MUTUAL COUPLING STUDY

Abstract

Abstract : The report gives the complete derivation (in an appendix) of the radiation admittance of a rectangular waveguide acting as an element in an infinite phased array. The derived equations are capable of predicting the experimentally observed anomalous notch that has been found to exist in arrays composed of large waveguides. The defining equations demonstrate that it is the existence of nonpropagating higher order modes inside the element waveguides that determine the behavior of an infinite array. It was the purpose of this study to determine what waveguide modes were important for a reasonably confident prediction of the radiation admittance of a rectangular waveguide in an array. It is shown that the number of modes needed for this is not excessively great, but that more are needed if it is desired to predict the position of an anomalous notch with any great degree of confidence.