Planar Polarization-Rotation Pattern Manipulation Surfaces With Patch-Microstrip Line-Patch Structure Under Different Incidences

This article presents a method to design and implement pattern manipulation surfaces (PMSs) with polarization rotation by employing a patch-microstrip line-patch (PMP) structure. The polarization-rotation PMSs (PRPMSs) receive plane waves from different angles and reradiate polarization-rotated plane waves to a wanted direction. The impedance transforming characteristic of the patch under different incident angles between spatial wave to guided wave is studied with an equivalent circuit model (ECM). All the parameters in the ECM are obtained through one full-wave simulation with periodic boundary conditions (PBCs) under normal incidence in CST. The polarization rotation ability is realized by converting TM10 mode to TM01 mode on the patch through a microstrip line. The polarization conversion ratio (PCR) of the PMS with different incidences, scan angles, and polarizations is modeled by the ECM. Then, PRPMS elements with different microstrip line lengths are studied for phase tuning. The relationship between the microstrip line length and the phase shift is calculated via ECM and verified via full-wave simulation, both of which show that a continuous phase shifting range of 360° can be easily provided. In this way, the scattered waves can be steered in an arbitrarily prescribed direction. To validate the design concept under different incident angles, three PRPMS prototypes with the main beam steered to 0°, 30°, and 50° are fabricated and tested. Measured normalized RCS results agree well with the calculated and simulated ones, which verifies the validity of the proposed ECM and the PRPMS. Therefore, the proposed PRPMS is a promising method for future smart radio environments (SREs).