Synthesis Design of Three-Dimensional Wideband Polarization-Rotating Surface

The synthesis technique for a wideband three-dimensional Polarization-Rotating Surface (PRS) is presented in this paper. Firstly, two types of circuit models with shunt short-ended stubs are discussed, whose frequency responses can be synthesized using Chebyshev functions. Upon specifying performance parameters, including filtering orders (N=4, N=5), fractional bandwidth (FBW), and return loss (RL), all circuit parameters can be derived from the filtering response specifications. A fourth-order wideband three-dimensional PRS with an FBW of 80% and an equal-ripple RL of 10 dB is then proposed, realized using a slotline-microstrip-slotline coupling structure. To further improve the frequency responses, a fifth-order wideband three-dimensional PRS with an FBW of 120% and an equal-ripple RL of 10 dB is proposed. The close alignment between the simulated and measured results with the predicted responses indicates that the proposed synthesis method is an efficient solution for designing a wideband PRS.