Journal articles: 'Sensor networks. Antenna arrays'

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Januszkiewicz, Łukasz, Paolo Di Barba, and Sławomir Hausman. "Optimal Design of Switchable Wearable Antenna Array for Wireless Sensor Networks." Sensors 20, no. 10 (2020): 2795. http://dx.doi.org/10.3390/s20102795.

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In the paper, we present a novel approach to the optimum design of wearable antenna arrays intended for off-body links of wireless body area networks. Specifically, we investigate a four-element array that has a switchable radiation pattern able to direct its higher gain towards a signal source and a lower gain towards an interference. The aim is to increase the signal to interference ratio. We apply a genetic algorithm to optimize both the spatial placement and the feed phasing of the elementary on-body antennas. We propose a simplified, computationally efficient model for the simulation of the array radiation pattern. The model is based on full-wave simulations obtained with a simplified cylindrical model of the human body. We also propose, implement, and evaluate four objective functions based on signal to interference ratio, i.e., min-max, nadir point distance maximization, utopia point distance minimization, and full Pareto-like. Our optimized design obtained with this approach exhibits a significant performance improvement in comparison to the initial heuristic design.

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Le, Anh Tuyen, Le Chung Tran, Xiaojing Huang, et al. "Unbalanced Hybrid AOA/RSSI Localization for Simplified Wireless Sensor Networks." Sensors 20, no. 14 (2020): 3838. http://dx.doi.org/10.3390/s20143838.

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Source positioning using hybrid angle-of-arrival (AOA) estimation and received signal strength indicator (RSSI) is attractive because no synchronization is required among unknown nodes and anchors. Conventionally, hybrid AOA/RSSI localization combines the same number of these measurements to estimate the agents’ locations. However, since AOA estimation requires anchors to be equipped with large antenna arrays and complicated signal processing, this conventional combination makes the wireless sensor network (WSN) complicated. This paper proposes an unbalanced integration of the two measurements, called 1AOA/nRSSI, to simplify the WSN. Instead of using many anchors with large antenna arrays, the proposed method only requires one master anchor to provide one AOA estimation, while other anchors are simple single-antenna transceivers. By simply transforming the 1AOA/1RSSI information into two corresponding virtual anchors, the problem of integrating one AOA and N RSSI measurements is solved using the least square and subspace methods. The solutions are then evaluated to characterize the impact of angular and distance measurement errors. Simulation results show that the proposed network achieves the same level of precision as in a fully hybrid nAOA/nRSSI network with a slightly higher number of simple anchors.

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Nabeel, Muhammad, and Falko Dressler. "Turning Sensor Networks into Distributed Antenna Arrays for Improved Communication Performance." IEEE Communications Magazine 57, no. 9 (2019): 100–105. http://dx.doi.org/10.1109/mcom.001.1800742.

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Hasan, Mohammed Zaki, and Hussain Al-Rizzo. "Beamforming Optimization in Internet of Things Applications Using Robust Swarm Algorithm in Conjunction with Connectable and Collaborative Sensors." Sensors 20, no. 7 (2020): 2048. http://dx.doi.org/10.3390/s20072048.

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The integration of the Internet of Things (IoT) with Wireless Sensor Networks (WSNs) typically involves multihop relaying combined with sophisticated signal processing to serve as an information provider for several applications such as smart grids, industrial, and search-and-rescue operations. These applications entail deploying many sensors in environments that are often random which motivated the study of beamforming using random geometric topologies. This paper introduces a new algorithm for the synthesis of several geometries of Collaborative Beamforming (CB) of virtual sensor antenna arrays with maximum mainlobe and minimum sidelobe levels (SLL) as well as null control using Canonical Swarm Optimization (CPSO) algorithm. The optimal beampattern is achieved by optimizing the current excitation weights for uniform and non-uniform interelement spacings based on the network connectivity of the virtual antenna arrays using a node selection scheme. As compared to conventional beamforming, convex optimization, Genetic Algorithm (GA), and Particle Swarm Optimization (PSO), the proposed CPSO achieves significant reduction in SLL, control of nulls, and increased gain in mainlobe directed towards the desired base station when the node selection technique is implemented with CB.

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Kakoyiannis, Constantine G., and Philip Constantinou. "Compact Printed Arrays with Embedded Coupling Mitigation for Energy-Efficient Wireless Sensor Networking." International Journal of Antennas and Propagation 2010 (2010): 1–18. http://dx.doi.org/10.1155/2010/596291.

