EASY FABRICATION OF A TUNABLE HIGH-PASS BIRDCAGE RESONATOR

A practical design for a high-pass birdcage resonator is presented. Pr ecision seamless telescoping tubes were used for easy tuning of resona nt frequency by adjusting the length of the coils. Three probes, of 4. 4, 5.0, and 25.0 cm in diameter, respectively, were constructed and te sted. An empirical formula is given that can be used to calculate the capacitance needed for a given frequency when the desired physical dim ension and the number of elements of the coil are specified. A simple three-step procedure is suggested for easy fabrication of resonators t hat are routinely tunable over tens of megahertz.