A compact high-efficiency circularly polarized antenna with thick EBG cells and integrated power divider/phase shifter

This paper presents a highly efficient and miniature planar electromagnetic bandgap (EBG) antenna with circularly polarized (CP) radiation. The antenna building blocks are the high aspect ratio (HAR) EBG cells recently introduced in literature, nine (3×3) of which are deployed in both lateral dimensions. As the top metal layer of this EBG surface is symmetrical, it simultaneously accommodates two orthogonal E-field components, excited by two microstriplines attached to the corners. A compact simplified shifter/power divider provides quadrature phase difference and equal power at feed points, enabling the structure to generate a broadside CP radiation pattern. Thanks to the natural capability of EBG cells, the low loss nature of HAR metal traces, and high capacitive coupling of gaps, this work features a planar CP antenna with dimensions as small as 0.26λ×0.29λ×λ/23 and efficiency as high as 94.3%.