Research On Non-bilateral Symmetry Cyclic Coupling Structure Left-handed Materials And Application

Left-handed material is an artificial composite material with unique electromagnetic characteristics.Its characteristics are different from common natural dielectric materials.Equipment loaded with left-handed materials may break the limitations imposed by traditional materials on equipment performance.At present,the study of left-handed materials can be roughly divided into resonant left-handed materials and transmission-lined left-handed materials.The resonant left-handed material is mostly composed of electrical resonant and magnetic resonant units which loaded on two sides of the dielectric substrate.Most of the left-handed cell structures in the past are completely symmetrical,which often limits the design space of the structure.At the same time,the structural changes are mostly simple changes.The main contents of this paper is to use the concept of circulation to design the left-hand structural unit and make use of the topological changes to improve it.The main research contents of the paper are as follows:1.This dissertation studies that how to use the topology theory and the current distribution map of left-handed structure to guide the design of the left-handed structure.This paper proposes applying three topological changes to the design of the left-handed structure,achieving a continuous gradient of the electromagnetic properties of the left-handed structure,generating spurious frequencies and electromagnetic mutations,respectively.At the same time,the topological changes of the simple circular-C left-hand structure are performed,then a gear-shaped and a clock-like left-handed structures are obtained,which verifies the effectiveness of the topology application.2.A series of LHMs based on circular-C cycle coupling structure are presented.The structure can effectively utilize the overall space,the structure realizes the magnetic resonance with the integral ring,and the electrical resonance is achieved through the metal rod structure,double negative band of the structure is 3.43 GHz-3.90 GHz.The cell structure is analyzed by combining the topology theory with the current distribution diagram,then topology change is made to the structure and a compact left-handed structure is obtained.The improved structure can make better use of the design space,and the double negative characteristics remain similar to the original structure.Finally,the two-unit left-handed structure is changed to a four-unit left-handed structure,the structure has two-dimensional characteristics.3.A series of LHMs based on overall cycle interactive coupling structure are presented.The series of units effectively utilizes the overall and local spaces to construct more magnetic resonant circuits,which achieve dual-band dual-negative characteristics of 3.44-3.71 GHz and 5.63-6.50 GHz.In order to further increase controllable parameters and improve space utilization,two different branches have been loaded inside.In the end,the two-cell structure was changed to a four-cell structure and the transformation from one-dimensional left-handed material to two-dimensional is realized.4.The designed two-series left-handed structure are loaded into the MIMO antenna in four different ways to achieving a variety of characteristics such as notching,isolation,and conduction.The designed dual-band antenna can be applied to the 5G mid-band communication system.The designed ultra-wideband MIMO antenna has a stopband in the 3.33-5.09 GHz band,which weakens the interference to the 5G mid-band communication system.Another dual-band MIMO antenna with a back-loaded left-handed parasitic structure can operates in the 3.40-3.60 GHz and 3.47-5.90 GHz bands,and this operating band covers the 3400-3600MHz and 4800-5000MHz bands in the 5G communications mid-band.Finally,a compact four-cell MIMO antenna is designed based on the two-dimensional left-handed structure.