The objective of this paper is to describe a new family of microwave bandpass filters in rectangular waveguide, based on resonant apertures, that can be used to implement both single and dual band transfer functions. The use of capacitive stubs and a staircase configuration is also discussed, in order to enhance the out-of-band response and the selectivity of the filter with respect to the state-of-the-art. Finally, simulations are compared with measured results, showing very good agreement, thereby fully validating both the new filter topologies and the design procedure.

The objective of this article is to describe the design of a new family of wideband filters in a rectangular waveguide based on hybrid couplings and a staircase configuration. The use of E-plane T -junctions and E-plane folded structures is also discussed, in order to enhance the out-of-band response and the selectivity of the filter with respect to the current state of the art. The design of several hybrid filter prototypes is discussed in detail, including manufacturing sensitivity and high-power analysis. Finally, simulations and measurements for an eight-pole filter prototype are also compared, showing very good agreement, thereby fully validating both the design procedure and the new filter topology that we propose.

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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.