Wideband side-lobe level suppression metamaterial based on foldable spoof surface plasmon polaritons

In this work, we propose a method of suppressing the side-lobe level for transmitted waves based on foldable spoof surface plasmon polariton (SSPP). To this end, an SSPP structure is designed and folded with different angles to manipulate the amplitudes of co-polarization transmission coefficients, while the phases remain unchanged. In order to obtain the corresponding relationship between the transmission amplitudes and the folded angles, a nonlinear fitting was performed to get the mapping. After this, SSPP structures are arrayed according to the corresponding amplitudes of the discrete Taylor-distribution, so as to suppress the side-lobe level. To verify this idea, a transmissive metamaterial with wideband side-lobe level suppression (SLLS) was designed, fabricated and measured. The results demonstrated that the metamaterial has a good SLLS performance for transmitted waves, with approximately -20 dB SLL in a wide frequency region. This work provides an effective alternative to achieving SLLS and may find applications in antennas, radomes and stealth techniques, etc.