Medio EBG basado en estructuras simples en forma de L

In the present work a study of the prohibited frequency bands produce in a microstrip line when introducing inclusions of metallic elements with "L" shaped has been carried out. The inclusion of these structures on both sides of the transmission line causes the appearance of a broad bandgap within the region of frequencies of interest. It has been found that the existence of more than one row on either side of the line does not significantly modify the response. In order to extend the bandgap and make it more uniform, several modifications to the parameters and structure distribution has been proposed. It has been found that both the arrangement of a thicker dielectric sheet and the structure tapering can improve the response. Furthermore, they produce a decreasing of the fields and, therefore, unwanted radiation in nearby elements can be reduced.Ingeniería, Industria y Construcció

Caracterización Electromagnética de Medios Quirales

Experimental techniques for chiral media characterization at microwave frequencies are reviewed. Free-wave, waveguide and resonators techniques found in the current literature and the author’s own experience are discussed. Some free-wave results are presented. Finally, a critical discussion about each technique feasibility is presented.Ingeniería, Industria y Construcció

Caracterización experimental de medios quirales basados en inclusiones periódicas. El resonador de cuatro manivelas

The periodical distribution of elements forming a bi- or three-dimensional periodical lattice has provided a fundamental tool to develop new materials with exotic and, sometimes, amazing electromagnetic properties. Here we have analyzed the effects related to the electromagnetic activity produced by a 2D array of four crank resonators (4CR), which is composed by same handeness cranks in a packed configuration forming a parallelepiped. The sample has been built using printed circuit technology and the unit cell was designed to fit its electromagnetic response into the X band frequency range. Using a free-wave system and the corresponding reciprocal algorithms, we have characterized the material and determined the rotation angle, refraction index and chirality parameter.Ingeniería, Industria y Construcció

Diseño de medios EBG basados en estructuras quirales

In this work, a new EBG structure with inclusions of chiral elements is presented. We have studied the effect of crank type chiral inclusions on the propagation along a microstrip line and compared with the effects produced by mushroom type inclusions. It has been found that the inclusion of a row of structures of high chirality on both sides of a transmission line produces a band gap of wider bandwidth, to that obtained by the inclusion of other known elements used to create EBG media such as mushroom type structures. The current structure works in X-Band (8.2-12.4 GHz) but is easily applicable to other frequencies changing the size of crank inclusions.Ingeniería, Industria y Construcció

Estudio de doble lámina con estructuras quirales de cuatro manivelas bajo incidencia normal

A double plate with chiral structures based on three segment cranks is analysed for normal incidence and lineal polarization. Each structure is made with four three segment crank arranging a rectangular parallelepiped. These structures are distributed in a periodic configuration in each sheet, being the respective unit cells perfectly lined up. The response depends on spacing between plates. Interesting results are obtained for small spacing: the chiral behaviour depends on the spacing then the double sheet system can be used as tunable rotator.Ingeniería, Industria y Construcció

Estudio experimental de inserciones metálicas quirales en medios guiados

A new manufacturing technique of chiral material and first measurements of the rotation of the polarisation angle are presented. We have developed a flexible and low cost method to produce chiral media based on the inclusion of three segment wire hook (crank) in lossless dielectric medium. Cylindrical samples are placed into a section of circular waveguide propagating an initial single TE plane-polarised mode in the X band. The S21 parameter is measured with a rotation of the output waveguide. We have found rotations of the polarised wave produced by the samples. The effect of chirality is analyzed by chiral crank versus non-chiral staples comparison.Ingeniería, Industria y Construcció

Estudio de medios EBG basados en estructuras metálicas en forma de paralelepípedo

In this paper microstrip lines with periodic metallic structures on both sides have been studied. The basic unit cell is a parallelepiped with different metallization at the edges. The effects on the transmission in a standard microstrip line have been analysed by using both experimental and simulation (CST Microwave Studio®) techniques, obtaining an EBG behaviour similar to the one obtained with mushroom-like structures. The proposed structures present advantages in band gap size. Furthermore, the response does not dependent on the number of rows at the sides of the microstrip line.Ingeniería, Industria y Construcció

Developing Chiral Media Based on the Inclusion of Metallic Cranks

A review of the manufacturing techniques for developing chiral media based on the inclusion of cranks is presented. Chirality is usually obtained by a randomdistribution of helices in a host medium. Here the chiral elements are obtained by bending thin metal-wires in three segments. We will show that a random distribution of cranks is able of rotate the polarization angle of the transmitted linearly polarized wave at microwave frequencies. This effect can be enhanced by the precise location of cranks forming a 2D periodic lattice. Several structures are analyzed looking for isotropy, reciprocity and homogeneity.Ingeniería, Industria y Construcció

Actividad electromagnética de medios quirales basados en manivelas

Materials with electromagnetic activity are usually made by spreading helices inclusions into a host medium. In previous work, a new manufacturing technique based on the inclusion of few three segment wire hooks (cranks) was presented and the rotation of the polarisation angle in circular waveguide discussed. Here we present that the random inclusion of many cranks into a host medium produces electromagnetically active materials. Based on a free-wave experimental system, we have found that the transmitted wave through the material is rotated with respect to the incident one. First results seem to be in agreement with the typical behaviour of chiral media at the resonant frequency.Ingeniería, Industria y Construcció

Diseño de medios quirales basados en estructuras individuales bidimensionales

In this paper, we present a new way of constructing chiral media, in 8.2-12.4 GHz band, starting from achiral individual metallic elements (right angle). We showed that an appropriate distribution of such inclusions in a dielectric host responds in a manner consistent to that obtained with other media constructed using chiral metal inclusions. Appropriately modifying the size and spatial distribution of right angles is possible to model the response of these media. The media manufactured by the inclusion of right angles can be fabricated using technology printed circuit board (PCB).Ingeniería, Industria y Construcció