Preliminary to a solution of the problem of horizontally polarized log periodic aerial arrays above ground, various types of log periodic aerials are analysed. Numerical design data for the former problem are displayed in charts which should reduce trial-and-error beam scanning designs to a minimum. The single mast sloping dipole log periodic aerial is given particular attention. Computer programmes and approximate formulae are developed for both free-space and above-ground designs. The far field of these aerials is shown to be predictable from near field data. Experimental investigations, although limited in scope, confirm most of the developed theory at least qualitatively. Suggestions for further investigations are included.