GPR system onboard a UAV for non-invasive detection of buried objects

Copia del artículo enviado al congreso (ya está aceptado para su presentación en el mismo)In this contribution, a novel subsurface imaging system to detect buried targets is presented. It is mainly composed by a Ground Penetrating Radar (GPR) mounted onboard an Unmanned Aerial Vehicle (UAV). Thus, the system can be used to inspect areas without being in contact with the soil, which makes it useful for detecting dangerous objects, such as landmines. The system architecture and some of the first prototype measurements, which are post-processed using a Synthetic Aperture Radar (SAR) algorithm, are presented in this contribution.This work has been supported by Government of Spain (under projects TEC2014-55290-JIN, TEC2015-73908-JIN and grant FPU15/06341), Government of Asturias (IDI/2017/000095) and Galician Government (under project GRC2015/018) and under agreement for funding AtlantTIC.IEEE Antennas and Propagation Society International Symposiu

Recent advances in high-resolution Ground Penetrating Radar on board an Unmanned Aerial Vehicle

European Conference on Antennas and Propagation (EuCAP) (13th. 2019. Krakow, Poland

Evaluation of Positioning Techniques for mm-Wave Portable Scanners

European Conference on Antennas and Propagation (12th, 2018, London

Synthetic aperture radar imaging system for landmine detection using a ground penetrating radar on board a unmanned aerial vehicle

This paper presents a novel system to obtain images from the underground based on ground penetrating radar (GPR). The proposed system is composed by a radar module mounted on board an unmanned aerial vehicle (UAV), which allows the safe inspection of difficult-to-access areas without being in direct contact with the soil. Therefore, it can be used to detect dangerous buried objects, such as landmines. The radar measurements are coherently combined using a synthetic aperture radar (SAR) algorithm, which requires cm-level accuracy positioning system. In addition, a clutter removal technique is applied to mitigate the reflection at the air-soil interface (which is caused by impedance mismatching). Besides the aforementioned advantages, the system can detect both metallic and dielectric targets (due to the use of a radar instead of a metal detector) and it allows to obtain high-resolution underground images (due to the SAR processing). The algorithms and the UAV payload are validated with measurements in both controlled and real scenarios, showing the feasibility of the proposed system.Ministerio de Economía y Competitividad | Ref. TEC2014-54005-PMinisterio de Economía y Competitividad | Ref. TEC2014-55290-JINMinisterio de Economía y Competitividad | Ref. TEC2015-73908-JINMinisterio de Economía y Competitividad | Ref. TEC2015-65353-RAgencia Estatal de Investigación | Ref. RYC-2016-20280Ministerio de Educación | Ref. FPU15/06341Gobierno del Principado de Asturias | Ref. PCTI 2013-2017Gobierno del Principado de Asturias | Ref. FC-15-GRUPIN14-114Gobierno del Principado de Asturias | Ref. IDI/2017/000095Xunta de Galicia | Ref. GRC2015/01

An Ultrathin 2-bit Near-Field Transmitarray Lens

A novel ultra-thin Near-Field 2-bit 24x24-element transmitarray lens working at X-Band is presented in this letter. The aim of this antenna is to focus in a point located in the Near-Field without using any complex feeding network. In order to obtain a planar lens with a very low profile, a 2-bit-design approach is used to diminish the number of layers used in the structure. The simulations have been done using a model based on the concept that the Near-Field of an array can be calculated as the sum of the Far-Field contributions of every single one of its elements. These are considered as plane apertures over which the tangential electric field is constant. In order to validate the results of this model, they are compared with both those obtained with a full-wave commercial software and those from measurements. Thus, a Near-Field-antenna is manufactured and measured showing the measurements good concordance with the results of the mode

Array Optimization for an On-The-Move 3D Imaging System Demonstrator

IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting ( 2018. Boston)In this work, array optimization for an imaging system demonstrator is presented. It is able to create 3D images of people as they walk through the scanner and it makes use of a very low number of transceivers. The array positions have been optimized to minimize grating lobes and maximize resolution for a given number of array elements

Unmanned aerial system for antenna measurement (UASAM)

European Conference on Antennas and Propagation (EuCAP 2018) (12th. 2018. London)The main goal of this contribution is to provide an overview of an Unmanned Aerial System for Antenna Measurement (UASAM), which will be presented at the AMTA Scientific Workshop on “UAV-based Antenna and Field Measurements”. UASAM is a compact low-cost system that can be used for in-situ antenna measurement and diagnostics. It makes use of a Real Time Kinematik (RTK) and a laser altimeter to georefer the measurements with cm-level accuracy. Field radiated by the Antenna Under Test (AUT) is measured with a low-cost power detector at several acquisition surfaces (even non-canonical surfaces) around the AUT (in the near field region). Next, an iterative phase retrieval technique is applied, being able to recover the AUT aperture fields. Furthermore, from these fields, Near-Field to Far-Field (NF-FF) transformation can be used to retrieve the radiation pattern. Several application examples for different kinds of AUTs will be shown in the workshop. In addition, the impact of positioning and geo-referring accuracy will be discussed as well. This system is of great interest for those industrial applications where antenna diagnostics and radiation pattern assessment capabilities are required (e.g. analysis of antenna arrays, tilt testing of base station antennas, etc.) avoiding the need of stopping operational conditions

Indirect Off-Axis Holography for Antenna Metrology

Phase acquisition in antenna measurement, especially at millimeter- and submillimeter-wave frequencies, is an expensive and challenging task. The need of a steady phase reference demands not only a very stable source but unvarying temperature conditions and strong positioning accuracy requirements. Indirect off-axis holography is an interferometric technique that allows for characterization of an unknown field by means of a simple filtering process of the hologram or intensity interference pattern in the spectral domain, provided that the reference field, employed to interfere with the unknown field, is known in amplitude and phase. This technique can be used to avoid the effect of the errors related to the phase acquisition and to further develop new efficient and robust techniques capable of phase retrieval from amplitude-only acquisitions allowing for cost and complexity reduction of the measurement setup. A short review of the state-of-the-art in antenna metrology is presented in this chapter, as well as a description of conventional indirect off-axis techniques applied to this field. Last sections are devoted to the description of novel measurement techniques developed by the authors in order to overcome the main limitations of the conventional methods