RF Sensor Considerations for Input Predistortion Correction of Transmit Arrays

Pascal Stang¹, Marta Zanchi¹, William Grissom¹, Adam Kerr¹, John Pauly¹, Greig Scott¹

Transmit arrays promise accelerated excitation, B1 shimming, and the potential for SAR and RF safety management. Yet good results demand high-fidelity RF playback in a challenging multi-channel environment. Parallel transmit RF systems must overcome a host of issues including mutual coupling, loading variations, RF amplifier non-linearity, ill-defined impedances, and memory effects. We have proposed Vector Iterative Predistortion and Cartesian Feedback as input predistortion methods to address PTx challenges. We now present our on-coil and in-line RF feedback sensors critical to these technologies, and discuss their relative capabilities in the context of PTx array control.