Programa del congreso

This article presents the theoretical study and numerical simulation for the implementation of a stub resonator in the microstrip ridge gap waveguide (MGCW) transmission line. The resonator is filled with liquid crystal (LC) and, thanks to LC’s dielectric anisotropy properties, the resonance can be easily controlled using an external electric or magnetic bias field. The resonance was designed to operate in the range of 7.8 to 8.8 GHz. Its frequency response, associated to both parallel and perpendicular LC’s permittivity, as well as intermediate state were computed. Finally, the results are discussed.

In this paper, we describe the design of a periodically air-filled substrate integrated waveguide (SIW) bandpass filter in which part of the dielectric substrate is removed to reduce insertion losses. The unit cell parameters of the structure, which are directly related to the center frequency (fc) and bandwidth (BW) of the first passband, and also to the first stopband or bandgap (BG) of the structure, have been appropriately selected for filtering purposes, thus providing some useful design rules. Furthermore, we apply the concept of glide symmetry for achieving a much larger fractional bandwidth (FBW). Additionally, a microstrip-to-SIW transition including a novel coupling iris is proposed. A prototype of the periodic SIW filter with glide symmetry has been manufactured and measured for validating purposes. The proposed filter proves to be a good candidate for millimeter wave applications.

This paper introduces a theoretical framework for deriving fully analytical and multi-modal equivalent circuits for periodic structures and metasurfaces in general. By introducing time as a new variable, classical versions of circuits for purely spatial scenarios are expanded to account for spacetime-varying ones. Throughout the document, various periodic structures are examined from a circuit perspective, exhibiting periodicity in space, time, and spacetime. The efficiency of the analytical circuits is confirmed through external full-wave solvers, affirming the models as valuable tools for investigating innovative and advanced spacetime scenarios.

A design methodology to realize Fabry-Pérot cavity antennas with very high aperture efficiency and improved bandwidth is presented. The antenna is based on a tapered Partially Reflective Surface, and its characteristics are determined through a combination of criteria from the simplified ray-model and the 2D leaky-wave approaches. Therefore, through a transmission line modelling of the PRS, its cells can be chosen to follow the required leakage factor function while satisfying the resonance condition and the positive phase-slope technique. Two different designs are carried out to present a quasi-uniform aperture field distribution. Their simulated behaviours are compared with the best design of a previous work, clearly showing the improvement achieved from incorporating the leaky-wave theory into these antennas.