Gate array beamformer for high frequency annular arrays

A beamformer for a high frequency (50 MHz) annular array is described. The beamformer is based on a variable frequency sampling technique and is implemented using two field programmable gate arrays. The gate arrays generate the variable frequency signals used to control the analog-to-digital conversion on each channel and also sum the digitized signals. A delay accuracy of greater than λ/22 was achieved by fine-tuning each delay path.