Gain Enhancement of $4\times 4$ mm-Wave Patch Array with Dielectric Shells and Metamaterial Lens: A Comparative Study

In this work, a comparative study between multilayered shells and multilayered metamaterial lens for gain enhancement of a $4\times 4$ array is carried out. A $4\times 4$ rectangular patch antenna array operating at 24GHz is designed. The patch has perturbations at the corners to achieve circular polarization (CP). The array has been designed on RT Duroid 5880 substrate of thickness 0.508mm. The antenna array is edge fed with unequally truncated corners on both diagonals. Initial design is analytically calculated using predefined equations, followed by several iterations to further refine i t. The $4\times 4$ a rray a chieved a gain of 17.3dB and an axial ratio of 0.55dB. The ARB (Axial Ratio Bandwidth) for the same design is 2.54% and IB(Impedance Bandwidth) is 6.532%. The narrower ARB is a compromise for obtaining the higher gain. Further to enhance the gain of $4\times 4$ array antenna, two case studies are considered. In the first case, four layered dielectric hemispherical shells is used and in the second case, a 4 layered metamaterial Lens is employed. A gain enhancement of 5.1dB and 4dB is observed in 4-layered dielectric shells and 4-layered metamaterial lens respectively. All the above results have been obtained by simulating with EM flow solver Ansys HFSS. As the dielectric shells developed has a wide band behaviour compared to the metamaterial lenses, the developed design can be extensively used for MIMO antennas for millimeter wave applications and 5G applications in FR2 band for gain enhancement.