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Wireless sensors emerged as narrowband, resource-constrained devices to provide monitoring services over a wide life span. Future applications of sensor networks are multimedia-driven and include sensor mobility. Thus, sensors must combine small size, large bandwidth, and diversity capabilities. Compact arrays, offering transmit/receive diversity, suffer from strong mutual coupling (MC), which causes lower antenna efficiency, loss of bandwidth, and signal correlation. An efficient technique to reduce coupling in compact arrays is described herein: a defect was inserted in the ground plane (GNDP) area between each pair of elements. The defect disturbed the GNDP currents and offered multidecibel coupling suppression, bandwidth recovery, and reduction of in-band correlation. Minimal pattern distortion was estimated. Computational results were supported by measurements. The bandwidth of unloaded arrays degraded gracefully from 38% to 28% with decreasing interelement distance (0.25 to 0.10). Defect-loaded arrays exhibited active impedance bandwidths 37–45%, respectively. Measured coupling was reduced by 15–20 dB.

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Panduro, Marco A., Alberto Reyna, and David H. Covarrubias. "Non-Uniform Concentric Rings Design for Ultra-Wideband Arrays." Sensors 19, no. 10 (2019): 2262. http://dx.doi.org/10.3390/s19102262.

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This paper presents the design of aperiodic concentric ring arrays for ultra-wide bandwidths (UW-ACRA). This design of ultra-wideband arrays considers the synthesis of concentric rings in two cases: 1) non-uniform spacing between rings with non-uniform spacing between antenna elements of the same ring (UW-ACRAelements); and 2) non-uniform spacing between rings assuming that spacing between antenna elements of the same ring to be equal (UW-ACRArings). This is in order to eliminate the occurrence of grating lobes and generating array structures with useful ultra-wideband properties. The synthesis process is carried out by the well-known method of differential evolution (DE). Wireless sensor networks can take advantage of these properties to achieve less data traffic, efficient delivery of information and better energy efficiency.

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Albagory, Yasser, and Omar Said. "Optimizing Concentric Circular Antenna Arrays for High-Altitude Platforms Wireless Sensor Networks." International Journal of Computer Network and Information Security 6, no. 5 (2014): 1–8. http://dx.doi.org/10.5815/ijcnis.2014.05.01.

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Sharma, Sanjeev, Vimal Bhatia, and Anubha Gupta. "Noncoherent IR-UWB Receiver Using Massive Antenna Arrays for Wireless Sensor Networks." IEEE Sensors Letters 2, no. 1 (2018): 1–4. http://dx.doi.org/10.1109/lsens.2017.2778430.

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Kułakowski, Paweł, Javier Vales-Alonso, Esteban Egea-López, Wiesław Ludwin, and Joan García-Haro. "Angle-of-arrival localization based on antenna arrays for wireless sensor networks." Computers & Electrical Engineering 36, no. 6 (2010): 1181–86. http://dx.doi.org/10.1016/j.compeleceng.2010.03.007.

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Milijić, Marija, and Branka Jokanović. "Advanced high-gain slot antenna arrays for 5G and radar applications." Telfor Journal 13, no. 1 (2021): 29–34. http://dx.doi.org/10.5937/telfor2101029m.

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This paper presents an advanced design of high-gain slot antenna array at K-band using slots as radiating elements serially fed by coplanar waveguide (CPW). The arrays consist of identical slots of rectangular shape positioned symmetrically relative to the CPW feeding line. Firstly, the linear arrays of 14 slots are examined considering mainly their bandwidth and radiation characteristics. In addition, two identical linear sub - arrays of 14 slots are investigated when they have separate feeding in the form of two generators for each sub - array. Last, a CPW T-junction is employed to feed the antenna consisting of 2 x 14 slots which resulted in a wide operating bandwidth and maximum gain of 21.0 dBi which proved to be 2.25 dB less gain than with independent feeding. In order to enhance the antenna gain, both arrays are terminated with open-circuited stubs, so that the energy remaining after the last array element is reflected from the stub and re-radiated through the slot arrays. The length of the stubs is optimized to provide that the reflected wave is in phase with the forward-traveling waves at all the slot locations. In that way, very little energy is wasted and consequently the antenna gain is increased. The feed simplicity and uniplanar configuration of the slot arrays, designed for the frequency range 24.25-27.5 GHz, makes them attractive for radar sensors and high capacity 5G technology applications.

