Calculations of electromagnetic fields in longitudinal irregular TEM-cells

TEM-cells can be used as a standardized field generator for field probe calibration purposes or electromagnetic compatibility measurements. Because of its practical use as a measurement environment, the electromagnetic behavior over a broad range of frequencies is essential. However, without the understanding of wave reflection, mode-conversion, and attenuation, using such a measurement environment is impractical. In this contribution, we calculate the electromagnetic fields in a longitudinal irregular coaxial TEM-cell. Using a semi-analytical approach, we can determine these wave characteristics. The method is based on the projection of Maxwell's equations onto eigenfunctions. This work's primary objective is to examine the effect of irregular deformed boundaries on the electromagnetic field and the resonance frequencies.

Characterization of Joints between Carbon Fiber Composite Parts Using a Microstrip Transmission Line Method

The electromagnetic performance of aerial platforms, which are composed mostly of nonmetallic materials, is a subject of great interest at present time. The behavior of this type of composite structure against electromagnetic environmental effects (E3), such as lightning, is not well-studied as in the case of metalic structures. The purpose of this article is to characterize the joints present in aerial platforms constructed mainly of nonmetallic composite materials. The study of these joints is fundamental because electrical discontinuities or preferential routes can produce changes in the electromagnetic behavior of an aircraft. The proposed measurement system for the characterization of these joints is a microstrip line. The flexibility of the test setup allows for evaluation of different joints in carbon fiber composite (CFC) samples with a different number of plies. Additionally, approximated models of the behavior of the joints as well as the detection of possible defects in the joining process are reported.

SpaceWire

SpaceWire is a point-to-point bit shipping protocol for high-speed data communication links and networks providing equipment compatibility and seamless component reusability. It has found great application in many space missions reducing the development cost, offering architectural flexibility, and improving reliability. This chapter delves into the standard describing the SpaceWire, focusing on the lower levels that play a key role in the electromagnetic behavior of the system and concern cable assemblies, shielding, bonding, and grounding. Findings regarding emissions affecting spacecraft components are presented as well as other EMC issues that have an impact on the system performance. Recent developments on the modelling of the cable of the system with a focus on radiated emissions of SpW systems are also presented and discussed.

Terahertz response of monolayer and few-layer WTe_2 at the nanoscale

Tungsten ditelluride (WTe_2) is a transition metal dichalcogenide whose physical properties depend critically on the number of layers. In this paper, we use apertureless scattering-type near-field optical microscopy operating at Terahertz (THz) frequencies and cryogenic temperatures to identify distinct THz range electromagnetic behavior of WTe_2 mono-, bi- and tri-layer terraces in the same micro-crystals. We observed clear metallic behavior of the near-field signal on tri-layer regions. Our data are consistent with the existence of surface plasmon polaritons (SPP) in the THz range confined to tri-layer terraces in our specimens. The near-field signal on bi-layer regions surprisingly shows moderately metallicity, but with negligible temperature dependence. Subdiffractional THz imaging data together with theoretical calculations considering thermally activated carriers favor the semimetal scenario over the semiconductor scenario for bi-layer WTe_2. THz images for monolayer terraces uncovered weakly insulating behavior consistent with transport data.

Design and Implementation of Stoppers to Capacitive RF MEMS Switch for Low Frequency Applications

This work presents the fixed-fixed type capacitive RF MEMS switch. The device additionally includes nonuniform meanders which can reduce the actuation voltage of the device. The switch accomplishes 0.5-1.5μN of applied force for actuation voltages of 6.9-7.9 V. The simulated and calculated spring steady is 1.49N/m to evaluate the actuation voltage the concept of stoppers is introduced in this work. Incorporating stoppers and meanders to the proposed device is to improve the RF performance. The proposed switch produces perfect electromagnetic behavior low insertion and high isolation with the addition of stoppers at the thickness of 1.2μm for 3μm air gap and aluminum nitride as dielectric layer followed by silicon nitride, silicon dioxide and Kapton polyimide in the device. The switch performance undergoes two conditions here with the addition and without inclusion of the stoppers. The RF Performance of the device with the stoppers, are lower insertion, better return losses and higher isolation are -0.07dB, -82 dB, -69dB at the 8- 8.1GHz frequency having Al3N4 as dielectric film followed by Si3N4 as-0.06dB, -77dB and -71dB then SiO2 as-0.06dB,-87dB, -71dB finally, Kapton polyimide as -0.06dB, -77dB,-76dB at 8- 8.5Ghz frequency. The S-parameter analysis like isolation, return loss and insertion loss are carried using FDTD tool CST which gives good performance.