Performance Improvement of Ka-Band Small Earth Stations for WINDS Utilizing Superconducting Filter

[Abstract] A next generation high capacity satellite WINDS (Wideband InterNetworking engineering test and Demonstration Satellite) is planned to be launched in 2008. This satellite has data transmission pipe line function of very high speed up to 622Mbps or to 1.244Gbps. We are proposing to use superconducting filter (SCF) in the earth station in this paper. SCF provides very superior characteristics for frequency selectivity as well as low loss performance. By utilizing these properties of SCF the satellite frequency can be efficiently used because the channel spacing can be reduced comparing to the case which uses conventional filter. However SCF has very sharp group delay characteristics at cut-off frequency that causes the BER degradation of PSK signal. This paper addresses the verification and investigation how the bandwidth and the delay affects to the BER performances of QPSK signal and shows the specification of necessary delay equalization.