Horn Antenna Radio Interferometer

  1. This is a strange experiment (or not so compared to some of the experiments I've done) that I am currently undertaking, and require your help.

    I have built an interferometer of sorts. Two metal funnels of diameter 200mm are attached together by copper tubing (20mm?) through a Y junction with all angles of 120 degrees. The distance between the centre of the funnels is 600mm. The lower tube connects directly into an LNB.

    I am trying to connect the LNB to a voltage data logger via a device called a satellite finder that is basically an analogue dial voltmeter. Currently the software isn't working, but it should do the job.

    What I need your help with.
    I don't know if it (what ever it is) will work, and if it does, why? I can't find any (seemingly) relevant equations.
  2. jcsd
  3. mgb_phys

    mgb_phys 8,809
    Science Advisor
    Homework Helper

    Unless there is some sort of mixer in the Y junction you haven't built an interferometer.
    It sounds like you are trying to make a directional signal detector.
    I would have thought you want to connect a LNB to each funnel and measure the relative signal strength of each.
    You will have to do some caibration because the Feed+LNBs are unlikely to be perfectly equal gains and sensitivity.
  4. Got this setup and it actually works! One can see some excellent fringes when a person walks past it, and there's certainly some stuff going on when a sweep of the sky is made.

    can anyone give me an equation relating the intensity of the em radiation detected and the size/angle of the horns? Or just some general electrostatics relations
  5. If anyone is interested, it works exceptionally well. Interference fringes are observed, and when sweeping the southern horizon, a pattern that is significantly similar to that obtained with a standard parabolic reflective dish is observed.
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