Electrostatic ion-cyclotron waves with spectral features below the ion gyrofrequency and spaced by small fractions of the ion gyrofrequency are reported, a result not possible for waves associated with the well-known current-driven electrostatic ion-cyclotron (CDEIC) instability. This is accomplished by producing a localized, transverse (to the magnetic field B z⁁) electric field E(x)x⁁ in a laboratory plasma to excite inhomogeneous energy-density driven (IEDD) waves and by exploiting the ky&ngr;E dependence of the IEDD mode frequency, where ky and &ngr;E are the components of the IEDD wavevector and plasma drift speed, respectively, along the E¿B direction. The IEDD frequency range is shown to reach down to one-third of the ion gyrofrequency, a range usually reserved for other types of waves, e.g., ion-acoustic waves. These results may be relevant to broadband ELF waves observed in the ionosphere. ¿ 1998 American Geophysical Union