The radiation patterns have been measured for five dielectric rods of circular cross section which were excited in theTM0,1mode. These rods were each 0.870&lgr;0in diameter, and the lengths were 2&lgr;0, 4&lgr;0, 6&lgr;0, 8&lgr;0, and 10&lgr;0. The theoretical radiation patterns have been computed by means of equivalent surface electric and magnetic currents. Excellent agreement is obtained when it is assumed that the diameter of the surface on which these currents are distributed is 0.65 of the diameter of the dielectric rod. Representative experimental and theoretical patterns are shown for the full 360°.