| OAM is a natural property of various types of helically phased beams. The related field has become a research hot spot in recent years. Theoretically, it has infinite orthogonal phase modes which can provide an infinite range of possibly achievable OAM states. Therefore using OAM multiplexing has the potential to tremendously increase the capacity of communication systems. The crucial part of OAM multiplexing is the generation of helically phased beams which is the research priorities in this paper. The main research works in this thesis are as follows:Firstly, we expounded the theory, research achievement, analysis and comparison about the general methods of OAM generation:crafted parabolic antenna, circular antenna array and spiral phase plate. Which could be a theory steppingstone to the following ways of generating OAM.Secondly, Analyzed the resonance characteristic of circular microstrip patch antenna based on cavity model theory, calculated the electric field distribution and the spiral phase distribution of the resonator. Got the generation of OAM by using elliptical patch with a single feed instead of circular patch with two feedpoints. The structure of proposed antenna was simple, can realize the OAM 2.Thirdly, designed multi-mode OAM antenna with two ports based on circular traveling wave theory. Combining the designed Wilkinson power divider with the OAM 3 antenna, we got the integrated OAM antenna with a single feed. We made some related research on the antenna and the transfer characteristic. The proposed antenna effective, reliable, can realize multiple OAM modes.Finally, Briefly introduced the conception and construction of software radio, expounded the advantages of LabVIEW by using a example program. Combined the proposed elliptic microstrip patch antenna with USRP and set up a wireless OAM transmission system, realized the instantaneous transmission of text, images and video in real channel. Which provided a experimental platform for OAM research. |
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