Investigating the effects of external fields polarization on the coupling of pure magnetic waves in the human body in very low frequencies

In this paper we studied the effects of external fields' polarization on the coupling of pure magnetic fields into human body. Finite Difference Time Domain (FDTD) method is used to calculate the current densities induced in a 1 cm resolution anatomically based model with proper tissue conductivities. Twenty different tissues have been considered in this investigation and scaled FDTD technique is used to convert the results of computer code run in 15 MHz to low frequencies which are encountered in the vicinity of industrial induction heating and melting devices. It has been found that external magnetic field's orientation due to human body has a pronounced impact on the level of induced currents in different body tissues. This may potentially help developing protecting strategies to mitigate the situations in which workers are exposed to high levels of external magnetic radiation

Leveraging space–time modulation for energy coupling control in electromagnetic coupled transmission lines structures

Abstract This article presents a technique for controlling energy coupling in a coupled transmission line system based on the space–time modulation concept. The per-unit-length mutual capacitance and mutual inductance of the structure are modulated in space and time. The main idea is based on the harmonic generation property of space–time modulated media. As the amplitude of harmonics is a function of modulation parameters it is demonstrated that by choosing an appropriate space–time modulation scheme energy of different harmonics can be engineered leading to crosstalk reduction. In the quest for designing an effective space–time modulation scheme, an analytical method is developed for the examination of the space–time modulated coupled transmission line. The proposed method which is based on the state space formulation and benefits from the coupled mode theory is fast and accurate making it feasible for design problems. To validate the proposed analytical method, a full-wave simulation method has been used. The time-varying nature of the problem makes the finite-difference-time-domain the most appropriate choice. The validity of the analytical method is rigorously verified against the developed finite-difference-time-domain technique. The interest in circuit design techniques in an IC-compatible fashion in microwave circuits and the introduction of tunable material such as graphene in the THz regime leads to a positive future for the proposed space–time modulation-based crosstalk reduction method

Cross‐talk reduction in metamaterial and non‐uniform transmission lines

Abstract The electromagnetic compatibility analysis of RF circuitry is essential due to the adverse effects on sensitive components. Two metamaterial unit cells with slow‐wave properties are presented for cross‐talk reduction in transmission lines. The analytical expressions for computing equivalent lumped elements of the lines are then provided. The dispersion diagram is obtained from the parameters extracted from the measurement. A microstrip as the generator line and five identical CRLH unit cells as the receptor line are then used and a significant reduction in cross‐talk is observed in comparison to conventional lines. A non‐uniform transmission line with two different CRLH unit cells as the receptor line is then employed and found effective in further cross‐talk reduction between the lines. The lengths of the lines and numbers of cells are kept the same in all lines for comparison. The simulated results are validated by measurements

Tunable Rectangular Waveguide Bandpass Filter Based on Plasma Technology

International audienceThis paper presents a novel tunable bandpass filter that exploits plasma conductors within a standard hollow waveguide framework. The operational principle of the filter leverages the reconfigurability of plasma and its tunable properties, allowing dynamic control over the lower frequency boundary. Through the adjustment of plasma frequency, the filter demonstrates remarkable adaptability, shifting the lower cutoff frequency within a range from 1.66 GHz to 1.75 GHz while maintaining a nearly fixed upper cutoff frequency at approximately 2 GHz. Additionally, the paper includes a parametric analysis that investigates the influence of post dimensions on filter performance. This analysis underscores the significance of initial post dimensions in shaping the bandwidth of the filter. Findings affirm the feasibility of this innovative filter concept