Short-range Radar Research Articles

A Broadband 77/79 GHz Transmitter With Dual VCOs and Third Harmonic Signal Extraction in a 28 nm CMOS Technology

A broadband 77/79 GHz transmitter (TX) front-end for automotive long range radar (LRR) and short range radar (SRR) applications is presented in this paper. To achieve the best system performance one new TX architecture with two specifically designed voltage controlled oscillators (VCOs) is implemented in a 28 nm CMOS technology. Furthermore, the degradation of the VCO phase noise due to the TX integration is analyzed in detail and solutions to minimize the impacts are proposed and verified. Experimental results of a 20 GHz push-push VCO1 measured at the 77 GHz TX output show a continuous tuning range of 4.75 GHz, a coarse tuning range of 3.2 GHz and an average phase noise of −100 dBc/Hz @ 1 MHz, while a 26 GHz VCO2 with third harmonic signal extraction achieves a continuous and coarse tuning range of 7.5 GHz and 4.2 GHz with an average phase noise of −96 dBc/Hz @ 1 MHz at 79 GHz TX output. Moreover, a record pushing performance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\rm {&lt;\!\pm }$</tex-math></inline-formula> 100 MHz/V at 77/79 GHz TX output has been achieved according to the authors’ best knowledge. The whole TX chip consumes about 860 mW from a single 2.1 V supply while providing more than 16 dBm output power over the whole frequency band.

A Duplexing Hybrid Slot Antenna Design With High Isolation for Short-Range Radar Detection and Identification Applications at 24 GHz Band

This paper presents a duplexing hybrid antenna architecture for short-range radar systems with high isolation and low loss between the two transmitting (TX) and receiving (RX) ports. The antenna utilizes a single slot for common resonance shared by the two TX and RX port excitations. These two ports were constructed through two parallel microstrip lines crossing over the specified shaped slot. The feeding structures of these two microstrip feedings and the separation are optimally designed to ensure the mutual coupling signals out-of-phase, and therefore the signal cancellation can be achieved, leading to a high isolation between these two ports. In this design, the slot length is 0.92λ at 24.125 GHz, forming an equivalent short circuit at the other port. Given the initial design criteria, the design with the optimal isolation could readily be found by minimal full-wave simulations. Meanwhile, the equivalent circuit model was used to investigate the working principles and to improve the isolation bandwidth and impedance matching at the central frequency. The measured maximum isolation is 70 dB at 24.125 GHz. The RF front-end modules with TX and RX amplifiers are also integrated to validate its feasibility for the radar system application. The mechanisms to widen the isolation bandwidth are also addressed.

High gain wide band grid array antenna for short range radar and vehicle-to-satellite communications

This paper presents the design of a Grid Array Antenna that covers both Short Range Radar applications at 24 GHz, the spectrum requirement of Ku-band transmit mode for Fixed Satellite Service and Direct Broadcast Service for Vehicle to Satellite communications. The proposed Grid Array Antenna design has vertical short radiating wire segments and long radiating wire segments loaded with parallel reactive disc structures to enhance the bandwidth. Taylor synthesis method of amplitude-tapering reduces the Side Lobe Level to −16.3 dB. The simulation and measurement results are in alignment with each other covering the bandwidth of 12.58 GHz (VSWR ≤ 2), Half Power Beam Width of 7.8° in E-plane, and 101.6° in H-plane at 24 GHz and broadside radiation for Vehicle-to-Satellite communication. The antenna parameters are analyzed for housing effect and mounted on a virtual model of a vehicle. The aforementioned results show that the proposed antenna is well suited for the spectral coverage of Vehicle-to-Satellite communication, Blind Spot Detection, and pre-impact sensing in Short Range Radar automotive communication.

The influence of the Advanced Emergency Braking System in critical scenarios for autonomous vehicles

This paper proposes use indications for an Advanced Emergency Braking System (AEBS) module developed in Matlab and included in a Simcenter Prescan simulation. The analysed indications depend on a Long-Range Radar (LRR) and Short-Range Radar (SRR) beam range, on the speed of the autonomous vehicle and on the time between the detection of the obstacle in front of the autonomous vehicle and the time the obstacle starts to move. The simulated scenario consists of an autonomous vehicle that travels at a certain speed, where another vehicle starts to move from a bus station after a sudden stop, challenging the autonomous vehicle to stop in a safe manner and in a short time.

