Design and Implementation of Compact and Reconfigurable Planar Filters

Abstract

The increasing development of wireless applications turns out to new requirements for transceiver architectures that have to feature excellent microwave performances (linearity, spurious rejection, noise figure and bandwidth) and enhanced integration density that are achieved through the miniaturization of the modules as well as the introduction of multi standard functionalities. All these requirements translate to the need of filter circuits as miniaturized as possible and featuring the highest performances in term of insertion loss and rejection. Microwave filters possessing various forms are essential components in radar, satellite and mobile communication systems. Increased demands for low-loss, miniature filters that can be mass produced at low cost have provided a significant challenge reinforcing the need for improving or even replacing the conventional microwave filters. This thesis introduces the investigation and development of design methodologies for the creation of multi-functional bandpass filters and lowpass filters at microwave frequencies. These filters are capable of tuning to different frequency bands as well as varying their fractional bandwidth. The work presented here relates to the evolving multifunction philosophy of RF systems. This thesis presents a comprehensive study of RF reconfigurable planar microwave filters, which generate reliable and scalable filter topologies with tunable properties. The study includes the analysis of single, dual -mode filters together with an investigation of the coupling behavior of synchronously and asynchronously tuned resonators. This study identified the main properties responsible for frequency and bandwidth control in a filter, and consequently systematically created innovative design techniques.