Double tuned single coil sampling head for NMR measurements - allows transmission line to be shortened if capacitors are includes in lower end of inner conductor

摘要

The RF sample coil is tuned by circuit elements to operate with a high freq. input and over a wide range lower freq. input to permit double resonance experiments. A transmission line on the high freq. side of the coil is open circuit at the far end and has a length, for example lambda/2, which is a multiple of 1/4 of the high freq. wavelength so that it does not affect the input. At the upper end of the low freq. range the line acts capacitatively. At the midpoint of the lambda/2 line is a jumper with interruptor. When the latter is closed the line acts inductively and enables the lwer end of the low freq. range to be used. The line is physically shortened if capacitors are included in the lower end of the inner conductor, and the input is coupling loop acting at the centre of the line 42. ADVNATAGAE - Broad freq. range.