This paper presents a novel system to obtain images from the underground based on ground penetrating radar (GPR). The proposed is composed by module mounted board an unmanned aerial vehicle (UAV), which allows safe inspection of difficult-to-access areas without being in direct contact with soil. Therefore, it can be used detect dangerous buried objects, such as landmines. measurements are coherently combined using synthetic aperture (SAR) algorithm, requires cm-level accuracy positioning...

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...

In this paper, we propose a ball grid array (BGA) module with an integrated 3-D-printed plastic lens antenna for application in dedicated 130 GHz OOK transceiver that targets the area of 5G backhaul/fronthaul systems. The main design goal was full integration small footprint energy-efficient transceiver. system must be compact and cost effective while delivering approximately 30 dBi gain working band, defined as 120 to 140 GHz. Accordingly, 2 × aperture-coupled patch antennas designed 7...

This paper presents a broadband and phaseless synthetic aperture radar (SAR) with efficient sampling. The design relies on novel monostatic element comprising transmitter receiver. element, together computationally inexpensive algorithm, can retrieve the phase of scattered field at all working band except for two small safety margins lower upper frequencies. Furthermore, retrieval works independently transmitter/receiver position. Consequently, conventional approaches to reduce number...

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...

A new submillimeter-wave imaging system based on the frequency scanning concept is presented. Using significantly less information than beam-steering techniques, scanning-based systems are able to provide angular in range-based radar which do not allow mechanical or electronic beam steering. Several strategies have been adopted overcome low dynamic range due propagation losses and non-specular reflection object-under-test. Moreover, only capable of detecting placement objects, but also their...

An optimisation framework for near field multifocusing on antenna arrays is proposed. Its aim to obtain the feeding weights that must be applied elements of array so focuses two or more targets simultaneously. The method based definition a proper cost function, which minimised using an algorithm over equivalent least squares problem. success technique noted in fact different parameters can obtained: magnitude and phase only synthesis. In order show efficiency method, several tests are...

An antenna diagnostics method based on off-axis holography is presented in this letter. In novel phaseless measurement setup, the reference wave synthesized by means of a mechanical phase shifting, and therefore use shifter avoided, yielding an accurate low-cost system. The technique validated simulation as well measurement. Accurate results prove system capability for tasks.

A new efficient method for broadband antenna characterization from phaseless acquisitions in the frequency-domain (FD) is presented. The phase-retrieval technique based on an extrapolation of off-axis indirect holography. In common with conventional approach, power interferometric field under test (AUT) and a reference antenna, whose known advance, as well AUT alone, measured at desired frequencies. Nevertheless, phase retrieval accomplished independently each spatial point by filtering...

A three-axes planar measurement setup for antenna characterization and inverse scattering applications is described. The need a new facility capable of working at millimeter sub frequency bands the main motivation this work. system can be divided into two blocks devoted to mechanical radiofrequency control respectively. Frequency band extended up 330 GHz by means mixing heads, surface 1450×1500×1100 mm, with 0.01 mm positioning accuracy achieved. Measurement provided an easy-to-use graphical...

A conventional synthetic aperture radar (SAR)-based technique for soil permittivity estimation is presented in this contribution. Ground penetrating imaging techniques are mainly based on SAR algorithms that take into account the wave velocity accurate of buried objects. Reflectometers, datasheets, and indirect observation methods commonly considered characterization. However, factors such as humidity temperature may cause some variations constitutive parameters. This contribution proposes a...

Millimetre-wave imaging is a powerful non-destructive inspection technique which has become widely used in areas such as through-the-wall or concealed weapon detection. Nevertheless, current systems are usually limited to either single view point providing 3D millimeter-wave model multiview relying on the accurate movement of robot arm through precise positions resulting very bulky systems. In this paper, we present set techniques achieve millimetre-wave scanner. The aperture scanner kept...

