TABLE OF CONTENTS Although a detailed consideration of array mutual coupling is beyond the scope of this book, this chapter introduces the subject by presenting and describing simple examples of the analysis, coupled with a number of figures that show the current state of research in this important area.
Throughout this text, the equations for pattern analysis and synthesis are given for arrays of radiators with known currents or aperture fields. Implicit in that formulation are three assumptions: that the current or fields are porportional to applied excitations, that the distribution of current or aperture field is the same for each radiator, and that the distribution does not change as the array is scanned. A primary challenge to modern array theory is that, in general, none of these statements is true. In a finite array, all of the currents and fields differ from element to element in magnitude, phase, and distribution, and these differences vary as a function of frequency and array scan angle. This complex dependence on geometry, frequency, and scan angle results from the mutual interaction among all of the elements of the array. The full analysis of antennas and arrays, including element coupling, is now discussed in a number of texts [1] [3] and available in many commercial microwave analysis programs, including variations of the numerical electromagnetics code (NEC) [4]. Integral and integrodifferential equation formulations have been used for many years for antennas structures and boundary conditions for which Green's functions could be...
