Research On Flexible Multifrequency Terahertz Band-top Filter Based On Metamaterial

In terms of the issue that wireless information transmission spectrum is increasingly extended currently,and the problem that the usable frequency band is increasingly compressed.Therefore,the THz technology is gradually becoming the most effective way to solve these problems.The spectrum of THz is between the microwave and infrared band,which has many advantages,such as low energy,strong penetrability,and wide band.Consequently,the demanding of the THz's function device is becoming more and more pressing.The metamaterial is through the geometric construction of natural materials about metals semiconductors,and insulators,which obtain the synthetic electronic material that with special dielectric constant and magnetic conductivity.It is applied to many fields.Such as superlens,invisibility,electromagnetically induced transparency and so on.This article take advantage of the alternative quality of metamaterial's frequency,and make it apply to within the frequency range of THz.Producing a Terahertz metamaterial filter,which has an important practical significance and scientific research value.The mainly contents of this article are as follows:(1)Based on the principle of metamaterial frequency selection,a closed-loop crossembedded metamaterial filter cell array is proposed.The structure of the filter is a metaldielectric(MD)double-layer structure.The dielectric substrate is a flexible Polyimide(PI).Through finite difference time domain simulation analysis,the metamaterial filter can achieve dual band-stop function in the frequency range of 80-230 GHz.The resonance points are 132.35 and 193.4 GHz respectively.The transmission performance indices of S21 are-46.733 and-43.677 dB,respectively.It has good band-stop performance.(2)According to the requirement of multi-frequency transmission of information,the quadrangular openings of dual band-stop metamaterial filter unit are analyzed by the model of metamaterial equivalent circuit.Capacitance is introduced to realize triple band-stop,enhance frequency selectivity and improve the transmission performance of the system.The array model is designed with MD double-layer structure.The simulation results show that the stopband resonance points of the three-band stop metamaterial filters are 107.3,167.45 and 209.2 GHz,and the S21 parameters are-30.217,-30.432 and-38.618 dB,respectively,showing good band-stop performance.At the same time,the simulation of electric field current on the surface of metamaterial shows that strong electromagnetic coupling occurs at the opening of the four corners of the metal element.With the increase of frequency,the coupling strength decreases.It shows that different stopband resonance points have different generating mechanism.The low frequency stopband resonance points are caused by the electromagnetic ohm loss on the surface of the metal element,and the high frequency stopband resonance points are caused by the phase reflection of the electromagnetic wave.(3)Exploring the fabrication process of triple band-stop metamaterial filter,using flexible PI as dielectric substrate to bond with silicon,and metal lift-off technology to make the sample.Due to the deformation of PI at high temperature during prebaking and postbaking,the surface of PI was uneven,which affects the exposure of positive glue and the sputtering of metal units,and the structure of a small number of metal units on the surface of the sample was incomplete.Finally,PCB printing process was used to produce the samples.THz-TDS system is used to test the electromagnetic transmission performance under normal conditions,and the results are similar to the simulation trend.This paper takes terahertz metamaterial filter as research object,making use of MEMS technology and standard PCB technology for processing,so it has a profound significance and effect on the future development of THz functional devices.