Abstract: A method and a device for measuring dielectric characteristics by generating a microwave signal, dividing the signal into reference and sounding signals, irradiating a body with the microwave signal, receiving the reflected, reference and total signals and in detecting said signals. The irradiation is carried out by a waveguide wave, the wave number of which in the free space filled with dielectric, is selected within a range from 1.0 to 1.07 the propagation number of the waveguide wave.