Filters for 5G mmWave. Filtros para 5G en Onda Milimétrica

Abstract

Periodic structures are an emerging field in nowadays's microwave designs. These structures have been proven to be capable of achieving compact, efficient solutions to problems such as leakage, or surface waves. In particular, higher order symmetries, such as glide-symmetry or twist symmetry have shown interesting properties in different microwave related areas, such as lens antenna design, and gap-waveguide technology. However, the application of higher symmetries in designing filters has not been investigated yet. The main contribution of this thesis is the introduction of a new form of glide symmetry -braided glide symmetry-. This new geometry has proven to improve in a great factor the attenuation properties of traditional glide symmetric structures by interleaving two different glide symmetries. In this work, the designs of several filtering structures are carried out with the aim of exploring the possibilities of the application of periodic surfaces and glide-symmetry to filter design. The filtering structures consist of passband filters at millimeter wave frequencies (28 GHz) for the fifth generation (5G) technology, which also must suppress the harmonics at twice the passband frequency. The complete design process is described, starting by the analysis of a unit cell using the dispersion diagram, continuing by designing the filter, and finalizing with the design of a tapering structure of a coaxial feed to the filter. Some numerical techniques will be explained for better understanding of the structures and for accelerating the calculations. A design will be manufactured and measured to assess its performance, comparing it to the simulated results.