Summary
Efficient digital phased array beams require a high resolution timing vector. The timing coefficients cause speed bottleneck in FPGA implementation of such systems in the HF frequency range. Distributed Arithmetic (DA) is a high speed multiplication technique used for implementation of digital filters and phased array beamforming. The DA is bit serial word parallel approach where throughput rate does not depend on filter length or data size. In this paper a DA method is employed for FPGA implementation of digital beamforming (DBF) for the TIGER radar. The radar requires a constant phasing vector to steer the beam over a specified region of the ionosphere. Sixteen digital beams are derived from the vector with beam resolution of approximately three degrees. The phasing weights can be employed either in the time domain or in the frequency domain. Comparison of phase delay and time delay methods is presented for broadband frequencies of the radar. Performance of the proposed DBF system is discussed using clock efficiency and beam resolution.