By virtue of their ability to resonate at a wavelength much larger than the maximum dimension, Split-Ring Resonator (SRR) cells can be densely stacked to create energy harvesting arrays having per-unit-area power efficiency higher than a single SRR cell. While the concept of using metamaterial particles for electromagnetic energy harvesting had been demonstrated in our earlier work, the overall efficiency of an SRR array in comparison to classical antenna arrays is fundamental to the viability of this technology. In this work, we focus on a comparative study based on numerical fullwave simulations where an array of SRRs is compared to an array of microstrip antennas. We show that an SRR array can provide significant enhancement in power efficiency and bandwidth in comparison to the classical microstrip patch antenna. Experimental validation is provided showing SRR arrays can provide significant energy-absorption enhancement.

This work introduces a class of electrically small resonators composed of a complementary split-ring resonator backed by a ground plane. The proposed structure has low profile, efficient for wide range of illumination angles and can be placed on metallic surfaces. An example unit cell was designed, optimized, and fabricated to resonate at around 5.8 GHz. It is shown through numerical simulations and laboratory measurements that the complementary split-ring resonator can efficiently deliver the incident power carried by an electromagnetic wave to a resistive load. V C 2014 AIP Publishing LLC. [http://dx.

This work demonstrates the viability of wideband Ground-backed Complementary Split-Ring Resonator (WG-CSRR) arrays with significant power conversion efficiency and bandwidth enhancement in comparison to the technology used in current electromagnetic energy harvesting systems. Through numerical full-wave analysis, we demonstrated the correlation between the topology of the WG-CSRR patch and the electric current distribution over the patch at different frequencies. A comparative study of power harvesting efficiency and frequency bandwidth through numerical analysis was presented where an array of WG-CSRRs is compared to an array of G-CSRRs and an array of microstrip patch antennas. A significant improvement in bandwidth is achieved in comparison to the G-CSRR array reported in earlier work.

This work presents a novel finite-element solution to the problem of scattering from multiple two-dimensional cavities in infinite metallic walls. The technique presented here is highly efficient in terms of computing resources and is versatile and accurate in comparison with previously published methods. The formulation is based on using the surface integral equation with the free-space Green's function as the boundary constraint. The solution space is divided into local bounded frames containing each cavity. The finite-element formulation is applied inside each frame to derive a linear system of equations associated with nodal field values. The surface integral equation is then applied at the opening of the cavities to truncate the computational domain and to connect the matrix subsystem generated from each cavity. The near and far fields are generated for different single and multiple cavity examples. The results are in close agreement with methods published earlier.

This work presents a novel finite-element solution to the problem of scattering from a finite and an infinite array of cylindrical objects with arbitrary shapes and materials over perfectly conducting ground planes. The formulation is based on using the surface integral equation with Green's function of the first or second kind as a boundary constraint. The solution region is divided into interior regions containing the cylindrical objects and the region exterior to all the objects. The finite-element formulation is applied inside the interior regions to derive a linear system of equations associated with nodal field values. Using two-boundary formulation, the surface integral equation is then applied at the truncation boundary as a boundary constraint to connect nodes on the boundaries to interior nodes. The technique presented here is highly efficient in terms of computing resources, versatile, and accurate in comparison with previously published methods. The near and far fields are generated for a finite and an infinite array of objects. While the surface integral equation in combination with the finite-element method was applied before to the problem of scattering from objects in free space, the application of the method to the important problem of scattering from objects above infinite flat ground planes is presented here for the first time, to our knowledge.