Analysis of multilayer frequency selective surfaces on periodic and anisotropic substrates

Infrared Emissivity of Capacitive Frequency-Selective Surfaces and its Application in Radar and IR Compatible Stealth Sandwich Structures

Infrared emissivity of capacitive frequency-selective surfaces is affected by many factors, such as metal area, emissivity of medium part, surface roughness, metal oxidation, and surface cleanness, etc. In this paper, the influence of metal area and emissivity of medium part on the emissivity of CFSSs were depicted in detail. Furthermore, a kind of radar and IR compatible stealth sandwich structures, radar absorbing properties of which were calculated by the finite-difference time-domain (FDTD) method, were designed and prepared. We conclude that emissivity of CFSSs will be below 0.3 while metal area is above 80% and radar reflectivity of fabricated sandwich structure will be below -10dB in 8-18GHz.

Analysis of semi-infinite periodic structures using a domain reduction technique

A new boundary condition is introduced to calculate the effective impedance matrix of semi-infinite periodic structures such as photonic crystals and metamaterials, which leads to a reduction of the solution space. The obtained effective impedance matrix allows one to relate a matrix to a PC, which includes all of its properties in terms of reflection from its interface. For one-dimensional photonic crystals or multilayer films, it is shown that a closed-form equation can be found for the effective impedance. For two-dimensional photonic crystals the impedance is obtained using the scattering matrices by solving a unilateral quadratic matrix equation. Several examples are outlined to validate the developed scheme. In the examples, the goal is mainly the computation of the reflection from a semi-infinite periodic structure when a plane wave illuminates its boundary.