PECULIARITIES OF SIGNALS FROM A MOVING TARGET USING AUTODYNE SHORT-RANGE RADARS WITH LFM

PECULIARITIES OF SIGNALS FROM A MOVING TARGET USING AUTODYNE SHORT-RANGE RADARS WITH LFM

Accurate Micro-Doppler Analysis by Doppler and $k$-Space Decomposition for Millimeter Wave Short-Range Radar

This study presents a highly accurate range and Doppler-velocity extraction scheme for millimeter-wave (MMW) short-range sensing using the Doppler-velocity and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k$</tex-math></inline-formula> -space decomposition in a weighted kernel density (WKD) scheme. The WKD method has been developed as one of the most promising micro-Doppler analysis methods for human motion; however, an original WKD method requires a highly decomposed range profile to achieve its maximum performance. As the main contribution of this article, the proposed method introduces the Doppler velocity and k-space decomposition via the 4-D fast Fourier-transform process, which significantly improves the range resolution and reduces computational complexity. The numerical and experimental results show that the proposed method achieves significantly higher range and velocity accuracy and resolution, as well as higher noise-robustness at a lower computational cost.

Doppler Velocity Enhanced Range Migration Algorithm for High Resolution and Noise-Robust Three-Dimensional Radar Imaging

Millimeter-wave and microwave short-range radar are among the most promising environmental sensing methods, with applications to situations that are otherwise optically invisible. This paper presents a Doppler velocity-enhanced range migration algorithm (RMA) that achieves both high spatial resolution and low-complexity three-dimensional (3-D) radar imaging. In this method, we address the problem of human body recognition with motion using the assumption that the motion of different human parts generates distinct micro-Doppler variations in the radar data. These variations could not only separate the RMA images with different Doppler velocities in a coherent integration-based radar imaging process, but enhances a noise reduction effect by decomposing in the Doppler velocity space. To achieve a low complexity in 3-D imaging, we incorporate the RMA method and Doppler velocity-based data decomposition. The results of numerical and experimental tests on a realistic human phantom with a walking motion demonstrate that our method provides more informative and highly separated 3-D images, even in much low SNR situation.

Design and Realization of Band Pass Filter in K-Band Frequency for Short Range Radar Application

Short range radar (SRR) uses the K-band frequency range in its application. The radar requires high-resolution, so the applied frequency is 1 GHz wide. The filter is one of the devices used to ensure only a predetermined frequency is received by the radar system. This device must have a wide operating bandwidth to meet the specification of the radar. In this paper, a band pass filter (BPF) is proposed. It is designed and fabricated on RO4003C substrate using the substrate integrated waveguide (SIW) technique, results in a wide bandwidth at the K-band frequency that centered at 24 GHz. Besides the bandwidth analysis, the analysis of the insertion loss, the return loss, and the dimension are also reported. The simulated results of the bandpass filter are: VSWR of 1.0308, a return loss of -36.9344 dB, and an insertion loss of -0.6695 dB. The measurement results show that the design obtains a VSWR of 2.067, a return loss of -8.136 dB, and an insertion loss of -4.316 dB. While, it is obtained that the bandwidth is reduced by about 50% compared with the simulation. The result differences between simulation and measurement are mainly due to the imperfect fabrication process.

