Zhanghong Tang

Absorbing properties of three dimensional honeycomb-structured absorbing materials

This article studied the absorbing properties of three dimensional honeycomb-structured absorbing materials based on the Finite Element Method (FEM) with periodical boundary conditions (PBCs). By applying the PBCs and Floquet theorem of two dimensional periodic structures, the factors that affect the absorbing performance of three dimensional honeycomb structure are studied. These factors include the height and thickness of honeycomb and the conductivity of materials, and so on. Basing on the studies, the optimal three dimensional honeycomb-structured absorbing materials are achieved which have best absorbing effectiveness for Ku-band electromagnetic waves.

Optimization of frequency selective surface by the genetic algorithm

In this paper, a new cost function is proposed to optimize the electromagnetic parameters of the frequency selective surface (FSS) with multi-object optimization (MO). All the objects including resonance frequency, the bandwidth and the transmission magnitude are considered with different weights in the cost function. The numerical result shows that both the transmission coefficient of different frequency and the resonance frequency satisfy the requirement very well.

Design and Optimize Spherical Particle Absorber by Fe-rich Hollow Cenosphere of Fly-ash for Broadband Electromagnetic Wave Absorbing Wall

In this paper, the absorbing effectiveness of spherical particle absorber made of cheap Fe-rich hollow cenosphere fly-ash is analyzed. The effects of the diameter of spheres, the number of layer and the stack modes of sphere particle on the absorbing effectiveness were explored. Based on the results, a three-layer structure with mixed sizes of spheres was designed, constructed and tested. Obtained results show that this structure has a maximal reflection loss of 9 dB and the bandwidth being higher than 5 dB is more than 17GHz. When applying the permittivity of Fe-rich hollow cenosphere fly-ash, and the thickness of absorber is 6.5 cm, the maximal reflection loss is 23 dB and the bandwidth being lower than −10 dB is more than 14GHz, which covers the C, X and Ku bands. The experimental test proved that the three-layer structure absorber has good absorbing effectiveness.

The analysis of electromagnetic waves transmitting on fabric based frequency selective surface

In this paper, a new method to use the selective electroless plating on fabric to prepare frequency selective surface (FSS) is presented. Different from other substrates which are compact layers and can form close coatings, the coating on the fabric by this method will form holes and gaps between fibers. The effect of holes and gaps to the transmission of electromagnetic waves was analyzed and results show that they do not affect the performance of the fabric which will be used for FSS.

A combination of algebraic multigrid method and adaptive mesh refinement for large-scale electromagnetic field calculation

A combination of algebraic multigrid method (AMG) and adaptive mesh refinement is presented in this paper to solve large-scale electromagnetic field problems. The oscillatory smooth error (the error not eliminated by the smoother) by the classical AMG method could be efficiently reduced by replacing the virtual coarse and fine grid of classical AMG method with the real coarse and refined mesh of adaptive mesh refinement and accordingly, the prolongation mapping the coarse to fine grid and restriction mapping the fine to coarse grid are established basing on the relationship between the coarse mesh and refined mesh.

A method to simulate the electromagnetic parameters of materials with quasi-periodic microstructures and its applications

In this paper, a method to simulate the electromagnetic parameters of materials with quasi-periodic microstructures is presented and the parameters of fly-ash cenosphere particles are simulated. Results prove that the permittivity and permeability by this method coincide with that from the Bruggeman formula. By applying this method, it is possible to propose some strategies to improve the current cheap fly-ash cenosphere particles to be used as EMI-shielding materials and microwave absorbing materials.