Characteristics Of Mode Theory And Its Application In The Antenna

In recent years, Characteristic Mode Theory(CMT) has attracted much attentions of the researchers. Characteristic Mode Theory could compensate both the limitations of anatical method and accuracy of the results. What’s more, the clear physical conception could guide the antenna design.In this article, the applications of CMT to the antenna designs and analysis are discussed. Through the analysis of CM appling to various antennas, this method is proved to have practical use and wide applications.Fristly, the CMT is used to analysis the wide-band characteristics of the wide-band antennas like the E-pattern antenna and Magneto-electric dipole antenna.Secondly, the CMT is applied to circular-polarized antennas. A wide-band and wide-beam circular-polarized antenna is designed, the basic conception and process of the CMT that used to analysis and design the circular-polarized antenna is presented. These would expand of the application of CMT.Then the CMT is applied to the designs of mobile terminals small antenna. Using the ground of the terminal devices as the main radiation structure and reasonably choosing the position of the feed point exciting the effective ground mode, this type of "antenna" has no resonant effect and could only bring about the ground characteristic mode. Hence, there is no particular requirement for the structure and the dimension of the antenna, which could effectively reduce the overall system’s dimension and achieve the purpose of compacting antennas.In the end, the CMT is used to design a desired radiation pattern. The main steps of this design are given and the simple dipole antenna that has wide-beam characteristic is presented for example.