A High Power Vector Network Analyzer for Testing MRI Transmit Hardware

Characterization of RF components is important to assure that components behave as expected under given conditions. Some of the most important conditions for testing are power tolerance and slew speed. With regards to RF power tolerance, an RF component may appear properly tuned at the low power levels applied by a standard vector network analyzer but may detune at the higher power levels for transmitting RF pulses for an MR scan. Isolating and debugging this issue can be di cult when the problem only occurs at high power. Using an MR scanner to debug can be impractical and expensive. Device speed plays an important role in beam steering which requires rapid phase changes. We report a system that can characterize one or two port RF components and systems at 1000W in microsecond intervals without need for an MR scanner and can characterize S-parameter behavior in microsecond intervals. To illustrate, we made measurements that show complete and partial failures of devices at high power as well as device slew speed.