A photonics-based scheme to measure microwave omnidirectional angle-of-arrival (AOA) is proposed. In the proposed system, an optical carrier is split into two branches. In one branch, the optical carrier is frequency-shifted by an acousto-optic modulator (AOM) and led to a Mach-Zehnder modulator (MZM) which is modulated by an echo signal from an antenna. In the other branch, a polarization-division-multiplexed MZM (PDM-MZM) is used to imprint two different echo signals received by another two antennas placed above and to the right of the previous antenna, respectively. Then, an optical bandpass filter is connected after each modulator to select one of the 1 st -order sidebands. The selected sidebands are sent to an optical ten-port receiver, which is consisted of a dual-polarization 90-degree optical hybrid and four balanced photodetectors (BPDs). After processing the low-frequency signals from the orthogonal outputs of the ten-port optical receiver, the azimuth and altitude AOA of the received RF signal could be simultaneously obtained. In a proof-of-concept experiment, the measurement error of the altitude AOA is less than ±1.63° within the angular range of −48.08°∼56.43°, and the measurement error of the azimuth AOA is smaller than ±3.09° when the angular range is from −68.35° to 64.65°.

中文翻译：

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基于十端口光接收机的微波全向到达角测量


提出了一种基于光子学的微波全向到达角（AOA）测量方案。在所提出的系统中，光载波被分成两个分支。在一个分支中，光载波由声光调制器 (AOM) 进行频移，并引导至马赫-曾德尔调制器 (MZM)，该调制器由来自天线的回波信号进行调制。在另一个分支中，偏振分复用 MZM (PDM-MZM) 用于印记分别放置在前一个天线上方和右侧的另外两个天线接收到的两个不同的回波信号。然后，在每个调制器之后连接光学带通滤波器以选择一阶边带之一。选定的边带被发送到光学十端口接收器，该接收器由双偏振 90 度光学混合和四个平衡光电探测器 (BPD) 组成。对十端口光接收机正交输出的低频信号进行处理后，可以同时获得接收到的射频信号的方位角和高度AOA。在概念验证实验中，在-48.08°∼56.43°角度范围内，高度角AOA测量误差小于±1.63°，方位角AOA测量误差小于±3.09°。角度范围为-68.35°至64.65°。