Closed-form expressions of multilayered planar Green's functions that account for the continuous spectrum in the far field

The rational function fitting method has been found useful in the derivation of closed-form expressions of spatial-domain Green's functions for multilayered media. However, former implementations of the rational function fitting method lead to Green's functions expressions that are not accurate in the far field when this far field is dominated by the continuous spectrum instead of being dominated by surface waves (as it happens, for instance, in the case of lossy multilayered media). In this paper, the authors introduce a novel implementation of the rational function fitting method, which leads to Green's functions expressions that are accurate in the far field when this is dominated either by the continuous spectrum or by surface waves. In the new approach, the far-field contribution of the continuous spectrum to the Green's functions is numerically fitted in terms of functions with closed-form Hankel transforms, and this far-field contribution is explicitly added to the total least squares approximations of the Green's functions. The numerical results obtained for the Green's functions with the new approach have been compared with numerical results obtained via direct numerical integration of Sommerfeld integrals, and excellent agreement has been found despite the contribution - continuous spectrum or surface waves - dominating the far field.Ministerio de Educación y Ciencia TEC2007-65376Junta de Andalucía TIC-25

Application of total least squares to the derivation of closed-form green's functions for planar layered media

A new technique is presented for the numerical derivation of closed-form expressions of spatial-domain Green's functions for multilayered media. In the new technique, the spectral-domain Green's functions are approximated by an asymptotic term plus a ratio of two polynomials, the coefficients of these two polynomials being determined via the method of total least squares. The approximation makes it possible to obtain closed-form expressions of the spatial-domain Green's functions consisting of a term containing the near-field singularities plus a finite sum of Hankel functions. A judicious choice of the coefficients of the spectral-domain polynomials prevents the Hankel functions from introducing nonphysical singularities as the horizontal separation between source and field points goes to zero. The new numerical technique requires very few computational resources, and it has the merit of providing single closed-form approximations for the Green's functions that are accurate both in the near and far fields. A very good agreement has been found when comparing the results obtained with the new technique with those obtained via a numerically intensive computation of Sommerfeld integrals.Ministerio de Educación y Ciencia TEC2004-03214Junta de Andalucía TIC-25

Computationally efficient analysis of extraordinary optical transmission through infinite and truncated subwavelength hole arrays

The authors present a computationally efficient technique for the analysis of extraordinary transmission through both infinite and truncated periodic arrays of slots in perfect conductor screens of negligible thickness. An integral equation is obtained for the tangential electric field in the slots both in the infinite case and in the truncated case. The unknown functions are expressed as linear combinations of known basis functions, and the unknown weight coefficients are determined by means of Galerkin's method. The coefficients of Galerkin's matrix are obtained in the spatial domain in terms of double finite integrals containing the Green's functions (which, in the infinite case, is efficiently computed by means of Ewald's method) times cross-correlations between both the basis functions and their divergences. The computation in the spatial domain is an efficient alternative to the direct computation in the spectral domain since this latter approach involves the determination of either slowly convergent double infinite summations (infinite case) or slowly convergent double infinite integrals (truncated case). The results obtained are validated by means of commercial software, and it is found that the integral equation technique presented in this paper is at least two orders of magnitude faster than commercial software for a similar accuracy. It is also shown that the phenomena related to periodicity such as extraordinary transmission and Wood's anomaly start to appear in the truncated case for arrays with more than 100 (10×10) slots

Radar cross section of stacked circular microstrip patches on anisotropic and chiral substrates

Galerkin's method in the Hankel transform domain (HTD) is applied to the determination of the radar cross section (RCS) of stacked circular microstrip patches fabricated on a two-layered substrate which may be made of a uniaxial anisotropic dielectric, a magnetized ferrite or a chiral material. Concerning the case of stacked patches printed on magnetized ferrites, the results show that substantial RCS reduction can be achieved inside the tunable frequency band where magnetostatic mode propagation is allowed. It is also shown that both the frequency and the level of the RCS peaks obtained for circular patches fabricated on anisotropic dielectrics or chiral materials may be substantially different from those obtained when substrate anisotropy or substrate chirality are ignored.Centro de Investigación Científicas y Tecnológicas TIC98-063

