Using sources of opportunity to compensate for receiver mismatch in HF arrays

The spatial processing performance of adaptive sensor arrays is often limit ed by the nonidentical frequency responses of the receivers in the array ov er the passband of interest. Addressed here is the problem of estimating di gital compensation for mismatches between receiver passbands in high freque ncy (HF) antenna arrays using interference sources of opportunity. A mathem atical model of ionospherically-propagated multipath HF interference is use d to develop an adaptive algorithm which estimates the receiver frequency r esponse corrections for each receiver. The effectiveness of the proposed al gorithm is experimentally demonstrated and compared against 1) a commonly u sed least squares technique, and 2) a highly accurate calibration system us ing data collected by the receiving antenna array of the Jindalee over-the- horizon (OTH) radar near Alice Springs in central Australia.