"New Wideband Miniature Branchline Coupler on IPD Technology for Beamforming Applications
Résumé
In this paper, we present a new wideband miniature branchline coupler as a key circuit to be integrated in 60-GHz packaged beamforming networks for phased-array antennas. First, the integrated passive device (IPD) technology from STMicroelectronics is investigated in the mm-wave range through the simulation, fabrication, and measurements of a microstrip line and a simple hybrid coupler. Then, a novel coupler topology with emphasis on miniaturization and broadband operation is theorized. Analytical equations are derived and a 60-GHz coupler is optimized on IPD technology. Measurement results are discussed and compared with state-of-the art publications. The whole 57-66-GHz bandwidth is efficiently covered with the three following performance: -10-dB impedance matching, ±1-dB amplitude imbalance, and ±5° phase imbalance. As an application example, the novel coupler is integrated into a 4 × 4 Butler matrix suitable for an array-antenna demonstrating stateof-the art performance in terms of insertion loss and phase error. The measurement of different samples shows low variation of the IPD process because of very good reproducibility making it a suitable candidate for circuits operating in the 60-GHz band.
Mots clés
impedance matching
antenna arrays
antenna accessories
microstrip couplers
millimetre wave couplers
wideband miniature branchline coupler
IPD technology
beamforming applications
beamforming networks
phased array antenna
integrated passive device technology
microstrip line
hybrid coupler
Butler matrix
frequency 57 GHz to 66 GHz
Couplers
Wideband
Microstrip
Topology
Antennas
Tuning
60 GHz
array antenna
beamforming network
coupler
IPD technology.