Nondestructive method of measurement of laminated plates dielectric parameters

The methods for measuring the parameters of dielectric materials of foil plates have been considered. It has been shown that for “non-destructive measurements” (i.e., without removing the metal foil from the dielectric plate), a method based on the excitation of electromagnetic oscillations in a rectangular plate considered as a resonator can be used. Based on the results of measurements of their resonant frequencies and Q-factors, the relative permittivity and the tangent of the dielectric loss angle of the material can be determined. The calculated relations obtained by the authors of the article in one of the early works using the electrodynamic model of a resonator with “magnetic walls” at the ends have been presented. The Q-factor of the resonator has been calculated by the perturbation method, taking into account the losses in the plate dielectric and metallization layers. The results of measurements for four samples from different dielectrics in the frequency range 200...1000 MHz have been presented. The experimental method has been described, in particular, the method of identifying the type of oscillation, the procedure for processing the measurement results. Due to the high sensitivity of the vector analyzer, measurements have been made with a possible small connection of the resonator (metallized plate) with the measuring circuit. This made it possible to minimize the influence of the coupling elements on the measured Qfactor of the oscillations and to consider this Q-factor close to its own. The presented results are in good agreement with the reference data for the materials. The conducted studies have shown the possibility of using a resonator model with “magnetic walls” at the ends for the analysis of electromagnetic oscillations in a foil dielectric plate and, accordingly, using the relations obtained in this case to determine the parameters of the dielectric plate. The conditions for using this model are the small thickness of the plate in comparison with its transverse dimensions and relatively low operating frequencies. The method, which is based on the calculated ratios of the electrodynamic model of the resonator with “magnetic” walls at the ends, provides a sufficiently high accuracy of determining the relative permittivity of the plate material, which led to the use of it (the method) in practice to control the parameters of foil dielectric plates intended for the manufacture of microwave and UHF-band microcircuits. The studies, the results of which have been presented in this paper, allow us to conclude that this method can also be recommended for determining the tangent of the dielectric loss angle of the plate material.

Electrodynamic Computer Model of a Metal Rod in a Concrete Medium Detection

The main aim of the present work is to describe a generalized electrodynamic model of the specific device operation, which provides detection and measurement of the geometric characteristics of the reinforcement cage in a concrete structure. The result of this study is the design of the device’s receiving-transmitting path that is optimal in a number of parameters, as well as a signal processing algorithm based on the operation of an artificial neural network trained on the generalized computer model output data. In addition to the main functionality of the device being developed, which consists in structureroscopy by the method of radar holography, useful target characteristics may be obtained during its operation: electrophysical parameters of concrete, structural defects, visualization of an object, etc. To solve this problem, on the basis of general radar principles, frequency-modulated continuous wave was chosen as the operating mode of the device. To create an electrodynamic model, the computer-aided design environment Pathwave EM Design (EMPro) 2021 was used. The developed generalized model may be optimized for a large number of parameters. In addition to the position and number of receiving antennas, the list of optimization variables may include parameters of the transmitting antenna (ray width, directivity, near-field distance), their number (i.e., the capacity of the MIMO system), power on the transmitting side, etc. The proposed scheme of the device is presented as the main result.

TRANSREFLECTOR ANTENNA DESIGN BASED ON FLAT MULTILAYER TRANSREFLECTOR

The paper considers an embodiment of the antenna design based on a flat non‑axis‑symmetrical transreflector made by using multilayer printed circuit board technology. The construction principle of a flat non‑axis‑symmetrical transreflector by cutting it from the flat polarizing structure is given. The form of the flat multi‑layer non‑axisymmetric transreflector board is determined by the projection of the non‑axisymmetric parabolic transflector onto a plane perpendicular to the focal axis. An electrodynamic model of the antenna with a flat non‑axis‑symmetrical reflector to study the radiation characteristics in the UHF range was constructed. A comparative analysis of the radiation characteristics of antennas on the basis of planar multilayer axisymmetric and flat multilayer non‑axis‑symmetrical transreflectors was performed. A number of technological advantages of the developed flat structure over a non‑axis‑symmetrical parabolic transreflector due to use of the known technology of multilayer printed circuit boards is also described.