Multi-Functional Imaging Method for Microwave or Millimeter-Wave Short Range Radar

Multi-Functional Imaging Method for Microwave or Millimeter-Wave Short Range Radar

Concept of Short-Range Radar and Counter-Projectile for Detecting and Countering Armour-Piercing Projectiles

During warfare and acts of terrorism an extreme threat to vehicles and other high-value assets comes from armour-piercing projectiles. Under these conditions, defence systems should include devices capable of rapid detection of these threats. Defence assets should also be provided with counter-projectile systems capable of destroying incoming armour-piercing projectiles at a safe distance from the asset to be protected. This paper describes the concept of a system comprising of a lightweight short-range radar and a counter-projectile for countering armour-piercing projectiles. The purpose of the radar is to monitor the environment and search for incoming armour-piercing projectiles. When an armour-piercing projectile is detected in a designated monitoring area, an automatic command is given for the counter-projectile launcher to be fired. The counter-projectile deployed can be equipped with a single or multi-sensor detection head unit and an explosive payload module, both being the primary components of the warhead. When the signal analysis blocks interfaced with the detection head determine that the armour-piercing projectile to be struck down is in the target position in relation to the counter-projectile deployed, they automatically command the explosive payload module to detonate. The components of the system concept were tested in proving ground conditions. The successful results of these tests confirmed the validity of the solutions initially adopted and the execution of the individual systems.

Моноимпульсный радиолокатор сопровождения по дальности и угловым координатам с широкополосным зондирующим сигналом.

A block diagram of the receiving part of a monopulse radar tracking by range and angular coordinates with a broadband sounding signal is presented. The features of correlation processing of a broadband linear-frequency-modulated signal with full frequency demodulation and algorithms for estimating coordinates are considered. A comparative analysis of the results of calculating errors in measuring the coordinates of air targets in short-range radars using narrow-band and broadband signals and different viewing angles is carried out.

79GHz Substrate Integrated Waveguide antenna for short-range radar applications

It is evident that radar sensing is robust technology compared to camera or LiDAR in the case of autonomous vehicles. Since, they are capable of working even under harsh weather conditions like thick fog, glaring sun, etc. The 77-81GHz frequency band for short range radar provides a global framework for automotive radar by preventing collisions, reducing traffic accidents and thus improvingvehicular safety. The proposed antenna resonates at 79GHz. Below-10dB, return loss characteristic greater than -35dB is obtained in the band of 77.5GHz to 80.4GHz (i.e., impedance bandwidth of 2.86GHz) and gain of above 8dB is achieved. Rectangular vias and complementary concentric square loops of the metamaterial structure are introduced to suppress the surface waves and to achieve the desired frequency of resonance. The feed line and the metamaterial structure are positionedaccordinglyto provide a better impedance matching. VSWR obtained is 1.04 and the antenna is linearly polarized and has a low profile. The total dimension of the antenna is 1.96×2.26×0.127mm3. The antenna structure can be used in an array for automotive radar applications.

Imaging radar for automated driving functions

AbstractThis work presents the implementation of a synthetic aperture radar (SAR) at 77 GHz, for automotive applications. This implementation is unique in the sense that it is a radar-only solution for most use-cases. The set-up consists of two radar sensors, one to calculate the ego trajectory and the second for SAR measurements. Thus the need for expensive GNSS-based dead reckoning systems, which are in any case not accurate enough to fulfill the requirements for SAR, is eliminated. The results presented here have been obtained from a SAR implementation which is able to deliver processed images in a matter of seconds from the point where the targets were measured. This has been accomplished using radar sensors which will be commercially available in the near future. Hence the results are easily reproducible since the deployed radars are not special research prototypes. The successful widespread use of SAR in the automotive industry will be a large step forward toward developing automated parking functions which will be far superior to today's systems based on ultrasound sensors and radar (short range) beam-forming algorithms. The same short-range radar can be used for SAR, and the ultrasound sensors can thus be completely omitted from the vehicle.

Reconfigurable orthogonal quad-port MIMO antenna for DSRC, WLAN, RADAR and Ku-band applications

