Evaluation of a double transmission measurement concept for the characterization of dielectric material compositions with microwaves
In this contribution a one port microwave measuring concept for the determination of effective permittivity of coal gas compositions is discussed. The proposed concept bases on the determination of the propagation velocity inside the interior of a defined test tube. Under the assumption of a dielectric medium, the transmission velocity is directly connected to the effective relative permittivity. Disturbing feed side reflections that prohibit the straight forward analysis of the double transmitted signals are eliminated by a two state modulator. Various electromagnetic field simulations have been performed for the evaluation of the proposed concept. A borosilicate glass test tube was built in order to perform measurements on true-to-life parameters. Results of simulations and measurements are presented and discussed in detail.