Transmission-line modelling of the cross-aperture-coupled circular polarised microstrip antenna

A circular polarised antenna fed through a cross-aperture in a ground plane by means of a microstrip feed line is modelled, and an original analysis using a transmission-line method is presented. The field linkages from the feed to the slots and the slots to the antenna are modelled as voltage transformers, which are employed in the synthesis of the overall transmission-line model of the structure. This analysis allows for an efficient computational procedure to predict the input impedance of the structure. The application of a full wave simulation package and the experimental results obtained for the structure support the theory presented