New Wide-Band Capacitive Filter Structures in Rectangular Waveguide Technology With Enhanced Out-of-Band Response

Abstract

The main objective of this doctoral thesis is the development of new capacitive ltering structures in rectangular waveguide that are able to provide wide bandwidths in the passband and improve, at the same time, the out-of-band response. These new guided structures have been developed in order to oer new technological solutions for high-frequency microwave lters, with a variety of dierent transfer functions, addressing specically the needs of future telecommunication systems for both ground and space applications.In this context, therefore, we discuss in this document the study, design and manufacture of several types of microwave lter in rectangular waveguide that show a signicant improvement with respect to the state-of-the-art. The new solutions that we propose are obtained by introducing simple modications in the structure of classic microwave lters. Several techniques based on hybrid irises, stepped impedance resonators, staircase conguration and E-plane T-junctions with shorted stubs or manifold connections, are successfully used in order to meet the very demanding specications of future systems for both ground and space applications. Furthermore, an additional current challenge faced by all designers of microwave components is the need to reduce both their physical size and mass (or weight). To address this issue, we discuss in this document the use of resonant apertures in rectangular waveguide, introducing a new family of lters which can be used to implement complex single and dual-band transfer functions with signicant size and mass reduction.In the following chapters of this doctoral thesis, each subject is discussed in detail including the basic theoretical formulations, design procedures, the results of full-wave electromagnetic simulations, manufacturing considerations, and the measured performance of a number of prototypes. Excellent agreement is found in all cases between measurement and simulations, thereby fully validating both the novel structures discussed and their design procedures.