Equivalence of adaptive array diagonal loading and omnidirectional jamming

Diagonal loading, where a diagonal matrix is added to the estimate of the covariance matrix, is often used in adaptive arrays to minimize the array´s responsiveness to random fluctuations in the estimate of the interference environment. Poor estimates of the covariance matrix often result in high random sidelobes in the sample matrix inversion (SMI) adapted pattern. It is shown in this communication that an omnidirectional spread of uniform jammers arriving at a linear array of half-wavelength spaced elements with cosine element patterns also produces a diagonal matrix. This equivalence of form is useful in visualizing the effects of diagonal loading and understanding the resulting patterns