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Thread: Will this dipole work to the best of it's ability?

  1. #1

    Default Will this dipole work to the best of it's ability?

    Hi all,
    First off: If this is the wrong place to post this please tell me and I'll remove it.
    Anyway: I've been trying to receive some weather images from NOAA satellites, and I'm building a double cross antenna but i have a few issues with the construction of the dipoles. My question is will the blocks of wood on the antenna I created (see attached) interfear with the operation of the antenna? Will the signal be weaker than if they weren't there?

    Thanks.
    (If you can't see the picture go to http://imgur.com/a/Qiebng3 )

  2. #2

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    To be honest the bits of wood won't have any impact but they do look a bit physically huge - seems a bit on the large side for what it does? Could you have not simply have soldered or used a block connector in the middle, which you could have screwed to one thin piece of timber, and then slid on another block connector to each element and used another screw to hold the things in place? Much easier to make? The wood, if outside for extended time will of course gradually become water-soaked which will reduce the performance a bit.

  3. #3

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    Quote Originally Posted by paulears View Post
    Could you have not simply have soldered or used a block connector in the middle, which you could have screwed to one thin piece of timber, and then slid on another block connector to each element and used another screw to hold the things in place?
    You're absolutely right. There are one or two problems though: firstly, this is mainly a proof of concept, and not permenent. Secondly, I don't have __any__ budget for this so I'm working with weak scrap wood, but I hope to improve this in the future.

  4. #4

    Default circular polarised

    Quote Originally Posted by Jachdich View Post
    You're absolutely right. There are one or two problems though: firstly, this is mainly a proof of concept, and not permenent. Secondly, I don't have __any__ budget for this so I'm working with weak scrap wood, but I hope to improve this in the future.
    i always thought you needed circular polerisaed antenna for sats, i made one out of copper earth wire, didn't look anything like yours though was double spiral

  5. #5

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    Proof of concept? It's a dipole - the concept is surely proven. A far, far simpler version can be made with coat hanger wire and a single block connector to attach the coax. You will get fading on a single polarisation, so many people use butterflys, or just crossed dipoles, so as one goes into a null, the other emerges from it. Simplicity is the best trick here.

  6. #6

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    Quote Originally Posted by mm3xia View Post
    i always thought you needed circular polerisaed antenna for sats, i made one out of copper earth wire, didn't look anything like yours though was double spiral
    Nope. Satellites use circular polarisation because they have no ground reference and also the signal gets twisted as it goes through the earth's atmosphere. The point of circular polarisation is that it doesn't matter which angle it hits the receiving aerial, at some some point it will be spot-on. Though, the most common simple aerial I've seen for receiving satellite signals is a grossed dipole. If you have a a helical aerial, then you need to know whether the transmitting station is using right-hand or left-hand rotation.

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