A microwave method to measure unburnt coal content in ashes

The determination of unburnt coal content in ashes of combustors without detailed chemical analysis 1·emains an important problem. In our previous paper, a method was proposed based on the determination of the complex dielectric permittivity of the ashes·By measuring the complex rejection coefficient from a suitably designed microstrip transmission system loaded by the material under test. A modified and greatly simplilìcd procedure is proposed here. The method is based on measurements of the modulus of the reflection coef­ficient of a sample holder loaded with the test sample.