42: Coil: 3T coil bench testing
Changing the capacitor value on the coil with switches SW1 and SW2 off can change the resonance frequency. Here we use the double probe to measure S12.
Turning on switches SW1 and SW2 connects the coil with the pre-amplifier via the impedance matching network. A characteristic "M" shape waveform will be shown in the S21 plot when the coil is matched to the low input-impedance pre-amplifier.
Appropriate overlapping between the neighboring coils is the most common approach to reduce the mutual inductance of neighboaring coils. In this demo, we first turned off SW1 and SW2. Then the distance between two coils was adjusted until the S21 plot shows a nice peak.
