Microwaves relative complex permittivity

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 ... 

Test Methods for Relative Permittivity and Dissipation Factor of Expanded Cellular Plastics Used for Electrical Insulation Test Method for Complex Permittivity (Dielectric Constant) of Solid Electrical Insulating Materials at Microwave Frequencies and Temperatures Up to 1650°C... 

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. 

The microwave response both of polar solvents and electrolyte solutions is usually represented with the help of its frequency-dependent complex relative permittivity, s(co) = 8 ((o) -f je"(co), cf. Ref. The characteristic parameters of such investigations are the relaxation times or relaxation time distributions of molecular processes and the extrapolated real permittivities of zero (Eq) and inifinite (e ) frequencies of one or more relaxation regions. 

Based on this theory, the material properties are of high importance in microwave processing. The complex relative permittivity, s,... 

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