REACTIVE ENERGY IN APERTURE FIELDS AND APERTURE Q

Abstract

An analysis of the properties of a radiating aperture in an infinite conducting screen is made by expanding the field in terms of plane waves. Expressions for the far zone field, power flow, and energy stored in the reactive electric and magnetic fields are obtained. This enables the Q of the aperture to be evaluated. A theorem on the frequency sensitivity of the aperture susceptance (the rate of change of susceptance with frequency is proportional to the total energy stored in the reactive field) is proved. Finally a method of optimizing the aperture field to obtain, for example, maximum gain and minimum Q is developed. The method is based on an application of the sampling theorem and reduces the optimization problem to one of optimizing a polynomial function.