The present evolution of telecommunication systems is characterized by the constant optimization in bandwidth assignment and utilization, in order to offer the widest range of services to the users at the lowest cost.

The field of passive microwave components for both terrestrial and satellite communication systems has also been affected by this evolution. In the last few decades, important advances have been obtained in this area to be able to fulfil a continuously increasing set of requirements. These demanding specifications have motivated the invention of new devices and the improvement of those currently available.

In this context, the work carried out in this Ph.D. thesis tries to contribute to the improvement of the analysis and design techniques for microwave passive devices operating in a wide frequency range. As a result of the recent progress in narrowband techniques, the importance of these wideband components in the performance of the entire telecommunication system is growing day after day.

This thesis will be focused on three families of microwave filters in waveguide technology widely used in practical applications: inductive filters, evanescent mode filters and corrugated filters. However, most of the procedures and results obtained here can be extended to other filter types and microwave passive devices with a wide frequency band of operation.

Firstly, several simulation tools based on modal methods have been successfully developed. These tools allow the efficient and accurate analysis of the different structures under consideration. To extend the range of application of modal analysis techniques, an improved procedure to characterize arbitrarily shaped waveguides has been developed. Using this procedure, the modal spectrum of any practical waveguide can be rigorously computed in just a matter of seconds.

Secondly, such simulation tools have been applied to the development of new techniques for the optimized design of inductive, evanescent mode and corrugated filters. In many cases, the obtained design procedures are fully automated, and only require minimal human intervention. Furthermore, other relevant aspects have also been investigated, such as the conception of design techniques also valid for inhomogeneous and wide bandwidth devices, the influence of the structure free parameters in the device performance (which allow to propose geometrical modifications to improve some particular features), or the choice of a suitable type of response to improve the robustness against manufacturing tolerances. 

Thanks to the new analysis and design techniques developed throughout this research work, the microwave industry will be able to perform the design of the components under consideration more accurately and efficiently, and at the same time will fully exploit their capabilities. These advances will eventually provide an improvement in communication system performance, thus allowing a better and wider telecommunication service deployment to end users.