The Design Of Broadband Absorption Composite Structure Embedded With FSS

As the wireless transmission system and high-frequency electronic equipment in life are widely popular,our daily environment has become a complex electromagnetic environment,and electromagnetic compatibility issues have become increasingly prominent,so that people have an urgent demand for ultra-thin broadband absorber structure.In this paper,we mainly studied the broadband absorption composite structure consisting of metal FSS and magnetic/dielectric materials,and analyzed the absorbing properties and oblique incident performance in the 2-18 GHz band.Firstly,transmission line theory is introduced,including the transmission line model of the absorbing structure and the distribution characteristics of the electromagnetic field in the model.The transmission line model revealed the impedance characteristics of the absorbing structure,and the electromagnetic field distribution was the basis of analyzing the energy loss.In addition,the absorption mechanism of Salisbury screen was analyzed in the view of impedance matching and energy loss mechanism.The HIS broadband absorbing structure based on impedance FSS was designed and the influence of FSS on microwave absorbing performance and its absorbing mechanism were analyzed according to the previous exploration.Then,a composite structure combining the metal FSS with magnetic material of different magnetic properties at a total thickness of 2.2 mm was designed and fabricated and the reflectivity of this is below-10 dB at 4-18 GHz.The fabrication cost is low and the process is simple,being conducive to mass production.And with the oblique incident angle of 30°,it still has less than-10 dB in the absorption bandwidth of the reflection;with the oblique incident angle of 45°,the sample 3 on The reflection results of the TE polarization wave tends to be deteriorated,and the reflection of the TM polarization wave excellent.In order to reduce the weight of the wave absorbing structure,it is considered to use a lightweight dielectric material having a high loss characteristic as the energy loss layer instead of the magnetic dielectric material 2.Compounding the dielectric material with the magnetic dielectric material 1 is an effective way to realize a bi-layer broadband absorber with a total thickness of 3.7 mm and a reflection loss of-10 dB from 4.3 to 18 GHz.Combined with a metal FSS,a broadband composite absorber structure at a total thickness of 3.2 mm and with reflection of-10 dB at 4.64-6.3 GHz and 7-18 GHz was presented.And these two structures both have excellent stability performance in the oblique incident angle range of 0-45°.