The authors propose a solution of the problem of radiovision using the reflective array, each element of which can change the reflection coefficient under the action of external control voltage. The focusing abilities of flat reflection array of monochromatic radiation were studied to solve the problem of radiovision. The array element based on waveguide with a controlled reflection coefficient was developed. The phase shift switching is 180°

Antipov, Vladimir B.

Eremeev, Aleksandr I.

Shipilov, Sergey E.

Yakubov, Vladimir P.

English

Tomsk State University Repository

Journal of Physics: Conference SeriesPAPER • OPEN ACCESSRadiotomographic system construction on thebasis of multi-elemental reflective arrayTo cite this article: A I Eremeev et al 2017 J. Phys.: Conf. Ser. 881 012016 View the article online for updates and enhancements.Related contentReflective Array with Controlled Focusingfor Radiotomographic ApplicationS E Shipilov, A I Eremeev and V PYakubov-Reflection of Plane Acoustic Waves at aSeawater-Marine Sediment InterfaceMasao Kimura-Measurements of Reflection Coefficient ofIon Waves in an Ion Beam-Plasma SystemShunichi Noda, Yoshiharu Nakamura,Yoshinobu Kawai et al.-This content was downloaded from IP address 92.63.68.50 on 23/10/2017 at 07:131Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing Ltd1234567890International Conference on Innovations in Non-Destructive Testing (SibTest) IOP PublishingIOP Conf. Series: Journal of Physics: Conf. Series 881 (2017) 012016  doi :10.1088/1742-6596/881/1/012016      Radiotomographic system construction on the basis of multi-elemental reflective array  A I Eremeev1, S E Shipilov2, V B Antipov3 and V P Yakubov4 1 Master Student, The Department of radiophysics, Tomsk State University, Tomsk, Russia 2 Candidate of Physico-mathematical Sciences, Associate Professor The Department of radiophysics, Tomsk State University, Tomsk, Russia 3 Candidate of Physico-mathematical Sciences, Head of laboratory, Siberian Physical-Technical Institute, Tomsk, Russia 4 Doctor of Physico-mathematical Sciences, Professor, The Department of radiophysics, Tomsk State University, Tomsk, Russia  E-mail: aleksandr_eremeev_93@mail.ru Abstract. The authors propose a solution of the problem of radiovision using the reflective array, each element of which can change the reflection coefficient under the action of external control voltage. The focusing abilities of flat reflection array of monochromatic radiation were studied to solve the problem of radiovision. The array element based on waveguide with a controlled reflection coefficient was developed. The phase shift switching is 180. 1.  Introduction Modern radiovision systems are applied for numerous purposes: to control the quality of materials, buildings and constructions as well as for medical applications. The development of computing technologies provided the application of the radiotomography techniques for the remote non-destructive testing and the diagnostics of the internal structure of radio-semitransparent media and the shape recovery of radio opaque objects. The task of radiotomography is the transformation of the data obtained from the multiangle scanning of target objects into the 3D visualization. The electronically and electromechanically scanned arrays are developed to obtain the multiangle projections of the wave field. However, the design and development of such arrays are complicated and expensive task, as it requires the development and control of numerous microwave transceiver channels. The development of the electronically scanned arrays widely prevails nowadays over the electromecanically scanned ones. Together with conventional phased arrays, the arrays of elements with controllable phase of reflection are extensively applied. The reflection elements are usually based on ferrite phase shifters, micromechanical systems or varactor diodes [1]. The phase switching of the array reflection coefficients enables the simulation of the Fresnel zone plate that provides the focusing of feeder radiation at a certain point. The waves from two neighboring Fresnel zones are counter-phased. The electronic scanning can be performed in a certain angle sector with the change in geometrical arrangement of zone rings [2-3]. In this case, the only transceiver at fixed position can be used. 21234567890International Conference on Innovations in Non-Destructive Testing (SibTest) IOP PublishingIOP Conf. Series: Journal of Physics: Conf. Series 881 (2017) 012016 doi :10.1088/1742-6596/881/1/012016      2.  Formulation of the problem In this research, the authors propose a solution of the problem of radiovision using the reflective array, each element of which can change the reflection coefficient by the external voltage control. The detailed task scheme presented in figure 1. A transmitted spherical wave be propagated in a free space defined in the Cartesian coordinate system. The transmitter (1) is placed at Z axis and at the h height from the reflective array (2). The test object (3) is placed above the array.  