Optimizing circular polarization in broadband lightweight patch antennas

The range of potential application areas for low profile microstrip antenna elements would certainly increase if it were demonstrated that they are capable of generating high quality circular polarization over very wide elevation angles, and not only in a narrow angle around the main axis of the antenna. This property is of great importance when application decisions are being made. In order to keep an appropriately low profile and weight, the patch feed should be made in the form of printed circuit on a thin piece of dielectric substrate bonded to a much thicker substrate bearing the wide printed lines needed to transmit electromagnetic energy over larger distances, such as those between an RF front-end and the antenna (P. Kabacik et al, IEEE APS Int. Symp., July 2005). The smoothness of printed lines and slots on such thin substrates make this a good approach for applications with wavelengths up to the lower millimeter range (the Ku band).