Analysis of Traveling-Wave-Fed Patch Arrays

The design and analysis of traveling-wave-fed, circularly polarized, concentric ring arrays are presented. Linearly polarized microstrip radiating elements were used in the arrays, and fed in series by non-radiating apertures. High quality circular polarization (CP) was achieved by arranging the radiating patches in a concentric ring, with the patches fed with currents of the same magnitude and the appropriate phase delays. For the first time in the literature, a full-wave based model of the power distribution to each element is presented. This model formed the basis of a rigorous analysis of the antenna, not addressed by previous authors. Such analysis is essential to ensure that all the elements radiate identical amount of power, and thus maintain pattern symmetry and optimum CP characteristics. The proposed designs were validated through practical measurements, which showed good CP quality and well-defined radiation patterns.