Advanced microwave filter design




Mokhtaari, Marjan

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This thesis presents new procedures and guidelines for the design of advanced microwave filters. Practical implementations include dual-band, multi-band and ultra-wideband filters for applications in wireless and telecommunication systems. The traditional narrow-band coupling-matrix approach is extended to include multiple and out-of-band resonances, which allows the model to accurately predict and design the filter performance over a wide frequency range. A variety of coupling scenarios are presented and their advantages over current designs demonstrated. The approach includes the placement of transmission zeros in order to obtain quasi-elliptic responses, improve stopband performance and generate sharp transitions from the passbands to their adjacent stopbands. In order to contribute to filter miniaturization, bandwidth enhancement and manufacturing simplicity, a new class of step-impedance resonators is proposed and their harmonic tuning properties utilized. Advanced coupling configurations are realized, which are applicable to single- or multi-band filter operations with bandwidths ranging from a few percent to fifty percent. Moreover, the developed design procedures are applied to ultra-wideband filters covering bandwidths of up to 150 percent. All filters designed with the procedures developed in this thesis are validated by several commercially available electromagnetic field-solver packages, in-house numerical codes and/or measurements. The excellent overall agreement between computational and experimental results verifies the advanced filter design procedures presented in this thesis.



Microwave filters, Wireless communication systems, Telecommunications