The Necessary Number of Elements in a Directional Ring Aerial

An investigation is made concerning the dependence of the array characteristic of a directional ring aerial on its number of elements. It is shown that an odd number of elements is more favorable than an even number in approximating the array characteristic of a similar ring aerial with infinitely many elements. It was previously shown by Page that a similar statement applies to an azimuthly omnidirectional, fading-reducing, concentric ring aerial; this result is contained as a special case in this investigation. The present paper deals especially with the case in which the principal direction of the antenna array is horizontal; the theory for this case is illustrated by a numerical example. Journal of Applied Physics is copyrighted by The American Institute of Physics.