Abstract: In an example embodiment, an electrodeless plasma lamp is provided which comprises a dielectric body having an effective dielectric constant greater than two. The dielectric body may have a surface with a first region coated with an electrically conductive material and a second region that is not coated with the electrically conductive material. A bulb is located proximate to the second region of the dielectric body and having an outer surface area and the second region may have an uncoated surface area that is less than about sixty percent (60%) of the outer surface area of the bulb. A power source is coupled to the dielectric body to provide radio frequency power to the dielectric body at a frequency that resonates at a fundamental mode in the dielectric body. The bulb contains a fill that forms a plasma when the radio frequency power is provided from the dielectric body through the second region.