Spread Spectrum Digital Beamforming (SSDBF) radar

Spread Spectrum Digital Beamforming (SSDBF) overcomes the CSWAP and the scalability in bandwidth-and-frequency limitations of Conventional Digital Beam Forming (CDBF) by eliminating the requirement of “one digital transceiver per element” while enabling fully capable digital beamforming with minimum hardware (and consequently minimum volume and heat dissipation) per element. SSDBF enables low-cost/low-profile/low-power digital beam forming phased arrays that scales in frequency (L through Ka and higher), bandwidth (100's MHz) and subarray size (100's elements per subarray) with a single down-converter, single digital receiver and single Nyquist-rate ADC for the entire subarray. It achieves this by replacing the MMIC T/R module at each element with much simpler bi-phase re-modulating hardware, and by re-modulating and aggregating the return signal incident at each element such that it can perfectly recover the complex baseband-equivalent of the RF signal of each element without mutual interference and with negligible noise performance degradation. The bi-phase re-modulator at each element can be extremely small and low power and amenable to implementations as simple as a single RF switch mounted directly at the antenna element with associated ON/OFF switch control logic built on the back. Thus SSDBF truly enables flat, thin, lightweight conformal phased arrays and has the potential of reducing phased array costs by, possibly, multiple orders of magnitude relative to CDBF state-of-the-art. The SSDBF parameters and waveforms are flexible, programmable and can be tailored and adapted, practically, to support any radar or communications applications. In a project for DARPA1, Applied Radar is developing an X-band SSDBF-based radar prototype in which the SSDBF features and performance have been demonstrated. In this paper, we describe the SSDBF method for a radar application including simulation, indoor testbed and open-range test results.