Synthesis of a polarisation‐rotating surface with reflective filtering response based on orthogonally inserted coupled slot‐lines

Abstract

AbstractIn this article, a three‐dimensional polarisation‐rotation surface (PRS) with reflective filtering response based on two orthogonally inserted coupled slot‐line is investigated, which can reflect a vertically/horizontally polarised incident wave by 90°. Each unit cell of the PRS is composed of a pair of meandered slot‐line sections with open‐short‐ends etched on the vertically and horizontally inserted single‐layer printed circuit boards. Under the incidence of a linearly polarised plane wave along the vertical/horizontal direction, the plane wave is converted into the guided wave by the open‐circuited end of the slot‐line section, and then the guided wave is obstructed by the short end of the slot‐line section and coupled to the other slot‐line section, thus leading to 90° polarisation rotation. To simplify the design procedure, a matrix coupling theory is applied to synthesise and design the proposed PRS. A sample with fractional bandwidth of 20% at the centre frequency of 5 GHz and return loss of 20 dB is designed, fabricated, and measured for verification. The measured and simulated results are in good agreement with the theoretical ones. The results confirm that the proposed PRS has low insertion loss, high polarisation conversion ratio, and stable filtering performance for oblique incident angle up to 60°.