Holographic Processing Of Wideband Antenna Data

To utilize the real-time two-dimensional coherent imaging devices for antenna data processing, the properties of a raster-scanned wideband signal are studied. To extend the processed bandwidth-duration product widely over the recording capability of a single line on the imaging device, the time signal is displayed on several lines of the raster. The time-Doppler ambiguity function of the resulting 2-D signal is defined, leading to the possibility of two-dimensional processing. For a 2-D or 3-D phased-array antenna with any geometry, the received signals from each channel can be raster scanned and spatially multiplexed in the full aperture of the imaging device, enabling the performance of the array-pattern synthesis in every direction simultaneously, with the theoretical directivity of the antenna. Holographic filters are designed to perform either the matched filtering of a rastered signal with many Doppler replicas, or the array-pattern synthesis, or these two operations simultaneously (complete processing) with a single hologram. The complete processing is demonstrated experimentally for the case of a sonar-Doppler circular-array antenna, with correlation detection and extraction of the three target parameters' range, Doppler, direction.