In various exemplary embodiments, an electrodeless plasma lamp includes a bulb configured to be coupled to a source of radio frequency (RF) power. The bulb contains a fill that forms a plasma when the RF power is coupled to the fill. An electrically-conductive convex shield is positioned proximate to the bulb with a convex surface of the shield being distal to the bulb. A resonant structure having a quarter wave resonant mode includes a lamp body having a dielectric material having a relative permittivity greater than 2 with an inner conductor and an outer conductor. The source of RF power is configured to provide RF power to the lamp body at about a resonant frequency for the resonant structure.