Broadband Circularly Polarized Antenna with a Tree Fractal Wide-slot and a L-shaped Strip

A novel tree fractal wide-slot broadband circularly polarized (CP) printed antenna array is proposed. The antenna array is parallel fed by L-shaped metal microstrip, and the element is coupled by a wide-slot. Two perturbation branches are applied to the L-shaped metal microstrip to construct the tree-fractal structure. This antenna is designed by simulations and experiments. And results show that the two perturbation branches can improve the axial ratio well, and realize the function of broadband CP. Thus the antenna element which works from 1.11 to 1.71GHz is designed. In order to increase gain, the element is made to compose a 1x2 antenna array, gain of which reaches 5.7dBi, and the CP properties are maintained.