Selecting Characteristic Modes in Multi-Mode Direction Finding Antenna Design by Using Reconstructed Incident Fields

The performance of a multi-mode direction finding antenna depends on the selection of the utilized characteristic modes. A numerically efficient way to determine the correlation of the incident fields reconstructed from these characteristic modes is introduced. These correlations are evaluated for several directions of arrival (DoAs) and assembled in a correlation matrix. This procedure is repeated for different combinations of characteristic modes and the Frobenius norm of the correlation matrices is used to determine the combination of modes best suited for a defined direction finding application. An example setup as well as computational results are provided and it is shown that the proposed method provides insight into the physical behavior of the direction finding setup.