| Millimeter-wave multi-beam antenna is one of the key techniques of the fifth generation(5G)mobile communication system.Due to the merits of high quality factor,low loss,low profile and easy integration,the substrate integrated technology has been widely used in the designs of the microwave and millimeter-wave circuits and antennas.Based on the substrate integrated technology,this thesis investigates the passive orthogonal multi-beam planar array in 5G millimeter-wave band.The main work is as follow:Firstly,a broadband planar integrated crossover is proposed and designed by utilizing the structures of the substrate integrated waveguide(SIW)and the stripline.Meanwhile,a compact orthogonal transmission network is studied and designed.Based on the proposed transmission network,a common aperture slot planar array antenna is proposed.The array is composed of the slot antenna elements fed by the SIW loaded with the stripline and the slot antenna elements fed by the stripline loaded with the metal sidewalls,of which each port has the-10 dB impedance bandwidth of 25.5-26.5GHz,and possesses the good radiation characteristics in the orthogonal planes.Secondly,a folded cassegrain reflector beam-forming network with six input ports and eight output ports is designed for the common aperture orthogonal multi-beam planar array,of which the beam scanning characteristics are verified by combing with the substrate integrated waveguide slot antenna.The simulation results indicate that the designed antenna can realize beam scanning within the range of ?42°in the frequency band of 25.5-26.5GHz,and have the symmetric radiation patterns.Thirdly,the feeding and transition structures of the stripline multi-beam antenna in the common aperture orthogonal multi-beam planar array are studied.Two transitions for the SIW to the shielded stripline(SSL)with semi-open and closed structures and one transition for the SIW to the substrate integrated coaxial line(SICL)are explored in depth.The fabrication and measurement are conducted to verify that the designed SIW-to-SICL transition possesses the advantages of ultra-wideband and low loss.Finally,the passive orthogonal multi-beam planar array with a common aperture for 5G millimeter-wave is designed systematically,and the designed antenna is processed by using the printed circuit board(PCB)technology.Measurement and tolerance analysis are also carried out to demonstrate the simulation.The experimental results show that the proposed planar array has good beam scanning performance in two orthogonal planes,which realizes beam coverage within the range of ?44°in XOZ plane and the range of ?40°in YOZ plane. |
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