We present the principle and the experimental verification of a distance measurement method based on the propagation of terahertz waves. The method relies on modulating the amplitude of a resonant-tunneling-diode (RTD) oscillator used as terahertz-wave source and on measuring the phase of the detected wave by applying a quadrature mixing technique. The distance measurement is found to have a residual error as small as 0.063 mm (standard deviation), which is a record for an RTD-based terahertz-wave radar system. This is almost five times better than our previous record of 0.29 mm, when an oscilloscope was used for phase measurements; additionally, the quadrature mixing brings about numerous practical benefits, such as greatly reduced cost, size, weight, complexity, and power consumption.

中文翻译：

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使用锁定相位测量的太赫兹范围内的调幅连续波雷达

我们介绍了基于太赫兹波传播的距离测量方法的原理和实验验证。该方法依赖于调制用作太赫兹波源的谐振隧道二极管（RTD）振荡器的幅度，以及通过应用正交混合技术来测量检测到的波的相位。发现距离测量的残留误差小至0.063 mm（标准偏差），这是基于RTD的太赫兹波雷达系统的记录。当使用示波器进行相位测量时，这几乎是我们之前记录的0.29毫米的五倍；另外，正交混合带来了许多实际的好处，例如大大降低了成本，尺寸，重量，复杂性和功耗。