Sea Technology

NOV 2013

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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Page 13 of 75

tailed model, circuit-system structure and read out, and RF components, is essential. However, state-of-the-art electromagnetic simulation technologies still have several critical gaps to be flled. In general, to perform an accurate simulation of a detailed model, the real challenge resides in its multiscale characteristics. Namely, the size of the simulated components varies from micrometers to meters. The simulation has to be able to handle thousands of small (from micrometers and centimeters) elements, such as the radiating unit of phased-array antennas, thin wires and circuit elements interacting with each other on large-meter platforms like the supporting frames and metal covers of a battleship. The ability to perform full-wave electromagnetic simulation with complex nonlinear circuit systems is not mature. Most of the available commercial software tools can only support simple linear circuits (resistor, inductor and capacitor). Transistors, diodes and other nonlinear circuit elements, which exist in nearly all weapon-electronic subsystems, cannot be fully supported in a full-wave environment. In addition, conventional hybrid feldcircuit simulation treats the 3D RF components as a black box and uses a synthesis matrix to describe the 3D interactions between circuits. Such a solution is still based on a circuit-simulation engine, which can only provide signal-integrity parameters, such as eye diagram or input impedance. Problems, such as radiation and electromagnetic compatibility/electromagnetic interference (EMC/EMI) that involve 3D parameters, such as 3D electromagnetic felds, surface currents and radar cross section (RCS) impacted by circuits, cannot be investigated with a circuitbased simulation. This brings a severe bottleneck in connecting advanced full-wave electromagnetic simulators with matured circuit-system simulators. Research has been conducted to address such kinds of problems in academia, but the CAE industry has not fully transferred and embedded the technologies into engineering simulation software solutions. (Top) Hybridizing SETD, FDTD and FETD solvers. (Bottom) Results of a system-level simulation with SQIF. use low-frequency communications in a limited space. The application of a SQIF B-feld receiver will improve the warfghter's situational awareness. A design tool has been developed by WCT called Wavenology EM for advanced nonlinear circuit modeling techniques of large-scale SQIF/ SQUID arrays. A cosimulation capability of SQIF/SQUID and conventional microwave devices, such as electric-feld antennas in a 3D electromagnetic-feld simulator, is also introduced through this effort. Concept of Multiscale and Hybrid Simulation To investigate the global performance of a SQIF sensor when integrated into the existing platform, a system-level electromagnetic simulation, which contains a highly de14 st / November 2013 Attention to Detail The platform has an obvious multiscale nature. Capturing details such as sharp corners, edges, joints, mounting bolts, rivets and all other fne features of a battleship challenge the simulator. Arguments were made that such fne features can be ignored, while it is actually very problem dependent. For conventional scattering problems where systems are assumed to be linear, fne and small features may have negligible contributions to the global solution, whereas for EMC/EMI problems the system is much more complicated. Lots of nonlinear components are embedded within the system, and chaotic interference might occur due to its nonlinear nature. Consequently, features with small dimensions do not necessarily mean small contributions to a system response. They have to be considered with full detail during the process of system-level simulation. This eventually creates the challenge of handling multiscale problems. Traditional electromagnetic simulation techniques focus on using a single method to simulate the electromagnetic

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