Beatriz Mencia-Oliva

3-D High-Resolution Imaging Radar at 300 GHz With Enhanced FoV

We have developed a 3-D high-resolution radar at 300 GHz with a cell resolution of 1×1.6×1.6 cm3 at a standoff distance of 8 m for security applications. The selection of an operating frequency of 300 GHz, a bandwidth of 27 GHz, and a field of view of 50×90 cm2 improves the through-clothes imaging of person-borne concealed objects. The radars antenna design allows single-pixel imaging at a frame rate of two frames per second. A reduction in cost and power consumption and improvements in image quality are additional requirements taken into account in the design of this radar system.

Low-Cost CW-LFM Radar Sensor at 100 GHz

This paper presents a W -band high-resolution radar sensor for short-range applications. Low-cost technologies have been properly selected in order to implement a versatile and easily scalable radar system. A large operational bandwidth of 9 GHz, required for obtaining high-range resolution, is attained by means of a frequency multiplication-based architecture. The system characterization to identify the performance-limiting stages and the subsequent design optimization are presented. The assessment of system performance for several representative applications has been carried out.

Bifocal Reflector Antenna for a Standoff Radar Imaging System With Enhanced Field of View

A unique multireflector bifocal antenna design for real-time standoff imaging applications is presented in this work. The antenna is used in combination with a 300 GHz radar sensor to acquire images at 8 m over a large (80 × 50 cm) field of view (FoV). The increased FoV is obtained by the use of an antenna system composed by a bifocal elliptical Gregorian with an extended subreflector to allow for fast scanning of a beam spot. The scanning is achieved by the combination of the rotation and vertical tilting of a flat small secondary mirror. The design, simulations, prototype description and experimental results of a manufactured working prototype are presented.

DDS-Based Signal-Generation Architecture Comparison for an Imaging Radar at 300 GHz

Submillimeter-wave imaging radars for standoff detection require broadband and fast-switch signal-generation architectures in order to achieve a high-range-resolution and near-video-rate imaging system. The signal generation has a strong influence on the radar image quality, primarily due to the transmitted phase noise. Two direct digital synthesis-based architectures for continuous-wave linear-frequency-modulated signal generation have been fabricated and tested for a high-range-resolution imaging radar at 300 GHz for standoff sensing of person-borne concealed threats. In order to select the signal-generation architecture that ensures the proper operation of the imaging radar with a cost-saving objective, three figures of merit have been used: 1) radar image quality; 2) power consumption; and 3) cost. The impact of the signal-generation architectures on the imaging radar indicates that both architectures present a similar radar performance in terms of radar image quality, although the narrowband direct-digital-synthesis/phase-locked loop scheme is a cost-effective solution compared with the broadband direct-digital-synthesis scheme in order to develop an affordable and energy-efficient high-performance preindustrial radar prototype.

Experimental radar imager with sub-cm range resolution at 300 GHz

This paper presents a high range resolution radar sensor working in the submillimeter-wave band for standoff detection and security applications. Low-cost technologies have been properly selected in order to implement a versatile and easily scalable radar system. A large operational bandwidth, required for high range resolution, is attained by means of a frequency multiplication-based architecture. This radar system sweeps a bandwidth of 27 GHz. The final application allows the generation of 3D images by means of the radar front-end integrated with a bifocal ellipsoidal Gregorian reflector system. The scene of interest is elliptically scanned at a standoff range of 8 m.

100-GHz FMCW radar front-end for ISAR and 3D imaging

This paper presents the design of a 100-GHz imaging radar system with operating bandwidth of 9 GHz and, thus, a theoretical range resolution below 2 cm. The high-resolution FMCW radar consists of a front-end of commercial components (COTS) operating at frequencies up to 100 GHz. Different technologies are involved in this development such as digital signal generation, microstrip designed circuits or waveguide components. An experimental trial has been performed. Results show that the effective range resolution is better than 3.1 cm, without resorting to any technique for compensation of amplitude non-linearities of the transmitted waveform.

Propagation Measurements at 19.7 and 99 GHz Using Ground-Based Radiometers

Radiometers are commonly used in order to assess the atmospheric propagation channel under low-attenuation and scatter-free conditions, with an increasing tendency toward using millimeter frequencies. In this letter, the interest is concentrated on the analysis of atmospheric attenuation measurements simultaneously obtained, under clear sky and the presence of clouds, by two independent and colocated ground-based radiometers at 19.7 and 99 GHz, in April of 2012 in Madrid, Spain. The experimental results obtained are in agreement with the estimations based on vertical meteorological profiles, and it is relevant to mention the high sensitivity to cloud liquid water provided by the measurements at 99 GHz. In general, the perspective of this work points toward the validity of using millimeter radiometry in propagation applications.

COTS technologies for radar sensors at millimeter-wave bands

Radar sensors at millimeter wavelengths offer significant advantages over systems operating at lower frequencies, such as transmitting large bandwidths while keeping compactness and cost-effectiveness. The implementation of these systems usually requires to resort to integration of heterogeneous technologies, which is a key issue addressed in this paper. A 100-GHz high-resolution FMCW radar, composed of both commercial-off-the-shelf (COTS) and designed-specific microstrip circuits, is presented. Different technologies are involved in this development: digital signal generation, microstrip designed circuits, waveguide components, etc. A simple experimental setup has been used to assess the system performance. An example of application of ISAR imaging is also presented.

Characterization of a 300 GHz imaging radar for standoff detection

A complete characterization of a 300 GHz high-resolution imaging radar with large Field of View is carried out in order to optimize its operational parameters. This imaging radar has been designed for standoff detection in security applications. The characterization is focused primarily on the spatial and range resolution. The results show that the imaging radar presents a resolution better than 2 cm. 3D images revealing a threat hidden under clothing validate the imaging radar performance.