Influence of the electromagnetic parameters on the surface wave attenuation in thin absorbing layers

Abstract

This paper describes the relationships between the surface wave attenuation properties and the electromagnetic parameters of radar absorbing materials (RAMs). In order to conveniently obtain the attenuation constant of TM surface waves over a wide frequency range, the simplified dispersion equations in thin absorbing materials were firstly deduced. The validity of the proposed method was proved by comparing with the classical dispersion equations. Subsequently, the attenuation constants were calculated separately for the absorbing layers with hypothetical relative permittivity and permeability. It is found that the surface wave attenuation properties can be strongly tuned by the permeability of RAM. Meanwhile, the permittivity should be appropriate so as to maintain high cutoff frequency. The present work provides specific methods and designs to improve the attenuation performances of radar absorbing materials.

Enhanced Microwave Absorption and Surface Wave Attenuation Properties of Co0.5Ni0.5Fe2O4 Fibers/Reduced Graphene Oxide Composites

“…Physically, these negative values mean that surface waves cannot be excited and thus no propagation occurs along the layers. The frequency at which the quantity vanishes can be considered as the upper cutoff frequency [ 48 , 49 ]. As the thickness of the sample increases, the upper cutoff frequency moves to the lower frequency, as shown in Figure 7 b.…”

Analysis of Surface Wave Attenuation in Double-Layer Magnetic Absorbing Sheet for Wide Frequency Range Application

“…Since the attenuation of EM wave in a thin absorbing sheet will not be too much, it is reasonable to ignore the tiny imaginary part of β x in the case of β x β x . Meanwhile, for a thin sheet, β x will be very close to k 0 , where k 0 is the wave number of the free space or air [2]. Accordingly, we can simplify the calculation for a thin absorbing sheet with almost no deviation if we set β x = β x = k 0 = ω √ ε 0 μ 0 .…”

“…As we all know, when the surface waves propagate to the electromagnetic discontinuities, such as edges, gaps, and steps, strong echoes contributing to the back scattering will arise, which is the main cause of non-specular scattering [1][2][3][4]. Much interest has been shown in magnetic absorbing materials (MAMs), whose main purpose is to control specular reflection meanwhile suppress non-specular scattering.…”

“…Much interest has been shown in magnetic absorbing materials (MAMs), whose main purpose is to control specular reflection meanwhile suppress non-specular scattering. By employing MAMs, the intensity of surface wave can be significantly reduced before reaching the electromagnetic discontinuities, thus the non-specular scattering can be suppressed [2][3][4]. Ling et al [5] analyzed the fundamental characteristics of the TM-type surface wave in single absorbing layer including propagation and attenuation constants, electric and magnetic losses, phase and energy velocities, etc.…”

“…Recently, resistive loading, impedance loading at margins and magnetic thin film loading on single-layer RAM for enhancement of surface wave attenuation were reported by Chen et al [2,8,9]. However, it is very hard for a single-layer microwave absorbing sheet to realize strong attenuation of surface waves over a wide frequency range (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) GHz) based on the previous reports. Unfortunately, the numerical analysis of surface wave attenuation constants in two or more layers composite absorbing sheets is very complicated according to the complex transcendental relationship in the dispersion equation of surface waves.…”