The Shielding of Radio-Frequency Ammeters

Radio-frequency current-measuring instruments, when operated at a point in a circuit at high radio-frequency potential with respect to ground or to other near-by low-potential objects, have introduced therein another type of error, that is, one additional to other basic or inherent errors. The error introduced by high-potential operation can be materially reduced by shielding the instrument. A design of shield for an instrument is described herein which has proved highly practicable for use in measuring radio-frequency currents at high-potential points in a circuit with less error than is present in an unshielded instrument.