Novel design for CSRR based electronically steered compact S-band microwave resonator

Novel design of electronically tunable compact RF resonator operating in the S-band (2.7-3.1 GHz) of microwave frequency range is proposed. The proposed design makes use of the CSRR loaded microstrip line coupled to the varactor diode, where the electronic steering in the designated frequency band is facilitated by changing the biasing voltage of the varactor. With improved design topology, the proposed structure is able to provide an improved tunable range using the single CSRR resonator. In this work, the lumped capacitors are introduced at both the end of microstrip signal line to isolate the DC voltage from the applied RF signals without deteriorating the performance of the resonator. The proposed resonator is designed using the 3D electromagnetic solver CST-MWS (Computer Simulation Technology-Microwave Studio), and accordingly various parameters are optimized to obtain the desired performance. After freezing various design parameters, the proposed resonator structure is fabricated on a commercially available FR-4 substrate. The testing of the fabricated structure is carried out using the network analyzer with a biasing voltage range of 0-28 V. A close match is observed between the measured and the simulated scattering parameters. The proposed resonator structure can be used for various applications in RF and microwave frequency range such as to design tunable filters and sensor for testing dispersive materials.