Multi-beam RF aperture using multiplierless FFT approximation

• Published in: Electronics letters 2014-11, Vol.50 (24), p.1788-1790
• Main Authors: Suarez, D, Cintra, R. J, Bayer, F. M, Sengupta, A, Kulasekera, S, Madanayake, A
• Format: Article
• Language: English
• Subjects: Algorithms; antenna array patterns; Antenna arrays; Antennas and propagation; Approximation; approximation theory; Beamforming; Beams (radiation); CMOS integrated circuits; CMOS simulation; CMOS technology; complementary metal oxide semiconductor; Devices; fast Fourier transform; fast Fourier transforms; FFT based beamformer; field programmable gate array; Field programmable gate arrays; FPGA device; Mathematical analysis; microwave imaging; multibeam RF aperture; multiple independent radio frequency; multiplier complexity; multiplierless approximation; multiplierless FFT approximation; Multipliers; radar imaging; radio astronomy; radio networks; receiver antenna array; RF beamforming; RF beams; RF multibeam receivers
• ISSN: 0013-5194; 1350-911X; 1350-911X
• DOI: 10.1049/el.2014.3561

Multiple independent radio-frequency (RF) beams find applications in communications, radio astronomy, radar and microwave imaging. An N-point fast Fourier transform (FFT) applied spatially across an array of receiver antennas provides N-independent RF beams at N/2 log2 N multiplier complexity. Here, a low-complexity multiplierless approximation for the 8-point FFT is presented for RF beamforming, using only 26 additions. The algorithm provides eight beams that closely resemble the antenna array patterns of the traditional FFT-based beamformer albeit without using multipliers. The proposed FFT-like algorithm was verified on-chip using a Xilinx Virtex-6 Lx240T field programmable gate array (FPGA) device. The FPGA implementation indicated bandwidth of 369 MHz for each of the independent receive-mode RF beams.