Research On Tightly Coupled Antenna Array Technology

Broadband array antennas are playing an increasingly important role in today's communications and sensing systems.The development and application of advanced radar technology,software-defined radio technology,hop-spreading and other technologies also place higher requirements on the bandwidth performance of the antenna array.At the same time,the array antenna is an important part of the radar system,and its low profile and low cost characteristics will also become a very important direction in practical applications.The traditional array antennas mostly adopt the patch units or use Vivaldi antennas to form array antennas to realize the characteristics of ultra-wideband,but these two often cannot fully meet the requirements of ultra-wideband and low profile.Therefore,this thesis focuses on the tightly coupled array antennas.By exploiting the coupling between array elements,tightly coupled antennas can achieve ultra-wideband characteristics while maintaining a small profile.This thesis first introduces the research significance and development status of broadband array antennas,analyzes the common forms and limitations of traditional broadband arrays,and derives the research significance and research status of tightly coupled array antennas.After that,the basic theory of the wideband array antenna is studied,and the impedance and matching theory of tightly coupled dipole elements are analyzed and discussed.Through the analysis,this thesis designs a square planar dipole radiating element based on a tightly coupled structure.Loaded with the resistive frequency selective surface(RFSS),the antenna is fed with a gradient line balun can cover 2GHz~20GHz.Through the simulation,fabrication and measurement of the 8×8 finite array,it is verified that the array has a good UWB performance and the scanning angle ±60° can be achieved.Finally,a compact linear polarization tightly coupled dipole is designed,which uses a coaxial differential feed.The polarization from the dual-linear polarization to the circular polarization is controlled by change the feed phase.The polarization reconfigurable operating band is 2GHz~25GHz.The frequency can be reconfigured by controlling the position of the RFSS at 14.95 GHz to 32.44 GHz,and the simulation verifies the feasibility of this idea.