RADAR Cross Section (RCS) is an essential factor in modern defense applications for detection and identification of platforms. Careful management of RCS requirements is crucial from initial design phase to integration stage. Electrooptical sensors create discontinuities on the frame of the platform which can negatively impact the low RCS requirement. To ensure the low RCS requirement, discontinuities, either as protrusion or opening, shall be electrically conductive and optically transparent. The use of metasurfaces, designed with a periodic mesh structure, is a widely adopted approach meeting these requirements. Electromagnetic and optical performance of periodic mesh structure depend on parameters such as shape of elements, dimensions of elements, interelement spacing, substrate material parameters etc. This paper starts with the analysis of electromagnetic shielding effectiveness of periodic mesh structure via equivalent circuit method (ECM) and Floquet Port Modes. ANSYS HFSS and CST MWS software are used for the analysis of Floquet Port Modes. Analysis results are compared with measurements via coaxial holder method stated in ASTM D 4935 standard. Samples used in coaxial holder is produced with photolithography. Aligned dual antennae method referred in IEEE 299 is used as verification technique. Additionally, diffraction effects from the mesh structure are analyzed and measured in the visible and mid-wave range.
Thermal imaging, particularly LWIR imaging, has several applications in commercial and security systems. The fundamental problem with the development of metalens is the lack of appropriate materials for LWIR applications. The development of silicon metalens is hampered by the material’s own LWIR spectral band absorption, although silicon is the ideal material for lithography due to its widespread use in CMOS applications. In this study, metalens working on LWIR spectral band has been designed and fabricated using the highly suitable material germanium and low-cost silicon. The focusing and imaging capacity of two types of metasurfaces has been investigated, and a comparison of the results has been presented in the paper.
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