| With the development of the mobile communication technology, the growth of the wireless communication rate is rapid. In order to improve the wireless communication rate further, a variety of technology are developed and applied. Among them, how to improve the spectral efficiency is a focal issue. After the existing multiplexing technologies, such as polarization multiplexing, orthogonal frequency division multiplexing, are becoming more and more mature, to improve spectrum utilization by using electromagnetic wave orbital angular momentum (OAM), becomes hot in electromagnetic field and communication field.In this thesis, the investigation on antennas and systems for vortex beam carrying orbital angular momentum is performed. Based on the transmission line theory, the impedance matched spiral phase plate (SPP) is designed. Its transmission efficiency and beam quality is improved, and, the reflectivity is reduced20dB compared with the traditional SPP. In order to solve the divergence problem of the beam carrying OAM, according to the theory of ring traveling wave antenna, a dual channel OAM mode ring resonator antenna is designed. Using hybrid coupler feed, a ring resonator generates two OAM beams, and the external ring focus paraboloid convergent beam, the OAM beam taking the divergence of very small angle can be emitted. Based on these antennas, a wireless communication link with two separate OAM channels is demonatrated, and the isolation between the two channels is measured. Finally a part receiving demodulation scheme is demonstrated, and verified in the optical band.The proposed antennas are designed, simulated, fabricated and measured in this thesis. The requirements for the applications in OAM multiplxing links are discussed, and improvement schemes and direction, and the development in this field are prospected. |
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