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** Complex dielectric permittivity **

** Dielectric permittivity complexity **

Figure 2. (a) Complex relative permittivity of Fe203 vs. temperature at 915 and 2450 MFIz. (b) Dielectric loss tangent of Fe2C>3 vs. temperature at 915 and 2450 MHz. [Pg.600]

The absorptive losses are referred to as the dielectric loss or the loss factor, and can also be expressed as the complex coefficient of the relative permittivity, i.e. [Pg.236]

Ceramic dielectrics and insulators cover a wide range of properties, from steatite with a relative permittivity of 6 to complex ferroelectric compositions with relative permittivities exceeding 20000. For the purposes of this discussion insulators will be classed with low permittivity dielectrics, although their dielectric loss may be too high for use in capacitors. Reference should be made to Table 5.10 and Fig. 5.40. [Pg.261]

Moreover, the relative permittivity of an insulating material depends on the frequency, v, in Hertz (Hz) of the applied electric field and can be described as a complex physical quantity, where the imaginary part is related to dielectric losses [Pg.520]

The quantity er is the relative dielectric constant or permittivity of a dielectric medium, eo = 8.85 x 10 12 As/Vm. The quantity tan 6 represents the loss tangent of a dielectric medium. Metals in the microwave range are usually described by a complex conductivity with dominant real part for normal metals and dominant imaginary part for superconductors. [Pg.100]

According to EM theory, the dielectric loss may be contributed by the processes like natural resonance, Debye dipolar relaxation and electron polarization relaxation, etc. In the Debye dipolar relaxation regime, the relative complex permittivity can be expressed as [Pg.495]

Here e represents the relative values of permittivity with respect to that of free space. The term permittivity is not in common usage in the United States in the field of food science. Instead, the term dielectric constant is used. Thus, in Equation 1, e is called the complex dielectric constant, e, the dielectric constant and e", the dielectric loss factor. [Pg.214]

It was also mentioned earlier, that quantitative information regarding the microwave-material interaction can be deduced by measuring the dielectric properties of the material, in particular of the real and imaginary part of the relative complex permittivity, f = — j , where the term ff includes conduction losses, as well as dielectric losses. The relative permeability is not a constant and strictly depends on frequency and temperature. A different and more practical way to express the degree of interaction between microwaves and materials is given by two parameters the power penetration depth (Dp) and the power density dissipated in the material (P), as defined earlier in a simplified version as follows [Pg.239]

A computer automated system, shown schematically in figure 5, has been developed to yield results for permittivity and dielectric loss over a range of temperatures. A real dielectric is considered to have an admittance, Y=j(oC. In practice, the measured admittance is found to have a conductive as well as a capacitive component, Y = G + jcoC. In order to account for this, the capacitance of the dielectric, C, is considered to be characterised by a complex relative permittivity, r [Pg.553]

** Complex dielectric permittivity **

** Dielectric permittivity complexity **

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