This paper presents a compact, low-cost unmanned aerial system for antenna measurement. The proposed overcomes existing limitations in terms of vehicle positioning and data geo-referring accuracy using real-time kinematic to achieve centimeter-level accuracy. Amplitude-only measurements acquired power sensor are processed by means the phaseless sources reconstruction method. is an iterative phase retrieval technique that allows recovering equivalent currents distribution, which characterizes...

Fourier-based methods for monostatic and bistatic setups have been widely used high-accuracy radar imaging. However, the multistatic configuration has several characteristics that make Fourier processing more challenging: 1) a nonuniform grid in k-space, which requires multidimensional interpolation methods, 2) image distortion when incident spherical wave is approximated by plane wave. This contribution presents imaging method systems, solving aforementioned limitations: first, using...

The optimization and use of a sparse array configuration for an active three dimensional (3D) millimeter wave imaging system personnel security screening is presented in this work. combination the procedure with Compressed Sensing techniques allows drastic reduction number sensors, thereby simplifying design fabrication reducing its cost. Representative simulation results showing good performance proposed are provided supported by sample measurements.

This paper presents a novel interrogation system that combines multiple millimeter wave transmitters and receivers to create real-time high-resolution radar images for personnel security screening. The main novelty of the presented is can be created as person being screened continuously moves across corridor where receivers, working in fully coherent architecture, are distributed. As moves, sequentially activated collect data from different angles inspect whole body. Multiple images, similar...

This work develops compressed sensing techniques to improve the performance of an active three dimensional (3D) millimeter wave imaging system for personnel security screening. The is able produce a high-resolution 3D reconstruction whole human body surface and reveal concealed objects under clothing. Innovative multistatic radar designs algorithms, which have been previously validated, are combined results over previous approaches. Compressed Sensing used drastically reduce number sensors,...

Burn excision, a difficult technique owing to the training required identify extent and depth of injury, will benefit from tool that can cue surgeon as where how much resect. We explored two rapid noninvasive optical imaging techniques in their ability burn tissue viable wound bed using an animal model tangential excision. Photoplethysmography (PPG) multispectral (MSI) were used image initial, intermediate, final stages excision deep partial-thickness burn. PPG maps blood flow skin's...

This contribution focuses on the limitations of Fourier-based imaging when applied to subsampled arrays used in multistatic millimeter-wave radar systems. The aim is determine relationship between size object under test (OUT), its position with respect aperture, and sampling requirements aperture so as recover aliasing-free images. Based analysis results, a method for recovering spectral information proposed, idea which replicate plane wave spectrum, then apply band-pass filter defined by...

An extension of compressed sensing (CS)-based millimeter-wave imaging techniques from two- to three-dimensional (2-D 3-D) is presented. The idea study the reduction in minimum number receivers with respect standard synthetic aperture radar (SAR) accurately recover geometry object-under-test. 3-D CS main drawback increased calculation time SAR algorithms. To overcome this limitation, a novel technique consisting splitting large problem as combination small ones proposed. These problems can be...

This article presents some recent developments in multiplebeam antennas (MBAs) based on reflectarrays for communication satellites the Kurz (K) and Kurz-above (Ka) bands. The existing high-throughput commonly employ four reflector to provide cellular coverage that is formed by multiple spot beams a four-color scheme. Reflectarray are proposed as an attractive solution design of novel MBA configurations produce multispot coverage, with smaller number apertures than conventional systems...

This article presents a novel low-profile broadband polarizing reflector to convert dual linear polarization (LP) into circular (CP). The cell is based on printed dipole technology and wideband performance in Ka-band. dimensions of the dipoles are adjusted by improve reflection phase against variations incidence angles or dimensions. A 25 cm flat demonstrator has been designed, fabricated, tested. design optimized for transmit (19.2-20.2 GHz) receive (29-30 frequencies Ka-band, but behavior...

This contribution describes the design of a multibeam parabolic reflectarray to produce two adjacent beams per feed in orthogonal circular polarization (CP) simultaneously at transmission (Tx) and reception (Rx) frequencies Ka-band. The variable rotation technique (VRT) has been applied cells based on types resonant elements, which makes it possible provide Tx Rx, as well implement an in-band optimization procedure reduce cross-polarization. A 90 cm designed, manufactured, tested multiple...

The main goal of this contribution is to present a clutter reduction technique for Ground Penetrating Radar (GPR) imaging. proposed based on subspace projection method applied the focused Synthetic Aperture (SAR) image. It consists decomposing image in its different eigenimages and classifying them as belonging clutter, target or noise subspaces. Several scenarios have been simulated order test performance has measured analyzing variation Signal-to-Clutter Ratio (SCR). In addition, it...