Full-wave analysis of nonplanar transmission lines on layered medium by means of mpie and complex image theory

In this paper, a multiconductor transmission line consisting of arbitrary cross-sectional perfect conductors printed on a layered isotropic or uniaxial anisotropic dielectric medium is analyzed by solving the mixed-potential integral equation for the free-surface currents. Closed-form expressions of the two-dimensional space-domain Green's functions for the electrodynamic potentials are used. These expressions are obtained by applying the complex image technique to the spectral functions remaining after removing the asymptotic and pole contributions from the original Green's functions. A single set of complex images is obtained for any guess value of the unknown propagation constant and for any pair of source/field points. In addition, the reaction integrals involved in the application of the method of moments are worked out in a quasi-analytical way. The final result is an accurate and highly efficient computation code for analyzing multiconductor structures printed on a layered medium

Evaluation of the radar cross section of circular microstrip patches on anisotropic and chiral substrates

Galerkin's method in the Hankel transform domain (HTD) is applied to the determination of the radar cross section (RCS) of a circular microstrip patch printed on a substrate which may be an uniaxial anisotropic dielectric, a magnetized ferrite, or a chiral material. The results obtained for circular patches on magnetized ferrites show that the RCS of these patches can be substantially reduced in a tunable frequency band when a bias magnetic field is applied. It is also shown that the results obtained for the RCS of circular patches printed on chiral materials can be substantially different from those obtained when substrate chirality is ignored

Full-wave analysis of tunable microstrip filters fabricated on magnetized ferrites

The method of moments in the spectral domain was employed in the rigorous full-wave numerical determination of the scattering parameters of two-port microstrip circuits fabricated on magnetized ferrite substrates. The numerical algorithm developed was applied to the analysis of microstrip bandpass filters fabricated on ferrites. Results show that the center frequency of the filters can be tuned over a wide range as a magnitude and/or the orientation of the bias magnetic field are varied. However, tunability was achieved at the expense of bandwidth reduction

Full-wave analysis of a wide class of microstrip resonators fabricated on magnetized ferrites with arbitrarily oriented bias magnetic field

A numerical code has been developed for the full-wave determination of the resonant frequencies and quality factors of microstrip patches with right-angle corners of arbitrary shape in the case in which the substrate of the patches is a magnetized ferrite with arbitrarily oriented bias magnetic field. The code is based on the solution of an electric-field integral equation by means of Galerkin's method in the spectral domain. The evaluation of the infinite integrals arising from the application of the numerical method is efficiently carried out by means of a technique based on the interpolation of the spectral dyadic Green's function. The numerical results obtained indicate that microstrip patches fabricated on ferrite substrates present cutoff frequency regions in which resonances cannot occur owing to the excitation of magnetostatic modes. The limits of these cutoff regions are shown to be dependent on the orientation and the magnitude of the bias magnetic field, on the shape of the patches, and even on the nature of every particular resonant mode. The numerical results also show that the resonant frequencies of microstrip patches on magnetized ferrites can always be tuned over a wide frequency range provided the orientation of the bias magnetic field is suitably chosen

Determination of the radar cross section of stacked circular microstrip patches

Galerkin's method in the Hankel transform domain (HTD) was used to determine the radar cross section (RCS) of stacked circular microstrip patches. Numerical results show that the RCS values of a pair of stacked circular patches may be very different from those obtained for one patch in the absence of the other patch

Estudio para la certificación energética del edificio TR7 del Campus UPC de Terrassa

El trabajo que se presenta a continuación trata de realizar un estudio mediante métodos simplificados, con el fin de obtener el certificado energético de un edificio en nuestro caso existente. Dicho estudio, no se limitará a realizar un simple certificado del edificio a estudiar, sino que tratará de realizar una certificación simplificada, y una exhaustiva del mismo. De esta forma se podrá comprobar, en función del tiempo requerido para cada una de ellas y la calidad obtenida, que es, en definitiva, el resultado de la certificación energética, las diferencias entre ambas. Por otro lado, mediante una base de datos real, podremos extraer los consumos reales del edificio y compararlos con los obtenidos mediante las modelizaciones expuestas previamente