Permittivity measurements of layers

A method for combined characterization of a dielectric layer and one of, a backing material or fluid behind the dielectric layer, wherein the method comprises:

• measuring a parameter in a first frequency range using a first apparatus, wherein the measured parameter in the first frequency range is at least one of, reflection coefficient, transmission coefficient, and impedance,
• measuring a parameter in a second frequency range using a second apparatus, wherein the measured parameter in the second frequency range is at least one of, reflection coefficient, transmission coefficient, and impedance,
• estimating a permittivity in the first frequency range from the measured parameter in the first frequency range using at least one of, experimentally and theoretically based calibration models,
• estimating a permittivity in the second frequency range by combining an application based model with the estimated permittivity in the first frequency range, wherein the application based model is a model for estimating permittivity as a function of frequency from one of, material or fluid composition, and further comprising estimating the permittivity from at least one of, theoretical models, numerical simulations, and measured data,
• providing an estimate of a thickness of the dielectric layer from the measured parameter in the second frequency range and at least one of, theoretical models, models derived from numerical simulations, and (c) models derived from measured data,
• wherein the first frequency range is a material characterization frequency range wherein reflections from an interface between at least one sensor and the dielectric layer is dominating compared with reflections from an interface between the dielectric layer and the one of, backing material or fluid,
• wherein the second frequency range is a thickness characterization frequency range wherein reflections from the interface between the dielectric layer and the one of, backing material or fluid interfere with reflections from the interface between the sensor and the dielectric layer,
• characterizing the dielectric layer in a first time period when a permittivity of the fluid or material behind the dielectric layer is known,
• measuring permittivity in a second time period when the permittivity of the fluid or material behind the dielectric layer is unknown, and
• estimating the permittivity of the one of, backing material or fluid behind the dielectric layer, from the measurement in the second time period.

A system for characterizing a dielectric layer with one of, a backing material or fluid behind the dielectric layer, the system comprising:

• a first apparatus for measuring a parameter in a first frequency range, wherein the measured parameter in the first frequency range is at least one of, reflection coefficient, transmission coefficient, and impedance,
• a second apparatus for measuring a parameter in a second frequency range, wherein the measured parameter in the second frequency range is at least one of, reflection coefficient, transmission coefficient, and impedance,
• estimating a permittivity in the first frequency range from the measured parameter in the first frequency range using at least one of, experimentally and theoretically based calibration models,
• estimating a permittivity in the second frequency range by combining an application based model with the estimated permittivity in the first frequency range, wherein the application based model is a model for estimating permittivity as a function of frequency from one of, material or fluid composition, and further comprising estimating the permittivity from at least one of, theoretical models, numerical simulations, and measured data,
• providing an estimate of a thickness of the dielectric layer from the measured parameter in the second frequency range, and at least one of, theoretical models, models derived from numerical simulations, and models derived from measured data,
• wherein the first frequency range is a material characterization frequency range wherein reflections from an interface between at least one sensor and the dielectric layer is dominating compared with reflections from an interface between the dielectric layer and the one of, backing material or fluid, and
• wherein the second frequency range is a thickness characterization frequency range wherein reflections from the interface between the dielectric layer and the one of, backing material or fluid interfere with reflections from the interface between the at least one sensor and the dielectric layer,
• the at least one sensor measuring the parameter in the first frequency range, and
• the at least one sensor measuring the parameter in the second frequency range.