Single-layer dipole array for linear-to-circular polarisation conversion of slotted waveguide array

A single-layer linear-to-circular polarisation converter is proposed for an application to a slotted waveguide planar array. It consists of dipoles which closely couple to slot arrays. The method of moments clarifies the mutual coupling between the dipoles and the slots on the waveguide. Numerical results promise the use of a uniform and parallel dipole array as a single-layer linear-to-circular polarisation converter for an existing linearly polarised slotted waveguide array. The measurements using a linearly polarised slotted waveguide array in 22.0 GHz band confirm the prediction; the axial ratio less than 1 dB and a negligible insertion loss is realised.