Design of reconfigurable filtering power dividers

This thesis presents a switchable, and bandwidth-adjustable filtering power divider (FPD) circuit having reconfigurable two channels for use in multi-band and multi-functional communication systems. The designed circuit has the potential for use in modern communication systems as it can perform both filtering and power division simultaneously in the microwave frequency domain. The design utilizes two dual-mode ring resonators (DMRR) with different electrical lengths. By employing single-pole double-throw-SPDT switches, only one of the resonators is activated at a time, allowing for the selection of one of the two distinct frequency channels. This mechanism enables the desired channel to be electronically turned on or off. Furthermore, the bandwidth of both channels can be electronically adjusted by varying the applied voltage across varactor diodes, which represent the perturbation capacitors. This approach provides significant flexibility compared to conventional fixed-frequency power dividers. The design process comprises three stages: theoretical filter design, electromagnetic (EM) simulations based on the integration of the filter and power divider circuits, and experimental studies. In the theoretical filter design, even- and odd-mode impedance analysis is conducted solely for the filter, and initial dimensions for the filter are derived. Subsequently, the entire circuit structure and its components are optimized through detailed electromagnetic (EM) simulations. Additionally, by designing a conventional Wilkinson power divider structure at a frequency centered between the two channels, optimum isolation and minimum insertion loss are achieved for both channels. In the third and final stage, a prototype is fabricated, and the measurement results are shown to be in good agreement with the EM simulations.