This presentation provides a summary of troubleshooting efforts on the power interface of the James Webb Space Telescope (JWST) during cryovac testing at Johnson Space Center (JSC). [Of special interest: OTIS (OTE (Optical Telescope Element) and ISIM (Integrated Science Instrument Module))].
This presentation provides an overview of common mode conducted emissions (CMCE) measurements on power and signal cables. The presentation focuses on how such measurements directly apply to electromagnetic compatibility at the system level and provides a discussion of different techniques for performing them correctly and accurately.
Research on optical TEMPEST has moved forward since 2002 when the first pair of papers on the subject emerged independently and from widely separated locations in the world within a week of each other. Since that time, vulnerabilities have evolved along with systems, and several new threat vectors have consequently appeared. Although the supply chain ecosystem of Ethernet has reduced the vulnerability of billions of devices through use of standardised PHY solutions, other recent trends including the Internet of Things (IoT) in both industrial settings and the general population, High Frequency Trading (HFT) in the financial sector, the European General Data Protection Regulation (GDPR), and inexpensive drones have made it relevant again for consideration in the design of new products for privacy. One of the general principles of security is that vulnerabilities, once fixed, sometimes do not stay that way.
The Institute of Electronics, Information and Communication Engineers, Communications Society (IEICE-CS)
Radiated emissions measurements as specified by MIL-STD-461 are performed in the frequency domain, which is best suited to continuous wave (CW) types of signals. However, many platforms implement signals that are single event pulses or transients. Such signals can potentially generate momentary radiated emissions that can cause interference in the system, but they may be missed with traditional measurement techniques. This demonstration provides measurement and analysis techniques that effectively evaluate the potential emissions from such signals in order to evaluate their potential impacts to system performance.
We performed a field isotropy study based on the reverberation chamber transfer function for three different reverberation chamber configurations. Guidance for reducing the anisotropy based on the polarization-balanced antenna is also provided. We show that chamber isotropy is strongly influenced by loading such that an unloaded chamber can be considered as an isotropic environment, while a loaded chamber is more-or-less anisotropic depending on the amount of loading present. The loading of the chamber is crucial for wireless tests involving modulated signals. Its purpose is to create a flat channel, which enables successful demodulation of the signal without distortion. Consequently, understanding this effect is important in quantifying measurement uncertainty in loaded conditions.
A compact, varactor-incorporated microstrip bandpass filter of controllable center frequency and bandwidth, as well as reconfigurable response is presented. The quasi-lumped dual-mode resonator is adopted for filter compactness, and the incorporated varactors are employed for resonance perturbation and mode coupling control pertinent to frequency agility. Compared to the authors' previous design, the electrical size is significantly reduced (4 times smaller), and the largest to smallest bandwidth ratio (6:1) is greatly extended.
This paper discusses flashover on a medium voltage line caused by nearby lightning. Simulations are carried out using analytical formulas for the lightning-induced voltage and the ground potential rise as a fundamental study. A flashover is determined using an integration method, which is a flashover model and can consider an influence of voltage waveform on the flashover. From the simulation results, the lightning overvoltages and the flashover on a medium voltage line are affected by the ground potential rise as the soil resistivity becomes higher.
This paper presents an analytical and closed-form solution, using a time domain (TD) physical optics (PO), for the fast analysis of transient scattering from a finite and perfectly conducting ellipsoidal surface when it is illuminated by a transient-step plane wave. The advantage of ellipsoidal shapes to resemble a variety of realistic surfaces such as spherical, parabolic or planar surfaces allows the developed solution applicable to model a realistic scattering object such as an aircraft in an effective fashion. Physical appealing interpretation of wave phenomena in terms of reflection and diffraction mechanisms is also provided in the solution. Numerical examples are presented to demonstrate its physical phenomena of scattering mechanisms.
This paper describes an explicit method in which modes are categorized into stable and unstable ones, and the latter are removed to make the method be stable. In general, an explicit method in numerical analysis has a strict stability condition related to a time step size. When power distribution network (PDN) including small apertures and curved contours is modeled by meshes, the PDN has small reactive components due to small meshes. The proposed method overcomes this problem by avoiding the instability and enabling us to use a large time step size.
In radiated emission measurement below 1 GHz, it is a common practice to use broadband antennas such as biconical antennas and LPD antennas. Another practice is to use hybrid antennas because they do not require replacement of the antenna throughout the frequency range below 1 GHz. While the use of a hybrid antenna at a 10 m distance is viewed as a viable option, its use at a 3 m distance is sometimes questioned because of technical issues. Comparison experiments in this paper aim to validate these issues and study the viability of hybrid antennas in radiated emission measurement below 1 GHz at a 3 m distance.
This paper reports charge induction phenomena caused by fluctuated static E-fields and multiple discharge phenomena at a small gap object triggered by the induced charge. A multiple discharge events were experimentally confirmed at the floating small gap, such as a 50μm gap width.
Electromagnetic (EM) simulators are commonly used for electromagnetic compatibility and signal integrity (SI) analysis of printed circuit boards (PCB). The accuracy of such analysis depends on the models used for PCB dielectrics and conductors. These models should be broadband and preserve the physical properties of the materials, such as causality and passivity. One such model for dielectrics is the Debye model. Conductors have typically been modeled using a simple surface impedance formula, which is accurate for smooth conductors and small skin depth. With the evolution of high-speed designs, surface roughness loss has also become increasingly important for signal integrity of PCB interconnects. In this paper, we propose a Debye-like model for conductors possibly having rough surfaces. The advantages of a Debye model are its flexibility for arbitrary variation of surface roughness; guaranteed passivity in SI analysis; and availability of an equivalent circuit representation.
We report on improvement of ESD characteristics of AlGaN/GaN high-electron mobility transistor (HEMT) using metal-insulator-metal (MIM) structure aluminium nitride (AlN) flip-chip (FC) submount. Compared with FC-free HEMT, measured results of the FC HEMT show the improvements of 25 and 150% under drain-to-source and gate-to-source electrostatic discharge (ESD) stress respectively, which is attributed to an extra path formed in the MIM structure AlN FC submount to flow the ESD current and to support the charge by the additional capacitances.
