A Scalable Ka-Band Active Electronically Scanned Array

• Main Authors: Chu, Ching-Yun, 儲青雲
• Other Authors: Wang, Yu-Jiu
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/7kt3e9

博士 === 國立交通大學 === 電子研究所 === 107 === This thesis analyzes the scaling properties of a generic phased array with different elementary error types, and presents a scalable hybrid phased-array system through the synchronization, analog complex-weighting and digital beamforming of numerous fully integrated Ka-band 4RX/4TX phased array transceiver ICs. A 1.09 GHz and a 50 MHz clock trees synchronize all array elements for their analog and sampling/digital part respectively. A global event trigger further synchronizes transmitting pulses and receiver sampling period for pulse-mode operations. Phase shifting is accomplished first in analog domain using optimal IF/LO complex weighting and signal summing in the 4RX/4TX IC to reduce the number of signals by a factor of four, followed by analog-to-digital sampling and the digital beamformer in FPGA and CPU. Phase shifting properties, programmable gain variations, and antenna pattern of each RTX channel are measured and tabulated to calculate optimal channel weights. Long-term phase stability is enhanced through temperature control by real-time monitoring all ICs’ temperature and adaptively adjusting the duty-cycle of the transmit mode of each IC to limit instantaneous temperature variations to ±0.5°C over each calibration session. This reduces random phase errors from 13.3° to 4.8° in TX mode. Reliable and repeatable pattern can be formed with less than 3.89% in maximum errors to main power ratio between theoretic prediction based on elementary properties and measurement results in both receive- and transmit- mode. Locating each Vivaldi antenna on a 2-D rectangular grid, an 8 x 4 subarray module with synchronized digital output is demonstrated.