Research On Reconfigurable Resonant Cavity Antenna Based On Active Metasurface

With the rapid development of wireless technology,various demands on antenna performance from the system are increasing.In some application scenarios,antennas are usually required to make adaptive adjustment according to mission requirement or to change in the electromagnetic environment,which promotes the development of reconfigurable antennas.Fabry-Perot Resonant Cavity Antennas have attracted widespread attention due to their potatial to achieve high gain with simple structure.In this thesis,Frequency reconfigurable and beam reconfigurable resonant cavity antennas by employing the contiguous electrical modulation characteristics of varactor diodes are studied,and a multifunctional reconfigurable resonant cavity antenna with broadband tunability and twodimensional beam scanning characteristics is realized.The major contributions of this thesis are summarized as follows:1.Two one-dimensional beam tilted passive resonant cavity antennas and one twodimensional beam tilted passive resonant cavity antenna are designed.Firstly,a partially reflective surface based on complementary structure is designed.By changing the size parameters of the unit,the scattering characteristics of relatively stable reflection amplitude with contiguous change of reflection phase can be obtained.Then,on basis of optical approximation model,a partially reflective surface and an artificial magnetic conductor whose reflection phases exhibit "sawtooth distribution" are constructed as the superstrate and ground of the resonant cavity antenna,respectively,yielding a resonant cavity antenna with one-dimensional beam tilted characteristics.Furthermore,the "sawtooth distribution" of reflection phases of artificial magnetic conductor and partially reflective surface are projected into two dimensions,and a resonant cavity antenna with two-dimensional beam tilted characteristic is realized.2.A reconfigurable resonant cavity antenna with frequency-agililty and beam-steerability is designed.First,a reconfigurable partially reflective surface loaded with varactors is designed,whose reflection phase can be contiguously adjustable with the bias voltage of the varactor.Then,a multifunctional reconfigurable resonant cavity antenna is realized by using the reconfigurable partial reflective surface as the superstrate of resonant cavity antenna.As expected,the operating mode can be configured by controlling the bias voltages of varactor diodes.(i)When the bias voltages of all varactors are adjusted synchronously,the antenna is operated in the frequency-reconfigurable state,where the maximum radiation direction is in the boresight direction and the resonant frequency can be adjusted by the common bias state of all varactor diodes.(ii)When the bias voltages of varactors are grouped and controlled in the form of “sawtooth distribution” or in the form of semi-zone,the antenna is operated in the beam-reconfigurable mode,and the maximum radiation direction can be contiguously scanned within a angular volume.