Dynamic Receive-Path Tuning After a Passive T/R Switch for 47 mT MRI

Conceptual Design and Experimental Validation of an Automatic Tuning Concept for the RF Path of an Anatomical Low-Field MRI System This record contains the hardware design files of the electronically adjustable tuning and matching network prototype, the Python tool used to calculate its Smith chart coverage, and the measured data reported in Chapter 4 (Experimental Validation). Files Zenodo does not allow nested folders, so the KiCad project and the data are each packaged as a zip archive. Unpack the KiCad archive into any folder and open PCB-TM.kicad_pro with KiCad. PCB-TM-KiCad-Project.zip : Complete KiCad 10 project of the prototype PCB: project file, schematic, board layout, project-local symbol library, footprint library and 3D models. The library tables use project-relative paths, so the project is self-contained. PCB-TM-Gerber-Drill.zip : Manufacturing output exported from the board: Gerber files for all copper, mask, paste, silkscreen and edge-cut layers, Excellon drill files (PTH and NPTH) and the Gerber job file. SmithSimulationTopologyRange.py : TopologyRange Calculator Tool, a small Tkinter GUI that calculates the Smith chart coverage of a secondary tuning and matching network. Measured-Data.zip : Measured data from Chapter 4 of the: four CSV files with the tabulated and transcribed measurement values and thirteen PNG figure images (see below). SHA256SUMS.txt : SHA-256 checksums of all files in this record. README.md : Description of the record. Measured data Measured-Data.zip contains: table_4-1_coil_equivalent_circuit.csv : Table 4.1, curve-fitting results of the VNA measurements of the Tx/Rx coil (series inductance, series resistance, parallel capacitance and resulting coil impedance) for the unloaded and loaded coil, inside and outside the bore. table_4-2_noise_signal_level.csv : Table 4.2, RMS noise level and signal amplitude of the MRI sequences for the four evaluated tuning and matching cases. vna_marker_readouts.csv : Marker readouts transcribed from the VNA screenshots in Figures 4.1 to 4.6: reflection coefficient in dB and Smith chart impedances at the Larmor frequency and at the drift offsets. scalar_measurements.csv : All further single-value measurements, instrument settings and the quantities derived from them in Chapter 4 (bandwidths, quality factors, oscilloscope voltages, voltage magnification, noise baseline). fig_4-*.png : The original measurement screenshots and MRI images from Chapter 4 at their embedded resolution: Figures 4.1, 4.2 a/b, 4.3 a/b, 4.4 a/b, 4.5, 4.6, 4.8 a/b and 4.9 a/b. All measurements were made at a Larmor frequency of 2 MHz. VNA measurements used a Keysight E5061B with a center frequency of 2 MHz, a span of 1 MHz and an IF bandwidth of 30 kHz. The loaded coil used the OSI2 Hello World phantom filled with aqueous CuSO 4 . The trace_status column in the marker readouts gives the instrument status shown on screen (Cor: calibrated, C?: calibration questionable, D&M: data and memory trace). The kind column in the scalar measurements distinguishes values read from an instrument (measured), instrument settings (setting, instrument) and values computes from measurements (derived). TopologyRange Calculator Tool The tool computes which points of the Smith chart can be tuned and matched with an adjustable series branch and an adjustable shunt branch, for both network topologies (series at the coax port with shunt at the LNA port, and vice versa), and plots the individual and combined coverage. Inputs: operating frequency, reference impedance Z 0 , optional lambda/4 line dimensions, component value ranges for the series and shunt branch, and an |S11| tolerance for the acceptable matching region. Requirements: Python 3 with tkinter, numpy, matplotlib and scikit-rf. pip install numpy matplotlib scikit-rf python SmithSimulationTopologyRange.py Verifying the download shasum -a 256 -c SHA256SUMS.txt