Advanced RF/microwave filtering circuits for wireless communications and radar applications.

Abstract

The recent rapid development in modern communication systems has presented some constraints caused by the introduced noises, as well as further requirements of low costs and miniature designs. Such noises are overcome using efficient designs of filtering devices which are essential components in many satellite, radar and mobile communication systems. As a result, balanced or differential filtering components have recently received increasing attention. A wideband microstrip balanced bandpass filter based on modified stub line approach is presented in here. The proposed idea of extended transmission lines (TLs) at the input and output (I/O) ports enables for very good stopband rejection and common-mode suppression. On the other hand, the recently introduced multilayer liquid crystal polymer (LCP) material and fabrication technique are exclusively applied in this work for adapting the potential solutions offered within. Therefore, a comprehensive in-house fabrication process has been developed and extensively illustrated in this thesis starting from mask preparation covering the entire procedure up to producing the final piece of output. As a demonstrator of the potential capability of multilayer LCP technology, a novel miniaturized ultra-wideband (UWB) balun with self-packaging is introduced in this study. The broadside coupled stripline structure is adopted in this work to realize UWB performance and TEM mode which results in excellent amplitude and phase balances. In turn, a novel compact UWB multilayer balanced bandpass filter using LCP technology is also presented in this thesis. The design utilizes the transversal signal-interference concept for realizing an outstanding common-mode suppression while constructed in a stripline configuration. All of the designs covered in this thesis are initially simulated using CAD tools to be then validated by measurements of fabricated prototypes.