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 TE1 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%.