Millimeter wave and sub-THz components with advanced manufacturing strategies

The millimeter wave and sub-THz region, which correspond to the region that contains the 30GHz-1THz zone of the frequency band, has wide types of application, that covers from space purposes, such as astronomy, to earth applications, weather study, and automotive industries, among other innovative uses. In recent years, this frequency range become more interesting for its use, related to obtaining more advantages from applications previously done at lower frequencies and the introduction of novel applications. However, the desire to use high frequencies implies the addition of new challenges to face, not only in the theory used for the design of new structures but in the measuring and the study of the prototypes to build. Working in a new frequency range implies the appearance of new phenomena that introduce changes in the properties that solutions at other frequencies may rely on, until a point that they are no longer usable in these frequencies. Moreover, the simulation programs and measurement equipment need to take these properties' change into account as well, otherwise, they will give inaccurate results that produce lower performance when they will be working in real conditions or even differences between the behavior of the structure in a simulation and measurement environment. To face this problem, various improvements can be made from different points of view to make structures in this design band more reliable and efficient in the future, with the lowest additional cost involved. First of all, novel and adapted old technologies can be used to manufacture the systems, solving or at least mitigating the challenges that appeared at these frequencies. In addition, new and precise models can be derived and studied to deal with the new phenomena appearing at high frequencies, applying them in simulation and measurement environments to obtain more precise results. Finally, the implementation of new measurement devices can be useful to have a faster and more reliable evaluation of potential prototypes, mitigating every source of error regarding the test of devices at high frequencies. Therefore, a study of the manufacturing strategies at millimeter and sub-THZ band is done in-depth, looking at different points of view, such as theoretical principles, machinery processes, actual solutions in the literature, simulation environment, and measurement results. The goal of this work is to identify the main problems that arise when designing at high frequencies, which can be from all the points mentioned before, analyze their behavior and nature, and check possible solutions that can be adopted in the future in a reliable, efficient, and low-cost manner. For this purpose, a deep investigation into the actual manufacturing technologies is done first, focusing on the silicon micromachining strategy, its advantages and main concerns. Subsequently, a bandpass filter made by silicon micromachining is mounted and measured to check its potential performance and to study the problems previously investigated, along with the appearance of new challenges. Finally, some structures that mitigate the impact of the error sources are proposed and analyzed. Specifically, choke flanges structures are studied in a similar way that the manufacturing strategies: the operation principle and actual devices in the literature are investigated, and their performance is estimated in a simulation environment.