Inductance of a coil in a slotted shield

The inductance of a coil in a slotted, conducting shell is investigated. At frequencies for which the coil is very small relative to wavelength, an integral equation is formulated and numerically solved for the electric field induced in the slots. From knowledge of the slot electric field, the inductance of the coil in the slotted shell can be calculated. The dependence of inductance on the presence of the slotted shell is assessed quantitatively and explained on the basis of physical principles. The inductance of a one-turn loop inside a slotted shell is measured, and the data are found to be in excellent agreement with computations. As an unslotted shield closes on a coil, inductance is reduced noticeably, but if the shield possesses axial slots, the reduction is much less significant.