Small Antenna With High Gain

Discussion in 'Digital Over the Air Television Talk By RabbitEars' started by rogerduncan100, May 1, 2011.

  1. rogerduncan100

    rogerduncan100 Thread Starter Active SatelliteGuys Member

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    Is there such a thing?

    I am looking into Yagis and Log Periodics for picking up WNGS channel 7, 80 miles away. The design software spits out antenna lengths of 12 to 15 feet for this wavelength but I really don't want something so big.

    Does anybody know of a type of antenna that will give something like 12 dBi gain in a smaller package, like 5 feet long?

    My intuition is that the physics involved make it impossible but I would love to be proven wrong!

    Regards:)
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  2. Mike500

    Mike500 Active SatelliteGuys Member

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  3. No Static At All

    No Static At All Active SatelliteGuys Member

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  4. No Static At All

    No Static At All Active SatelliteGuys Member

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    The shortest antenna that I know of that provides around 12 dbi gain is the Winegard YA-1713 at 8.3 feet. To get up to 13 dbi gain the size goes up a lot more. Unfortunately you can't fight the laws of physics when dealing with fringe VHF.
  5. Iceberg

    Iceberg We're here....RUN!!!! Supporting Founder

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    thats the antenna I use for a distant VHF and it works great :)
  6. Don_M

    Don_M Member

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    One antenna fits within your dimensional requirements: AntennaCraft's Y5-7-13. (Winegard's competing model, YA-6713, has been discontinued.) The Y5 will only get you to maybe 9 dBi of gain, which is about half of what you seek. Therefore, you'll need to deploy other strategies for getting that last three dBi:

    More height above ground level. The classic rule of thumb is that every additional 3 metres of height is worth about another decibel of gain. This factor can be dependent on the intervening terrain, and occasionally, more height doesn't help at all. (On the bright side, this isn't usually the case in flat areas such as the Toronto-Buffalo lake plain.)

    Different location on the roof. Signals have horizontal-plane "hot spots" whose sizes vary inversely with increasing frequency. In other words, you can move a UHF antenna several centimetres laterally to find (or lose) a hot spot, but it can take a couple of metres, or more, to achieve the same effect in mid-VHF frequencies such as channel 7. This strategy will require quite a bit of experimentation. Translation: You'll likely be up on the ladder and/or roof repeatedly.

    Use a Jointenna or signal injector with the dedicated VHF antenna. The antenna will pick up signals from many other channels besides the one you want in a heavily saturated market like Toronto. Together, they will interfere with the weak signal you seek, even if they're on other channels (and even the FM band!). Think of this device as a "collar" that lets channel 7's signal through while attenuating everything else on both sides of channel 7. Channel Master Jointennas are inexpensive, but their F-connectors have a bad reputation for snapping off under anything more than the slightest pressure; Tin Lee Electronics right in Toronto makes high-quality signal injectors, but you'll pay dearly for their custom work.

    • Finally, a low-gain pre-amplifier added to the VHF antenna might help to counteract cable losses, but note that you will need to insert the amp and its power injector before a Jointenna/signal injector to avoid creating other reception headaches.

    All of this is a very roundabout way of saying you'd probably be much better off compromising on those dimensions by getting the YA-1713 everyone else recommends and feeding it into a Jointenna/signal injector... :D
    Last edited: May 1, 2011
  7. rogerduncan100

    rogerduncan100 Thread Starter Active SatelliteGuys Member

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    Thanks, everybody!

    Some time later I will actually do something instead of just dreaming....

    I appreciate all the advice!
  8. Jim5506

    Jim5506 SatelliteGuys Family Pub Member / Supporter

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    It is surprising how small a really large antenna looks when you put it up in the sky.

    The lower the channel is you are trying to receive, the larger the antenna must be to harmonize with the frequency of the channel (match the 1/2 wavelength).

    For VHF high band antennas (there is no small antenna that will get you high gain) when compaired with UHF antennas.

    Sorry, but we have not advance so far as to be able to repeal the laws of physics no matter what the sellers of the little 150 mile antennas say.
  9. rogerduncan100

    rogerduncan100 Thread Starter Active SatelliteGuys Member

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    It's amazing how different the propogation characteristics are for UHF compared to VHF. For the UHF stations my 8-bowtie antenna is very sensitive to the direction I set with the rotor, I'd say I must aim within five degrees. For VHF channel 7 this antenna shows way less directionality.
  10. Jim5506

    Jim5506 SatelliteGuys Family Pub Member / Supporter

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    The 8 bay bow-tie antenna is more directional because it has two different sets of driven elements in the horizonal plane.

    Rotating the antenna left or right puts these receptors out of phase with the incoming signal so signal is lost.
  11. rogerduncan100

    rogerduncan100 Thread Starter Active SatelliteGuys Member

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  12. rogerduncan100

    rogerduncan100 Thread Starter Active SatelliteGuys Member

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    Home-made Yagi

    Yagi Above OTA and FTA Antennas.jpeg Well, I made the Yagi and here's the picture.
  13. Don_M

    Don_M Member

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    Well, then, don't be coy! Please tell us: What is it made of, how high up is it mounted and, most importantly, how well does it work in capturing WNGS?
  14. rogerduncan100

    rogerduncan100 Thread Starter Active SatelliteGuys Member

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    OK!

    The idea was to get WNGS (now re-branded as WBBZ) which is a low powered station design
  15. rogerduncan100

    rogerduncan100 Thread Starter Active SatelliteGuys Member

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    OK!

    The idea was to get WNGS (now re-branded as WBBZ) which is a fairly low powered station designed to reach to the US side of Lake Ontario only. The station is 82 miles away across the lake and I want to see the Yankee's baseball games it broadcasts here in Toronto.

    The spine is wood with an aluminium stiffening member from an old antenna. The pieces are bolted together. The elements (also from the old antenna) are fitted into grooves cut in the wood with a router. The elements are held in with galvanized strapping and screws. I put a coat of wood preservative on the wood (8 foot birch 1 by 4 from Home Depot). I got a high quality balun and UHF/VHF joiner from the local antenna installer. It's mounted on a ten foot long one and three quarter inch electrical conduit. I figure it is about twenty feet high.

    It works pretty well. Reception is best at night but is often strong in the daytime too. I don't get the channel at all during sunrise and sunset usually. Also, just like with other distant OTA channels (like channel 51 ION), I find that my digital converter box is much more sensitive and therefore picks up the signal much better than my HD TV. So, if I can't watch the game in 720p I can usually watch it in SD (480i on channel 3) anyway.

    Overall, I am pleased! Why wouldn't I be?

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