60 GHz Printed Yagi-Uda Beam-Deflector Integrated Refractive Index Metamaterial

An approach for deflection of the main radiation of the end-fire dipole antenna in a specific direction by changing the effective constitutive parameters of metamaterials are introduced. The concept of this phenomenon is creating a new medium that has different characteristics, in front of the electromagnetic waves to enforce it to propagate in a specific direction. This act has been done by embedding Modified Gradient Refractive Index Metamaterial (MGRIM) unit-cells (UCs) in front of the dipole-printed antenna. However, by changing the load dimensions of MGRIM, the permittivity and permeability of unit cells are going to change. Because the refractive index (n) of the medium changed, the phase of entered EM waves to this medium will be changed. So, the aim here is to create a new medium with different properties to provide a proper phase shift to tilt the end-fire radiation pattern. The challenge in this approach is are provide a high tilting beam angle, high gain, and low side lobe level simultaneously. Two unit cells are used in this paper to provide a high deflection angle and keep a high gain with a low side lobe level. First one to get medium has a gradient refractive index. The second one uses as a band stop structure in order to minimize the side lobe level (SLL) and enhance the gain. The simulation results show that by using the nonperiodicity arrangement of MGRIM UCs in front of a dipole-printed antenna, the main beam of the radiation pattern in the E-plane can be tilted 43
^o
in the end-fire direction at 60 GHz. The proposed design exhibits an increasing gain of about 2.7dB and reduces the side lobe level to -11.2dB.