A method and apparatus for tuning and matching extremely small sample
coils with very low inductance for use in magnetic resonance experiments
conducted at low frequencies. A circuit is disclosed that is appropriate
for performing measurements in fields where magnetic resonance is
beneficially utilized. The circuit has a microcoil, an adjustable tuning
capacitance, and added inductance in the form of a tuning inductor. The
microcoil is an electrical coil having an inductance of about 25
nanohenries (nH) or less. Because additional inductance is purposefully
added, the capacitance required for resonance and apparatus function is
proportionally and helpfully reduced. The apparatus and method permit the
resonant circuit and the magnet to be made extremely small, which is
crucial for new applications in portable magnetic resonance imaging, for
example.