Abstract
The back-scattering from front edge diffraction contributes significantly to mono-static radar cross section under TE-polarization when the specular reflection of an object is eliminated by elaborate shaping. With the aim to suppress the back-scattering of thin metallic edge, we propose to achieve wideband radar cross section (RCS) reduction by integrating an absorbing structure (AS) in front of the edge. The unit cell of AS is composed of a longitudinal array of metallic strips with linearly decreasing lengths. Under TE-polarized illumination, spoof surface plasmon polariton (SSPP) can be excited with high efficiency. Due to the deep-subwavelength property of SSPP, electromagnetic waves are highly confined around the AS, leading to strong local field enhancement and hence to wideband absorption. In this way, back-scattering of the edge is suppressed and the mono-static RCS can be reduced significantly over wide band. To verify this method, we designed, fabricated and measured a prototype. The results of both simulation and measurement indicate that our proposal can significantly suppress edge scattering, whose RCS reduction more than 10 dB achieves at range of 8.8–17.8 GHz under TE polarization. This work provides a new alternative of suppressing edge diffraction and may find applications in electromagnetic compatibility, radar stealth, etc.
Highlights
The edge diffraction as potential scattering source is existed extensively on discontinuous surfaces or boundaries, which can be interpreted by the impedance mismatch between the object edges and their surroundings
When the specular reflection is effectively controlled by the shape design and radar absorber material or the incident plane wave is in a grazing condition, the edge diffraction becomes the major contributor to radar cross section (RCS)
It is crucial to reduce RCS caused by the edge diffraction that in order to improve the performance of the research targets [1,2,3]
Summary
The edge diffraction as potential scattering source is existed extensively on discontinuous surfaces or boundaries, which can be interpreted by the impedance mismatch between the object edges and their surroundings. When the specular reflection is effectively controlled by the shape design and radar absorber material or the incident plane wave is in a grazing condition, the edge diffraction becomes the major contributor to radar cross section (RCS). Considering the distance between the source and objects, the incident plane wave is often in a grazing condition when it comes to detected objects [25] In this case, the diffraction from the front edges is a major scattering source [26]. Different from the traditional absorbing material, this work suggests a new strategy which involves replacing the thin metallic front edges of rectangular plate by the SSPP framework of AS This would result in highly effective excitation of SSPP and a great elimination of the edge diffraction in the backward direction. Both results indicate that this approach is highly effective at the issues of suppressing edge diffraction in wideband frequency range
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