Modeling of circularly-polarized CTS arrays

This paper presents an efficient numerical tool for the analysis of circularly-polarized continuous transverse stub (CTS) arrays. The proposed structure comprises oversized open-ended parallel-plate waveguides (PPWs), radiating in free space. The operation of the antenna relies on the simulataneous excitation of two orthogonally-polarized modes in the PPWs, i.e. the fundamental TEM and the first higher order TE 1 mode. The developed numerical model provides the active reflection coefficient of the radiating slots and the radiated fields. The axial-ratio (AR) is computed as well. Results are in excellent agreement with full-wave simulations. Guidelines are then provided to help the design of the antenna. A design example is presented. It attains an axial ratio of less than 1.5 dB and an input reflection coeffcient lower than -10 dB over a relative bandwidth of 43.9%.