Pere J. Ferrer

Transpolarizing Surfaces and Potential Applications

Transpolarizing surfaces are characterized for their property of rotating by 90deg the reflected electric field with respect to the incident one. Several transpolarizing surface designs are presented, and their potential applications and limitations, mostly for oblique incidence, are discussed.

Broadside radiation enhancement using a spiral resonator MNZ metamaterial substrate

The broadside power radiation enhancement has been tested for the case of a magnetic dipole in presence of an MNZ metamaterial substrate. In order to assess the theoretical estimations, a slot antenna on a ground plane has been fabricated and an AMC composed of 1 layer square spiral resonators has been used as an MNZ metamaterial slab. The radiation patterns have been measured in the anechoic chamber, achieving a gain in directivity of more than 1 dB. However, it should be taken into account that the thickness of the fabricated metamaterial slab (6 mm) is much smaller than the theoretical optimum thickness (hundreds of mm). The directivity of the antenna might be improved when increasing the number of layers of the metamaterial slab; in fact, in such a case, the leaky waves responsible of directive radiation are expected to be more significantly excited giving rise to the sought broadside power enhancement.

Design and measurement of a spiral-cell PMC for metamaterial applications

Simulations and measurements have been carried out of a 1-layer metamaterial slab made of spiral resonators that shows an AMC behavior, with an equivalent electrical width of lambda/12 for the thickness (z dimension) of the slab. This behavior has been experimentally verified through radiation pattern measurements. The results show that similar results are obtained by placing a PEC at a lambda/4 distance and by placing the antenna close to the AMC. This latter solution is lower profile

Transpolarizing Trihedral Corner Reflector Characterization Using a GB-SAR System

The use of a low-profile, lightweight, and easy-to-fabricate transpolarizing surface placed on one side of a trihedral corner reflector (TCR) as a polarimetric calibrator is presented in this letter. The transpolarizing TCR presents a high backscattered cross-polar response contrary to standard TCRs. The performance of this device has been tested at the X-band using the Universitat Politecnica de Catalunya ground-based synthetic aperture radar.

Transpolarizing surfaces for polarimetric SAR systems calibration

A novel transpolarizing or crosspolarizing surface has been proposed to be applied in polarimetric SAR calibrating systems, like trihedrals, since they can not provide initially a crosspolar response. So the trans-surface has been designed and measured in an anechoic chamber, providing good results for normal incidence.

Bidirectional metamaterial separator for compact antenna systems

In this paper, a new solution to improve the correlation matrix of two closely spaced antennas is illustrated. Contrary to the use of a decoupling network, a physical separator between the antennas is considered. And hence, the use of a metallic plane (PEC) and a metamaterial surface (with bidirectional PMC response) are compared in terms of correlation matrix improvement and radiation patterns.

Designs for bifrequency and bidirectional AMC surfaces

The AMC behavior of a reflecting surface is mainly related to the frequency where the 0deg crossing in the phase of its reflection coefficient takes place. This frequency gives the resonant frequency that characterizes the AMC surface. Two different designs of AMC surfaces showing quite different properties are presented in this communication. A first design proves the AMC behavior using metallic tubes with slotted square profile instead of the typical periodic arrangement of strips printed on a dielectric substrate; and the latter, shows the AMC performance of an artificial material when the electromagnetic waves impinge on its opposite faces.

Assessment of the Performance of a Metamaterial Spacer in a Closely Spaced Multiple-Antenna System

A metamaterial spacer composed of spiral resonators (SRs) and narrow metal strips has been tested to operate like a bidirectional artificial magnetic conductor (AMC) reflector at 2.45 GHz. The performance of the spacer has also been evaluated in a closely spaced multiple-antenna system applied to successfully increase the transmission capacity of a commercial wireless IEEE 802.11b router.

Transpolarizing trihedral measurement using UPC X-band GB-SAR

The use of a transpolarizing surface placed on one side of a trihedral corner reflector (TCR) as polarimetric calibrator is presented in this paper. The transpolarizing-TCR presents a high back-scattered cross-polar response. This structure has been tested at 9.65 GHz (X-band) with the help of the UPC GB-SAR system.

Reactive fields above an artificial PMC

In this paper, an effective numerical method to carry out a modal analysis in infinite-array approach is presented. Strong reactive fields, with a non-negligible vertical component, at the resonant frequency are evidenced. The same effects are observed for a finite array, in which evanescent waves are reflected by the edges, resulting in strong array truncation effects at the resonance. This work may lead to the establishment of new design criteria for artificial ground planes devoted to low-profile antennas