Liquid Dielectric Property Determination using Monopole Probes Operating at Microwave Frequencies

Determination of the dielectric properties of liquids has high practical potential in many industrial, medical, as well as environmental sectors. Hence, there is an increasing demand for efficient liquid dielectric properties measurement systems. In this paper, a microwave nondestructive evaluation (NDE) system intended to satisfy this need is proposed. The system utilizes a monopole antenna to transmit microwave signals into a liquid and monitors the reflected waves in the feeding coaxial line. The functional dependence of reflection coefficient, measured at the input of the monopole, on the dielectric property of the liquid surrounding the monopole will he employed in the measurement schema - i.e. the reflection coefficient will he measured and then the inverse problem will be solved. In general, this dependence is nonlinear in nature and requires multiple measurements. In this paper, a lookup table algorithm is utilized in conjunction with multi-frequency measurements to solve the inverse problem. The proposed inverse problem solution relies on diversity of measurements over operational frequencies. This is basically achievable in the broadband inspection schema proposed here