Fatemeh Ghasemifard

Dispersion Analysis of 2-D Glide-Symmetric Corrugated Metasurfaces Using Mode-Matching Technique

In this letter, wave propagation in 2-D doubled corrugated metasurfaces, including glide-symmetric corrugated metasurfaces, embedded in a thin parallel plate waveguide have been analyzed using the mode matching method. The general dispersion equation for propagation at different directions is derived and dispersion surfaces have been obtained for three different cases. The results are in good agreement with reference results obtained using CST Microwave Studio. Moreover, the method is accurate and computationally much faster than CST Microwave Studio and similar commercial software.

Contact-free measurement of currents in two-dimensional parallel conductors using the Green identity approach

The Green identity approach is used to reconstruct currents in very long parallel conductors above the ground from magnetic field data measured at some points under the conductors. By assuming that the conductor positions are known, this method can be used for contact-free measurement of currents in transmission lines in power system. This method gives the possibility of measuring high-frequency currents which cannot be measured with current transformers.

Twist and Polar Glide Symmetries: an Additional Degree of Freedom to Control the Propagation Characteristics of Periodic Structures

New high-frequency 5G and satellite communication systems require fully-metallic antennas and electromagnetic components. These components can be implemented with truncated versions of periodic structures. In order to achieve the desired performance of these future devices, it is of crucial importance to have a precise control of the propagation properties, i.e. the frequency dispersion behavior and stop-bands. Here, we demonstrate the potential use of higher symmetries to diminish the frequency dispersion of periodic structures and control the width of stop-bands with a new type of fully-metallic transmission line, which is loaded with holes on a twist-symmetric configuration. Simulated and experimental results confirm the intrinsic link between the propagation characteristics and the symmetries of a periodic structure. Additionally, we provide a definitive explanation of the recently discovered polar glide symmetry and its potential combination with twist symmetries to produce low-dispersive materials and reconfigurable stop-bands. The promising properties of these structures are demonstrated with a fully-metallic reconfigurable filter, which could be used for future high-frequency 5G and satellite communication systems.

Sensor selection via convex optimization in remote contact-free measurement of currents

The sensor positions have substantial effect on the accuracy of remote contact-free reconstruction of currents in power transmission lines from magnetic field data, measured by a set of sensors located under the conductors. By maximizing a performance metric, based on the Fisher information matrix, Nopt sensors are selected from N candidate sensors. The main optimization problem is changed to a convex optimization problem using a relaxation of the integer constraints. The result for optimized sensor positions for a remote current reconstruction in power transmission lines using a planar sensor array is demonstrated.

Handling the ill-posedness of current retrieval in power lines from magnetic field data using Tikhonov regularization method

An inverse source problem of reconstructing the currents in parallel conductor structures from magnetic field data is considered. In this kind of inverse source problems which arise in contact-free measurements of currents in bus bars, power lines, and cables, the magnetic field data collected by a set of sensors in the vicinity of the conductors is used to determine the currents in conductors. The method is based on inversion of the direct map from the currents to the magnetic field data using a proper model of the problem.