This paper presents the development of an electromagnetic probe to accurately measure the soil electromagnetic properties such as dielectric constant and loss factor in the field. The in-site dielectric probe sensor is designed and methods have been developed to calibrate and validate the accuracy of the sensor in measuring dielectric properties of the material. Clean saturated sandy soil material with porosity 40% was used. The soil samples were contaminated by leachate from municipality solid waste from the landfill site. Five levels of leachate contamination were prepared, ranging from 0% to 10%. Dielectric properties of soil polluted sample were measured using the proposed in-site dielectric sensor. Dielectric properties of contaminated soil were evaluated at a different frequency and leachate content. The result showed that both dielectric constant and loss factor decree with increasing frequency due to the reduction of conductance current at high frequency. Also, the result showed that the dielectric properties of leachate-contaminated soil decrease with increasing leachate content while the loss factor increase with increasing leachate content. Mathematical models were developed to determine the relationship between soil dielectric constant, loss factor and soil leachate pollution content.