Modeling of bend discontinuity in plasmonic and spoof plasmonic waveguides

The paper proposes a method to characterize the bend discontinuity for plasmonic and spoof plasmonic waveguides in terms of scattering parameters. By means of this method, the waveguide is modelled by a two-port network and its scattering parameters are extracted. The parameters for the L-shaped sharp curved bends at different frequencies and under different bending angles are determined

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

Analysis and design of defected ground structure for EMC improvement in mixed-signal transceiver modules

In this research, the return path discontinuity (RPD), located under the power amplifier (PA) substrate, of X-band transceiver module (Base), mounted on a four-layer printed circuit board (PCB), is investigated to improve the signal integrity by reducing the difference in the reference potential. This study is performed by initially employing the wirebond method, through the assessment of both numbers and sizes of bondwires by advanced design system (ADS). Six bondwires of 25 µm are added, producing an improvement of 6.82 dB for the reflection coefficient and 1.19 dB for the isolation and insertion loss. For further improvement, spiral shape defected ground structure (DGS) is implemented in the inner ground layer (layer 2) without using bond wires. The DGS simulation results illustrate an improvement of 3 dB for S11 and 0.6 dB for S12. To improve the electromagnetic compatibility (EMC), the authors propose combination and integration of both wirebond and DGS methods, called wirebond–DGS method, which results in an improvement of 11.86 dB for S11, 1.34 dB for S12 and S21, and 12.03 dB for S22. Finally, the wirebond–DGS RF module was fabricated and the measurement results exhibit an improvement of 8.07 dB for S11 and 9.39 dB for S22 in comparison with the fabricated Base module. In addition, 0.53 dB improvement for both S12 and S21 is also achieved

Meander Antennas.

http://deepblue.lib.umich.edu/bitstream/2027.42/20971/2/rl0727.0001.001.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/20971/1/rl0727.0001.001.tx

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