A novel and compact reconfigurable quad-port orthogonal Multi-Input-Multi-Output (MIMO) antenna is proposed for Dedicated Short Range Communication (DSRC), WLAN, RADAR and Ku-band applications. The proposed MIMO antenna is fabricated on FR-4 substrate of dimensions 40 × 40 × 0.8 mm3. Each element of MIMO antenna has attained different Ku-band frequencies and lower frequency operating band 5.5–9.2 GHz suitable for DSRC, WLAN and RADAR applications is obtained by M-3 element of proposed MIMO antenna for diode ON condition in ground plane. Individual MIMO element is investigated with respect to S-parameters, isolation, current distribution, radiation pattern, gain, radiation efficiency, Total Active Reflection Coefficient (TARC) and diversity performance parameters like Envelope Correlation Coefficient (ECC), Diversity Gain (DG) and Mean Effective Gain (MEG). Overall gain of MIMO antenna ranges between 3.36 and 7.57 dB in operating bands and radiation efficiency ranges between 70.4 and 89.7%. Time domain characteristics are analyzed using group delay with respect to all ports and group delay is less than 1.5 ns. ECC values are below 0.05, DG is very close to 10 and MEGi < −3 dB. The proposed quad-port MIMO antenna exhibits good diversity performance and is validated by comparing computer generated and experimental results.

TinyRadarNN: Combining Spatial and Temporal Convolutional Neural Networks for Embedded Gesture Recognition With Short Range Radars

This work proposes a low-power high-accuracy embedded hand-gesture recognition algorithm targeting battery-operated wearable devices using low-power short-range RADAR sensors. A 2-D convolutional neural network (CNN) using range-frequency Doppler features is combined with a temporal convolutional neural network (TCN) for time sequence prediction. The final algorithm has a model size of only 46 thousand parameters, yielding a memory footprint of only 92 KB. Two data sets containing 11 challenging hand gestures performed by 26 different people have been recorded containing a total of 20'210 gesture instances. On the 11 hand gesture data set, accuracies of 86.6% (26 users) and 92.4% (single user) have been achieved, which are comparable to the state of the art, which achieves 87% (10 users) and 94% (single user), while using a TCN-based network that is 7500× smaller than the state of the art. Furthermore, the gesture recognition classifier has been implemented on a parallel ultralow power processor, demonstrating that real-time prediction is feasible with only 21 mW of power consumption for the full TCN sequence prediction network, while a system-level power consumption of less than 120 mW is achieved. We provide open-source access to example code and all data collected and used in this work on tinyradar.ethz.ch.

Pedestrian and Multi-Class Vehicle Classification in Radar Systems Using Rulex Software on the Raspberry Pi

Nowadays, cities can be perceived as increasingly dangerous places. Usually, CCTV is one of the main technologies used in a modern security system. However, poor light situations or bad weather conditions (rain, fog, etc.) limit the detection capabilities of image-based systems. Microwave radar detection systems can be an answer to this limitation and take advantage of the results obtained by low-cost technologies for the automotive market. Transportation by car may be dangerous, and every year car accidents lead to the fatalities of many individuals. Humans require automated assistance when driving through detecting and correctly classifying approaching vehicles and, more importantly, pedestrians. In this paper, we present the application of machine learning to data collected by a 24 GHz short-range radar for urban classification. The training and testing take place on a Raspberry Pi as an edge computing node operating in a client/server arrangement. The software of choice is Rulex, a high-performance machine learning package controlled through a remote interface. Forecasts with a varying number of classes were performed with one, two, or three classes for vehicles and one for humans. Furthermore, we applied a single forecast for all four classes, as well as cascading forecasts in a tree-like structure while varying algorithms, cascading the block order, setting class weights, and varying the data splitting ratio for each forecast to improve prediction accuracy. In the experiments carried out for the validation of the presented approach, an accuracy of up to 100% for human classification and 96.67% for vehicles, in general, was obtained. Vehicle sub-classes were predicted with 90.63% accuracy for motorcycles and 77.34% accuracy for both cars and trucks.

Improving Classification Accuracy of Hand Gesture Recognition Based on 60 GHz FMCW Radar with Deep Learning Domain Adaptation

With the recent development of small radars with high resolution, various human–computer interaction (HCI) applications using them have been developed. In particular, a method of applying a user’s hand gesture recognition using a short-range radar to an electronic device is being actively studied. In general, the time delay and Doppler shift characteristics that occur when a transmitted signal that is reflected off an object returns are classified through deep learning to recognize the motion. However, the main obstacle in the commercialization of radar-based hand gesture recognition is that even for the same type of hand gesture, recognition accuracy is degraded due to a slight difference in movement for each individual user. To solve this problem, in this paper, the domain adaptation is applied to hand gesture recognition to minimize the differences among users’ gesture information in the learning and the use stage. To verify the effectiveness of domain adaptation, a domain discriminator that cheats the classifier was applied to a deep learning network with a convolutional neural network (CNN) structure. Seven different hand gesture data were collected for 10 participants and used for learning, and the hand gestures of 10 users that were not included in the training data were input to confirm the recognition accuracy of an average of 98.8%.

