A New Method to Calculate the Degree of Electromagnetic Impedance Matching in One-Layer Microwave Absorbers

Abstract

A delta-function method was proposed to quantitatively evaluate the electromagnetic impedance matching degree. Measured electromagnetic parameters of α-Fe/Fe 3 B/Y 2 O 3 nanocomposites are applied to calculate the matching degree by the method. Compared with reflection loss and quarter-wave principle theory, the method accurately reveals the intrinsic mechanism of microwave transmission and reflection properties. A possible honeycomb structure with promising high-performance microwave absorption according to the method is also proposed.

Transform between the permeability and permittivity in Ni@C C NbC nanocomposites with enhanced microwave absorption properties

“…The EM impedance matching degree could be described as a delta function by means of the following expression [38]:…”

Ag3PO4 nanoparticle-decorated Ni/C nanocapsules with tunable electromagnetic absorption properties

“…The weakening of the ε r and ε r responses is mainly caused by the lagging of dipole polarization response with respect to the change in electric field at elevated frequencies. 7,10 This is the typical behavior of a dielectric material outside the vicinity of a dielectric resonance. Following the effective-medium theory of three-phase inclusions, the dielectric resonance behavior originates mainly from the special geometries and structures of the inclusions of Ag 3 PO 4 @Ni/C nanocapsules, the intrinsic permittivity of each component in the composite (e.g., Ni, C, Ag 3 PO 4 , and paraffin), and the dispersion of the nanocapsules.…”

“…6 Recalling that the EM absorption performance of an absorber relies on the degree of EM impedance match, which can be characterized by the delta function expressed as ∆ = sinh 2 (Kfd) M , where K and M depends on ε r andµ r . 10 A smaller ∆ value implies a higher degree of EM impedance match. Figure 5 presents the calculated 3D ∆-f -d mapping plots of PC NC100 , PC NC200 , and PC NC300 .…”

Dual-Band Binary Metamaterial Absorber Based on Low-Permittivity All-Dielectric Resonance Surface

“…As shown in Figures 5a and 5b, on decreasing l 1 (from 15 to 7 mm) or increasing h 1 (from 7 to 15 mm), the two resonance peaks shift slightly accompanied by a significant decrease in reflection loss and demonstrates that the dimensions (l 1 , h 1 ) of the rectangular-hole array in layer1 strongly influence the attenuation of the incident EM wave. Layer1 as the upper unit can be viewed as an impedance-matching layer, whose dimensions and permittivitty dictate the degree of impedance-matching between the BMA and free space [29]. In the case of determining the material, unit sizes, and the thickness of ADRSs, scaling directly affects absorption properties.…”