1 2 3 y z x r  0r  o  a rFigure 1. Task scheme. Set the focusing point coordinates as  0 0 0, ,x y z . Then, the Fresnel zone boundaries are defined by the equation:    2 22 2 2 20 0 02z x x y y h x y n          (1) where n is the number of the Fresnel zone boundary, λ is the wavelength of the sounding signal. Previously, two problems were solved [4]. The equation for reflection coefficient distribution was obtained, which provided the radiation focusing at the certain point. Also, the equation describing the field at the receiver point was obtained as well. The using of the 2D reflective array with controlled reflection coefficient to focus the monochromatic radiation for radiotomographic application were analyzed. This problem is solved by changing the focusing point, by switching the array elements. The numerical simulations with a test object approved the recovery of the test object shape. 3.  Waveguide element of the reflection array A waveguide was used as an element of the reflection array. The scheme of the waveguide array element and its pilot prototype are presented in figure 2.   Figure 2. Array element structure (1- semiconductor diode capacitor, 2- shorting plunger, 3- waveguide, 4- impedance transformer) and its external view. 31234567890International Conference on Innovations in Non-Destructive Testing (SibTest) IOP PublishingIOP Conf. Series: Journal of Physics: Conf. Series 881 (2017) 012016 doi :10.1088/1742-6596/881/1/012016      The varactor diode was installed into the waveguide section 11x5.5 mm in size. The waveguide impedance could be switched from low to high by altering the varactor capacity through the voltage adjustment. In that case, the installed varactor diode could either shunt the waveguide or transmit the propagated wave to the shortening plunger. In the latter, the phase shift to be set as 180 by the shorting plunger position. The waveguide element is simply constructed that makes possible its volume production as well as provides its cost competitiveness with printed phase shifters. 4.  The numerical and experimental results In the program CST Microwave Studio, we were investigated the model of waveguide element of the reflective array. Figure 3 is an image of model and a graph, which illustrate the phase reconstruction of the reflection coefficient due to a change in the capacitance of the varactor.   Figure 3. The numerical model of the waveguide element of the reflectance array and the result of simulation. The array element experimentally demonstrated the reproducibility of characteristics. In figure 4 is an experimental plot that shows the phase shift of the reflection coefficient by 180  when the control voltage on the varactor changes (for 24 GHz frequency). Varactor capacity varies from 0.2 to 2 pF. 22 23 24 25700650600550500450400350300250200150100500φ, deg. f, GHz С=0.2 pF, -180 deg. С=2 pF, -364 deg. 41234567890International Conference on Innovations in Non-Destructive Testing (SibTest) IOP PublishingIOP Conf. Series: Journal of Physics: Conf. Series 881 (2017) 012016 doi :10.1088/1742-6596/881/1/012016        Figure 4. Change in the phase of the reflection coefficient (1 – voltage applied to varactor +5 V, 2 – varactor voltage -5 V). To develop the experimental sample of the reflection array, the waveguide element and the array were simulated in CST Microwave Studio. Array model is presented in figure 5a.   а b Figure 5. Numerical model of reflective array made of waveguide elements of size 10x10 elements, and the Fresnel zone distribution. The distribution of the reflection coefficient  a r  was predefined, which was calculated by the algorithms [4] corresponding to the array size. The calculations were performed for the frequency of 24 GHz. The distribution of the reflection coefficient, which provides the focusing at the coordinates 0,0,10  sm is presented in figure 5b. The field focused with the waveguide-based reflection array is presented in figure 6. It was calculated in CST Microwave Studio. 22 23 24 25 2618016014012010080604020020406080100120140160180f, GHz φ, deg. 1 2 51234567890International Conference on Innovations in Non-Destructive Testing (SibTest) IOP PublishingIOP Conf. Series: Journal of Physics: Conf. Series 881 (2017) 012016 doi :10.1088/1742-6596/881/1/012016        а)   б)   c) Figure 6. Radiation focusing with the reflection array. The field distribution in the yz plane is presented in figure 6a. Figure 6b presents the field distribution in the xz plane. Figure 6c shows the field distribution in the xy plane as well as the field strength variation depending on the distance from the array. It is indicated that the field was focused at a certain point  0,0,10  sm which the distribution of the reflection coefficient corresponded to (figure 5b). An experiment was carried out with a array consisting of 100 elements (figure 7). The essence of the experiment was as follows: the transmitting antenna irradiated the array, the receiving antenna, which was installed in a two-coordinate scanner. The scanning was carried out in the focusing plane in the vertical and horizontal directions. The Agilent N5230C vector network analyzer was used as source and receiver. In this array, the distribution of the reflection coefficient was determined by means of a control voltage. 