Summary form only given, as follows. The authors considered a fundamental power conservation relation, full wave solutions for fields, and power absorption in moderate- and high-density tokamaks to third order in the gyroradius expansion. The power absorption, conductivity tensor, and kinetic flux associated with the conservation relation as well as the wave differential equation were obtained. Cases examined included D-T and D-3He scenarios for JET and CIT at the fundamental and second harmonic. Optimum single-pass absorption cases for D-T operation in JET and CIT were considered as a function of the <e1>k</e1>|| spectrum and of the antenna width, and without a minority 3He resonance. Fast wave low- or high-field incidence or high-field ion Bernstein wave incidence was considered. The effects of a 10-keV bulk and 100-keV tall helium distribution on the second-harmonic absorption in a deuterium plasma for JET parameters were studied. For high-field operation at high density in CIT. it was found that a higher part of the <e1>k</e1>|| spectrum yields good single-pass absorption with a 5% minority helium concentration in D-T