The letter introduces the first highly miniaturized low-pass filter that combines the use of modal distortions, internal reflections, and magnetodielectric cover. The filter is implemented on an FR-4 printed circuit board with compact external dimensions of 17x14x0.25 (mm) covered with an elastic magnetodielectric material. We conducted electrodynamic simulations of this filter using FDTD in Keysight EMPro and FEM in COMSOL Multiphysics. To validate the simulation results, the filter prototype was designed, manufactured, and tested. The EMI attenuation in the range from 4 to 20 GHz was more than 42 dB. The standing wave coefficient in the passband did not exceed 1.5. The effectiveness of broadband and mesoband interference suppression was evaluated using N-norms analysis. Signal integrity was analyzed by exciting a pseudo-random bit sequence with data rates of 0.25 and 0.5 Gbps at the input of the filter. The examination of N-norms and eye diagrams confirms that the filter can be employed to protect signal circuits.

This paper presents a novel technique for improving the performance of a modal filter by using an electromagnetic absorber. The study considers a two-conductor modal filter based on a microstrip transmission line. The authors analyzed the effect of the absorber on the MF performance in suppressing conducted and radiated interferences (in the near and far fields). The frequency characteristics of the device were then redefined into the time characteristics in the Advanced Design System. As an excitation, the authors used an ultra-wideband interference pulse of 155 ps (at 0.5 level) and then employed N-norms to estimate and characterize the decomposed pulses. The results show that the use of the absorber can significantly improve the attenuation of the ultra-wideband interference. It was experimentally demonstrated that the value of N1 decreased by a factor of 4.31, N2 – by a factor of 6.52, N5 – by a factor of 1.87. In terms of radiated interference in the near field, the improvement in attenuation of each norm achieved at least 2.81 times. The analysis of the characteristics in the far field showed that the use of the electromagnetic absorber allows reducing the transmission coefficient on average by 2.25 times at a distance of 1 m. To validate the measurement results, the electrodynamic simulation of the modal filter characteristics in the frequency range up to 6 GHz was carried out and showed full agreement with the experimental results.

This article analyzes novel, adventurous routing schemes employed in designing microwave transmission lines (TL). In contrast to traditional schemes, we propose to locate two independent traces close to each other. The strong electromagnetic coupling thus formed can cause unwanted crosstalk between traces. However, if their level is acceptable, we can use the suggested routing schemes to significantly increase the powerful interference immunity of the electrical circuits by using modal distortion. Two prototypes of such TLs in the form of a serpentine and a spiral were made in which the far-end crosstalk voltage waveforms do not exceed 4.4% of the useful signal amplitudes. We performed electrodynamic simulations and measurements of such TLs in a transverse electromagnetic cell in the frequency range from 10 MHz to 5.3 GHz. The investigated lines have a low level of radiated emissions. Experimental results show that the proposed TLs decrease the voltage amplitude of the ultra-wideband pulse by at least 4 times and the voltage change rate by 10.7 times and more. In addition, the effective voltage value on the load is decreased by at least 2.2 times. The spiral scheme was found to be better than the serpentine scheme in almost all parameters. Simultaneously, the electrodynamic approach is in full agreement with the experimental study.

The paper presents a new method for experimental studies of typical prototypes with triple modal reservation. The authors propose to define the investigated devices in the frequency domain and then by using Advanced Design System software to redefine their characteristics in the time domain. The paper contains recommendations for the preparation and conduction of such experimental studies. Using these recommendations, the authors conducted measurements of the complex S-parameters of the circuits with triple modal reservation in the frequency range from 10 MHz to 18 GHz before and after failures. Then, to analyze the response to ultra-wideband interference, a pulse in the trapezoidal waveform with a duration of 150 ps was excited in Advanced Design System to the input of the reserved circuit. The maximum amplitude value at the end of the reserved circuit is obtained for all the faults studied. The authors also present the optimal order of switching the reserving circuits. This paper proposes the methods for analyzing the frequency and time characteristics. It makes possible to analyze the characteristics of circuits with multiple modal reservation and to determine the optimal switching order for reserving circuits. The proposed method requires commonly used equipment and a minimum set of technical tools that can reduce economic expenditures and time costs.

The article presents the results of a study of a modal filter (MF) based on a microstrip line with two side conductors grounded at both ends. New analytical expressions for calculating the time response in such a structure are given. For their validation, an MF prototype was made and the transmission coefficient was measured in the frequency range from 0 to 12 GHz. In addition, the full-wave electrodynamic simulation and the analysis based on the transmission line theory were carried out. The frequency responses of the MF were converted into time domain responses in the ADS system. At the MF output, the response to an ultra-wideband (UWB) pulse was analyzed. The results for the analytical model are in good agreement with the results of measurements and simulations by the two approaches. It was experimentally proven that the structure under study provides the protection of electrical circuits from a UWB pulse by separating it in time and decreasing its effect on the components.