Abstract: A communication system suitable for use at a broad range of radio frequencies utilizes a parametric magnetic dipole antenna. This antenna incudes an elongated core, favorably formed of a hexagonal bundle of ferrite rods, each composed of a stack of apertured ferrite cups, with the apertures defining axial bores extending through the respective rods. A helical antenna winding of n turns extends around a central part of the bundle of rods, and a control winding extends through the axial bores to carry a control current, which generates a magnetic field generally orthogonal to that of the helical antenna winding. The phase of the control current is locked to that of the frequency to which the antenna winding is tuned.