![]() They are specifically developed for low losses (low tangent delta value) and provide an almost constant broadband imaginary part. Higher order models for constant tangent value fitting are also available. Obviously, it is less frequency dependent than the conductivity model. The green curve demonstrates the tangent delta dispersive behavior of such a model. To realize an almost constant tangent value, or to set up a specific tangent delta curve, an internal dispersive first order Debye model (see the section Relaxation Process ) will be fitted to the tangent delta input. This model realizes a broadband constant conductivity, however, the corresponding tangent delta value is frequency dependent, as displayed in the right picture. Where corresponds to the real part of the dispersive model, is the conductivity and is the frequency in rad/s.Īccordingly to the general complex permittivity model the real and imaginary part are therefore One definition is the following conductivity model : Besides the special dispersive models explained later, different possibilities for loss definitions are available in CST Microwave Studio. In general, every linear material behavior is described with help of the expressions above. The signs used here correspond to those commonly used in engineering, whereas for the physics convention one should reverse all imaginary quantities. It is important to realize that the choice of sign for time-dependence - so that the time dependency of the field is - dictates the sign convention for the imaginary part of permittivity. The losses are specified by the dielectric or magnetic loss angle or its corresponding tangent delta values:Ĭonsequently, the tangent delta value is given as the negative ratio between imaginary and real part of the complex permittivity or permeability, respectively: This means that the material parameters have a real and an imaginary part, both frequency dependent. Introducing material losses leads to complex permittivity or permeability values, respectively. Contentsīiased Plasma (Electric Gyrotropic) Materialsīiased Ferrite (Magnetic Gyrotropic) Materials In the following section, some special material declarations are discussed. The vacuum permittivity and permeability are defined as and The material properties can be defined either as normal, describing isotropic media or with consideration of anisotropic behavior. In the following the description of the material is specified by its relative parameters with respect to the vacuum case. Considering linear behavior, in the frequency domain the dielectric and magnetic material parameters determine the ratio of the electric field and flux density and of the magnetic field and flux density, respectively: Each material is distinguished by its unique name and can be visualized in a selectable color and transparency. ![]() Other more complex materials may be defined in the Material Properties dialog box. The two basic materials available are PEC ( Perfect Electrically Conducting material) and Vacuum. Material Overview Material Overview (HF) For the high frequency solvers, several different material properties are considered to allow realistic modeling of practical simulation problems. ![]()
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