Abstract: An electromagnetic field is produced by an oscillating magnetic frill that is generated at a slot gap in a resonating toroidal cavity. The magnetic frill's generating structure is physically small in relationship to its operating wavelength. Due to its small size relationship, the structure would be classified as a small antenna. The internal placement of inductance or capacitance allows the ability to raise or lower the resonant frequency of the structure. The structure's function can be changed by moving the placement of the frill generating gap. The structure can be made to radiate, partially radiate or completely nonradiate. The invention can function for example as a small antenna, a nonradiating probe or coil, or a resonant transformer.