Broadband circularly polarized micostrip antenna

The invention discloses a broadband circularly polarized micostrip antenna. The broadband circularly polarized micostrip antenna is used for solving the problem of narrow working band of existing circularly polarized microstrips. The broadband circularly polarized micostrip antenna comprises a dielectric slab (1), a radiating unit (2), a radiating bottom slab (3) and a coaxial cable (4). The upper surface and the lower surface of the dielectric slab (1) are printed with the radiating unit (2) and the radiating bottom slab (3) respectively; the radiating bottom slab (3) is composed of a square patch (33), eight quasi-fractal units (31) and a metal strip (32), wherein the diagonals of the square patch (33) are symmetrically etched with four composite-structured slots (331) and equal-arm L-type slots (332),the eight quasi-fractal units (31) are uniformly distributed outside the square patch (33) and connected through the metal strip (32); along the diagonal without truncated angles of the square patch, the radiating unit (2) is symmetrically etched with two U-type slots (21) with outward openings. The broadband circularly polarized microstrip antenna has the advantages of being broad in band and small in size and can be applied to radio frequency identification, radar and wireless communication.