Broad band electromagnetic characterization method of nematic liquid crystals using a coplanar waveguide

A broad band electromagnetic extraction method of the dielectric tensor for nematic liquid crystals, associated to a measuring cell, is presented. The dielectric tensor is computed from S-parameter measurements obtained at the input planes of a coplanar waveguide supporting the nematic liquid crystal to be characterized, which is used as measuring cell. The extraction method of the dielectric tensor is based on the propagation of the dominant mode in the measuring cell. It is fast and easy. It uses analytical relationships, which are presented in this paper. The simulations results have demonstrated the validity of this extraction method in the 1GHz-40GHz frequency range for the electromagnetic characterization of nematic liquid crystals.J. Hinojosa is grateful to Ministerio de Ciencia y Technología and Region de Murcia Fundación Séneca of Spain for the grants TIC2002-01266 and PB/39/FS/02, which have allowed the present research activity

Multiple adaptive neuro-fuzzy inference systems for accurate microwave CAD applications

An approach for applying fuzzy logic for accurate CAD of microwave circuits is presented. Our proposed method combines space-mapping (SM) technology and multiple adaptive neuro-fuzzy inference systems (MANFIS) for the modeling of microwave devices. MANFIS is trained to predict a nonlinear vector multidimensional mapping function, which is obtained from SM approach. Optimization by micro-genetic algorithm is used to find nonlinear vector multidimensional mapping function for singular systems. This approach is applied to a shielded microstrip line within a region of interest. The parameter values (ε reff ( f ) , Zc ( f )) computed with our proposed method are in excellent agreement with those obtained from electromagnetic simulations

Double-sided open split ring resonator for compact microstrip band-pass filter design

A metamaterial structure, called the double-sided open split ring resonator (DOSRR), which combines two open split ring resonators (OSRRs) aligned over the opposite faces of the substrate in an inverted fashion is presented. A study of this resonator from full-wave electromagnetic and circuit simulations is performed. As with the OSRR cell, the DOSRR cell allows a series connection along a microstrip transmission line and it has a small electrical size. Moreover, the DOSRR cell has the ability to add a transmission zero in the out-of-band region without increasing its size. This DOSRR cell is used for the design of compact microstrip slow-wave type band-pass filters. Two strategies based on circular windows etched in the bottom plane instead of square windows and U-shape slots etched in the microstrip transmission line are designed to increase the stop band and to add extra zeros in order to suppress the spurious band. The experimental results have confirmed the possibilities of this electrically small resonator (DOSRR) and the efficiency of both strategies to improve the out-of-band rejection.The authors gratefully acknowledge Ministerio de Ciencias e Innovación of Spain for financial support of this work under the grant no.: TEC2010-21520-C04-04/TCM

Shunt series LC circuit for compact coplanar waveguide notch filter design

A shunt series LC resonant circuit based on an open version of an interconnected split ring resonator (OISRR) is proposed. This OISRR exhibits half the resonant frequency of the split ring resonator, allows a parallel connection with a coplanar waveguide (CPW) section and according to its frequency response is an attractive cell for compact CPW notch filter design. 3 dB stop-band bandwidth lower than 4.5% with more than 11 dB insertion loss in the stop-band can be achieved with a CPW loaded with a single OISRR. The experimental results have confirmed the possibilities of this OISRR, which can be easily connected to CPW antennas to reject undesirable signalsThe authors gratefully acknowledge Ministerio de Ciencias e Innovación of Spain and FEDER for the financial support of this work under the grant no.: TEC2010‐21520‐C04‐04/TCM

Microstrip notch filters based on open interconnected split ring resonators (OISRRs)

An open interconnected split ring resonator (OISRR) is proposed for use in compact microstrip notch filters. This OISRR behaves as a shunt series L  C resonant circuit and allows a parallel connection with a microstrip line. This cell presents half the resonant frequency of the split ring resonator (SRR) and, therefore, is electrically very small. The measured results show a 3 dB stop-band bandwidth lower than 2 % with more than 10 dB insertion loss in the stop band. This OISRR can be useful in microwave communication systemsThis work was supported by of Spain and by FEDER (TEC2010-21520-C04-04/TCM)

Compact double notch coplanar and microstrip bandstop filters using metamaterial—inspired open ring resonators

