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研究了一种通过电光调制将毫米波信号加载到光载波上进行处理的毫米波辐射计。天线接收的毫米波信号由电光调制器(EOM)调制加载到光载波的边带上,并通过光纤传输该信号;利用光纤布拉格光栅(FBG)滤波器滤掉载波分量,滤波后保留的边带分量信号由光电探测器(PD)探测。为提高探测灵敏度,使用锁相放大器对PD输出的信号进行检测。分析了采用光学方法处理毫米波信号时的能量转换效率和噪声特性。使用50GHz毫米波信号源对毫米波信号进行了探测实验,测量了实验系统中的能量转换效率和噪声等效功率,并分析了改进探测灵敏度的方法。设计了毫米波辐射测量实验装置,并进行了探测实验。实验结果表明,本文方法可应用于毫米波辐射计。
A millimeter wave radiometer that processes millimeter wave signals onto optical carriers by electro-optic modulation is studied. The millimeter wave signal received by the antenna is modulated by an electro-optic modulator (EOM) onto the sideband of the optical carrier and transmitted through the optical fiber. The carrier wave is filtered by a fiber Bragg grating (FBG) filter and the filtered sideband The component signal is detected by a photodetector (PD). To improve the detection sensitivity, the use of lock-in amplifier to detect the PD output signal. The energy conversion efficiency and noise characteristics when using the optical method to process the millimeter wave signal are analyzed. A 50 GHz millimeter-wave signal source was used to probe the millimeter-wave signal. The energy conversion efficiency and the noise equivalent power in the experimental system were measured. The method to improve the detection sensitivity was also analyzed. Design of millimeter wave radiation measurement experimental device, and the detection experiment. Experimental results show that this method can be applied to millimeter wave radiometer.