Single-structure Orbital Angular Momentum Antenna Based On Characteristic Mode Theory Analysis

The rapid development of communication technology has brought the problem of shortage of spectrum resources at the same time.The eme-rgence of orbital angular momentum has changed this situation,because its different modes have orthogonality,thus another degree of freedom is produced to improve the utilization of spectrum and the ability of transm-ission information by beam.which showed great development potential in relevant fields.The related design of the OAM antenna is focused in this paper,and the research is conducted using the characteristic theory and the perturbation theory.The main work are as follows:First of all,the development history and important research achievements of the current orbital angular momentum and the characteristic mode theory at home and abroad are reviewed,and the relevant principles of the characteristic mode theory and orbital angular momentum are introduced,and the necessary formulas are deduced,which lays a theoretical foundation for the research of seven new patch antennas designed later.Secondly,the principle of generating orbital angular momentum at double feed points is studied.An UWB petal shaped patch antenna is designed by using two feedpoints with the same amplitude and phase difference of 90°,which can effectively broaden the bandwidth performance of the patch antenna.At the same time,three kinds of double feed point patch antennas are designed,and the performance of the above four patch antennas is given through simulation analysis,which verifies the rationality of generating orbital angular momentum.Finally,the characteristic mode theory and perturbation theory are studied.Three new orbital angular momentum single feed point patch antennas are designed by means of angle cutting and slot cutting.The steps to determine the specific position of the single feed point and the necessary conditions for generating orbital angular momentum by using characteristic mode analysis are summarized.The performance of these three patch antennas is studied and the advantages of these patch antennas are illustrated.