High-Performance Broadband Microwave Absorbers Using Multilayer Dual-Phase Dielectric Composites

The Electromagnetic Absorption of a Na-Ethylenediamine Graphite Intercalation Compound

“…According to the measured S parameters (S11, S21, S12, and S22), the complex permittivity (ε r ) and permeability (μ r ) can be calculated by the Nicolson−Ross−Weir (NRW) method. 37 The reflection loss (RL) is derived from transmission line theory: 3,38…”

“…In GIC/ paraffin and graphite/paraffin composites, the major contributions to ε′ are orientational polarization, dipolar polarization, and interfacial polarization. 38,39 The polarization effects included in ε′ can also contribute to the loss mechanism because of the relaxation associated with the polarization processes. 40 With increasing GIC content, a larger interfacial area between the GIC and the paraffin is produced and the larger number of charges accumulated at the interface causes a higher ε′, as predicted by the Maxwell−Wagner−Sillers (MWS) effect, 41 which is caused by the impedance mismatch between the GIC filler and paraffin matrix, where the charges are entrapped at the interfaces.…”

Microwave Absorption in Ceramics: Different Mechanisms and its Optimization

“…Z in is not a real number like Z o : Z in = Z real + j Z img (Z real is a real part of the impedance and Z img is imaginary part of impedance). The large RL will result from equation (7) when │Z in │is near to Z o =377Ω. Thus both Z real should be near to 377 Ω and zero respectively and RL decreases if either or both of Z real and Z img higher or lower than 377 Ω and zero respectively.…”

“…It can be deduced from equation (7) of RL (microwave absorption) is dependent on Z in (input impedance) of the absorber in equation (8). Thus RL is dependent on 6 parameters viz a viz µꞌ, µꞌꞌ, εꞌ, εꞌꞌ, t and f i.e.…”

“…Researchers have investigated magnetic and dielectric ceramics for possible application as a microwave absorber [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The absorption has been optimized by increasing dielectric and/or magnetic losses through doping of divalent, trivalent, tetravalent ions, etc.…”