| The degradation phenomenon of vortex characteristics and various limitations of orbital angular momentum(OAM)antenna make it difficult to apply the OAM beam in microwave and millimeter-wave communication.This paper studies the degradation phenomenon of vortex characteristics,explores the application potential of OAM antenna in near-field communication,designs a kind of multiple resonant cavities antenna structure and realizes the OAM mode multiplexing.Firstly,this thesis designs an array antenna to research the degradation phenomenon of vortex characteristics,and then designs a RFID orbital angular momentum antenna used in near-field communication to make the radiation hole affect far-field communication less.Secondly,this thesis designs a circular SIW cavity to generate traveling-wave according to the theory of circular loop antenna,which has advantages of simple structure,low-cost,small volume and it is easy to integrate with peripheral circuits.Thirdly,the circular SIW cavity can be designed as leaky-wave antenna to radiate the rotating traveling-wave by HM-SIW technology,which can be switched to generate two OAM beams.The multipoint feeding technology is used in the cavity antenna to generate OAM beams of higher purity and higher-order modes.Finally,the dual HM-SIW cavities antenna can be designed by two resonant cavities.Then two 3dB 90° bridges are also designed to connect with the dual HM-SIW cavities antenna to generate four OAM beams.Moreover,more cavity antennas can be used to design the multiple HM-SIW cavities antenna to improve spectrum efficiency and communication capacity at the same time. |
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