Communication satellite antenna testing

Abstract

C ommunication satellite systems necessarily require multi-disciplinary tests to assure and maintain effective system operation. This overview summarizes the overall testing for satellite communication systems and describes the subset of antenna and antenna-related testing in particular. Antenna test requirements address both RF and environmental specifications that include both launch and on-orbit extremes for space systems and wind and climate conditions for ground systems. In addition to characterizing antenna performance, other system test requirements have antenna-related measurements and test requirements. Satellite System RequirementsSatellite system evaluations have three distinct test phases, development tests, qualification tests, and on-orbit tests [1], as Fig. 1 shows. Development tests establish design compliance with system requirements. Qualification tests establish flight hardware that maintain the performance achieved in development testing, identify any workmanship shortfalls, and determine flight-worthiness of the integrated satellite. On-orbit tests initially establish operational compliance with the system's requirements, and have the capability to monitor, diagnose, and identify potential performance shortfalls over the satellite's lifetime.Ground segment evaluations [1] follow a similar path, as illustrated in Fig. 2. However, these evaluations must also address both cost effective tests for the large volume of user terminals manufactured and more extensive tests for large ground terminals (e.g., in mission control and gateway applications) and the additional requirements they have for system control and diagnostics. Ground segment designs significantly capitalize on available commercial off-the-shelf (COTS) products, require equipment selection between alternative vendors, and need to be developed using specific program requirements. The larger ground terminal antennas have decades-long lifetimes, and because of their cost, have separate sustainment plans that allow terminal antennas to incorporate and satisfy new requirements and to replace older equipment with maintenance issues.A requirement verification matrix is constructed at the program inception that describes the tests needed to demonstrate design compliance. This matrix is then used to determine test and facility requirements, instrumentation, test methodologies, software processing for the program, and detailed test plans. System designs must pay particular attention to provide an adequate number of test points to allow both characterization and diagnostic measurements. The space segment requires attention to telemetry points to provide insight for operational diagnostics. Larger ground terminals are typically financially incentivized by availability requirements and require close attention to redundancy and built-in-test equipment (BITE) capabilities to restore service in a timely fashion, particularly with today's trends toward remote operation. Providing proper attention to these issues at the program's inception is essential...