V. Razevig - Academia.edu (original) (raw)

Papers by V. Razevig

Holographic radar of Rascan type produce plan view subsurface images using five simultaneous freq... more Holographic radar of Rascan type produce plan view subsurface images using five simultaneous frequencies. Since it is continuous wave radar with no time-of-flight data, the reflections coming from different depths are superimposed into a single plan view. The first reflection is usually dominant on the image. However, if the reflectivity is large at the second boundary both reflected waves are received and interference occurs. As a result the image looks different from ones produced by only a first reflection. This interference might affect the proper interpretation of radar images. However, there is a benefit in that by observing the pattern of interference over five frequencies, the distance between two boundaries could be determined.

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Abstract Holographic subsurface radars (HSR) are not in common usage now; possibly because of th... more Abstract Holographic subsurface radars (HSR) are not in common usage now; possibly because of the historical view amongst radar practitioners that high attenuation of electromagnetic waves in most media of interest will not allow sufficient depth of penetration. It is true that the ...

FIELD: radio engineering, communication. SUBSTANCE: method includes stepwise variation of a signa... more FIELD: radio engineering, communication. SUBSTANCE: method includes stepwise variation of a signal in a given frequency range with a uniform step from f min = k min c D to f max = k max c D , where k min =0.72. k max =0.81, D is antenna diameter and c is the speed of light. The number of separate frequencies in the range from f min to f max is not less than five. The analysed portion of a surface is scanned. The radio hologram of the analysed portion is recorded and the orientation of the conducting subsurface cylinder is determined. The antenna is first oriented relative to the axis of the subsurface cylinder such that the electric field vector is situated perpendicular to the axis of the cylinder, and the surface is scanned with perpendicular polarisation. The antenna is then oriented relative to the axis of the cylinder such that the electric field vector is situated parallel to the axis of the subsurface cylinder, and the surface is scanned with parallel polarisation. The radio ...

2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall), 2019

This paper describes the setup and the experiment technique that were used to imitate the perform... more This paper describes the setup and the experiment technique that were used to imitate the performance of the new microwave personnel screening system. Its concept is based on the use of the relative motion of the subject in the vicinity of a sparse stationary antenna array to obtain both synthetic aperture, required to attain high radar image resolution, and multi-view geometry. The ambiguity of the subject's position and pose during the radar signal processing in the system is removed by the use of an RGB-D sensor that captures the depth map of the scene. Advantages and limitation of the experimental setup and technique are presented along with selected experimental results. Further development of the setup and the experimental technique is suggested.

2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall), 2019

Appeared on the market a decade ago devices, capable of capturing a depth map of the scene with h... more Appeared on the market a decade ago devices, capable of capturing a depth map of the scene with high spatial resolution and video frame rate, are frequently used in research in all areas of science and engineering where possibility of measuring depth at no additional cost gives a significant advantage. In the proposed paper, an application of such a device, an RGB-D videosensor, is considered for capturing the motion of a walking person with the aim of numerical simulation of the microwave personnel screening system of a new kind. In such a microwave screening system the synthetic aperture, required for obtaining the radar image with high spatial resolution, is formed by subject’s natural motion in the vicinity of a sparse stationary antenna array. The radar image for the whole surface of the subject’s body is computed with the trajectories of the articulated body parts provided by the RGB-D sensor data using modern computer vision methods. This paper describes the numerical experim...

2017 Progress In Electromagnetics Research Symposium - Spring (PIERS)

Dinosaurs are an interesting group of ancient animals, the study of which can give valuable infor... more Dinosaurs are an interesting group of ancient animals, the study of which can give valuable information about the evolution of life on the Earth. Study of their fossilized tracks can provide information not only about these animals' morphology, but also their behavior. Until now, research has been limited to dinosaur tracks and trackways fortuitously exposed on rock surfaces. The use of subsurface imaging radar provides the potential to detect tracks that remain hidden by younger strata in cases where a dielectric contrast exists between the layers, or a dielectrically anomalous film separates the track mold from overlying cast. In this paper the possibility of using the method of holographic subsurface radar to detect hidden tracks of dinosaurs is investigated. Research was carried out under laboratory conditions on a gypsum plaster mold and cast of an Anamoepus track using a radar scanning system operating in different bands at centimeter wavelengths.

2016 16th International Conference on Ground Penetrating Radar (GPR), 2016

This paper focuses on the development of the new holographic subsurface radar data acquisition te... more This paper focuses on the development of the new holographic subsurface radar data acquisition technique in which the position and the polarization of the microwave probe are established by its tracking with video. This technique allows adaptive interactive data acquisition when probe trajectory could not be predefined or be equally dense in the areas with no target. The data processing technique is based on an FFT-algorithm which allows interactive operation. The concept of the data acquisition is demonstrated on the data obtained with a prototype of the system consisting of a holographic subsurface radar and a web-camera. Contrast markers are used to detect and track the antenna. Further development of the system is suggested. The augmented reality devices are considered as more suitable systems for the realization of the considered technique.

