08197 - 0 - Advances in Multi - Band Microstrip Filters

Filters play an irreplaceable role in virtually any type of radio frequency (RF)/microwave system today. With the recent rapid development and widespread use of various wireless communication systems, ever-more stringent requirements are posed on RF/ microwave filters – smaller size, higher performance, and lower cost are all simultaneously required today. Even more recently, multi-band operation is considered necessary to solve the challenges of insufficient capacity of the various wireless systems. To that end, high-performance and compact microwave filters that operate at two or more non-harmonically related frequencies are greatly needed, and several different approaches to their design are being investigated today. While waveguide architecture has been traditionally used to design filters with high quality factors and capable of handling high power, their bulky construction proved to be a limiting factor for applications where miniaturization is a primary concern. To that end, various planar solutions were developed, based on transmission electron microscopy (TEM) or quasi-TEM transmission lines. Besides compact dimensions, the main advantages of planar filters are easier integration in the circuit or module environment, and well-developed and automated manufacture procedures that typically require no manual tuning. In this book, we present the most recent results in the development of multi-band planar filters. We focus on the microstrip architecture, but note that most of the filters presented here could easily be redesigned in other architectures, such as coplanar waveguide, or stripline. This edited book presents the results of the research efforts of four well-established research groups, all working in the field of multi-band filter design, performed within the FP7 project MultiWaveS funded by the European Commission under Framework Programme 7, grant no. PIRSES-GA-2009-247532. The book presents in detail six competing approaches and concepts which are used to solve a common problem: the design of compact microstrip multi-band filters with high performance. The approaches presented range from the conventional one, to the application of advanced multi-layer fabrication technologies, and to the development and application of several novel resonator geometries and filter concepts. The book consists of eight chapters, where each chapter starts with an introduction and ends with conclusions and a list of references. Chapter 1, the Introduction, is followed in Chapter 2, by a comprehensive overview of the existing methods for the design of dual-band and tri-band filters, together with