Research On PSOAM Antenna Based On Substrate Integrated Waveguide

Because of its vorticity and orthogonality,the electromagnetic wave carrying orbital angu-lar momentum(OAM)has evoked great interests in wireless communications,radar detection and electromagnetic sensing applications.However,the traditional OAM beam has some problems,such as beam divergence,black hole in the propagation path and different divergence angles of different modes,which make it difficult to multiplex different OAM beams in practical.Thus,plane spiral orbital angular momentum(PSOAM)is proposed.Different from the traditional OAM beam,PSOAM wave is compressed into a two-dimensional plane and propagates along the raidal direction,which can solve the above problems.Considering the disadvantages existed in the pro-posed PSOAM generation methods,for example,bulk structure and complex feeding network,the miniaturization and integration of multi-mode PSOAM antenna is given in this thesis.With the de-signed structure,some related applications,including beam forming and beam scanning,are further discussed.In this paper,a compact PSOAM antenna based on substrate integrated waveguide(SIW)is introduced.Several ring resonators are placed symmetrically on the two sides of the center plane to generate PSOAM beams(l=±1,±2,±3,±4,±5,±6).The working frequency is at 10 GHz,and each ring resonator is fed by four orthogonal points to generate a single-mode PSOAM beam.Using the ring resonator theory,the theoretical calculation and simulation analysis of the PSOAM antennas is given,indicating the possibility of generating PSOAM beams.In order to adjust each PSOAM beam more conveniently and reduce the number of feeding points,two kinds of feeding networks,including the parallel feeding network based on T-structure and the series feeding network based on ring structure,are given in this paper.Power division and phase shift will be realized by using the proposed feeding network.According to the simulation and experiment results,the SIW cavities fed by the designed networks also can generate different PSOAM beams.However,compared with coaxial feeding,because of the error caused by the feeding network,the performances of the PSOAM beams excited by the feeding networks have a little descent to some extent.Based on the result mentioned above,beamforming and beam scanning based on OAM are also discussed in this thesis.Different OAM beams are regarded as a set of complete orthogonal basis of electromagnetic wave.Thus,the structured electromagnetic wave can be generated by superposing different OAM beams effectively.Due to the radial propagation direction and the compact SIW structure,high directional structured beams superposed by different PSOAM modes can be obtained using the proposed stack SIW antenna.In addition,by adjusting the feeding signal's phase of each mode regularly,the high directivity beam can have a 360° undistorted scanning in the two-dimensional plane,which will have great potentials for the applications of structure electromagnetic wave in wireless communication,radar detection and other fields.