2016 16th International Conference on Ground Penetrating Radar (GPR), 2016

This paper describes a system for non-destructive testing of radio transparent samples at microwa... more This paper describes a system for non-destructive testing of radio transparent samples at microwaves. The main components of the system are a vector network analyzer (VNA), one or several stationary antennas connected to it, and a two-coordinate flat mechanical scanner that moves the sample in the antennas vicinity. The VNA and the scanner are controlled by a personal computer, which can acquire the parameters measured by the VNA in a set of pre-programmed positions over the sample. The technical description of the setup, software components, and sample radar images are provided. Possible research applications of the setup and its future improvements are suggested.

2016 16th International Conference on Ground Penetrating Radar (GPR), 2016

In recent years, there has been a surge of new applications of composite materials and structures... more In recent years, there has been a surge of new applications of composite materials and structures in aerospace industry. The composites have many advantages over traditional metal alloys. They have, as a rule, better strength/weight ratio, withstand to unfavorable weather conditions and aggressive environments. Corrosion also doesn't affect them. Traditional methods of ultrasonic diagnostics are ineffective for porous composites such as polyurethane foam insulation, silicate fiber tiles as well as for honeycomb prepreg construction details due to high levels of acoustic wave attenuation in them. In some cases, microwave holographic subsurface radars can be a reasonable alternative to ultrasonic testing. A specially designed test setup, which uses a vector network analyzer for generating and receiving signals, was created. Operational frequency band of the test setup gives opportunity to carry out experiments in the broad range of 10MHz-24 GHz. The setup records complex multi-frequency holograms, for the reconstruction of which the software was developed. A sample of polyurethane foam insulation, which is used for shielding of rocket cryogenic fuel tanks, was tested in the setup. The sample had preliminary produced defects. Comparison of the samples testing results and the defects maps showed that they are in a good coincidence.

Proceedings of the 15th International Conference on Ground Penetrating Radar, 2014

Manual data acquisition with holographic subsurface radar is quite tedious as it requires monoton... more Manual data acquisition with holographic subsurface radar is quite tedious as it requires monotonous scanning with precise positioning at the beginning of each scan line and requirement to move along straight lines to obtain a microwave hologram. A good result with manual scanning requires some practice, which still leaves such difficulties as maintaining constant press to evade image interlace and rapidly degrading performance of the operator. To address these issues an electromechanical scanning system equipped with holographic subsurface radar is considered in the paper. The system allows automated acquisition of microwave holograms over an area with maximum dimension 77 by 84 cm and gives reproducible results through precise positioning. The scanning is performed with an adjustable distance to the surface without direct contact. The influence of a gap between scan plane and the sounding surface is later compensated by hologram reconstruction technique. The main mechanical and electronics components of the system are described as well as driver control strategy. A selection of acquired images is presented. The system is shown has significant increase in performance over manual scanning and recommended for automated data acquisition with other types of contact sensors.

Eighth International Conference on Ground Penetrating Radar, 2000

The purpose of our investigation is to develop sounding radar for non-destructive inspection of b... more The purpose of our investigation is to develop sounding radar for non-destructive inspection of buildings and structures designed for different uses, which can obtain high resolution radio-images representing the interior structure, objects and heterogeneities in load bearing and protecting construction. Our primary goal is to resolve problems dealing with the determination of strength of structures in service, repair and renovation of buildings.

Ninth International Conference on Ground Penetrating Radar, 2002

In this paper the mathematical models and results on processing the experimental single-frequency... more In this paper the mathematical models and results on processing the experimental single-frequency microwave holograms received by scanning subsurface radar with sine wave signal are submitted. The holograms reconstruction method with the use of support functions, which take into account the near field of the aperture antenna with round cylindrical waveguide, is analysed. The models consider both known and unknown phase shift of the signal reflected from the point object. It is theoretically and experimentally shown that single-frequency holograms reconstruction allows to estimate depth of shallowly buried objects and improve the resolution on the probing surface with the growth of objects depths.

This paper presents a reconstruction approach which exploits the field detected by a holographic ... more This paper presents a reconstruction approach which exploits the field detected by a holographic radar in order to localize and geometrically qualify a set of scattering objects. In particular, thanks to the adoption of the Kirchhoff Approximation, the problem is formulated as a linear inverse one wherein the unknown function is the characteristic function accounting for the support (location and geometry) of the target(s). The reconstruction performances of the approach are investigated through an accurate numerical analysis, and an experimental validation is also performed with the aim of testing the effectiveness and the practical relevance of the proposed method.

