| Owing to the wide application and rapid development of wireless communication technology,the utilization rate of the electromagnetic spectrum has become increasingly saturated.Therefore,in different complex scenarios,requiring wireless communication equipment has the ability of broadband operation and multi system compatibility.As one of the key modules in the wireless communication system,it also needs to have the ability of wideband and compatible with multiple communication standards,so it is of great significance to study the wideband reconfigurable array antenna.At present,the research on reconfigurable array antennas mainly focuses on the three directions of frequency reconfiguration,polarization reconfiguration and pattern reconfiguration.However,there are not many researches on frequency reconfiguration,polarization reconfiguration and pattern reconfiguration in the case of broadband,and there are few researches on any combination of frequency,polarization and pattern or all three can be reconfigured.Therefore,the thesis studies the broadband reconfigurable array antenna system.The specific research contents are as follows:(1)Aiming at the problems of few polarization reconfiguration states and narrow axial ratio bandwidth,the thesis combines microstrip patch antenna,slot coupling structure and Wilkinson power divider,and proposes a 2*2 broadband polarization reconfigurable array antenna.Firstly,the potential bandwidth,directivity coefficient and radiation mode of the microstrip rectangular patch antenna are analyzed using the characteristic mode theory;then the broadband characteristics are realized through the slot coupling feeding;finally,The feeding phase difference of the Wilkinson power divider can realize three reconfigurable polarization states.The test results show that when working in the linear polarization state,its impedance bandwidth of the array antenna is 4.38-5.72 GHz,the peak gain is 7.9d Bi;the 3d B axial ratio bandwidth is 4.32-5.6GHz and the impedance bandwidth is 4.04-5.44 when working in the left-handed circular polarization.the relative bandwidth of the overlapping part of the two is 23% and the peak gain is 5.5d Bi;the 3d B axial ratio bandwidth is 4.25-5.72 GHz,and the impedance bandwidth is 4.04-5.44 GHz when working in the right-handed circular polarization.the relative bandwidth of the overlapping part of the two is 24.6% and the peak gain is 5.2d Bi.Furthermore,the overlapping bandwidths of the three polarization states are 4.38–5.44 GHz.The designed reconfigurable array antenna has the characteristics of low profile,multi-polarization state,wide frequency band,and compact feeding network,and can be applied to in-vehicle communication and navigation compatible with multiple communication standards in the 5G frequency band.(2)Aiming at the problems of complex feeding network,small impedance bandwidth and scanning range,a 1*4 frequency and pattern simultaneous reconfigurable array antenna is proposed by fusing four octagonal microstrip patch units and twelve parasitic patches.Firstly,the characteristic current of the octagonal patch antenna is analyzed through the characteristic mode,and it is obtained that different feeding positions on the unit antenna produce different initial current phases;then the combination of the initial current phase differences of the four antenna units is used to realize five radiation directions switching;finally,the frequency can be reconfigured by loading a varactor diode.The test results show that the array antenna pattern can be discretely reconfigured in the directions of 0°,±15°,±25°,±30°and ±55°,the operating frequency error of the five radiation states is within 100 MHz,and its frequency tunable range is 3.5-4.5GHz or so,the relative bandwidth reaches more than 23%.The array antenna has the characteristics of large frequency tunable range and large coverage,and can be used in indoor communication or base station communication. |
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