Design Of Beamwidth Reconfigurable Antenna Based On Characteristic Mode Fusion

With the rapid development of wireless communication systems,modern antenna research is developing in the direction of multi-function,high integration and intelligence.People have higher and higher requirements for antenna performance,such as operating frequency bandwidth,small size,and flexible radiation characteristics.However,since the physical size of the antenna determines the operating frequency,gain,and beam direction,some traditional antennas have only fixed operating performance and cannot meet the increasingly diverse needs.In order to maintain a compact size while possessing more functions,multifunctional reconfigurable antennas have attracted extensive attention.These antennas will far meet the requirements of new and more demanding modern systems.Reconfigurable antennas can increase the diversity of antenna operating frequencies,patterns and polarization modes by dynamically adjusting the impedance and radiation characteristics of the antenna,that is,the realization of frequency,pattern,and reconfigurability of polarization.Among them,in order to achieve high integration of the antenna,a lot of research has been carried out on the pattern reconfigurable antenna.The beamwidth reconfigurable antenna can realize beam switching of different widths without increasing the number and size of the antenna,which greatly enhances the applicability of the antenna.However,the existing implementation methods have certain shortcomings and limitations,such as large loss,complex implementation methods,slow tuning speed,the beamwidth reconfigurable range is small.Aiming at these shortcomings,this paper conducts an in-depth study on beamwidth reconfigurable antennas.The main contents are as follows:(1)A reconfigurable water antenna with continuously variable beamwidth based on the characteristic mode theory is designed.The basic structure consists of an array of three patches microstrip antenna,and the circular truncated cones tructure filled with distilled water are loaded between the upper and lower dielectric substrate of the microstrip antenna.The antenna operates at 2.1GHz,Since changing the height of distilled water can effectively adjust the effective dielectric constant of the patch,by rationally designing the different effective dielectric constant distributions under the three patches,when feeding the middle patch,the beam width is wider The range(60.3°-134°)is reconfigurable.The beamwidth is reconfigurable in a narrow range(31.4°-36.3°)when the left and right patches are fed and the antenna has been processed.(2)A reconfigurable liquid metal antenna with continuously variable beamwidth based on the characteristic mode theory is proposed.The basic structure consists of an array composed of three patches microstrip antenna.Two 3D printed containers are added to each side of the left and right patch,and liquid metal--Eutectic gallium indium(EGa In)is injected into the antenna.The antenna operates at 3.1GHz,By controlling the on-off of two PIN diodes in the feed network,the feed port can be switched,and the width of eutectic gallium indium injected into both sides of the patch can be changed to realize the reconfiguration of the beamwidth within a wide range(55.9 °-127.9 °)when feeding the intermediate patch.When the feed ports were switched to the left and right patches,the beam width was switched to 23.8° and the antenna has been processed.