scholarly journals Mathematical description of imaging processes in ultra-wideband active aperture synthesis systems using stochastic sounding signals

2021 ◽  
pp. 166-182
Author(s):  
Valeriy Volosyuk ◽  
Simeon Zhyla ◽  
Volodimir Pavlikov ◽  
Eduard Tserne ◽  
Anton Sobkolov ◽  
...  
Keyword(s):  
Spectral Density ◽  
Antenna Arrays ◽  
Mathematical Description ◽  
Phase Distribution ◽  
Coherence Function ◽  
Antenna System ◽  
Aperture Synthesis ◽  
Ultra Wideband ◽  
Radio Image ◽  
Wideband Signals

Mathematical models of the fields of stochastic ultra-wideband signals that are necessary for solving problems of aperture synthesis of images using active radar methods are presented. The expediency of using V-transformations in these problems has been substantiated, the effectiveness of which has already been proven for the mathematical description of ultra-wideband spatio-temporal fields in the methods of passive and active radar, as well as remote sensing, that are used to solve problems of radio astronomy, medicine, navigation. Using modern methods of mathematical analysis and the theory of ultra-wideband systems, the physical essence of radio images obtained with the help of algorithms for coherent and incoherent signal processing is investigated. According to these algorithms, it is proposed to divide images into coherent and incoherent. Coherent images include those in which its amplitude and phase are recorded separately. In the case of an incoherent image, only its amplitude (power or related characteristic) is recorded. To describe of the obtained radio image structure, new concepts of the spectral density of the complex spatial coherence function (SDCSCF) and the spectral density of the spatial autocorrelation function of the amplitude-phase distribution (SDFSAF APD) are introduced. Application-use of functions is expedient and fundamentally necessary for solving problems of aperture synthesis using stochastic ultra-wideband signals. A mathematical description of the structures obtained by aperture synthesis of radio images is given. Here, studies are conducted for the general case of using a continuous (idealized) aperture, and for using an antenna system with spatially separated receiving elements. Simulation of the heuristic synthesized algorithm for constructing incoherent radio images is conducted. The possibility of using antenna arrays and synthesized aperture synthesis algorithms for solving problems of image formation in a survey located directly under the aircraft (at sounding angles close to vertical) are substantiated.

scholarly journals Vivaldi Antenna Arrays Feed by Frequency-Independent Phase Shifter for High Directivity and Gain Used in Microwave Sensing and Communication Applications

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6091
Author(s):  
Jiwan Ghimire ◽  
Feyisa Debo Diba ◽  
Ji-Hoon Kim ◽  
Dong-You Choi
Keyword(s):  
Antenna Arrays ◽  
Phase Shifter ◽  
Antenna System ◽  
Phase Shifters ◽  
Ultra Wideband ◽  
Feed System ◽  
Power Splitter ◽  
Frequency Independent ◽  
Vivaldi Antenna ◽  
The Right

This paper describes a novel feed system for compact, wideband, high gain six-slot Vivaldi antenna arrays on a single substrate layer using a unique combination of power splitters based on binary T-junction power splitter topology, frequency-independent phase shifter, and a T-branch. The proposed antenna system consists of six Vivaldi antennas, three on the left, and three on the right arm. Each arm connects with T-junction power divider splitter topology, given that the right arm is linked through a frequency-independent phase shifter. Phase shifters ensure that the beam is symmetrical without splitting in a radiating plane so that highly directive radiation patterns occur. The optimal return losses (S-parameters) are well enriched by reforming Vivaldi’s feeding arms and optimizing Vivaldi slots and feeds. A novel feature of our design is that the antenna exhibits the arrangements of a T-junction power splitter with an out-of-phase feeding mechanism in one of the arms, followed by a T-branching feeding to even arrays of proper Vivaldi antenna arrangement contributing high realized gain and front-to-back ratio up to 14.12 dBi and 23.23 dB respectively applicable for not only ultra-wideband (UWB) application, also for sensing and position detecting. The high directivity over the entire UWB frequency band in both higher and lower frequency ranges ensures that the antenna can be used in microwave through-wall imaging along with resolution imaging for ground penetration radar (GPR) applications. The fabricated antenna parameters are in close agreement with the simulated and measured results and are deployed for the detection of targets inside the voids of the concrete brick.

