Split aperture array for increased short range target coverage

A phased array radar system having a plurality of radiating elements configured in a common array aperture of m×n elements, said system comprising:

• a controller for configuring a first subset of said elements of said common array aperture into a first sub-aperture for providing a first interrogating beam;
• and a second subset of said elements of said common array aperture distinct from said first subset, into a second sub-aperture for providing a second interrogating beam;
• a pair of transmitters, each one coupled to a corresponding one of said first and second sub-arrays and responsive to said controller in a first mode for simultaneously generating said first and second interrogating beams, said beams being independently steerable;
• a pair of receiver beamformers, each one coupled to a corresponding one of said first and second sub-arrays for providing beamformed output data indicative of target reflections from each of said first and second interrogating beams;
• a signal processor arrangement responsive to said beamformed output data for determining target detection and tracking according to each said sub-array;
• wherein said controller is operable for providing in said first mode a signal waveform to said pair of transmitters differing in at least one of frequency, phase, and pointing direction to generate said first and second interrogating beams;
• and
• wherein said controller is operable for providing in a second mode a signal waveform to said pair of transmitters of the same frequency, phase, and beam pointing direction such that the interrogating beams are coherently combined into a single narrowband beam output from said subarrays and corresponding to the full array aperture.

In a phased array radar system having a plurality of radiating elements configured in a common array aperture of m×n elements, a method for detecting and tracking targets comprising;

• electronically separating said common array aperture of m×n elements into a first sub-aperture comprising a first subset of said m×n elements defining a first sub-array, and a second sub-aperture comprising a second subset of said m×n elements distinct from said first subset defining a second sub-array;
• in a first mode, generating a first interrogating beam of a first frequency from said first sub-array and a second interrogating beam of a second frequency from said second sub-array, said first and second interrogating beams differing in at least one of frequency, phase, and beam pointing direction;
• independently steering said first and second interrogating beams;
• receiving beamformed data from each of said first and second sub-apertures corresponding to said interrogating beams, and independently processing said beamformed data to provide target information for each of said first and second sub-apertures;
• in a second mode, coherently operating said first and second sub-arrays to generate a narrowband interrogating beam of a given frequency corresponding to the full common array aperture;
• receiving beamformed data from each of said first and second sub-apertures corresponding to said narrowband interrogating beam, and combining said beamformed data to provide target information indicative of the full common array aperture.