Microwave antenna alignment

Discussion in 'Wireless & RF Design' started by kennybaba, Nov 19, 2013.

  1. kennybaba

    Thread Starter New Member

    Nov 19, 2013
    Last edited by a moderator: Nov 19, 2013
  2. WBahn


    Mar 31, 2012
    What does this have to do with the OP (original poster's) problem?

    Please don't hijack someone else's thread. Start your own. I've reported your post to the mods, who will probably split it off into it's own thread. So don't go starting another one just yet.
  3. Georacer


    Nov 25, 2009
    Greetings! And welcome to AAC!

    Your post has been moved into its own thread, where it will draw more responses.

    Please refrain from "hijacking" existing threads with tangent or off-topic questions. You can create new threads for new questions using the "New Thread" button on the upper left of the page.
  4. Papabravo


    Feb 24, 2006
    You might be able to do it with a sophisticated industrial vision system. Point the camera at an "illuminated" target and move the camera in azimuth and elevation until the spot is where you want it.

    We align our antennas with rifle scopes.
  5. gootee

    Senior Member

    Apr 24, 2007
    I am not an expert, but...

    If you had electric positioners, one for elevation and one for azimuth, you could use a test signal and have a simple feedback control system to servo the antenna(s) to the peak received signal level.

    You would probably want the electric positioners to only have a small range of motion. So you'd probably have to get the antennas kind of close to the correct alignment, first.

    I assume that this would only be done once, or only occasionally. So you'd probably want to make only one or two positioning systems that could be used on any antenna, when needed, and then lock down the antenna however you normally do.

    I'm not sure what kind of mechanical environment the antennas have around them. But it would probably be good to consider using motorized threaded rods for the positioning actuators (using stepper motors or servo motors or maybe even plain cheap reversible motors).

    However, you might want some kind of torque sensing, or some way that the system could know if something was stuck, so it would stop cranking if there was a problem. Maybe just cutting the rod and joining it back together by jamming the cut ends into a short piece of some rubber or plastic tubing would work, so it would slip instead of bending some metal. (And of course, you'd want limit switches, at the very least.)

    You could have a deep nut (like a "coupling nut"), to prevent backlash (hysteresis/slop), attached in some kind of fixture that could be clamped or bolted onto the antenna structure, for each axis, through which the actuator's threaded rod would go. Of course, the other ends of the rods, with the motors, would need to be "grounded", against something (preferably some non-moving part of the antenna structure, I guess).

    I'm not familiar with the mechanics of your antenna mounts, so there might be some better way to do the positioning. The main trick would probably be putting together the feedback control system that would seek the peak received signal level. Two identical channels would probably work. It would probably have to move each axis, initially, to sense the slope of the RSL, to know which way to start moving to go toward the peak RSL.


    Alternatively, you could use a computer and a differential GPS. The computer would need to know the coordinates of the target. So maybe you could have a second GPS affixed to the target antenna (possibly internet/phone/radio-linked to the pointing system at the other antenna). If there was some standard way to attach the gps antenna to the microwave antenna so that it would be very-accurately positioned every time, then the computer could calculate the position of the uW antenna's boresight vector, at the target's range, and calculate how far to rotate each axis of the antenna being pointed. But I'm not sure if the differential GPS's angular resolution would be fine-enough. You would obviously also need a positioner system, as in the previous suggestion. But you wouldn't need the signal level feedback control system (although, I like that way better, I think, since it directly maximizes the real objective).

    I'm sure there's also an easy way to use a laser, and optical sensors. But that would depend on being able to boresight a laser on an antenna, just by mounting it a certain way, and ditto for the optical sensor array.
  6. WBahn


    Mar 31, 2012
    When they installed the satellite dish on the roof the mount itself was indexed, but of course that was only as good as the alignment of the mount. They only seemed to care about the elevation and not the azimuth. They then swept the dish slowly listening for a pilot signal (they had a battery powered modem and laptop with them). It didn't take them very long to get it aligned -- perhaps ten minutes. They only had to tweak the elevation slightly, but they swept the azimuth over a pretty good range.