In this contribution, a novel subsurface imaging system to detect buried targets is presented. It mainly composed by Ground Penetrating Radar (GPR) mounted onboard an Unmanned Aerial Vehicle (UAV). Thus, the can be used inspect areas without being in contact with soil, which makes it useful for detecting dangerous objects, such as landmines. The architecture and some of first prototype measurements, are post-processed using Synthetic Aperture (SAR) algorithm, presented contribution.

This work presents a new radar system concept, working at millimeter wave frequencies, capable of detecting explosive related threats standoff distances. The consists two dimensional aperture randomly distributed transmitting/receiving antenna elements, and Passive Array Scatters (PAS) positioned in the vicinity target. In addition, novel norm one minimization imaging algorithm has been implemented that is producing super-resolution images. paper also includes numerical example which 7.5 mm...

This contribution describes the design of a dual-reflector multibeam antenna based on parabolic polarizing main reflector with flat reflectarray subreflector. concept is proposed to produce multiple beams in orthogonal CP for enabling broadband satellite communications Ka-band. The generates two per feed at transmit (19.7 GHz) and receive (29.5 frequencies Ka-band, which would make it possible reduce by half number conventional antennas required onboard same multispot coverage. set high-gain...

Broadband communication satellites in Ka-band commonly use four reflector antennas to generate a multispot coverage. In this paper, different multibeam antenna farms are proposed the complete coverage using only two reflectarrays, making it possible halve number of required onboard satellite. The solutions include flat and curved reflectarrays with single or dual band operation, operating principles which have been experimentally validated. designed for each farm analyzed evaluate their...

This contribution introduces a novel airborne system for subsurface sensing and imaging applications. The consists of Ground Penetrating Radar (GPR) mounted on an Unmanned Aerial Vehicle (UAV). Since the does not need to be in contact with soil, it is particularly useful some Non-Destructive Testing (NDT) applications such as landmine detection or archeological surveys. An overview first flight tests are shown this contribution. results these prove feasibility detect both metallic dielectric...

This article presents a physical optics-based simulator for the analysis of terahertz (THz) imaging systems. The simulation starts by calculating electromagnetic interactions inside multireflector system and incident field that focusing creates on target under inspection. In second step, electric modeled scatters back to receiver, is also calculated. allows predict behavior different targets before manufacturing. results are validated using measurements from an existing 300-GHz...

A study of the capabilities for phase error correction compressed sensing (CS) imaging techniques is presented. The idea to show that CS method able recover reflectivity images with a reduced number sensors even if system suffers from errors. comparison sparsity-driven approach (SDA) technique presented, analyzing SDA and performance different numbers sensors, values, sensor placement uncertainties. Validation synthetically blurred experimental data-collected using multistatic radar-is

This contribution is based on an novel imaging system able to create real time radar images for personnel security screening recently presented. The performed as the person being screened continuously moves across a corridor populated with transmitters and receivers, taking advantage of person's movement increase number observation angles. As part preliminary study build prototype on-the-move scanner, this work presents design sparse array perform multistatic imaging. Optimal operation...

In this work, the prototype of an array antennas to be used in a GPR mounted UAV is presented. The array, while light enough UAV, allows for faster scanning large areas and create high resolution radar images using Synthetic Aperture Radar algorithms. Preliminary calibration results show good imaging capabilities system.

This paper presents a novel approach to synthesizing curved reflectarrays using Geometrical Optics (GO). It introduces the concepts of virtual normal and path length shift, which enable vector-based formulation problem that can be solved ray tracing techniques. The is applied for design two different versions Dual Bifocal Reflectarray with parabolic main surface flat subreflectarray. first version aims enhance performance multibeam antenna by providing focal ring located at feed cluster...

This study presents the design process and preliminary results of a 1.8‐m reflectarray antenna able to generate complete multi‐spot coverage for transmission from geostationary satellite operating in Ka‐band (18.2–20.2 GHz). The is designed using newly validated method which makes it possible four spaced beams per feed at different frequencies polarisations. Two configurations have been evaluated: first, flat has produce total 108 spot two polarisations 27 dual‐polarised feeds; then,...

pNN50 is a metric derived from heart rate (HR) measurements, and it known to correlate with mental-workload changes in human subjects. Conventionally, this calculated based on the variability of successive time periods peak-to-peak occurrences HR data. In case noisy measurements HR, however, detection may not be reliable. Here, we present combined time-frequency domain analysis, benefiting Short Time Fourier Transform, by which can more accurately extract An experimental measurement added...