A plasma lamp for an electrodeless plasma lamp having a compact dielectric waveguide body. Example embodiments may use a shaped body to allow operation at a lower frequency (or at the same frequency with a body of smaller volume) than a solid cylindrical or rectangular waveguide body having the same...http://www.google.com/patents/US7701143?utm_source=gb-gplus-sharePatent US7701143 - Plasma lamp with compact waveguide
