A portable 24-GHz frequency-modulated continuous-wave (FMCW) radar with continuous beam steering phased array is presented. This board-level integrated radar system consists of a phased array antenna, a radar transceiver and a baseband. The phased array used by the receiver is a 4-element linear array. The beam of the phased array can be continuously steered with a range of ±30° on the H-plane through an array of vector controllers. The vector controller is based on the concept of vector sum with binary-phase-shift attenuators. Each vector controller is capable of independently controlling the phase and the amplitude of each element of the linear array. The radar transceiver is based on the six-port technique. A free-running voltage controlled oscillator (VCO) is controlled by an analog “sawtooth” voltage generator to produce frequency-modulated chirp signal. This chirp signal is used as the transmitter signal, as well as the local oscillator (LO) signal to drive the six-port circuit. The transmitter antenna is a single patch antenna. In the baseband, the beat signal of the FMCW radar is detected by the six-port circuit and then processed by a laptop in real time. Experiments have been performed to reveal the capabilities of the proposed radar system for applications including indoor inverse synthetic aperture radar (ISAR) imaging, vital sign detection, and short-range navigation, etc.
(This abstract is for the profiles session.)
This paper presents a multiple input multiple output (MIMO) wireless radar sensor network capable of measuring lower-frequency vibration and static deflection in bridges. An integrated simulation model that combines a multi degree-of-freedom structural model with a realistic model of the radar sensor network is introduced and used to characterize and predict the network’s functionality in different measurement conditions. In addition, a series of laboratory experiments have been performed for comparison with the simulation model. Finally, challenges associated with achieving accurate measurements from the radar network in a range of testing environments are discussed.
The development of effective structural health monitoring (SHM) strategies is critical as aging infrastructure remains a
national concern with widespread impact on the quality of our daily lives. Wireless smart sensor networks (WSSNs) are
an attractive alternative to traditional SHM systems for their lower deployment cost and their ability to enable new
methods of distributed data processing. While acceleration has been the primary measurement utilized in most WSSN
SHM applications, practically and accurately capturing structural deflections has been proven much more challenging.
Displacement sensors produce reliable low-frequency measurements but are often difficult to implement in long-term
field deployments. Conventional technologies for measuring deflection, both dynamic and static, are either too bulky or
expensive to be integrated into WSSNs or lack sufficient accuracy. This paper presents the validation and
characterization of a network of low-cost, wireless radar-based sensors for the enhancement of low-frequency vibrationbased
bridge monitoring and the measurement of static bridge deflections. Experimental results utilizing a laboratoryscale
truss bridge are presented and the performance of the wireless radar sensors is compared to conventional vibration
and displacement transducers. In addition, challenges associated with detection distance, interference rejection and
signal processing are discussed.
Wireless smart sensor technology offers many opportunities to advance infrastructure monitoring and maintenance by
providing pertinent information regarding the condition of a structure at a lower cost and higher density than traditional
monitoring approaches. Many civil structures, especially long-span bridges, have low fundamental response frequencies
that are challenging to accurately measure with sensors that are suitable for integration with low-cost, low-profile, and
power-constrained wireless sensor networks. Existing displacement sensing technology is either not practical for
wireless sensor implementations, does not provide the necessary accuracy, or is simply too cost-prohibitive for dense
sensor deployments. This paper presents the development and integration of an accurate, low-cost radar-based sensor for
the enhancement of low-frequency vibration-based bridge monitoring and the measurement of static bridge deflections.
The sensors utilize both a nonlinear vibrometer mode and an arctangent-demodulated interferometry mode to achieve
sub-millimeter measurement accuracy for both periodic and non-periodic displacement. Experimental validation results
are presented and discussed.
Based on the measurement results of a 5 GHz CMOS radar microchip, it is shown that low power CMOS radar-on-chip
integration can have high detection sensitivity despite the large flicker noise and phase noise contributions around the
signal of interest. Key technologies to further increase the detection sensitivity will be discussed, including software
configured DC offset calibration, noise suppression using tunable baseband bandwidth limiter, and special receiver
architecture for flicker noise reduction. The applications of low-cost high-sensitivity on-chip radar will be focused on
surveillance and reconnaissance, sensing through-wall radar, ground penetration radar, border monitoring, and moving
Getting to wounded soldiers on the battlefield is a precarious task, and medics have a very high casualty
rate. It is therefore a vital importance to prioritize which soldiers to attend to first. The first step is to detect
life signs - if a soldier is dead or alive, and prioritize recovery of live soldiers. The second step is to obtain
vital signs from live soldiers, and use this to prioritize which are in most urgent need of attention. Our
team at Kai Sensors, University of Hawaii and University of Florida is developing Doppler radar heart
sensing technology that provides the means to detect life signs, respiration and/or heart beat, at a distance,
even for subjects lying motionless, e.g., unconscious subjects, wearing body armor, and hidden from direct
view. Since this technology can deliver heart rate information with high accuracy, it may also enable the
assessment of a subject's physiological and psychological state based on heart rate variability (HRV)
analysis. Thus, the degree of a subject's injury may also be determined. The software and hardware
developments and challenges for life signs detection and monitoring for battlefield triage will be discussed,
including heart signal detection from all four sides of the human body, detection in the presence of body
armor, and the feasibility of HRV parameter extraction.