A Portable FMCW Interferometry Radar with Programmable Low-IF Architecture for Localization, ISAR Imaging, and Vital Sign Tracking

Zhengyu Peng, Jose Maria Munoz-Ferreras, Yao Tang, Chenhui Liu, Roberto Gomez-Garcia, Lixin Ran, Changzhi Li

Research output: Contribution to journalArticlepeer-review

124 Scopus citations


This paper presents a portable radar system for short-range localization, inverse synthetic aperture radar imaging, and vital sign tracking. The proposed sensor incorporates frequency-modulated continuous-wave (FMCW) and interferometry (Doppler) modes, which enable this radar system to obtain both absolute range information and tiny vital signs (i.e., respiration and heartbeat) of human targets. These two different operation modes can be switched through an on-board microcontroller. To simplify the system, the proposed radar utilizes the audio card of a laptop to sample the baseband signal. The FMCW mode of the radar uses operational-amplifier-based circuits to generate an analog sawtooth signal and a reference pulse sequence (RPS). The RPS is locked to the sawtooth signal to obtain coherence for the radar system. For the interferometry mode, a low-intermediate-frequency modulation method is implemented to avoid the slow vital signs from being distorted by the high-pass filter of the audio card. Several experiments were carried out to reveal the capability and distinct operational features of the proposed portable hybrid radar. The experiments also showed that the system can easily detect glass, which is usually difficult to identify for optical-based sensors. In addition, 2-D scanning in a complex environment revealed that the proposed radar was able to differentiate human targets from other objects. Moreover, ISAR images were used to isolate moving human targets from surrounding clutter. Finally, the proposed radar also demonstrated its ability to accurately measure vital signs when a human subject sits still.

Original languageEnglish
Article number7784794
Pages (from-to)1334-1344
Number of pages11
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number4
StatePublished - Apr 2017


  • Frequency-modulated continuous-wave (FMCW) radar
  • hybrid operation mode
  • interferometry radar
  • inverse synthetic aperture radar (ISAR)
  • low-intermediate-frequency (low-IF)
  • vital Doppler information
  • vital sign measurement


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