Measurement of Radiophysical Properties and Electromagnetic Parameters of Material Samples in the Millimeter Microwave Range

This work is devoted to the developed method and the experimental bench based on this method for high-precision measurements of the radiophysical properties (reflection and transmission coefficients) and electromagnetic parameters (complex dielectric permittivity and magnetic permeability) of materials in the millimeter wavelength range from 3 to 4 mm. The proposed method is based on the measurement in free space of the S-parameters of a quasi-plane electromagnetic wave using broadband lens horn antennas and a vector network analyzer. During the measurement process, a test sample is placed on the diaphragm located in the near zone of the antennas. In order to reduce errors in measuring S-parameters, a set of special calibrations with background subtraction is used. In order to extract the useful signal against the background of spurious re-reflections (noise), the Time Domain procedure is performed. As a result, a description of the method is given and the experimental bench developed on its basis, which makes it possible to measure the reflection and transmission coefficients, as well as the complex dielectric permittivity and magnetic permeability of materials in the W-band from 75 to 110 GHz. The measurement results of the dielectric and magnetic properties of a number of material samples, in particular, fused quartz, the values of the permittivity of which are well known from the literature, are presented. On the example of quartz glass samples with different thicknesses, good convergence of the calculated and experimental data on the frequency dependences of the reflection and transmission coefficients is demonstrated. Measurements of the radiophysical properties and electromagnetic parameters of materials in W-band are especially relevant for a number of areas in the development of modern microwave technology: radar systems, sensors in experimental automatic vehicles, including unmanned vehicles, high-precision studies of weather phenomena, satellite communications, etc.