An S-band digital array radar testbed

Future naval radars will perform a combination of functions including volume search, track, and high resolution imaging. These radars, which must operate in littoral regions (i.e., near coastlines), will need to contend with strong clutter and jamming. As such, digital phased array technology, wherein transmit and receive signals are digitized at (or near) the antenna element, can offer significant advantages. However, it appears that digitizing a large wideband microwave phased array has never before been attempted. Directly fielding such a system would come with some perceived risks; many of these risks can be mitigated through the development of a small scale testbed. Recently, MIT Lincoln Laboratory funded the development of a wideband digital array radar testbed. The system consists of a 14' reconfigurable digital linear array aperture, 500+MHz imaging bandwidth, 90+dB dynamic range, and element-level digital recording. The initial system configuration uses direct digital waveform synthesis, analog signal distribution, and stretch processing at the receivers. Digital downconversion, time-delay beamsteering, and space-time adaptive processing (STAP) are performed by an offline processor. This paper provides an overview of the testbed's design and construction. Initial test results are also presented.