Compared with a conventional Doppler radar in which target displacement results in phase modulation, target displacement in a self-injection-locked oscillator (SILO)-based radar results in frequency modulation. Since the instantaneous phase is the time integral of frequency, the SILO-based radar is considered to have higher sensitivity than the conventional Doppler radar. However, a direct comparison between the SILO-based radar and the conventional Doppler radar is still needed to quantitatively understand the sensitivity difference. This article provides a rigorous time-domain analysis of the sensitivity of the SILO-based radar with a delay-based frequency demodulator for small-amplitude periodic motions. The analysis follows an approach similar to the time-domain analysis for the conventional Doppler radar. It reveals that two null detection point mechanisms could arise in SILO-based radar systems. The target distance may introduce one null detection point, and the delay added in the frequency demodulator may introduce another. Furthermore, this article also proposes an SILO-based radar with dual null detection points’ removal. Unlike the Doppler radar, where I/QI/Q demodulation eliminates the null detection point introduced by the target distance, I/QI/Q demodulation in the SILO-based radar only eliminates the null detection point introduced by the delay cable. To overcome the other null detection point mechanism, a phase shifter is introduced after the LNA. Experiments were carried out to validate the proposed time-domain analysis and demonstrate that both the techniques need to be used simultaneously to remove both null detection points in the system. The sensitivity comparison was performed using a conventional Doppler radar and an SILO-based radar built with identical microwave components.

中文翻译：

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用于小幅度运动传感的自注入锁定雷达的双空检测点去除和时域灵敏度分析


与目标位移导致相位调制的传统多普勒雷达相比，基于自注入锁定振荡器 (SILO) 的雷达中的目标位移导致频率调制。由于瞬时相位是频率的时间积分，因此基于SILO的雷达被认为比传统的多普勒雷达具有更高的灵敏度。然而，仍然需要对基于 SILO 的雷达和传统多普勒雷达进行直接比较，以定量地了解灵敏度差异。本文对基于 SILO 的雷达的灵敏度进行了严格的时域分析，该雷达具有基于延迟的频率解调器，用于小幅度周期性运动。该分析采用与传统多普勒雷达的时域分析类似的方法。它揭示了基于 SILO 的雷达系统中可能出现两种零检测点机制。目标距离可能引入一个零检测点，并且在频率解调器中添加的延迟可能引入另一零检测点。此外，本文还提出了一种基于 SILO 的雷达，具有双零检测点去除功能。与多普勒雷达不同，I/QI/Q 解调消除了目标距离引入的零检测点，基于 SILO 的雷达中的 I/QI/Q 解调仅消除了延迟电缆引入的零检测点。为了克服其他零检测点机制，在 LNA 之后引入了移相器。进行实验是为了验证所提出的时域分析，并证明需要同时使用这两种技术来消除系统中的两个空检测点。 使用传统多普勒雷达和采用相同微波组件构建的基于 SILO 的雷达进行灵敏度比较。