Electromagnetic absorbers based on chiral honeycomb slab

A bi-isotropic hexachiral grid in PCB

“…A mayor difference with the one-layer grid is the apparition of resonant transmissions, the first at f=9. 5 GHz, which may be attributed to the electromagnetic coupling between both metal layers.…”

“…Other implications of its geometrical chirality, in terms of mechanical properties, have been studied, like enhanced compressive strength capabilities, shear stiffness compared to classical centresymmetric honeycomb configurations, or a sinclastic curvature feature [1], [4]. In 2009, David et al proposed their application in electromagnetic absorbers [5] and, in 2010, Kopyt et al studied the electromagnetic behavior of such structure implemented with dielectrics (polymers), in order to check whether their structural chirality translates into chiral electromagnetic behavior (bianisotropy) [1], with negative results. It is worth noticing that they characterized a single layer of the structure: that means the result is not geometrically chiral in the 3D space, so no bi-anisotropic behavior should have been expected [6], [7].…”

A Full-Dielectric Chiral Material Based on a Honeycomb Structure

“…This is in contrast with 3D chirality, where the sense of such rotation does not change upon reversal of the observation direction [16]; in this case, the eigenmodes are two corotating elliptical polarizations, instead of contrarotating circular polarizations, as in 3D chiral (bi-isotropic) materials [14,19]. This "asymmetric transmission" is a dissipative effect and can only be observed in lossy anisotropic structures [16], while the structures studied in [1,10] are isotropic in the plane.…”

“…In 2009, David et al proposed the application of a chiral honeycomb in electromagnetic absorbers [10]; later, in 2010, Kopyt et al studied the electromagnetic behavior of such structure implemented with dielectrics (polymers), in order to check whether their structural chirality translates into chiral electromagnetic behavior (bianisotropy) [1], with negative results. That is, the structural chirality of the investigated honeycombs did not induce electromagnetic chirality effects.…”

Polymer Composites for Flexible Electromagnetic Shields

“…Following two parameters quantitatively describe reflection, absorption, and transmission of such EM waves in materials: 1) Shielding Effectiveness (SE) (or its negative, called Shielding Efficiency) and 2) Reflection Effectiveness (or its negative, called Reflection Efficiency). As illustrated in Figure , a Vector Network Analyzer (VNA), can measure Input Power ( P in ) for the EMI shield, the Reflected Power ( P refl ), and the Transmitted Power ( P out ) – as a function of EM wave frequency. These yield Shielding and Reflection coefficients as will be shown in next sections.…”