A Meander-Line Circular Polarizer Optimized for Oblique Incidence

This paper presents the design of a meander-line circular polarizer optimized for oblique incidence and for a direction off from the principal planes (phi = 0 degrees, 90 degrees, 180 degrees, or 270 degrees). This polarizing screen converts linearly polarized (LP) waves into circularly polarized (CP) waves and vice versa. To illustrate the design process, a three-layer meander-line circular polarizer is designed for an oblique incidence angle of (theta = 40 degrees, phi = 45.) and its performance is examined in detail over the 18-20 GHz band. Measurements and simulations are in good agreement. Moreover, the sensitivity of the results to frequency and incidence angle variations is studied. The results show that the bandwidth of the meander-line circular polarizer is maximum when it is designed for normal incidence or for an oblique incidence in the two principal planes because coupling between orthogonal modes is weaker.