Summary
Spatial beamforming using distributed arrays of RF sensors is treated. Unlike the observations from traditional RF antenna arrays, the distributed array's data can be subjected to widely varying time and frequency shifts among sensors and signals. These shifts require compensation upon reception in order to perform spatial filtering. To perform beamforming with a distributed array, the complex-valued observations from the sensors are shifted in time and frequency, weighted, and summed to form a beamformer output that is designed to mitigate interference and enhance signal energy. The appropriate time-frequency shifts required for good beamforming are studied here using several different methodologies.