A broadband and wide beam circular polarization LTCC microstrip antenna analysis and design with characteristic modes theory

In this paper, characteristic modes theory was used in analysis and design of a broad axial ratio band circular polarization LTCC microstrip antenna. An ellipse slot couple structure was proposed to take the place of traditional circular slot couple structure for enlarging circular polarization broadband. And the theory of how to improve the axial ratio band was researched in detail by characteristic mode method. The characteristic angle phase difference of two orthogonal characteristic modes and the phase difference of feed line in whole frequencies are the key points in these kind of designs. Finally, the designed broadband axial ratio band circular polarization LTCC microstrip antenna was been successfully implemented, and the experimental results are presented and discussed. Good agreement between simulation and testing was achieved.