Affordable Naval Surveillance Radar Concept

Current planned large surveillance radars for shipboard applications employing active aperture technologies are projected to be very expensive. The current planned radars for smaller ships, although less expensive, are limited in performance. This paper provides a new innovative naval surveillance radar architecture that promises to provide naval surveillance radars with high performance at lower cost. The radar uses a fairly inexpensive line array antenna for transmitting a broad beam and fairly inexpensive planar phased array antenna having digital beamforming in one dimension to form many narrow receive beams. The innovation is to rotate the antennas about 45 degrees on the ship relative to the local horizon so that the multipath and antenna sidelobes for most clutter and targets are minimized. For a mechanically rotating array, a transmitter can be located below deck and the transmission signal can be transferred through a passive rotary joint and passive line array antenna thus providing a simple low cost transmission system. On receive, the receive only phased array antenna can be fairly low cost and digital beamforming of multiple beams along the fan transmit beam can easily be accomplished. For non rotating radars, high power phase shifters would need to be employed in the transmit line array antenna to scan the beam.