The spreading of electromagnetic waves from a Hertzian dipole

The previous experimental work on the spreading of a wave from a Hertzian dipole is discussed and is shown to be incomplete. An experimental investigation of the variation of the electric and magnetic fields with distance, in a wave from a source which approximates to a Hertzian dipole, is described. A long wavelength (1000 m) is used, and the results agree with theory up to distances of 0.01¿. The field re-radiated from a receiving aerial is investigated, using long waves, and is found to be in accordance with the ordinary theory. Finally it is shown, experimentally, that the field due to an aerial with its lower end connected to earth is, at a nearby point on the earth´s surface, equal to twice the field which the aerial alone would give in free space. The theoretical significance of this fact is discussed.