基于光采样的微波光子矢量网络分析仪设计

Design of Microwave Photonic Vector Network Analyzer Based on Optical Sampling

矢量网络分析仪是射频微波领域的重要测量仪器,设计实现了一套基于光采样的微波光子矢量网络分析仪。该系统使用锁模激光器的超稳光脉冲序列通过马赫-曾德尔调制器直接采样单音信号,再采用数字信号处理技术获取待测器件的散射参数。实验测试表明:采用20 GHz电光调制器实现的系统带宽可达20 GHz,更大的系统带宽可以通过采用更大带宽的电光调制器达到。系统的动态范围约为60 dB,最小频率分辨率为11.92 Hz。对中心频率为10 GHz的带通滤波器的散射参数(S参数)进行了测试,在通带范围内,与商用矢量网络分析仪的测试结果相比,S21的幅度平均偏差为0.1241 dB,S21的相位平均偏差为3.6356°,具有很好的一致性。

Vector network analyzer is an important measurement instrument in the fields of radio and microwave.In this paper,we design and implement a microwave photonic vector network analyzer(MPVNA)based on optical sampling,which uses ultrastable optical pulse trains,generated by mode-locked laser,to directly sample single tone signals via a Mach-Zehnder modulator,and then processes the sampling data with digital signal process to obtain the scattering parameters of the device under test.The experimental result shows that MPVNA bandwidth is 20 GHz when using an electro-optic modulator with bandwidth of 20 GHz in the system and a larger system bandwidth can be achieved by using an electro-optic modulator with larger bandwidth.The system dynamic range is about 60 dB and the minimum system frequency resolution is 11.92 Hz.Then we use this system to test the scattering(S)parameters of a bandpass filter with a center frequency of 10 GHz and compare the test result with that of a commercial vector network analyzer.The comparison results show that the average amplitude deviation of S21is 0.1241 dB and the average phase deviation of S21is3.6356°in the passband of the bandpass filter,which proves that the test results of the system is well consistent with that of a commercial vector network analyzer.