High Performance Patch Antenna using Circular Split Ring Resonators and Thin Wires Employing Electromagnetic Coupling Improvement

In this paper, three dimensional periodic structure composed of circular split ring resonators and thin wires is used to improve the performance of a microstrip patch antenna. The three dimensional periodic structure is placed at the top of the patch within a specific separation distance to construct the proposed antenna. The radiated electromagnetic waves intensity of the proposed antenna is improved compared with the conventional patch antenna due to the electric and magnetic coupling enhancements. These enhancements occur between the patch and the periodic structure resonators and between the different resonator pairs of the periodic structure. As a result, the electric and the magnetic fields at the top of the patch are improved, the radiated electromagnetic beam size reduces which results in a highly focused beam and hence the antenna directivity and gain are improved, while the beam are is reduced. The proposed antenna has been designed and simulated using CST microwave studio at 10 GHz. An infinite two dimensional periodicity unit cell of circular split ring resonator and thin wire is designed to resonate at a 10 GHz and simulated in CST software, the scattering parameters are extracted, the results showed that the infinite periodicity two dimensional structure has a pass band frequency response of good transmission and reflection characteristics around 10 GHz. The infinite periodicity of the two dimensional periodic structure is then truncated and multi layers of such truncated structure is used to construct a three dimensional periodic structure. A parametric analysis has been performed on the proposed antenna incorporated with the three dimensional periodic structure. The impacts of the separation distance between the patch and three dimensional periodic structures and the size of the three dimensional periodic structure on the radiation and impedance matching parameters of the proposed antenna are studied. For experimental verification, the proposed antenna operating at 10 GHz is fabricated; the return loss and the gain for the proposed antenna with and without meta-material are measured. Furthermore, the results show that, the antenna gain is improved by 4.6 dB while the beam width is reduced from 75 degrees to 41 degrees which validate the concept of beam focusing using electromagnetic coupling between the patch and the three dimensional periodic structure and between the different unit cells of the periodic structure, and also the return loss is improved by -20 dB, while the bandwidth is slightly reduced. The simulation and experimental results investigated the idea of the beam focusing using electromagnetic coupling improvement based on three dimensional periodic structures of circular split ring resonators and thin wires in microwave regime.