Dielectric constant

The complex permittivity (ε*) is composed of a real part relative dielectric constant  (ε’)  and an imaginary part  dielectric loss (ε’’).  Dielectric constant (e’) and dielectric loss (e’’) of pure groundnut oil are measured at different temperatures and frequencies. X-band microwave bench operating in the frequency range 8.2-12.4 GHz is tuned to desired constant frequency. It is observed that the dielectric constant (e’) of groundnut oil decreases with increase in temperature while the dielectric loss (e”) increases with increase in temperature. The dielectric constant (e’) of groundnut oil decreases with increase in frequency, while dielectric loss (e”) increases with increase in frequency. The dielectric constant and dielectric loss of groundnut oil samples are in good agreement with the earlier reported work.

The real (ε’) and imaginary (ε’’) parts of the complex dielectric constant (ε*) of different unsaturated edible oils were measured at different temperatures ranging from 30 0C to 70 0C at 9.435 GHz microwave frequency. The X-band setup in the TE10 mode with slotted section and crystal detector were used for this measurement. The values of dielectric constant and dielectric loss show remarkable variation with temperature. It observed that the dielectric constant and dielectric loss are different for different oils, due to their different physical and chemical properties.