Wideband Radar Cross Section Reduction Based On Absorptive Coding Metasurface With Compound Stealth Mechanism*

A scheme of combing wave absorption and phase cancellation mechanisms for widening radar cross section (RCS) reduction band is proposed. An absorptive coding metasurface implementing this scheme is derived from traditional circuit analog absorber (CAA) composed of resistive ring elements which characterize dual resonances behavior. It is constructed by replacing some of the CAA elements by another kind of resistive ring elements which is singly resonant in between the original two resonant bands and has reflection phase opposite to that of the original elements at resonance. Hence the developed metasurface achieves an improved low-RCS band over which the lower and higher sub-bands are mainly contributed by wave absorption mainly while the middle sub-band is formed by joint effect of wave absorption and anti-phase cancellation mechanisms. The polarization-independent wideband RCS reduction property of the metasurface is validated by full-wave simulation results of a preliminary and an advanced design examples which employ the same element configuration but different element layout schemes as partitioned distribution and random coding. The advanced design also exhibits broadband bistatic low-RCS property and keeps a stable specular RCS reduction performance with regard to incident elevation angle up to 35 degrees. The advanced design is fabricated and the experimental results of the sample agrees qualitatively well with their simulated counterparts. The measured figure of merit (i.e., low-RCS bandwidth ratio versus electrical thickness) of the sample is 40.572, which is superior to or comparable with those for most of other existing metasurface with compound RCS reduction mechanism. The proposed compound metasurface technique also features simple structure, light weight, low cost and easy fabrication compared with other techniques. This makes it promising in applications such as radar stealth and electromagnetic compatibility.