An anisotropic PRS for squinting the radiation pattern with gain improvement of MIMO system

Abstract

This work presents the design and analysis of a new anisotropic Partial Reflective Surface (PRS) to address beam squinting as well as gain improvement, using the phase gradient property of periodic structure in a 3-port Multiple Input Multiple Output (MIMO) system. An angular tilt of 30° is obtained relative to the boresight direction by manipulating the transmission properties. Additionally, the gain is improved by utilizing a homogenous PRS. Gradation constant is realized by changing the radius of adjacent unit cells in a dielectric host structure, ensuring a continuous variation in PRS properties. The formation of a Fabry-Perot antenna reduces the overlap between the adjacent beams, improving field correlation and isolation performance, in addition to gain enhancement. Furthermore, two 1 × 5 absorbers are strategically placed between the radiating elements to minimize the surface currents and achieve high port isolation. This combination of PRS and absorber leads to reduced field-to-field coupling and port-to-port coupling, thus achieving high signal isolation and beam squinting accuracy. The effectiveness of the proposed approach is validated through simulations, which are further supported by an equivalent circuit model. Experimental validation is also conducted to verify the results obtained.