Circularly polarized patch antenna array fed by coplanar waveguide

A novel design of a circularly polarized linear patch antenna array fed by a coplanar waveguide (CPW) is presented. The array elements are placed in the direction transverse to the feeding CPW line and are excited by a couple of 100 Ω slotlines, which are combined to form the 50 Ω feeding CPW. The circularly polarized radiation is obtained by placing similar perturbation segments to each of the array elements. The simulated and measured axial ratios, return losses, and radiation patterns are presented for an 1 × 2 and an 1 × 4 arrays with good results. The proposed feeding structure can be extended to design a two dimensional array with good front-to-back ratio on a single substrate with only one straight CPW line.