitting antenna to line up with the lobes of the receiving antenna. Anyway doesn’t cost much to try, and could be worth the effort, if you aren’t in a fringe area. BTW Mike S. that’s the first I read of roof shingles being a problem TV reception.

  10. Pouncer says:

    Just use aluminum duct tape, or foil tape(available at most hardware stores), and cut it out with an exacto-knife. no gluing, or printing required.

  11. Maave says:

    Neato. I just started making a TV antenna (cheapo made from a hanger). I was thinking of making a Gray-Hoverman but if I have some plastic lying around I’ll make one like this first.

  12. kabukicho2001 said, says:

    See too: A simple helix antenna directly connected to the rf input ***simple helix 4 turns wifi antenna the ground is the pc case. – YouTube http://bit.ly/LvdjyS

  13. echodelta says:

    Fractal simply makes the dipole smaller while keeping it’s effective length the same, I think. Making the antenna smaller makes it intercept less cross-sectional area of signal. That is why a big HF beam that an old school ham uses, works with such weak signals. So less is less. If you need the small size and have medium to local range go ahead. This is a 2 bay downsized. The classic 4 bay UHF array is the best bang for the effort. It goes up by the powers of 2, some hams work moonbounce with monster arrays. Get the tape out or print up one of those. Copper tape is used by art glass crofters, big box hobby store good bet. Aluminem however you say it, foil may rot quickly in weather and even window use. It’s the surface that conducts here and it can’t be crinkled over itself. Better to get the copper foil and solder perfect joints. Conductive adhesive is for permanent placement seals, and should not be considered for a soldering substitute. It probably will rot in time and fail as a conductor at UHF.

    • Whatnot says:

      Bigger also means the material has to have low-loss to work best.

      As for aluminium rotting.. I don’t know what industrial area you live in but you best get the hell out of there :)

  14. nimitzbrood says:

    Okay here’s a silly question – they sell foil laser printer overlays for things like certificates and such. In theory couldn’t you print one of those with the design on one side then laminate it?

    Not sure how conductive that is but in theory it should work just fine.

    Or here’s one even better – use one of the foil overlays on a laser-safe clear transparency sheet. That would be the best for simple window-pane hanging.

    And you could even get it in different colors!

    • HTPC-DIY says:

      That’s what I was hoping I could do but I contacted one of the manufacturers of those types of foils and they told me the foils aren’t real metal and are non conductive. I think they’re actually some sort of plastic.

      Real copper or gold leaf might work but you still have to lay out the glue carefully or cut out the shapes.

      Transulcent PCB sheets aren’t all that cheap and I haven’t seen any that were completely transparent.

  15. Vlad says:

    I have built this antenna, tested it and found it quite ineffective. I’ll try the Gray-Hoverman design next.

  16. bunnyhero says:

    have you compared the performance of this to, say, just a plain old sheet of tinfoil of that size? i’m just curious!

  17. waooooo………great invention!!!

  18. computothought says:

    Looks like a combination of Ruckmans Antenna (Instructables) and mine that I made back in 2011. http://www.instructables.com/id/Foil-based-fractal-antenna/

  19. Robert says:

    UHF TV Band is 400MHz to 900MHz so it is a vide band. It isn’t any mgic antena to provide you a high gain and a steady 50 ohm impedance for this range. Using transmission lines and impedance matching transformers you create a filter that affect anything higher or lower than 4 times the length of transformers. Most UWB antenas use a 1:1 balun or conect the coaxial cable direct at antenna with an air space 1/10 inch for all UHF Band with a gain around 6db. More common are biconical and horn antennas. Logperiodic antennas are wideband but 2 to 3 elements works for a specific frequency. The shorter elemen is half wave length of higher ftrequency and the larger element related to the lower frequency. There are Hybrid LOGPERIODIC ANTENNAS bur they cost $10000 and still don’t do miracles. The preferred range of signal at TV input is 0.2 – 1mV for digital and 1-11mV for analog.

  20. robert says:

    An antenna resonates in a certain frequency band, and doesn’t make any difference if the information is modulated analog, digital, encoded or whatsoever. Electricity inside antenna oscillates cloning the electromagnetic RF field. Could you please tell us in what frequency band your antenna resonates, the vsrw value for this band, and the antenna gain for this band?
    I copied a UHF wideband 470MHz to 770 MHz antenna, with VSRW less than 2 and the maximum gain 4dbi. I copied a VHF / UHF quad antenna for the bands 144, 220 and 430 MHZ with gain 6 dB with 3 separate feeding lines with VSRW less than 2. I constructed a copy of Dual Band DK7ZB 144 / 430 MHz yagi antenna with gain 9 to 10 dBi, MAX SWR 1.5:1 but you have to tune all antennas with a digital SWR meter for the band 200 MHz to 1GHz that isn’t cheap or at least rent one, and tell us the tell story of your antenna.

  21. Brad says:

    This worked quite well. Better than a few store bought ones I tried.

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