The objective of this paper is to present a microwave photonic system that can measure the angle of arrival (AOA) of multiple microwave signals with improved measurement accuracy. It is based on a photonic mixer approach to down convert the incoming microwave signals into IF signals, which enables a low-frequency electrical spectrum analyser to be used for measuring the power of the IF signals to determine the incoming microwave signal AOAs. AOA measurement errors can be reduced by operating the optical modulator at a different transmission point for a different range of microwave signal AOA. The system also has the ability to remove the incoming microwave signal amplitude dependence in the AOA measurement. Measured results demonstrate 0°−81.5° AOA measurement with less than ±2° errors over the 0°−30° and 30°−81.5° AOA measurement range when the optical modulator is biased at the minimum and maximum transmission point respectively. The errors remain below ±2° even when there is a ±0.1 dB change in the output IF signal power. AOA measurement of two microwave signals is also demonstrated.

中文翻译：

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测量精度更高的多信号 AOA 光子方法

本文的目的是提出一种微波光子系统，该系统可以测量多个微波信号的到达角 (AOA)，并提高测量精度。它基于光子混频器方法将传入的微波信号下变频为 IF 信号，这使得低频电频谱分析仪能够用于测量 IF 信号的功率以确定传入的微波信号的 AOA。对于不同范围的微波信号 AOA，可以通过在不同传输点操作光调制器来减少 AOA 测量误差。该系统还具有在 AOA 测量中消除传入微波信号幅度依赖性的能力。测量结果表明 0°−81.5° AOA 测量在 0°−30° 和 30°−81 范围内误差小于 ±2°。光调制器分别偏置在最小和最大传输点时的 5° AOA 测量范围。即使输出 IF 信号功率有 ±0.1 dB 变化，误差仍保持在 ±2° 以下。还演示了两个微波信号的 AOA 测量。