Miniaturised multi-beam-controlled circular eight-port beamforming network for long-range UHF RFID hemispheric coverage

• Published in: IET microwaves, antennas & propagation Vol. 12; no. 2; pp. 154 - 159
• Main Authors: Jeong, Min-Gyo, Kim, Ji-Hong, Bae, Sang-Hyeon, Lee, Wang-Sang
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 07.02.2018
• Subjects: amplitude imbalances; antenna feeds; array signal processing; circular three‐layer FR‐4 substrate; dipole antenna arrays; eight‐element dipole antenna array; eight‐port feeding network; frequency 902 MHz to 928 MHz; insertion loss; integrated beam‐control block; long‐range UHF RFID hemispheric beam‐coverage systems; miniaturised multibeam‐controlled circular eight‐port beamforming network; phase imbalances; phase shifters; quadrature hybrid couplers; radiofrequency identification; Research Article; switches; two‐stage RF switch block; UHF antennas; UHF couplers; UHF phase shifters; ultra‐high‐frequency radiofrequency identification systems; frequency 902 MHz to 928 MHz; amplitude imbalances; radiofrequency identification; circular three-layer FR-4 substrate; eight-port feeding network; switches; insertion loss; dipole antenna arrays; miniaturised multibeam-controlled circular eight-port beamforming network; eight-element dipole antenna array; two-stage RF switch block; phase imbalances; phase shifters; integrated beam-control block; UHF couplers; ultra-high-frequency radiofrequency identification systems; UHF antennas; quadrature hybrid couplers; UHF phase shifters; antenna feeds; long-range UHF RFID hemispheric beam-coverage systems; array signal processing
• ISSN: 1751-8725; 1751-8733; 1751-8733
• DOI: 10.1049/iet-map.2017.0416

In this paper, a miniaturised multi-beam-controlled circular eight-port beamforming network for long-range ultra-high-frequency radio-frequency identification (UHF RFID) hemispheric beam-coverage systems (e.g. unmanned aircraft systems) is proposed. For multi-beam control and compact implementation, the proposed eight-port feeding network consists of an integrated beam-control block with a two-stage RF switch block, 12 quadrature hybrid couplers, and 12 90° phase shifters, and was designed and fabricated on a circular three-layer 1.2 mm FR-4 substrate. The diameter of the fabricated network is ∼0.47 λ0 at 915 MHz. The measured maximum insertion loss, and amplitude and phase imbalances of the fabricated network at the authorised UHF RFID frequency band (902–928 MHz) are ∼4.5 dB, ± 1.3 dB, and ± 17.5°, respectively. An eight-element dipole antenna array with the proposed feeding network shows feasibility of hemispheric beam coverage by generating multiple beams simultaneously regarding port controls. Beam coverages, where the simulated realised gain is higher than 3 dBi, are ∼180° and 130° at ϕ = 90 and 0°, respectively.