RF direction finding with a reduced number of receivers by sequential sampling

Because of the high receiver costs superresolution methods applied to array antennas with a smaller number of receivers than antenna elements are very attractive. Thus, in this paper the Capon and MUSIC methods are modified to apply them to array antennas with a restricted number of receiver channels. In comparison to the MUSIC or Capon method of an array antenna with the same number of antenna elements as receivers, the proposed configuration conserves the resolution given by the aperture without yielding grating lobes. With a restricted number of receivers the necessary number of time samples to estimate the covariance matrix with respect to the S-MUSIC or S-Capon spectra does not correspond to the number of antenna elements but to the number of receivers. A limitation of the proposed methods is given by the stationarity constraint of the received signals during the total sampling period.