Patent ID: 6856140

Claim:
A method for measurement of a material's complex permittivity, comprising the step of: positioning a near-field microwave probe at a predetermined distance d* from a first standard sample having a dielectric constant ∈ r1 ; measuring a relative resonant frequency shift δf 1 =(f e −f 1 )/f e of said near-field microwave probe for said first standard sample; positioning said near-field microwave probe said predetermined distance d* from at least one second standard sample having a dielectric constant ∈ r2 ; measuring a relative resonant frequency shift δf 2 =(f e −f 2 )/f e of said near-field microwave probe for said at least one second standard sample, wherein f 1 and f 2 are the resonant frequencies of said probe positioned said distance d* from said first and said at least one second standard samples, respectively, and f e is the resonator frequency of said probe for an empty resonator; calculating geometrical coefficients A and B using said measured relative resonant frequencies δf 1 and δf 2 and dielectric constants ∈ r1 and ∈ r2 for said first and at least one second standard samples; positioning and maintaining said near-field microwave probe said distance d* from a sample under study; measuring a relative resonant frequency shift δf s =(f e −f s )/f e of said near-field microwave probe for said sample under study; measuring a change in the quality factor Δ(1/Q) of said near-field microwave probe for the resonator loaded with said sample under study and for an empty resonator; calculating the dielectric constant of said sample under study using said resonant frequency shift δf s and said geometrical coefficients A and B; and calculating the dielectric loss tangent (tan δ) of said sample under study using said Δ(1/Q) and said geometrical coefficients A and B.