6. An experimental and computational method for predicting the characteristics of dielectric products in the millimeter wave band

Annotation: The paper investigates an experimental and computational approach to the determination and prediction of the electrodynamic characteristics of dielectric products in the millimeter wave band. The relevance of the study is associated with the widespread use of dielectric materials in various radio engineering, telecommunication, measurement, and sensor systems, as well as with more and more demanding requirements for the accuracy in determining the electromagnetic parameters of these products at higher operating frequencies. Particular attention is paid to the determination of complex permittivity based on the results of free-space measurements using two antennas, followed by numerical data processing and electromagnetic simulation. The paper analyzes the specifi c features of the contact, coaxial, waveguide, resonant, and free-space methods for determining dielectric properties. It demonstrates that free-space techniques are advantageous for investigating complex-geometry fi nished products because they do not require the placement of the object inside a waveguide or a resonant structure and allow examination of relatively large-sized samples. The proposed approach involves measuring signal characteristics with a vector network analyzer, normalizing the results to the reference measurement, and accounting for the infl uence of antenna parameters, measurement system geometry, parasitic refl ections, transmission-path losses, and object placement accuracy. The paper discusses the feasibility of determining electromagnetic parameters by solving an inverse electromagnetic problem and conducting a numerical simulation. Combining experimental data with the geometric parameters of a product and its electromagnetic model enables the improvement of parameter estimation accuracy and the prediction of product characteristics over a specifi ed frequency range. Independent experimental verifi cation is considered a technique to assess the reliability of the results. The proposed approach can be practical for investigating dielectric materials and products for which the fabrication of specialized test specimens or the use of conventional waveguide and resonant measurement techniques is technically diffi cult or limited.