A circuit model for mutual coupling analysis of a finite antenna array

Mutual coupling effects within an antenna array play a very important role in the areas of EMC (electromagnetic compatibility) and antenna array design. A circuit model is developed to represent the input admittance of an antenna array with a finite number of elements. This model consists of a component to represent the input admittance of an isolated antenna element and infinite shunt components with each to represent different degrees of antenna mutual coupling effects. Twersky's (1952) algorithm of multiple scattering analysis is used to illustrate the physical meaning of each circuit component. Numerical results show that good accuracy for the antenna input admittance calculation can be obtained by using this model to the second order approximation. As the array is large and sparse, a very small amount of computation can yield good accuracy. This model is shown not only to be numerically efficient compared to the full wave analysis using the moment method, but also to give a physical insight into the antenna array mutual coupling mechanism. Furthermore, this model has no limitation on antenna array geometry and excitation.