@Islander wrote:
Hi. I am a boater/cruiser and particularly interested in receiving weather data (GRIB). I have experience designing stabilized VSAT antennas. Noticed a thread on this topic but lost it after registring but would like to make my contribution based on experience. If the criteria is within 2 degrees accuracy for elevation and azimuth, som type of active solution is required. Also cost and complexity should, in the spirit of things here, be low. A pan/tilt solution is potentially a way to go but introduces complexity in requiring slip-rings for power and RF. A solution that uses the fact that the patch antennas basically has no cost/complexity tickles the concept of several switchable arrays (4). This will only get you into a rough pointing direction requiring finer tracking. This may be accomplished by simple model servos allowing for around +-45 degrees in azimuth and -20 to 90 degrees in elevation. As patches are switched no full rotation occurs. The mechanical complexity is moved to the control domain. With off-the shelf model/robots 9DOF sensors and GPS data, accurate pointing is possible. This will get us to a point where the l-band signal may be picked up and used to peak the RSSI using a simple search pattern. This creates a closed loop lock to the sat. Antenna switching can be done by PIN diode arrangement after LNA but requires good knowledge of RF circuit design. Then you need a MCU and code for the steering of servos and antenna switching.
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