THERMAL DISTORTION OF OVER 10 METER DIAMETER REFLECTORS FORMED BY TRUSS STRUCTURE.

This paper describes how an on-board satellite large reflector structure was designed based on the thermal distortion predicted by structural analysis in coordination with thermal estimation. As the reflector consists of many small similar modules, it is possible to simplify the analytical model and the fabrication process. Module size and number are decided by estimating the surface accuracy for a 13 m aperture reflector. The maximum thermal distortion is found to be occurred during eclipses. As the module number increases, the thermal distortion increases. When the antenna system is used in 2.5 G Hz ( S frequency bands), total surface accuracy needs to be 2.4 mm RMS (specified value). This requirement is satisfied by a reflector composed of 14 modules; maximum error is 1.6 mm RMS by slight repositioning the reflector.