Fabrication and Characterization of S-Band Compact Dual Mode Close Loop Microstrip Resonator Filter

Existing communication systems require efficient, compact and portable microstrip filters so that it contributes in enhancing the performance of communication system. Existing communication at S-band system requires spurious free signal transmission as well as reduced insertion and return loss, improved bandwidth and sharp roll off rate. The stated parameters could be improved through the design of a compact resonator filter. Hence, in this paper the design, development and characterization of a dual mode close loop resonator filter on microstrip structure at S-band is discussed. The proposed resonator filter design exhibits performance improvement in terms of insertion loss (<1 dB), return loss (Better than 12 dB), Bandwidth (>5%), sharp role off as compared to existing filter. Dual mode operation of close loop resonator filter is explained through the time varying field distribution. The size optimization of the designed resonator filter is accomplished without altering electrical parameter. The designed resonator filter has also been fabricated on two different substrates and comparative analysis has been carried out. Finally the realized filters have been characterised for its suitability in space applications.