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Simple formulas and graphs are given which represent the ground-wave field intensity at the surface of the earth as radiated from a short vertical antenna at the surface of the earth. The theory is compared to some experimental results reported by other investigators to determine its range of application. The diffraction formula given is theoretically valid only at the lower frequencies; however, it was shown that sky waves are important both day and night and over land and sea at those distances where diffraction would otherwise cause a marked decrease in the received field intensity. The attenuation formula given for the short distances where diffraction may be nelgected is theoretically valid for any frequency and set of ground constants; experimental data are given which show that the formula may be used even at the ultra-high frequencies.