Affordable Programmed Satellite Pointing System for Propagation Experiments

The development of future communication systems at Q-/V-band requires extensive characterization of the atmospheric propagation channel. The European Space Agency funded the TDP-5 payload that was installed on the Alphasat satellite and is now available for performing propagation measurements in Europe at Ka- and Q-/V-bands. However, as the satellite has an orbit that can reach up to 3° inclination and the antennas have a much smaller half-power beamwidth (HPBW), the received signal amplitude variation along the day would be unacceptably high to perform propagation measurements. A commercial antenna pointing system with adequate specifications represents a severe cost burden on the already expensive beacon receiver hardware. After analyzing the requirements, we describe the detailed project, hardware development, calibration, test, and field measurement performance of a very affordable pointing system for medium-sized parabolic antennas, based on standard linear actuators. An innovative method for fine-tuning the pointing system against the satellite, requiring only equipment that is easily available, is also described in detail. The estimated price is several orders of magnitude less than a commercial one and, upon a careful tuning of the pointing system, the target angular resolution of ±0.026° was achieved in the experimental scenario.