Compact double notch coplanar and microstrip bandstop filters are described. They are based on a version of the open interconnected split ring resonator (OISRR) integrated in microstrip or coplanar waveguides. The OISRR introduces an RLC resonator connected in parallel with the propagating microstrip line. Therefore, this resonator can be modeled as a shunt circuit to ground, with the R, L and C elements connected in series. The consequence for the frequency response of the device is a notch band at the resonant frequency of the RLC shunt circuit. The number of notch bands can be controlled by adding more OISRRs, since each pair of rings can be modeled as a shunt circuit and therefore introduces an additional notch band. In this paper, we demonstrate that these additional rings can be introduced in a concentric way in the same cell, so the size of the device does not increase and a compact multi-notch bandstop response is achieved, with the same number of notch bands as pairs of concentric rings, plus an additional spurious band at a higher frequency.The authors gratefully acknowledge financial support from Agencia Estatal de Investigación (AEI) of Spain (grant no.: PID2019-103982RB-C42/AEI/10.13039/ 501100011033)

Sistema y método para caracterización electromagnética de materiales.

Número de publicación: 2 611 553 Número de solicitud: 201630964El sistema tiene: un primer sensor (S1) aplicado a un material desconocido (M); un equipo de medidas (EM); una primera guía de transmisión (G1) conectando el primer sensor (S1) con el equipo de medidas (EM); una primera transición (T1) para realizar una conexión entre el primer sensor (S1) y la primera guía de transmisión (G1); una segunda transición (T2) para realizar una conexión entre la primera guía de transmisión (G1) y el equipo de medidas (EM). El método incluye acondicionar el material desconocido (M). El acondicionamiento puede incluir: el material desconocido (M); el material desconocido (M) depositado sobre un material conocido (Mc); el material desconocido (M) depositado sobre un material conductor (Mcond); el material desconocido (M) depositado sobre dos capas que tienen un material conocido (Mc) y un material conductor (Mcond); un material conocido (Mc) depositado sobre dos capas que tienen el material desconocido (M) y un material conductor (Mcond).Universidad Politécnica de Cartagen

Optimization of chirped and tapered microstrip koch fractal electromagnetic band gap (KFEBG) structures for improved low-pass filter design

This study presents electromagnetic bandgap (EBG) structures in microstrip technology based on onedimensional Koch fractal patterns (Koch fractal EBG (KFEBG)). This fractal geometry allows to adjust the radius r and distance a between patterns so that a low-pass filter response is obtained when the ratio r/a is higher than 0.5. However, in such case undesired strong ripples appear in the low bandpass region. We demonstrate that the performance in the passband of this filter can be improved by applying a tapering function to the Koch fractal dimensions and to the width of the microstrip line, while simultaneously chirping (modulating) the Koch fractal periodic pattern distance (a) so as to maintain a constant r/a ratio. Several tapering functions scaled by a factor K are presented, and the results of their application to the KFEBG microstrip structure are compared by means of relevant characteristic parameters. Optimal performance has been obtained for the Kaiser and Cauchy distributions applied to the Koch fractal pattern, combined with a rectangular and Cauchy distribution applied to the microstrip width, respectively.This work was supported by the Ministerio de Economía y Competitividad of Spain and the European Regional Development Funds (TEC2013-47037-C5-5-R)

2D to 3D rectangular waveguide filter designs from linear iterated prediction space mapping optimization

In this article, an optimization procedure is described to align electromagnetic (EM) three-dimensional (3D) models with two-dimensional (2D) models for the design of RF/microwave circuits. The optimization procedure is realized from a modified standard space mapping (SM) approach. The mapping function between the 2D and 3D parameter spaces is directly obtained from a linear iterated prediction method, which reduces the computational cost and also avoids inverse transformations. The linear iterated prediction 2D to 3D SM optimization of evanescent rectangular waveguide bandpass filters with inductive posts for the 2D models and non-inductive posts for the 3D models illustrate the advantages and the challenges of this approach. The proposed method is simple to be implemented, it requires a reduced computational cost and it can be useful for CAD environment with 2D and 3D circuit structure electromagnetic (EM) analysis.This work was supported by Ministerio de Educación y Ciencia of Spain (TEC2007–67630-C03–02/TCM)

Substrate integrated waveguide (SIW) with koch fractal electromagnetic bandgap structures (KFEBG) for bandpass filter design

High-performance bandpass filters (BPFs) based on substrate integrated waveguide (SIW) and half mode SIW (HMSIW) with Koch fractal electromagnetic bandgap (KFEBG) patterns etched on the waveguide surface are proposed. These BPFs are designed using a new methodology. The BPF responses are improved by applying a chirped and tapered technique to the KFEBG patterns, which exhibit a radius-to-period ratio r / a ≥ 0.5. Simulation results and experimental verification are presented. Low insertion loss and high rejection are achieved.This work was supported by the Spanish Ministerio de Economía y Competitividad (TEC2013-47037-C05-5-R) and European regional funds (FEDER)