Design And Application Of THz Absorber Based On Metamaterial

In 2008,for the first time,N.I.Landy et al achieved a perfect microwave absorber by using a symmetrical metal ring as a patch,and the metal line as a substrate arranged periodically through a periodic structure..Since then,absorbers based on electromagnetic metamaterials become the researching focus of absorbing materials and have been widely studied.However,the current structure of metamaterials absorbers mainly works in the microwave band,while there is less research on the terahertz band,especially for the broadband absorbing structure.In this paper,two kinds of absorbers are designed by CST electromagnetic simulation software,and one of them is combined with terahertz microstrip antenna to discuss the RCS reduction of the antenna radar cross section after the absorber is loaded.The main work of this paper is as follows:(1)An ITO THz broadband transparent wave absorber based on a loopback structure was designed by using conductive glass ITO instead of the traditional metal as the resonant unit of the top of the absorber.In the frequency range from0.38 THz to 0.58 THz,the absorption was found to be above 80%.It is highly transparent compared to metal-based absorber constructions and therefore does not damage the appearance of the object being loaded.In addition,it has the advantages of insensitive polarizations and wide angle of incidence.When the electromagnetic wave is incident perpendicularly,the TE polarization and the TM polarization have the same absorption performance.(2)A type of broadband microwave absorber based on jagged metal structure terahertz polarization is designed,which has the characteristics of ultra-wideband absorption for both TE and TM polarizations.When the incident wave frequency is between 3.55 THz and 5.21 THz range,the absorption always keep at 80%or higher.In addition,one advantage of this configuration is that serrated notches are used to ensure multiple absorption peaks,making the patch more compact as no resonant stacks of metal rings of different sizes are required.(3)The combination of broadband absorbers and terahertz microstrip antennas reduces the antenna RCS.Research on RCS reduction of antenna based on loading absorption technology has been extensively designed and practiced in the microwave band.However,for the RCS reduction of terahertz antennas,there is currently no relevant report.Based on this situation,a terahertz microstrip antenna was designed with its operating frequency at 0.53 THz,and a gyrochrome-based ITO THz absorbing unit was loaded on its dielectric board.The change of RCS before and after the loading of the antenna was simulated.It was confirmed that the RCS of the antenna after the loading was reduced and the maximum reduction was 15 dB.The analysis was given from the theoretical point of view.