Abstract :
In an earlier paper¿ the author described a graphical method for determining the magnitude and phase of the electric field in the neighbourhood of an aerial carrying a current of known distribution. The major portion of that paper neglected the effect of the earth, although an indication was given of a method for taking account of the image of the aerial in the earth. The first part of the present paper elaborates this explanation and shows how the results given in the earlier paper may be modified in order to take account of the electrical constants of the earth´s surface. A formula is deduced for the field at any point near the earth´s surface due to a given doublet, and it is shown how this formula may be extended in order to determine the field at various distances from an aerial carrying a current of known distribution. The second part of the paper shows how the field at any distant point may be found directly for any number of equal aerials and reflectors from a knowledge of the field at the same point due to one aerial and reflector alone. The current in the reflector wire need not be equal in magnitude or in phase to that in the aerial, and the components of the array may be either vertical or horizontal.