A novel ultrathin near-field (NF) 2-bit 24 × 24element transmitarray lens working at X-band is presented in this letter. The aim of antenna to focus a point located the NF without using any complex feeding network. In order obtain planar with very low profile, 2-bit-design approach used diminish number layers structure. simulations have been done model based on concept that an array can be calculated as sum far-field contributions every single one its elements. These are considered plane...

Airborne-based Ground Penetrating Radar (GPR) systems have proved to be an efficient solution for safe and accurate detection of buried threats such as Improvised Explosive Devices (IEDs) anti-personnel anti-tank landmines. The design these prototypes is influenced by several parameters the working frequency band or maximum weight size payload placed on board Unmanned Aerial Vehicle (UAV). In this sense, one main bottlenecks found in proper selection GPR antenna. This contribution focuses...

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 letter, a radio frequency identification (RFID)-based location and tracking system that uses receiver signal strength (RSS) measurements is presented. The intended to be deployed at industrial scenarios or warehouses involving heavy machinery vehicles in motion such as forklifts, and/or low visibility areas, aiming preventing accidental collisions with workers. For purpose, RFID tags are attached helmets of the UHF reader antennas located vicinity area where workers creating coverage...

The aim of this paper is to introduce the use sparse multistatic arrays reduce number elements in novel portable and muti-view millimiter-wave scanners. Thus, complexity these scanners significantly reduced. Furthermore, sparsity expected enable embedding a conventional optical camera sensor inside aperture scanner allowing reduction size. This used build complementary 3-D model as well estimate millimeter-wave position so that imaging merging techniques can be applied. approach validated...

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 paper introduces a hybrid method that combines two 3-D imaging methods of very different nature but complementary. On the one hand, depth camera, also known as RGB-D is used in order to obtain scan target under test. other synthetic aperture radar at millimeter-wave frequency band exploit penetration capabilities these waves, allowing electromagnetic imaging. As result, system can provide complementary and aligned models. In contrast previous work, which position estimation external...

The low cost and compactness of transmit-array antennas (TAs) make them attractive for 5G backhaul links. However, the TA advantage is less obvious when considering broadband operation requirement. Two main factors influence bandwidth performance, namely: 1) unit cells, 2) number 360° phase wrapping zones in aperture, which are designed a specific frequency. Herein, we overcome these limitations by using all-dielectric cells (inherently broadband) developing general method to quantify manage...

This letter presents a dual-band Smart Electromagnetic Skin (SES) for millimeter-wave 5G applications, which provides simultaneous operation at the 28/39-GHz bands with independent reflection performance each band (i.e., different incidence and angles). The SES consists of two-layer reflectarray panel 202.5-mm side, produces two reflected beams in dual-polarization when it is illuminated from feeders (one operating band). A prototype has been fabricated tested, measured radiation patterns...

The aim of this study is to present a technique for object geometry retrieval using scattered field information based on phaseless acquisition, so that scanning system can be implemented without the need an expensive vector network analyser. inverse scattering accomplished through two-step strategy powered thanks combination signal with synthesised reference wave. Thus, phase firstly recovered by considering spectral properties mixed signal. Secondly, reflectivity computed means algorithm...

A phaseless data acquisition applied on a reduced set of points is presented for inverse scattering problems. The setup based the Leith-Upatnieks holography with synthesized reference waves so that phase wave can be adjusted to acquire so-called "reduced field" instead regular field. Thus, nonregular sampling techniques resulting in strong reduction number points. technique validated using simulation and measurement examples at microwave frequencies.

This letter presents a cost-effective technique for through-the-wall imaging of objects beyond wall. The approach relies on an amplitude-only multimonostatic radar that operates as synthetic aperture radar. In contrast to conventional approaches, the system employs recent broadband techniques phase retrieval. Thus, complexity scanner is reduced, whereas it preserves capacities retrieve 3-D profile objects. Moreover, compatible with state-of-the art require full (i.e., amplitude and phase)...