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Abstract #2742

Closed-Loop Control for Transmit Array Matching

Giorgos Katsikatsos1, Klaas P. Pruessmann1

1Institute for Biomedical Engineering, Zurich, ZH, Switzerland

A closed-loop controlled matching for Tx-arrays in ultra-high field has been implemented as an autonomous system to react to load changes in various stages of an MR experiment. Building blocks of the system are the L-matching networks, built from custom low-loss capacitors actuated by piezoelectric motors and controlled by an external computer. The feedback is provided by a network analyzer which triggers the re-matching procedure. The matching algorithm is based on previous knowledge about the matching circuit connected to the array and uses common objective functions to detect the best matching settings for arbitrary loads.

Keywords

able accomplished account accurate achieve actuated acute aforementioned allow among analyzer arbitrarily array arrays assumption automated automatic autonomous biomedical bottom built cable calculation calling capacitor capacitors channel characterization characterize closed coil collecting combinations combined communicate condition conditions connection connections connectors consists constant constitute control controlled copper coupled criteria critically custom dependent dielectric dimensions dissipation done electric electrically electronically element encountered epoxy evolves exhaustive feedback field final finally find fixated fully function great heuristic independently inductive initial input institute introducing investigation iterative jump keeping keeps load logs lookup loop loss made manipulation match matched matching matrices matrix mechanical memory minimize minimizes moreover motor motors moved network networks objective operates optimization optimum part parts piezoelectric plates port position positions power procedure react reflective reproducible rest returned returns search serial series shape solutions stability stages step steps subject substrate successfully system table taken taking termination threshold transmission transmit tuning variable various walls whole withstand