Development of electrical test procedures for qualification of spacecraft against EID. Volume 2: Review and specification of test procedures

A combined experimental and analytical program to develop system electrical test procedures for the qualification of spacecraft against damage produced by space-electron-induced discharges (EID) occurring on spacecraft dielectric outer surfaces is described. A review and critical evaluation of possible approaches to qualify spacecraft against space electron-induced discharges (EID) is presented. A variety of possible schemes to simulate EID electromagnetic effects produced in spacecraft was studied. These techniques form the principal element of a provisional, recommended set of test procedures for the EID qualification spacecraft. Significant gaps in our knowledge about EID which impact the final specification of an electrical test to qualify spacecraft against EID are also identified

Investigations on electromagnetic noises and interactions in electronic architectures : a tutorial case on a mobile system

Electromagnetic interactions become critic in embedded and smart electronic structures. The increase of electronic performances confined in a finite volume or support for mobile applications defines new electromagnetic environment and compatibility configurations (EMC). With canonical demonstrators developed for tutorials and EMC experiences, this paper present basic principles and experimental techniques to investigate and control these severe interferences. Some issues are reviewed to present actual and future scientific challenges for EMC at electronic circuit level

A Multi-Physics Computational Approach to Simulating THz Photoconductive Antennas with Comparison to Measured Data and Fabrication of Samples

The frequency demands of radiating systems are moving into the terahertz band with potential applications that include sensing, imaging, and extremely broadband communication. One commonly used method for generating and detecting terahertz waves is to excite a voltage-biased photoconductive antenna with an extremely short laser pulse. The pulsed laser generates charge carriers in a photoconductive substrate which are swept onto the metallic antenna traces to produce an electric current that radiates or detects a terahertz band signal. Therefore, analysis of a photoconductive antenna requires simultaneous solutions of both semiconductor physics equations (including drift-diffusion and continuity relations) and Maxwell’s equations. A multi-physics analysis scheme based on the Discontinuous-Galerkin Finite-Element Time-Domain (DGFETD) is presented that couples the semiconductor drift-diffusion equations with the electromagnetic Maxwell’s equations. A simple port model is discussed that efficiently couples the two equation sets. Various photoconductive antennas were fabricated using TiAu metallization on a GaAs substrate and the fabrication process is detailed. Computed emission intensities are compared with measured data. Optimized antenna designs based on the analysis are presented for a variety of antenna configurations

Impedance Boundary Conditions in a Hybrid FEM/MOM Formulation

When numerically modeling structures with imperfect conductors or conductors coated with a dielectric material, impedance boundary conditions (IBCs) can substantially reduce the amount of computation required. This paper incorporates the IBC in the finite-element method (FEM) part of a FEM/method of moments (FEM/MoM) modeling code. Properties of the new formulation are investigated and the formulation is used to model three practical electromagnetic problems. Results are compared to either measured data or other numerical results. The effect of the IBC on the condition number of hybrid FEM/MoM matrices is also discussed

A Study on the Correspondence of Common-Mode Current in Electromagnetic Radiation from a PCB with a Guard-band

A PCB, in which the ground plane has a finite width and the trace has unbalanced positioning, can result in common-mode (CM) radiation. So far, CM current which is generated by the unbalance of a trace and ground plane has been investigated by experiment and numerical method. It was clarified that CM current is well explained the radiation from PCB up to a few hundred megahertz, and addition of a guard band geometry, which is well connected to the ground plane, can be effective in suppressing the CM current. But it is seemed to be insufficient description for the phenomena observed at higher frequency. This study newly focuses on the correspondence of the CM current in total electromagnetic (EM) radiation from a PCB with a guard band up to 5 GHz. In results, although total radiated power and near electric field up to 1 GHz were related to CM current, the increase in EM radiation in higher frequencies (a few gigahertz) could not be predicted from only the frequency response of CM current. There should suggest two radiation components for a PCB configuration; radiation as a result of a CM current due to the current driven mechanism, and direct radiation from a trace. At the higher frequencies, direct radiation from the trace may be more significant relative to the radiation due to the CM current. This research will be very useful and applicable to estimate the detail of EMC radiation problem from PCBs with attached cables

An efficient 1-D periodic boundary integral equation technique to analyze radiation onto straight and meandering microstrip lines

A modeling technique to analyze the radiation onto arbitrary 1-D periodic metallizations residing on a microstrip substrate is presented. In particular, straight and meandering lines are being studied. The method is based on a boundary integral equation, more specifically on a mixed potential integral equation (MPIE), that is solved by means of the method of moments. A plane wave excites the microstrip structure, and according to the Floquet-Bloch theorem, the analysis can be restricted to one single unit cell. Thereto, the MPIE must be constructed using the pertinent 1-D periodic layered medium Green's functions. Here, these Green's functions are obtained in closed form by invoking the perfectly matched layer paradigm. The proposed method is applied to assess the radiation onto 1) a semi-infinite plate, 2) a straight microstrip line, and 3) a serpentine delay line. These three types of examples clearly illustrate and validate the method. Also, its efficiency, compared to a previously developed fast microstrip analysis technique, is demonstrated

EMI suppression of DC-DC synchronous buck converters by layout optimizations and EMI prediction using non-linear and SPICE circuit co-simulation

The oscillation on the phase voltage is due to the resonant structure formed by a parasitic loop (consisting of two FETs and the input decoupling capacitors) inductance and the output capacitance of the low side FET. Therefore, it is important to minimize this parasitic loop inductance. A simulation guideline is developed on full-wave modeling and simulation of buck converter layouts to estimate the parasitic loop inductances. Furthermore, this method is taken one step further to estimate the far-field radiation from the loop. These simulations were verified on six PCB variants of the buck converter and were compared with measurements in a semi anechoic chamber. Later a layout optimization technique for dc-dc synchronous buck converter to suppress its EMI and minimize its parasitic loop inductance is discussed. Three different loop orientations were optimized for lowest loop inductance by proper placement of FETs, decoupling capacitors, vias, etc. The radiated emissions of these loops were compared and were also compared with full-wave simulation. Co-simulation is a method which combines full-wave and non-linear SPICE solutions to obtain a model which reflects the real circuit behavior of the PCB. In the first part of this thesis, co-simulation is used to estimate the EMC related parameters of the dc-dc synchronous buck converter. Three different co-simulated strategies were examined and analyzed. Initially the phase voltage ringing was estimated and compared with the measured ringing on the phase voltage. After achieving a decent match, EMC parameters such as coupling in a TEM cell and coupled voltage on a conical antenna were co-simulated. These simulations were then verified by lab measurements. Important aspects, pros and cons of co-simulation are also discussed --Abstract, page iv