2016 Progress in Electromagnetic Research Symposium (PIERS), 2016

The idea of using the emerging augmented reality (AR) devices with scanning contact sensors is co... more The idea of using the emerging augmented reality (AR) devices with scanning contact sensors is considered in this paper. This concept is illustrated by the experimental setup which includes a holographic subsurface radar as a contact sensor, web-camera, and personal computer. The data acquisition is accomplished by tracking the radar antenna tagged by an AR-marker. The radar image is updated periodically in real time as more data samples become available, making the data acquisition adaptive. It is shown that the use of a video-based tracking system may increase the data acquisition speed by a factor of ten in comparison with the traditional scanning approach which requires collecting data along consecutive parallel lines over the whole area before calculating the radar image. The data visualization with AR removes the problem of radar data mapping from the computer screen to the probed scene. Further advantages of using AR-devices, which may influence the signal processing, includi...

A relatively new type of subsurface radar – holographic radar – is considered as means for nondes... more A relatively new type of subsurface radar – holographic radar – is considered as means for nondestructive testing (NDT) of buildings and edificial structures. Principle of its operation, advantages and disadvantages are considered, and compared to those of traditional subsurface radars of impulse type. The RASCAN family of holographic radars is presented along with technical specifications and typical case of applications in edificial field. Civil and historic building surveys, NDT of dielectric materials are considered in row with others applications. Each application area is illustrated by relevant data acquired in laboratory experiments or field tests. INTRODUCTION A family of holographic subsurface radars, named RASCAN, has been produced following more than ten years of research and development. RASCAN radars are a completely unique and innovative type of subsurface radar that operates with continuous wave, discrete frequencies around 2 GHz, 4 GHz or 7 GHz depending upon the mod...

2017 Progress In Electromagnetics Research Symposium - Spring (PIERS), 2017

The modern microwave personnel screening systems use either mechanical scanning by a linear array... more The modern microwave personnel screening systems use either mechanical scanning by a linear array to form synthetic aperture, or electronic switching of the antennas distributed over a surface in a form of a screen or portal. The microwave part of a screening system with mechanical scanning is simpler than the system with electronic switching due to the lesser number of channels. All the modern microwave screening systems have a bulky form factor, which is either a portal or a screen. This paper describes a new architecture of the microwave screening system in which the natural motion of a subject in the vicinity of a linear antenna array is used to form synthetic aperture. Such an architecture allows building a system in the smallest possible form-factor and with the minimal number of antennas with the capability to screen people on the move. In this paper, the experimental data are obtained by the setup consisting of a vector network analyzer and mechanical linear actuators used t...

Lack of effective non-contact ways for fall detection, which may result in development of health-... more Lack of effective non-contact ways for fall detection, which may result in development of health-threatening and life-threatening conditions, is a great problem of modern medicine, and in particular, geriatrics. In present work, we propose a concept of a low-cost portable fall detection framework utilizing bioradar technique for smart home environment. The bioradar was designed using a single-chip transceiver K-LC5 (RFbeam), a customized amplifier, a 16-bit precision ADC and a microcontroller. It was tested in experimental conditions with the help of 5 volunteers. We achieved accuracy of 97% and the Cohen's kappa of 89% for classifying fall episodes among other daily activities.

Relatively rare type of subsurface radars – the holographic radar – is considered in the article.... more Relatively rare type of subsurface radars – the holographic radar – is considered in the article. Its principle of operation, advantages and disadvantages are considered and compared to that of impulse radars. The RASCAN family of holographic radars is presented along with technical specifications and typical usage cases. Among the applications considered are civil and historic building surveys, non-destructive testing of dielectric materials, security applications, and humanitarian demining. Each application area is illustrated by relevant data acquired in laboratory experiments or field tests.

Antennas

Microwave imaging technique allows obtaining images of hidden objects in structures and media usi... more Microwave imaging technique allows obtaining images of hidden objects in structures and media using microwaves. This technique has various applications such as: nondestructive testing, medical imaging, concealed weapon detection, through-the-wall imaging, etc. Obtaining radar images in these applications is based on processing phase and amplitude of the reflected signal recorded over an aperture (a microwave hologram). Recently, systems began to appear in which the radar part is supplemented by an RGB-D sensor, which allows to obtain new capabilities. For example, there is the a microwave screening system architecture in which inverse synthetic aperture is formed by the natural motion of the subject in the vicinity of a stationary linear antenna array. The microwave system is complemented with an synchronous RGB-D video sensor which captures the trajectory of the moving subject in 3D and allows coherent processing of the radar signal. Another system detects objects buried under irre...

Insight - Non-Destructive Testing and Condition Monitoring

The study of ancient Egyptian monuments attracts the attention of experts from around the world. ... more The study of ancient Egyptian monuments attracts the attention of experts from around the world. A recent event that confirms this is the discovery, using muon sensors, of previously unknown cavities in the Great Pyramid of Giza (or Khufu's Pyramid). Since it is unfeasible to directly confirm this discovery by drilling, another independent non-destructive method is necessary to confirm this discovery and provide accurate determination of the locations and shapes of the cavities. Following a literature review of the different methods used in evaluating cultural objects, this paper analyses a possible framework for simulation of a holographic radar for detecting openings or other unknown structures of interest to archaeologists/Egyptologists and the public.