Aerial characteristics

The paper covers vertical aerials and is divided into an Introduction and six other sections. In Section (2), low aerials are considered in relation to approximate formulae for radiation resistance and for terminal reactance, whilst the importance of the earth system is also examined. In Section (3), van der Pol´s analysis for the radiation resistance (Rr) of vertical aerials, of all heights, is discussed, and various curves are given for Rr values likely to be met with in practice. The effect of retardation of current is dealt with briefly, and curves for modified Rr values are given. Vertical polar diagrams are next considered, in Section (4), while in Section (6) the knowledge thus gained is applied to determine the optimum height of anti-fading aerials. Technical details of anti-fading aerial design are discussed. Section (5) deals with feed current, and to a great extent bridges Sections (4) and (6). In Section (7), terminal values are considered, while two groups of curves are given for computing terminal resistance and terminal reactance. Appendix 1 outlines the calculation of field strength and of radiation resistance. Appendix 2 is a discussion of the distribution of current along an aerial, and gives a résumé of Dr. Bohm´s analysis for feed current. Appendix 3 contains particulars of two new aerials, and gives notes relative to an observed variation of measurements.