Electrical properties of aerials for medium and long wave broadcasting

The first part of the paper is theoretical and deals mainly with the treatment of an aerial as a dissipative transmission line and the statement of formulaelig whereby the radiation and driving impedance of an aerial can be estimated. Attention is paid to anti-fading aerials of the mast and loaded top types. In the case of mast aerials the problems of the current distribution and vertical radiation polar diagram are analysed in detail. An approximate method is given for the derivation of these properties on the basis that the actual current can be replaced by a wattless component as assumed on the conventional theory of sinusoidal distribution, together with an energising current in time quadrature with the wattless current. The second part is devoted to the citation of measured values of current distribution, impedance, etc., from various sources on both real and model aerials and to the discussion of the light thrown by these measurements on the applicability of the general method of treatment described.