Dielectric Loss Mechanism in Electromagnetic Wave Absorbing Materials

Abstract

Electromagnetic (EM) wave absorbing materials play an increasingly important role in modern society for their multi-functional in military stealth and incoming 5G smart era. Dielectric loss EM wave absorbers and underlying loss mechanism investigation are of great significance to unveil EM wave attenuation behaviors of materials and guide novel dielectric loss materials design. However, current researches focus more on materials synthesis rather than in-depth mechanism study. Herein, comprehensive views toward dielectric loss mechanisms including interfacial polarization, dipolar polarization, conductive loss, and defect-induced polarization are provided. Particularly, some misunderstandings and ambiguous concepts for each mechanism are highlighted. Besides, in-depth dielectric loss study and novel dielectric loss mechanisms are emphasized. Moreover, new dielectric loss mechanism regulation strategies instead of regular components compositing are summarized to provide inspiring thoughts toward simple and effective EM wave attenuation behavior modulation.

Oxygen Vacancy‐Induced Dielectric Polarization Prevails in the Electromagnetic Wave‐Absorbing Mechanism for Mn‐Based MOFs‐Derived Composites

“…In principle, the presence of a layer gap cannot only reduce the dielectric constant and thus harmonize impedance matching but also effectively decrease the density of the system and achieve lightweight absorption characteristics. [17][18][19][20][21] Simultaneously, shortening the electron transmission distance is beneficial for improving the EM wave attenuation ability by dielectric loss.…”

An Equivalent Substitute Strategy for Constructing 3D Ordered Porous Carbon Foams and Their Electromagnetic Attenuation Mechanism

“…For polarization loss, the main contribution can be ascribed to interface polarization and dipole polarization, because the electron/ion displacement polarization phenomenon doesn’t seem to have an impact on ε r . In order to clarify the source of dielectric loss of the EDCF samples, the conduction loss and polarization loss should be analyzed in detail, which can be measured according to the following equation [ 62 , 63 ]: where represents the contribution of polarization loss; is the contribution of conduction loss; σ refers to the dielectric conductivity, and ε 0 ( ε 0 = 8.854 × 10 –12 F m −1 ) denotes the vacuum permittivity. The theoretical fitting calculation values of σ for various EDCF samples were shown in Fig.…”

Recent Progress in Iron-Based Microwave Absorbing Composites: A Review and Prospective

“…Currently, EMWAMs are divided into three categories according to the loss mechanism: dielectric, resistive and magneto-dielectric. Dielectric-type absorbing materials such as semiconductors and oxides own the advantages of low dielectric constants, good impedance matching properties, and chemical stability, but their electromagnetic loss capability is insufficient [7,8]. Resistive absorbing materials such as carbon materials have the advantages of high conductivity loss, low density and abundant dipoles, but they have poor impedance matching characteristics and high reflectivity; thus, it is difficult for electromagnetic waves to incident into the material, and a large number of electromagnetic waves are reflected into space, resulting in secondary pollution [9,10].…”