This article describes the principles of noise radar, emphasizing the importance of its electronic counter–counter measure (electronic protection) and electromagnetic compatibility performance and reviews some noise radar demonstrators trialed by NATO Research Task Groups. We now understand how to build noise radars with performance comparable with, e.g., a low-power marine navigation radar. Furthermore, this article discusses the distinctive issues involved in verifying the performance of noise radars.

This paper presents a novel technique to estimate the initial coordinates and velocity vector of moving targets, including those with velocities above the Nyquist limit, using a single synthetic aperture radar (SAR) sensor without increasing the pulse repetition frequency (PRF). The basic reasoning is that, although the returned echoes may be undersampled in the azimuth direction, their phase and amplitude are informative with respect to the moving target trajectory parameters. Therefore, the so-called blind angle ambiguity, inherent to systems using a single SAR sensor, is overcome. The proposed method samples the data in the spatial domain, along the signature curve which depends on the moving target trajectory parameters. The resulting algorithm is a highly efficient (from the computational point of view) ID matched filter. The effectiveness of the proposed scheme is illustrated using simulated SAR data and real data from the MSTAR public release data set, corresponding to a static SAR scene and a static BTR-60 with simulated motion.

In a pandemic, the availability of health indicators among at-risk populations, such as the elderly, is vital due to the disease’s rapid transmission and the need to act quickly to contain its evolution. Traditional clinical methods for monitoring vital signs typically require contact-based sensors that must be precisely attached by a skilled healthcare professional, are less practical for repeatable measurements, and are not suitable for long-term monitoring. Contactless vital signs monitoring, such as radar-based techniques or IR-thermal imaging, on the other hand, does not require the attachment of physical electrodes and can be useful for remote health monitoring and therefore reduce physical contact between subjects and healthcare professionals, ensuring social distancing, in particular, in nursing homes, and protecting the elderly population in this way from other external factors that increase the likelihood of infection. This article presents three main contributions: (i) vital signs characterization in the elderly population; (ii) a state-of-the-art review on the most prominent techniques and methods for Contactless Health Monitoring (CHM); (iii) the design, specification, and evaluation of a low-cost proof-of-concept CHM system for nursing homes, which includes an IoT Edge Device , which enables real-time vital signs monitoring (cardio-respiratory rates and elevated body temperature) using a multimodal approach based on Doppler radar and IR thermal imaging sensors, and thus generates health indicators without any type of contact or invasiveness. By direct comparison with reference instruments, results have shown an error below 10%, in 74%, 52%, and 96% of the cases for Heart Rate, Respiratory Rate, and Body Temperature measurements, respectively.

Currently, space debris represents a threat for satellites and space-based operations, both in-orbit and during the launching process. The yearly increase in space debris represents a serious concern to major space agencies leading to the development of dedicated space programs to deal with this issue. Ground-based radars can detect Earth orbiting debris down to a few square centimeters and therefore constitute a major building block of a space debris monitoring system. New radar sensors are required in Europe to enhance capabilities and availability of its small radar network capable of tracking and surveying space objects and to respond to the debris increase expected from the New Space economy activities. This article presents ATLAS, a new tracking radar system for debris detection located in Portugal. It starts by an extensive technical description of all the system components followed by a study that estimates its future performance. A section dedicated to waveform design is also presented, since the system allows the usage of several types of pulse modulation schemes such as LFM and phase coded modulations while enabling the development and testing of more advanced ones. By presenting an architecture that is highly modular with fully digital signal processing, ATLAS establishes a platform for fast and easy development, research, and innovation. The system follows the use of Commercial-Off-The-Shelf technologies and Open Systems which is unique among current radar systems.

Plastic marine litter is becoming a major environmental concern. Microwaves (MW) have potential for remote detection of floating macroplastics operating from Satellites or Airborne platforms, but very scarce and limited studies exist in the literature evaluating MW radar effectiveness for this purpose. We present first results of a systematic study on MW scattering of floating low-mass macroplastics at 2-20 GHz frequency band using radar techniques. Data was first collected in small-scale measurement campaigns carried out in an indoor facility capable of producing deep sea-like wave patterns, with different floating single-use plastic items. The study reveals that, for these targets, one important scattering contribution arises from the indentation they produce on the water. For the tested conditions, targets, and metrics, it was possible to detect several types of floating plastic targets down to 10 g/m ² concentration. Detection tended to significantly improve at the X-band, although the detection threshold depends on the combination of the mentioned conditions. Tests were extended also to two small-scale outdoor scenarios with natural wind and capillary waves. Detection of macroplastics was successful in these tested scenarios.

The paper presents a new methodology to retrieve slant-range velocity estimates for moving targets which induce a Doppler-shift beyond the Nyquist limit determined by the Pulse Repetition Frequency (PRF). The proposed scheme takes advantage of the fact that the range velocity of a moving target induces a Doppler-shift in the azimuth spectra which depends linearly on the fast-time frequency. We present results that take real and simulated SAR data.