Analysis of Finite Antenna Arrays Using the Characteristic Modes of Isolated Radiating Elements

This paper proposes an efficient method for analyzing the radiation, scattering, and port properties of finite antenna arrays based on the theory of characteristic modes. Using the characteristic modes of isolated radiating elements, we obtain the electrical properties of a finite antenna array, which is different from the traditional modal analysis method for the entire array. The modal excitation coefficients of radiating elements in an array environment are derived by considering the mutual coupling effect that is characterized from the perspective of modal coupling between different elements. The characteristic modes of isolated radiating elements are analyzed using the method of moments. The proposed method can handle the array problems with arbitrary spacing between elements and arbitrary excitation distributions. Since the characteristic currents are used as higher order basis functions and the periodicity of the arrays is considered, the computational efficiency could be significantly improved. Numerical experiments are provided to demonstrate the proposed method.