A K-Band FMCW Frequency Synthesizer Using Q-Boosted Switched Inductor VCO in SiGe BiCMOS for 77 GHz Radar Applications

In this article, a fractional-N phase-locked loop (PLL) with integrated chirp generation circuit block for a 76~81 GHz frequency-modulated continuous-wave (FMCW) radar system is presented. Thanks to the switched inductor voltage-controlled oscillator (VCO) topology, the linearity, phase noise, chirp bandwidth, and chirp rate of the FMCW synthesizer can be optimized for the short-range radar (SRR) and long-range radar (LRR) applications, with switch at ON/OFF states, respectively, according to different requirements and concerns. In this way, the proposed FMCW synthesizer shows improved phase noise for switch OFF-state, good for LRR applications, compared to the conventional single-varactor VCOs or cap-bank VCOs. The switch loss at ON-state is further decreased with the Q-boosting technique, which helps the FMCW synthesizer to simultaneously obtain a wide chirp bandwidth, steep modulation rates and good phase noise for SRR applications. The FMCW synthesizer is fabricated in 0.13 µm SiGe BiCMOS technology, occupies an area of 1.7 × 1.9 mm2, and consumes 330 mW from a 3.3 V voltage supply. Measured results show that the FMCW synthesizer can cover 25.3~27 GHz (with a frequency tripler to fully cover 76~81 GHz band), showing optimized phase noise, chirp bandwidth, linearity, and modulation rates performance. The measured K-band phase noise is −110.5 dBc/Hz for switch OFF-state, and −106 dBc/Hz for switch ON-state at 1 MHz offset. The normalized root mean square (RMS) frequency error is 518 kHz for chirp rate of ±14.6 MHz/μs and 1.44 MHz for chirp rate of ±39 MHz/μs for the 77 GHz band. Moreover, the integrated waveform generator offers fully programmability in chirp rate, duration and bandwidth, which supports multi-slope chirp generations. With a frequency tripler, the chip is well suited for the 76~81 GHz FMCW radar system.

K-Space Decomposition-Based 3-D Imaging With Range Points Migration for Millimeter-Wave Radar

In this article, we present a novel method that incorporates the range points migration (RPM) method, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k$ </tex-math></inline-formula> -space decomposition-based accurate, and noise-robust range extraction filter for microwave or millimeter-wave (MMW) short-range radar using a considerably lower fractional bandwidth signal. The advantage for higher angular resolution in higher frequency systems, such as MMW radar, has been implemented to the incoherent-based RPM method, using the simple 1-D or 2-D Fourier transform-based processing to maintain the imaging accuracy in RPM processing for both the range and the angular directions. As an additional advantage of our method, it also offers data clustering in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k$ </tex-math></inline-formula> -space, which can enhance the imaging accuracy of the RPM method. The numerical and experimental tests demonstrated that the proposed method offers numerous advantages over the Capon-based super-resolution algorithm or coherent-based imaging approaches.

Rectangular DRA Array for 24 GHz ISM-Band Applications

A planar array antenna consisting of 6 units of rectangular dielectric resonators fed by means of novel microstrip lines through aperture coupling is presented. The structure is designed in such a way that two different modes are excited in the array elements that yield a high bandwidth and gain. Based on the experimental results, the antenna is seen to have an impedance bandwidth of 6.98% centered at 24.09 GHz. Furthermore, the antenna gain is seen to lie between 7 and 9.5 dBi within its entire bandwidth, whereas the cross-polarization discrimination is better than 45 dB in the boresight. These features, along with its low-profile structure, make this antenna a suitable candidate for usage in short-range radars, wireless sensor nodes, and other sensors for the 24 GHz Industrial, Scientific, and Medical (ISM) band.