Research On Frequency And Pattern Reconfigurable Planar Antenna

With the development of modern communication technology,the communication system is developing towards broadband,high frequency and intelligence.The antenna,as a signal transceiver,also faces problems such as high cost,high loss,and long design cycle.The reconfigurable antenna not only reduces the weight of the entire system,but also reduces the cost of construction,shortens the design cycle,and facilitates numerical control,so it is suitable for use in a variety of communication systems.Based on extensive review and summary of the literature,this paper studies the basic implementation of frequency reconfigurable and pattern reconfigurable antennas,and designs two frequency reconfigurable antennas and two pattern reconfigurable antennas.The main work of this paper is as follows:(1)A new type of open resonant ring structure is proposed,and on the basis of the RF switch,a spilt resonant ring structure with reconfigurable resonant frequencies of five states is realized.And the structure is applied to the ultra-wideband monopole antenna as a parasitic unit,and five kinds of frequency reconfigurable notch states are realized,and the notch band covers WLAN,satellite communication C band and X band.Moreover,the notch band has a wide bandwidth and the pattern is relatively stable.(2)A novel waveguide slot antenna reconfigurable method is proposed,which realizes three working states by inserting liquid metal on the wide side of the waveguide.The waveguide slot antenna operates in the millimeter band and the slots are arranged in a Chebyshev array.The research shows that the gain of the antenna is higher than 12.5 dBi in three states,and the insertion of liquid metal has little effect on the gain of the antenna,which is about 4dBi.On this basis,a frequency reconfigurable waveguide slot array antenna composed of four waveguides is designed.Compared with the single-tube antenna,the bandwidth is slightly reduced,but the frequency switching effect is more obvious and the gain is higher(both greater than 19 dBi).In addition,the antenna has a port isolation greater than 20 dB and has good isolation characteristics.(3)A new type of reconfigurable antenna pattern is proposed.On the basis of the printed dipole,the current distribution of the printed dipole is changed by using liquid metal to realize different feeder forms,thereby realizing 3 radiation patterns in different directions.The working frequency band of the antenna in the three working states is not much different,and the relative bandwidth is 48.2%,which is wider than other reconfigurable antennas.And maintain a more stable pattern in the working frequency band.(4)A new type of beam-switchable antenna is proposed.On the basis of four pairs of printed dipoles,by using liquid metal as a feeder,the operation of each pair of dipoles is controlled,and four directions covering 3600° are realized.Figure,the switching interval angle is 60 °.Moreover,the orientation and gain of the antenna are improved by adding a metal strip as a director.The relative bandwidth of the antenna is 35.2%.In this working frequency band,the antenna pattern is stable,the lobe width is greater than 80°,and the gain is greater than 4.4 dBi.