Application Of Reconfigurable Antenna In Phased Array

With the rapid development of the information technology,antenna performance plays a more and more important role in the communication system.For the antenna element,sometimes,people desire that the antenna has a wide beam characteristic to have a high level of low elevation gain.For the antenna array,aircraft airborne antennas and radar systems need to constantly change the beam pointing,which places high demands on the flexibility of the antenna pattern.Phased array antennas have become a hot spot in the development of antennas because they can quickly adjust the beam direction.The antenna design in the paper differs from the traditional phased array antenna unit,because the antenna element pattern is reconfigurable.Two different reconfigurable antenna elements working in different frequency bands are designed in the application of phased array large angle scanning,they achieve a large angle of scanning of the antenna array.1.Taking advantage of the fact that the phase difference of the current between the radiation patch and the parasitic patch will cause the antenna radiation pattern to deflect,a kind of pattern reconfigurable antenna is designed.The antenna works at 15 GHz,and has three operating modes according to the different situations of the switch,it also has three different patterns(the deflection angle ?=-24°,0°,+24°),the maximum radiation gain in the deflection state is 8.02 d Bi.On the basis of this optimum element,we have tried the arrays with different unit spacing,it is found that small unit spacing will cause the antenna unit to lose the deflection characteristic of its own pattern due to mutual coupling,while large unit spacing will cause the premature appearance of the far-region grating lobes.Final determined arrays can achieve wide-angle beam scanning with a gain fluctuation of no more than 3 d B within an angle range of ? within-54°~+54° by selecting different unit operating modes in different scanning angle ranges.2.The combination of high-impedance surface structure and reconfigurable quasi-microstrip Yagi antenna has successfully reduced the size of the pattern reconfigurable antenna.The antenna pattern deflection effect is more significant,the maximum gain of this antenna unit is 5.67 d Bi,the deflection angle can reach ?=-46°,+46°.It provides good conditions for subsequent array scanning.On the basis of this element,the simulation analysis of the 1×4 linear array and the 1×8 linear array is carried out.Both antenna arrays work at 5.9 GHz.The 1×4 array can finally achieve a gain fluctuation of no more than 3 d B in the scanning range of ? within-70°~+70°,the maximum gain reaches 10.9 d Bi;the 1×8 array can finally achieve a gain fluctuation of no more than 3 d B within the scanning range of ? within-68°~+68°,and the maximum gain reaches 14.25 d Bi.During the entire scanning process,the two antenna arrays within the scanning angle range show good impedance matching characteristics,while there is no scanning blind spot.