Time delay digital beamforming for wideband pulsed radar implementation

Radar system has been using a hybrid of analog and digital beamforming. Sub-arrays of phase shifters in the analog domain are digitized at the sub-array outputs for further digital beamforming processing. Such system suffers from limited bandwidth and is unable to create more than one simultaneous beam. Digital time delay beamforming brings many benefits such as wide bandwidth pulse waveform and simultaneous beams at different angles, wave forms and frequencies. Such capabilities may have been deemed too expensive in the past, but is now within reach due to the high density of multipliers in the FPGA and introduction of transceiver based ADC (Analog to Digital Converter)/ DAC (Digital to Analog Converter). This paper will present the design and implementation of a fractional delay (FD) filter used in time delay beamforming with Altera FPGAs and tools. Other beamforming issues like wide bandwidth, adaptive beamforming and high density interconnect architectures for phased arrays will also be investigated.