| With the rapid development of modern communication technology,new technologies such as 5G and millimeter wave have gradually been widely used in military and civilian fields.Therefore,more and more requirements are put forward for the beamscanning technology of the antenna.Traditional beam-scanning antennas,such as mechanical beam-scanning antennas and phased array antennas,usually have the disadvantages of complex antenna structures,high cost,and large volume and weight.The leaky-wave antenna(LWA)has the advantages of low profile,low cost,easy integration and frequency scanning characteristics.Therefore,it has been one of the research hotspots in the field of antenna since its emergence.However,the beam-scanning angle of frequency beam-scanning leaky-wave antenna is limited,and the beam-scanning characteristics are realized with the change of frequency.At present,various kinds of communication systems usually work in a specific frequency band.When the spectrum resources are tight,the frequency beam-scanning leaky-wave antennas have gradually been insufficient for our needs in communication system.In recent years,fixed-frequency beam-scanning leaky-wave antenna has been proposed and developed rapidly to overcome this problem.A new way to realize the fixed-frequency beam-scanning leakywave antenna is proposed in this paper.Based on spoof surface plasmon polaritons(SSPPs)structure,fixed-frequency beam-scanning leaky-wave antennas with simple structure,low processing cost and high gain are designed.The main work and innovations of this paper are as follows:1.A tunable phase shifter structure based on double-sided parallel stripline is proposed.The phase shifter is loaded with four pin diodes.The working states of the diodes are controlled by the applied voltage.The phase difference between the two output ports can be switched between 0° and 180° in 5 GHz ～ 7 GHz,and has a good power distribution effect.2.A fixed-frequency beam-scanning leaky-wave antenna based on spoof surface plasmon polaritons transmission line is proposed.Based on the principle of mode reconfiguration,flexible switching between scanning beams and the endfire beams can be realized.A dual-channel microstrip line-slotline feeding structure is designed to feed the spoof surface plasmon polaritons transmission line,which can flexibly switch the modes on the transmission line between odd mode and even mode.Disturbance units are placed periodically along both sides of the transmission line,and PIN diodes are loaded on the units.The period reconfiguration method is used to realize the tunability of the perturbation period through the PIN diodes,thereby realizing fixed-frequency beamscanning.Finally,the antenna can realize 96 ° beam scanning range in the even mode state,and the peak gain is 5 d Bi;The end-fire beams can be realized in the odd mode state,and the peak gain is 12 d Bi.3.A fixed-frequency beam-scanning antenna based on spoof surface plasmon polaritons is proposed.The proposed antenna is fed by a coplanar waveguide,which can form two beams in the upper and lower half spaces of the antenna to realize beamscanning.The average gain of the antenna is 8.5 d Bi and the maximum beam-scanning range is 42 °.4.A fixed-frequency beam-scanning antenna based on spoof surface plasmon polaritons is proposed.The proposed antenna is fed by a coplanar waveguide,which can realize the scanning of a single beam on the lateral side of the antenna,and solve the problem of mirror beams in the upper and lower half spaces.The average gain of the antenna is 8 d Bi and the maximum beam-scanning range is 140 °. |
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