On the number of degrees of freedom used by an adaptive antenna array in a non-narrowband noise environment

The relative measures of the eigenvalues of the noise covariance matrix of an adaptive array which is subjected to a non-narrowband jamming source are investigated. These measures are important because they determine the convergence rate and the upper limit of the output signal-to-noise ratio of the adaptive array. It is found that the adaptive array's performance as measured by the output signal-to-noise ratio degrades in quantum jumps as the input noise bandwidth increases. A methodology is developed whereby given the number of elements of the array, the array spacing, the array element antenna pattern, the power, and direction of arrival of an external jammer, these discrete bandwidths of the jammer that limit the output signal-to-noise ratio can be calculated.