Adaptive Processing at Multiple Frequencies Using the Same Antenna Array Consisting of Dissimilar Nonuniformly Spaced Elements Over an Imperfectly Conducting Ground

In this communication, an adaptive processing is carried out simultaneously at multiple frequencies using the same antenna array consisting of nonuniformly spaced dissimilar antenna elements. The antenna array may not be deployed in free space but may be located over an imperfect ground plane. First, to correct the various electromagnetic effects affecting the array performance, an electromagnetic transformation technique is described that can compensate for the various coupling effects in the nonplanar array consisting of nonuniformly spaced dissimilar antenna elements operating over an imperfect ground. Then, a direct data domain least-squares method is used to extract the signal of interest in the presence of fluctuating jammer and clutter simultaneously at multiple frequencies, using a single snap shot of the data. In this procedure, there is no need to have any information about noise or clutter, whatsoever.