APERTURE SYNTHESIS OF SURFACE IMAGES USING ACTIVE REMOTE SENSING WITH ULTRA-WIDEBAND STOCHASTIC SIGNALS

2020 ◽  
Vol 79 (15) ◽  
pp. 1327-1347
Author(s):  
M. V. Nechyporuk ◽  
V. V. Pavlikov ◽  
A. D. Sobkolov ◽  
E. O. Tserne ◽  
Valerii K. Volosyuk ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Aperture Synthesis ◽  
Ultra Wideband ◽  
Stochastic Signals ◽  
Surface Images

Cuboidal quad-port UWB-MIMO antenna with WLAN rejection using spiral EBG structures

2021 ◽  
pp. 1-8
Author(s):  
Sumon Modak ◽  
Taimoor Khan
Keyword(s):  
Close Agreement ◽  
Ground Plane ◽  
Antenna System ◽  
Ultra Wideband ◽  
Electromagnetic Bandgap ◽  
Mimo Antenna ◽  
Simulated Performance ◽  
Notched Band ◽  
Multiple Input ◽  
Band Characteristic

Abstract This study presents a novel configuration of a cuboidal quad-port ultra-wideband multiple-input and multiple-output antenna with WLAN rejection characteristics. The designed antenna consists of four F-shaped elements backed by a partial ground plane. A 50 Ω microstrip line is used to feed the proposed structure. The geometry of the suggested antenna exhibits an overall size of 23 × 23 × 19 mm3, and the antenna produces an operational bandwidth of 7.6 GHz (3.1–10.7 GHz). The notched band characteristic at 5.4 GHz is accomplished by loading a pair of spiral electromagnetic bandgap structures over the ground plane. Besides this, other diversity features such as envelope correlation coefficient, and diversity gain are also evaluated. Furthermore, the proposed antenna system provides an isolation of −15 dB without using any decoupling structure. Therefore, to validate the reported design, a prototype is fabricated and characterized. The overall simulated performance is observed in very close agreement with it's measured counterpart.

scholarly journals A Graphene-Assembled Film Based MIMO Antenna Array with High Isolation for 5G Wireless Communication

2021 ◽  
Vol 11 (5) ◽  
pp. 2382
Author(s):  
Rongguo Song ◽  
Xiaoxiao Chen ◽  
Shaoqiu Jiang ◽  
Zelong Hu ◽  
Tianye Liu ◽  
...  
Keyword(s):  
Antenna Array ◽  
Antenna Arrays ◽  
Multiple Input Multiple Output ◽  
Frequency Selective Surface ◽  
Antenna System ◽  
Antenna Element ◽  
Mimo Antenna ◽  
High Isolation ◽  
Input Multiple Output ◽  
Alternative Material

With the development of 5G, Internet of Things, and smart home technologies, miniaturized and compact multi-antenna systems and multiple-input multiple-output (MIMO) antenna arrays have attracted increasing attention. Reducing the coupling between antenna elements is essential to improving the performance of such MIMO antenna system. In this work, we proposed a graphene-assembled, as an alternative material rather than metal, film-based MIMO antenna array with high isolation for 5G application. The isolation of the antenna element is improved by a graphene assembly film (GAF) frequency selective surface and isolation strip. It is shown that the GAF antenna element operated at 3.5 GHz has the realized gain of 2.87 dBi. The addition of the decoupling structure improves the isolation of the MIMO antenna array to more than 10 dB and corrects the antenna radiation pattern and operating frequency. The isolation between antenna elements with an interval of 0.4λ is above 25 dB. All experimental results show that the GAF antenna and decoupling structure are efficient devices for 5G mobile communication.

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