Wide-bandwidth circularly polarized array consisting of linearly polarized annular slots and parasitic microstrip patches

A technique for generating wide-bandwidth circularly polarized (CP) radiation with a low cross-polarization level by using a printed array of special linearly polarized (LP) elements is presented. The technique is based on using a doubly rotated sequential feed structure and LP elements. In this manner, the technique combines the simplicity and reduced feed complexity of wide-bandwidth LP elements with the performance advantages obtained when rotation is applied to LP elements and CP subarrays. The basic element of the array is a printed annular slot with a parasitic circular microstrip patch, resulting in an element with wide impedance and gain bandwidth. Results on array performance are presented.<>