OPTIMIZATION OF THE PERFORMANCE OF UHF RADIATORS INSTALLED ONBOARD SPACECRAFTS, USING NUMERICAL METHODS

摘要

VHF and UHF antennas installed aboard small and medium size satellites usually strongly interact with the bus structure and with appendages, due to the fact that their dimensions can be resonant with respect to the antenna wavelength. This may significantly deteriorate performance and requirements may not be met due to the electromagnetic interaction between the radiator and the superstructures. Moreover, radiating Tx antennas can cause RS (Radiated Susceptibility) problems on equipment (e.g. IRES) located on the satellite top-floor, due to the fact that such equipment are electrically near to the antenna and to the resonant appendages. AAS-I and IDS dealt with a problem in which a UHF array was designed and then installed aboard a geostationary satellite. Each of the aforementioned problems was recognized at installation level and analyzed by means of numerical modeling of the whole array and satellite. The problems were solved by optimizing the array position and orientation. This paper reports a description of the RFC problems related to V/UHF radiators installed aboard spacecrafts, focusing on the above mentioned real life application. The numerical models and the applied optimization procedure are reported and discussed.