A bone growth stimulator is provided. In one embodiment, the device has an elliptically shaped transducer coil. The coil provides increased therapeutic benefit to a wearer. An elliptically shaped housing supports and contains the coil. The housing includes a curvature when viewed in profile, such that a first surface of the housing is convex. The convex surface is adapted to be positioned against a wearer's lower back, to nest within the natural curvature thereof.