Relative permittivity

Relative permittivity is also commonly known as the dielectric constant, a term still used but deprecated by standards organizations in engineering[15] as well as in chemistry.

It is still commonly used, but has been deprecated by standards organizations,[15][16] because of its ambiguity, as some older reports used it for the absolute permittivity ε.

[15][18][19] The permittivity may be quoted either as a static property or as a frequency-dependent variant, in which case it is also known as the dielectric function.

The imaginary part corresponds to a phase shift of the polarization P relative to E and leads to the attenuation of electromagnetic waves passing through the medium.

An indirect technique to calculate εr is conversion of radio frequency S-parameter measurement results.

A description of frequently used S-parameter conversions for determination of the frequency-dependent εr of dielectrics can be found in this bibliographic source.

[24] The relative permittivity is an essential piece of information when designing capacitors, and in other circumstances where a material might be expected to introduce capacitance into a circuit.

The layers beneath etched conductors in printed circuit boards (PCBs) also act as dielectrics.

They consist of dielectric materials that are purposely doped with impurities so as to control the precise value of εr within the cross-section.

Using the capacitance change, along with the measured temperature, the relative humidity can be obtained using engineering formulas.

[26] This information is important when designing separation, sample preparation and chromatography techniques in analytical chemistry.