An electrosurgical device (10) operable to deliver microwave energy to cause targeted tissue ablation is provided. The electrosurgical device (10) comprises an antenna (26), a reflector (30), and a dielectric material (34) disposed therebetween. The selection of the dielectric material (30) and the relative positioning of the antenna (26) and the reflector (30) provide impedance matching between the antenna (26) and a transmission line (12) so as to minimize heating along the length of the device (10) during use.