Programa del congreso

The characteristic resonances of a patch-like frequency selective surface (FSS) are obtained in this paper by solving an appropriate eigenvalue problem. While the eigenvalues yield the resonance frequencies, the associated eigenfunctions constitute a suitable basis to expand the surface current solution for the periodic structure illuminated by a plane wave under oblique incidence conditions. The use of this basis leads to small size Method of Moment (MoM) matrices and thus to reduced numerical effort. Besides, the solution of such MoM problem directly gives place to a canonical Foster equivalent

circuit describing the reflection and transmission properties of the FSS. A systematic procedure to extract the values of the components of the Foster equivalent circuit is described in this contribution. The accuracy of this approach is established by proper comparison with the results obtained using and ad-hoc in-house MoM computer code.

The development of devices for In-Situ Reosurce Utilization (ISRU) of the lunar surface powder (regolith) by means of microwaves needs regolith simulants with electromagnetic properties similar to the lunar regolith. Electromagnetic properties of EAC-1A and JSC-2A simulants had never been measured before. This document deals with the measurement of complex permittivity, complex permeability, and tangent loss of the aforementioned regolith simulants at ambient temperature from 400 MHz to 20 GHz. The obtained results will be applicable for comparing the measured values of EAC-1A and JSC-2A among them and with other previously measured simulants and real samples. The measurements were carried out applying two different non-resonant techniques. The DAK and EpsiMu kits were used to carry out the measurements according to the Open-Ended Coaxial Probe (OECP) and Transmission Line Methods.

En este trabajo, se realiza un estudio de la viabilidad de usar hormigón para aplicaciones de enfriado radiativo. Esto se realiza estudiando teóricamente algunos de los principales compuestos del cemento: C3S, CH y CSH. Se realizan simulaciones atomísticas para determinar la estructura de los materiales y sus respuestas dieléctricas. Sorprendentemente, los materiales exhiben teóricamente una capacidad de enfriamiento nocturna de 55.68W, 60.69W y 62.43W respectivamente. Este estudio preliminar muestra el potencial del hormigón como material barato, escalable y de amplio uso para enfriado radiativo nocturno. Se requiere una mayor investigación para conseguir gran reflectividad solar para poder usar estos materiales como enfriadores diurnos. Para calcular la emisividad de los compuestos, se ha usado un modelo analítico que tiene un error cercano a cero y calcula los datos con una rapidez mucho mayor que un simulador.

Waveguides with rotationally higher-order symmetries, also called C_N waveguides, are defined as periodic structures with cross sections having discrete rotational symmetry. Recently, a tailored method for modal analysis of said waveguides has been proposed. The formulation it presents, based on the Finite Element Method, allows for the characterization of homogeneous, perfectly enclosed C_N waveguides with arbitrary (non analytic) cross sections, and has the advantages of automatically identifying degenerate modes, improving performance and categorising the complete set of modes into independent classes based on their physical properties. In this communication we discuss the method into further detail, analysing and quantifying its most important features.