Transmitting aerials for v.h.f. broadcasting usually consists of a number of similar groups or tiers of radiating elements, spaced at intervals along a supporting mast. The power gain of such an arrangement depends on the number of tiers, on the spacing between them, and also on the vertical radiation pattern of each individual tier. A method of calculating the gain is described in this report. Results computed for a comprehensive range of variables are presented in the form of tables.