Utilization of the Geometrical Theory of Diffraction for antenna pattern prediction on satellites

The increased number of antennas to be mounted on spacecrafts has led to accommodation issues due to potential interactions between antennas and satellite structure and appendages. For application on TCR and Horns antennas, Astrium is using a simulation tool, SYSTEMA-GTD, based on the Geometrical Theory of Diffraction (GTD) during the early phases of the programme for antennas accommodation and during development phases for pattern prediction. SYSTEMA-GTD is based on ray tracing techniques that offers unique advantages with respect to other methods: simulation of large structures for frequencies from S to K band, reduced calculation time, possibility to identify and visualize effects of each obstacle, availability of simplified shapes, etc. This tool has been validated by comparison with measurements on satellite mock-up and with simulations using other numerical methods, which demonstrated its very good accuracy. The paper presents SYSTEMA-GTD simulation tool, its applications on different cases, and examples of validation campaign results.