16 th IMEKO TC4 Symposium Exploring New Frontiers of Instrumentation and Methods for Electrical and Electronic Measurements Sept. 22-24, 2008, Florence, Italy The numerical simulations of the electromagnetic shield based on chiral honeycomb slab Valeriu David 1 , Ionut Nica 1 , Romeo Ciobanu 1 , Alexandru Salceanu 1 1 Technical University of Iasi, Faculty of Electrical Engineering, Bd. D. Mangeron, 53, Iasi, Romania, phone +40 232 278680, fax+40 232 237627, e-mail valdavid@ee.tuiasi.ro Abstract -In this paper, by means of electromagnetic numerical simulations using CST software, we determined the electromagnetic shielding proprieties of the chiral-honeycomb slab. We represented and we made an optimization of the electromagnetic transmission coefficients, depending on the unit cell’s geometrical parameters of chiral-honeycomb slab. Finally we proposed some shield panels based on dielectric hexachiral-honeycomb slab coated with thin metallic layer, with a view to be used in the electromagnetic protection at the buildings level. I. Introduction Generally, the electromagnetic compatibility is considered at electronic component level, board level and electrical system level. In order to achieve the electromagnetic protection of the electrical devices and the human beings, it is very important to consider the electromagnetic compatibility problems and to make a corresponding design at the buildings level, such as: hospitals, control rooms of radar or radio transmitters, offices or just houses. The materials used in electromagnetic shielding range from classical metallic plate to new advanced materials [1]. In the last time there is a great interest in the development, design and electromagnetic characterizations of the metamaterials [2] because of their potential electromagnetic applications. Because of their good mechanical performances [3], [4] and their special electromagnetic proprieties [5], the chiral-honeycomb structures were considered to obtain the sandwich panels, used as electromagnetic absorbers or/and shields for inside or outside the buildings. Thus, we proposed two basically types of absorber or/and shielding in view to be used as panels for shielding at the building level: the sandwich panel type Salisbury screen or Jaumann layers, which use the chiral honeycomb slab as dielectric between resistive sheet and perfect electric conductive sheet [6]; the shield panel obtained by metallizing a chiral honeycomb slab made of dielectric materials. The second type of shielding panel, which is presented in this paper, can be used also in the case of the vent hole. Referring to the determination of electromagnetic proprieties of the periodic structures there are two basically methods: homogenisation method and numerical simulation [7]. Because of the complex configuration of the chiral honeycomb structure we used numerical techniques for electromagnetic proprieties determination. Thus, we determined the transmission coefficients and we optimised the shielding effectiveness of the panel based of metallized chiral honeycomb slab, depending on their geometrical parameters using CST software. The determination of the absorption, reflection and transmission properties of the materials is very important in the case of the electromagnetic absorbers/shields and the periodic structures [8]. II. The proposed shield panels We considered a hexagonal unit cell of the periodic structure as hexachiral honeycomb slab developed in CHISMACOMB FP6 EU project. Thus, the honeycomb structure shown in Figure 1a is composed of circular elements –cylinders - of inner diameter, D, each of them joint by six tangent straight ligaments with the thickness of wall, g. The distance between the centres of adjacent cylinders or nodes is L. The thickness of the hexachiral honeycomb panel is H. For the considered dimensions of the unit cell the effective-homogeneity condition ( 4 λ < p ) is accomplished for frequencies ( GHz f 5 < ). Figure 1 shows the unit cell of the periodic structure for hexachiral honeycomb slab, respectively for classical honeycomb slab.