In this paper the scanning properties of dual reflector antenna systems constituted by two confocal paraboloidal reflectors fed by a planar array are investigated. This antenna architecture combines the interesting features of reflectors and array antennas. Because of the offset configuration the radiation pattern exhibits an anomalous deviation in the beam pointing when the beam is scanned out of the boresight direction. Heuristic equations, representing an extension of the linear equations available in the literature, are derived, which permit predicting the pointing direction of the overall system as a function of the pointing direction of the feeding array in a significant field of view.
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