Maxim E. Komnatnov

This work focuses on the study of shield systems consisting of nested enclosures. In the first step, using FDTD simulations and measurements in an anechoic chamber, we investigate the shielding effectiveness (SE) of the system of two nested rectangular enclosures in the frequency range of up to 3 GHz. It is shown for the first time that for a number of frequencies, the SE of the nested shields can be improved by 40–50 dB due to the asymmetric arrangement of the enclosures, their electrical connection, and the mutually perpendicular arrangement of the apertures. Next, we analyze the emissions from the electromagnetic radiation sources in the presence and absence of a nested shield system. The results show that a nested shield system may not attenuate the emission amplitude but increases it by more than 58 dB at the resonant frequencies of the enclosures. Then, we prove that a single enclosure can have a higher SE than the same enclosure as a part of a poorly designed nested shield system. The final part of the article formulates practical recommendations for the design of nested shield configurations.

This paper focuses on the combination of the method of moments and the wire-grid approximation as an effective computational technique for modeling symmetrical antennas with low computational cost and accurate results. The criteria and conditions for the use of wire-grid surface approximation from various sources are presented together with new recommendations for modeling symmetrical antenna structures using the wire-grid approximation. These recommendations are used to calculate the characteristics of biconical and horn antennas at different frequencies. The results obtained using different grid and mesh settings are compared to those obtained analytically. Moreover, the results are compared to those obtained using the finite difference time domain numerical method, as well as the measured ones. All results are shown to be in a good agreement. The recommendations used for building a symmetrical wire-grid of those symmetrical antenna elements provided the most advantageous parameters of the grid and mesh settings and the wire radius, which are able to give quite accurate results with low computational cost. Additionally, the known equal area rule was modified for a rectangular grid form. The obtained radiation patterns of a conductive plate using both the original rule and the modified one are compared with the electrodynamic analysis results. It is shown that the use of the modified rule is more accurate when using a rectangle grid form.

This paper focuses on the combination of the method of moments and the wire-grid approximation as an effective computational technique for modeling symmetrical antennas with low computational cost and quite accurate results. The criteria and conditions for the use of wire-grid surface approximation from various sources are presented together with new recommendations for modeling symmetrical antenna structures using the wire-grid approximation. These recommendations are used to calculate the characteristics of biconical and horn antennas at different frequencies. The results obtained using different grid and mesh settings are compared to those obtained analytically. Moreover, the results are compared to those obtained using the finite difference time domain numerical method, as well as the measured ones. All results are shown to be in a good agreement. The used recommendations for building a symmetrical wire-grid of those symmetrical antenna elements provided the most advantageous parameters of the grid and mesh settings and the wire radius, which are able to give a quite accurate results with low computational cost. Additionally, the known equal area rule was modified for a rectangular grid form. The obtained radiation patterns of a conductive plate using both the original rule and the modified one are compared with the electrodynamic analysis results. It is shown that the use of the modified rule is more accurate when using a rectangle grid form.

An analytical model is proposed for evaluating shielding effectiveness (SE) of a rectangular enclosure populated with conducting plates. The conducting plates are considered as capacitive diaphragms that fill the width of the enclosure, and SE is calculated using the equivalent circuit of the enclosure. The letter presents an improved approach to evaluating enclosures populated with printed circuit boards (PCBs) or plates coated with a composite or radar-absorbing material. The evaluation of the model error was performed when the plate height changed. Both this model and finite element method were used to calculate the SE for enclosures populated with conducting plates, PCBs and the plate coated with a magnetic composite material. The results obtained in the range up to 1 GHz are in good agreement.

The use of multiphase power supply of a group of Peltier elements (PE) is considered to reduce the load on the power source. Schemes and a control layout with the use of the H-bridge, allowing the invert of the current through the PE, are given. The analysis of the operation of the used H-bridges and PE in the frequency range of the control PWM signal from 30 Hz to 32 kHz is performed. The algorithm for monitoring the current sensors is presented and the time diagrams of the currents are represented through the PE and H-bridges using a two-phase and four-phase control PWM signal for one, two and four phases of the supply. The results showed stable heating and cooling of the PE at frequencies from 30 Hz to 1 kHz. The use of multiphase power supply of PE made it possible to significantly reduce the load on the power source.