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 1700.10.20.30.40.50.60.70.80.910 10 20 30 40 50 60 70 80 90 100 110 120 130 14000.10.20.30.40.50.60.70.80.910 10 20 30 40 50 60 70 80 90 10011012013014015016017001 1032 1033 1034 103BI_Y1 BI_Y0 0 100 200 300 400 50000.10.20.30.40.50.60.70.80.91P_centr1 max P_centr1 P_centr0 0 50 100 150 200 250 300 350 400 450 50000.10.20.30.40.50.60.70.80.91y, mm E,  R.U x, mm E,  R.U  z, mm E,  R.U  61234567890International Conference on Innovations in Non-Destructive Testing (SibTest) IOP PublishingIOP Conf. Series: Journal of Physics: Conf. Series 881 (2017) 012016 doi :10.1088/1742-6596/881/1/012016       Figure 7. Automated experiment of focusing properties of a reflective array. As a result, we obtained the field intensity distribution in the focusing plane (figure 8). For the reliability of the results obtained, a similar experiment was carried out, but only in this case the array was in the off state. In other words, no distribution of the reflection coefficient was specified. For electromagnetic radiation, the grating was represented as a metal plate.   Figure 8. The distribution of the field intensity in the focusing plane in the vertical and horizontal directions (1 - the distribution of the reflection coefficient is given, 2 - the distribution of the reflection coefficient is not specified). The bars show the geometric dimensions of the array. When the array was in the off state, the intensity of the reflected field decreased by approximately 10 times. In order to shift the focus point, it is necessary to change the distribution of the reflection coefficient. The distribution for the focusing point with coordinates  6,0,20  sm is given. See the results of the experiment in figure 9. 100 80 60 40 20 0 20 40 60 80 10001.4 1032.8 1034.2 1035.6 1037 10370 70100 80 60 40 20 0 20 40 60 80 10000.20.40.60.8170 70150 120 90 60 30 0 30 60 90 120 15000.20.40.60.81100 1001 2 1 2 I,  R.U. I,  R.U. x, mm y, mm 71234567890International Conference on Innovations in Non-Destructive Testing (SibTest) IOP PublishingIOP Conf. Series: Journal of Physics: Conf. Series 881 (2017) 012016 doi :10.1088/1742-6596/881/1/012016 Figure 9. The distribution of the field intensity in the focusing plane in the vertical and horizontal directions (1 - the distribution of the reflection coefficient is given, 2 - the distribution of the reflection coefficient is not specified). It can be seen from the results that when the focus point is shifted from the central position, the intensity of the field at the focusing point decreases, and the side-lobe level increases. This is due to the fact that the array has a low-density filling and a small aperture. Thus, carried out experiments with a reflective array based on waveguide elements confirm its focusing properties. Hence, with the help of such an array and one transceiver, you can scan a certain area of space. Electronic scanning is carried out. To obtain radioimages of objects in this area. 5. ConclusionSo, the capability of the flat reflection array to focus a monochromatic radiation at a certain point were studied. The element of the array based on waveguide with a controlled reflection coefficient was developed. The controlled phase shift is 180 . The array model based on waveguide elements was simulated in CST Microwave Studio. These simulations proved the monochromatic radiation focusing with the array made up of waveguide elements. Experimental studies of a reflective array consisting of 100 waveguide elements confirmed the focusing properties of such a array. A hardware and software complex to control the array is being currently developed. The proposed structure of the reflection array provides the high-rate focusing at a certain point. Acknowledgments The research was supported by the Russian Ministry of Education and Science as a part of the state order No 3.2068.2017/4.6. References [1] Hum S V and Perruisseau-Carrier J 2014 IEEE Trans. Antennas Propag. 62 183-98 [2] Leon G, Herran L, Munoz M, Las-Heras F and Hao Y 2014 Prog. Electromagn. Res. 54 125-31 [3] Hajian M and Vree G, Ligthart L 2003 Antennas Propag.Mag. 45 13-25 [4] Shipilov S E, Eremeev A I and Yakubov V P 2016 J. Phys.: Conf. Series 671 012052 100 80 60 40 20 0 20 40 60 80 10000.10.20.30.40.50.670 70150 120 90 60 30 0 30 60 90 120 15000.10.20.30.40.50.6100 1001 2 1 2 I, R.U. I, R.U. x, mm y, mm 

Radiotomographic system construction on the basis of multi-elemental reflective array

http://vital.lib.tsu.ru/vital/access/services/Download/vtls:000623341/SOURCE1

Radiotomographic system construction on the basis of multi-elemental reflective array

Abstract

Similar works

Full text

Available Versions

Tomsk State University Repository