CASSINI FREQUENCY-SELECTIVE SURFACE DEVELOPMENT

This paper summarizes the design and development of a 4-frequency sele ctive surface (FSS) for the NASA Cassini high gain antenna (HGA). Spec ifically, two FSS/HGA design approaches were considered for multiplexi ng the four frequency bands (S-, X-, Ku-, and Ka-band) of the Cassini Project. In the first approach (with two transmit and two reflect band s), a double screen FSS with double ring patch elements was developed to transmit the S- and Ku-band signals and to reflect the X- and Ka-ba nd signals. However, this FSS presents relatively high insertion loss at the S-band. Therefore, the second approach (with one transmit and t hree reflect bands) was developed, using a single screen FSS with doub le square loop slot elements to transmit the Ka-band and to reflect th e S-, X-, and Ku-band waves. Significant improvement in the S-band los s performance is obtained with this second approach. However, it will require a dual reflector shaping study to optimize the subreflector si ze for minimizing the spill over and blockage losses.