Abstract: A microstrip-type microwave sensor for the measurement of the dielectric properties of a solid or liquid material, constituted by a main line and two connected transmission lines integral at one of their extremities to the main line, the main line and two connected transmission lines being spaced from one another by a slot and being made integral with a substrate. The main line is connected to an electrical circuit by each of its two extremities to inject a sinusoidal signal, and wherein said main line has a width giving it an impedance in the range 50 Ohm, the two connected transmission lines being of the same width and of a length equal to one quarter of the wavelength guided in the substrate, the substrate having a height or thickness giving it flexibility or rigidity, the substrate being applied to a metallic support formed of a layer of metallic material.