Circular Array N-Beam Digital Beamformer Having Low Arithmetic Complexity: 16 Simultaneous 100 MHz Beams at 2.4 GHz

• Published in: IEEE transactions on radar systems Vol. 1; pp. 318 - 324
• Main Authors: Ariyarathna, Viduneth, Madanayake, Arjuna
• Format: Journal Article
• Language: English
• Published: IEEE 2023
• Subjects: Antenna arrays; Array signal processing; Circular multibeams; Complexity theory; digital multibeam beamforming; Digital signal processing; Radar; Radar applications; Radio frequency
• ISSN: 2832-7357; 2832-7357
• DOI: 10.1109/TRS.2023.3299186

This paper proposes a <inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula>-element uniform circular array (UCA) <inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula>-beam multibeam beamformer having <inline-formula> <tex-math notation="LaTeX">\mathcal {O}(N \log N) </tex-math></inline-formula> arithmetic complexity. The architecture achieves a reduction of the arithmetic complexity in the order of <inline-formula> <tex-math notation="LaTeX">\frac {N-2\log N-1}{N} </tex-math></inline-formula> compared to matrix-vector computation. Circular symmetric RF beams are in general desired for applications such as wireless internet of things (IoT), multibeam base stations, Wi-Fi access points, and multibeam radar systems where a 360° field of view is required. The proposed digital signal processor achieves <inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula> RF beams using an <inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula>-element UCA which are steerable in both azimuthal and elevation planes. The aperture array patterns of the proposed digital beamformer have been experimentally verified using a receive-mode 2.4 GHz 16-element UCA. Such beamforming systems can specifically be beneficial to multi-directional radar sensing systems which find applications in aviation and weather radars, electronic warfare, drone detection, and situational awareness radar systems that require 360 degree field of view. The digitally realized 16-beams have been measured in real-time and are in agreement with simulated array factors. The digital signal processing occurs in real-time using Xilinx SX475t FPGA chip on ROACH-2 platform, and supports 100 MHz Nyquist bandwidth per beam at a clock frequency of 200 MHz. The beam-bandwidth product is 1.6 GHz.