Microwave interferometer for measurements of small displacements

Two microwave interferometer systems developed for noncontact measurements of small displacements in an electromagnetically semitransparent medium are described. Arrangements for testing the instruments and experimental results are presented. The principal characteristics of the systems, e.g., the output signal versus the displacement of the scattering object, are linear for the two-way losses in the medium between the antenna and the object below 60 dB. The maximum displacement of the object is limited to a half-wavelength in the test medium by the interference between the signal backscattered by the test object and the signal reflected from the antenna.