| Summary: | Approved for public release; distribution is unlimited. === A system that incorporates distributed digital subarrays working cooperatively as a single array can potentially increase the output signal-to-noise ratio and provide better spatial resolution compared with using the subarrays individually. However, collectively combining periodic widely separated subarrays results in unacceptable grating lobes, and these lobes cannot be suppressed using traditional windowing methods. In this research, we focus on distributed subarray antennas that are comprised of subarrays that can operate individually or collectively. We develop techniques for grating lobe suppression on both the transmitting and receiving sides of the distributed array system. Traditional solutions and new methods are examined in detail via numerical simulation to quantify the performance limitations when applied in combination. One contribution of this research is a hybrid approach that uses a combination of suppression techniques on both the transmitting and receiving sides. Another contribution is the development of new receiving processing methods to suppress grating lobes and improve the signal-to-clutter ratio and signal-to-interference ratio. A final contribution shows the relationship between thermal noise, array errors, and the grating lobe suppression effectiveness. The consideration of array errors addresses the issue of array calibration and synchronization, which are critical concerns when multiple arrays operate coherently.
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