A full wave technique has been developed to calculate the field intensities both in the upper ionosphere and on the ground when a dipole source immersed in the lower ionosphere radiates ELF/VLF waves. The radiated wave is divided into a large number of elementary plane waves, for each of which the propagation in the horizontally stratified model consisting of the ionosphere, the free space and the ground is calculated by the full wave technique. Then the plane waves are summed up to give a horizontal distribution of the radiated wave intensities at any altitudes. This technique is applied to investigate the propagation characteristics of radiation from a polar electrojet (PEJ) antenna modulated at an ELF/VLF frequency, which was created by the Troms¿ heating facility. Comparison between the results of experiments and the calculation is given in the companion paper <Kimura et al., this issue>. We discuss several propagation characteristics, such as the frequency dependence of the radiated wave propagation up to the upper ionosphere and down to the ground. Under the conditions that the frequency is 2.5 kHz and the ionospheric dc electric field is 5 mV/m, the calculated results are roughly consistent with the experimental results and the radiation efficiency of the PEJ antenna is found to be extremely small, 2.5¿10-6 upward and 3¿10-8 downward.