Design Of A New Type Of Left-handed Material Based On Periodic Structure

The left-handed material is the new type electromagnetic structure achieves equivalent dielectric properties through a periodic structure much less than the wavelength.When the LHM(left-handed material)satisfies the resonance conditions,the dielectric constant ? and the permeability ? of the equivalent dielectric structure could be negative in the corresponding frequency band.The constitutive parameters of the LHM are all negative,which makes the electromagnetic properties of the LHM greatly different from those of the conventional medium,and has extremely high application value in the aspects of microwave device design and electromagnetic stealth.In this paper,the realization principle of left-handed material and the extraction of its equivalent medium parameters are deeply studied and analyzed.Based on this,A new type of dual-frequency left-handed material is designed.The bandwidth of dual frequency structure is much higher than that of previous designs,and the left-hand band can be controlled by adjusting the cell size.Then the structure is analyzed and optimized and the improved structure based on the resonant ring is proposed.The main work of this paper is as follows:1,Through the analysis of SRR array structure of Rod and open-ended resonant ring structure,the principle of electromagnetic properties,negative permeability and negative dielectric-constant of left-handed material are discussed.And introduced the main verification method of the left-handed material.The transmission medium reflection method is used to extract the medium parameters.The parameters of the equivalent medium are calculated by using the transmission parameters of the left-hand material at both ends.The dielectric constant ? and the permeability ? are calculated by K-K relation Function of the multi-branch solution to the problem of optimization.2,designed a new dual-band left-handed material.The structure realizes the control of the coupling relationship between the resonant rings by adding openings and adjusting the size of the resonant ring,and combines the I-shaped metal line structure to achieve the dual-band left-handed property with bands of 7.8-8.2 GHz and 8.4-13.4 GHz respectively.Using PCB technology for sample processing,the rectangular waveguide measuring system to test the samples,through the electromagnetic simulation and physical testing to verify the structure of the dual-band characteristics.3,A detailed analysis of the relationship between the resonant ring size and resonant ring coupling and the relationship between the left-hand band.With the reduction of the size of the resonant ring,the left-handed material structure produces a significant frequency shift in a specific frequency band,and as the size decreases,the left-handed frequency band gradually approaches and eventually converges.Based on this discovery,a new wide-band left-handed material structure was proposed to improve the design,which left-handed frequency is 7.2~13.8GHz.Compared with the previous design,the proposed method improves the bandwidth and reduces the cell loss.