Wideband Multi-Channel AESA Manifolds

Multi-channel array manifolds are required for wideband AESA applications. In modern solid-state AESA arrays, MMIC-based T/R modules generally utilize digitally-controlled phased shifters to steer the beam on transmit and receive. The given phase value is only accurate at one frequency, and so for wide bandwidths of several hundred MHz (at X-band for example), the beam does not get formed properly and significant dispersion is encountered, particularly at wide scan angles. This may be avoided by using multiple frequency-overlapped pulses, where the MMIC phase shifters are adjusted for the different frequency pulses, and combined digitally. Alternately, time-delay compensation may be used in a multi-beam system such as a Rotman lens or a Blass matrix. Monopulse sum/difference processing may also be replaced with multi-beam processing in this case. Such a beamforming network may be readily implemented in stripline circuitry, and Applied Radar has both the design tools and experience to implement such a design. Applied Radar recently implemented a 3x8 Blass matrix at X-band, which may be used as the basis for this design. Combining the beamformer manifold outputs into a switch matrix fed to three parallel receivers is also readily accomplished. Applied Radar proposes to design the multi-channel wideband AESA manifold in Phase I, and build and test a prototype in Phase II.