Research Of Frequency Selective Rasorber

The radome based on the traditional frequency selective surface(FSS)has the main function of ensuring the transmission characteristics of the signals in the radar operating band and reflecting the out-of-band signals to non-threatening areas away from the enemy's reconnaissance direction,so as to make the target invisible to monostatic radar.In recent years,with the continuous development of radar stealth technology,the anti-stealth system for monostatic radar cross section(RCS)reduced radome is also rapidly improved.Therefore,the traditional ‘Transmission-Reflection(T-R)' radar radome can no longer meet the requirements of omni-directional stealth of the radar system.In response to these problems,this thesis focuses on the study of frequency selective rasorber(FSR),which has the integrated characteristics of in-band transmission and out-band absorption,and lays a foundation for its application in the field of radar stealth.When the FSR technology is applied to the design of the radome,considering that the enemy and our radar systems work in different bands,the FSR structure can transmit our signals in the working band and absorb the detection signals outside the working band,presenting the characteristics of non-transmission and non-reflection.This technology can reduce bistatic RCS of multistation radar detection,improve the omni-directional stealth of radar system and the battlefield survivability,which has great research meaning and application value.This thesis mainly focuses on the high performance FSR design.For the two types of FSR,the narrow transition band,the wide transmission band and the miniaturized design are studied.The specific main research contents are as follows:Firstly,based on the work and design principles of the 2D FSR structure,a ‘TransmissionAbsorption(T-A)' FSR structure with a narrow transition band is proposed.The improved gap-shaped slit is used to pull the center frequency of the reflection band to the center frequency of the transmission band,and the wide energy dissipation band generated by the double lumped resistance loading structure is used to cover the reflection band.This FSR realizes transmission characteristic in L-band and absorption characteristic in S-band.Meanwhile,the ‘T-A' transition bandwidth of this FSR is only 0.61 GHz.Then,the miniaturization of the aforementioned ‘T-A' FSR is designed,and a miniaturized2.5D ‘T-A' FSR structure is proposed.Parallel-plate capacitors(PPC),metallized vias,and bending methods are used to make the dimention of the partial reflect surface(PRS)same as the lossy structure.This FSR achieves the transmission characteristic in L-band and the absorption characteristic in S-,C-,and X-bands.The dimention of this miniaturized ‘T-A'FSR is as compact as 0.036?.Secondly,a 2D ‘Absorption-Transmission-Absorption(A-T-A)' FSR structure with a wide transmission band is designed.The high selective stopband generated by the composite hexagonal ring is used to suppress the effect of the ‘sunflower-shaped' composite lossy structure at the edge of the transmission-loss band,so as to realize the integrated characteristics of transmission in C-,X-bands and absorption in C-,Ku-bands.The transmission bandwidth with insertion loss(IL)less than 3d B is 64.3%.Then,a miniaturized 2.5D ‘A-T-A' FSR structure based on the above-mentioned wide transmission-band ‘A-T-A' FSR is proposed.The bending lines and metallized vias are used for miniaturization.The basic wave generated by the miniaturized PRS is located in the low frequency reflection band and the high-order harmonic is located in the high frequency reflecting band.Meanwhile,the basic wave generated by the miniaturized lossy structure is located in the low frequency loss band,and the high-order harmonic wave is located in the high frequency loss band.The single structure can realize double absorption bands to reduce the size of this FSR.Eventually,the characteristics of transmission in C-,X-band and absorption in C-,Ku-band can be realized.The dimension of this miniaturaized ‘T-A-T' FSR is as compact as 0.062?.Finally,for the designed ‘T-A' FSR structure,a microstrip antenna with the same operating frequency is loaded as an example to simulate the radiation/scattering characteristics of the planar FSR array.For the designed ‘A-T-A' FSR structure,the radiation/scattering characteristics of the planar FSR array are simulated and analyzed,and the prototype is processed and tested.By the above experimental analysis,the validity and accuracy of the proposed FSRs' theory and design method are verified.