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Schäfer, Sassan, Simon Müller, Daniel Schmiech, and Andreas R. Diewald. "Radar system with dedicated planar traveling wave antennas for elderly people monitoring." Advances in Radio Science 18 (December 10, 2020): 97–110. http://dx.doi.org/10.5194/ars-18-97-2020.

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Abstract. Radar systems for contactless vital sign monitoring are well known and an actual object of research. These radar-based sensors could be used for monitoring of elderly people in their homes but also for detecting the activity of prisoners and to control electrical devices (light, audio, etc.) in smart living environments. Mostly these sensors are foreseen to be mounted on the ceiling in the middle of a room. In retirement homes the rooms are mostly rectangular and of standardized size. Furniture like beds and seating are found at the borders or the corners of the room. As the propagation path from the center of the room ceiling to the borders and corners of a room is 1.4 and 1.7 time longer the power reflected by people located there is 6 or even 10 dB lower than if located in the center of the room. Furthermore classical antennas in microstrip technology are strengthening radiation in broadside direction. Radar systems with only one single planar antenna must be mounted horizontally aligned when measuring in all directions. Thus an antenna pattern which is increasing radiation in the room corners and borders for compensation of free space loss is needed. In this contribution a specification of classical room sizes in retirement homes are given. A method for shaping the antenna gain in the E-plane by an one-dimensional series-fed traveling wave patch array and in the H-plane by an antenna feeding network for improvement of people detection in the room borders and corners is presented for a 24 GHz digital beamforming (DBF) radar system. The feeding network is a parallel-fed power divider for microstrip patch antennas at 24 GHz. Both approaches are explained in theory. The design parameters and the layout of the antennas are given. The simulation of the antenna arrays are executed with CST MWS. Simulations and measurements of the proposed antennas are compared to each other. Both antennas are used for the transmit and the receive channel either. The sensor topology of the radar system is explained. Furthermore the measurement results of the protoype are presented and discussed.

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Dihissou, Akimu, Aliou Diallo, Philippe Le Thuc, and Robert Staraj. "DIRECTIVE AND RECONFIGURABLE LOADED ANTENNA ARRAY FOR WIRELESS SENSOR NETWORKS." Progress In Electromagnetics Research C 84 (2018): 103–17. http://dx.doi.org/10.2528/pierc18032403.

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Varum, Tiago, João Caiado, and João N. Matos. "Compact Ultra-Wideband Series-Feed Microstrip Antenna Arrays for IoT Communications." Applied Sciences 11, no. 14 (2021): 6267. http://dx.doi.org/10.3390/app11146267.

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Modern communication systems require high bandwidth to meet the needs of the huge number of sensors and the growing amount of data consumed, and an exponential growth is expected in the future with the integration of internet of things networks. Spectrum regions in the millimeter waves have aroused new interests, mainly because of the contiguous bands available to meet these needs. In return, and to combat the high losses of propagation in these frequencies, higher gain antennas are needed. This paper describes the use of a logarithmic architecture in the design of microstrip antenna arrays, creating structures with high gain and ultra-wide bandwidth. Three different solutions are presented with five, seven, and nine elements, reaching about 25%, 30%, and 44% of bandwidth, achieving ultra-wideband behavior, efficient and with a compact structure operating at frequencies in around 28 GHz.

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Van Nieuwenhuyse, A., L. De Strycker, N. Stevens, J. P. Goemaere, and B. Nauwelaers. "Analysis of the Realistic Resolution with Angle of Arrival for Indoor Positioning." International Journal of Handheld Computing Research 4, no. 2 (2013): 1–16. http://dx.doi.org/10.4018/jhcr.2013040101.

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The increasing importance of localizing objects in indoor environments is the motivation for much research on localization algorithms. This paper focuses on the maximum achievable resolution for Angle of Arrival as a means to position objects inside rooms using equipment within the field of wireless sensor networks, thus dealing with restricted resources. A clear view on beamforming using antenna arrays is represented and is proven to be useful in Angle of Arrival measurements. A detailed overview of a dedicated algorithm, leads the authors to draw conclusions concerning the resolution. A reference value is defined, which allows the authors to calculate the realistic resolution for all room dimensions. In order to verify these theoretical outcomes with practical results, the development of a quadrature demodulation based antenna array architecture, operating at 2.4 GHz, is presented. The latter is based on a study of different phase shifting technologies.

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Zhang, Ruonan, Jiawei Liu, Xiaojiang Du, Bin Li, and Mohsen Guizani. "AOA-Based Three-Dimensional Multi-Target Localization in Industrial WSNs for LOS Conditions." Sensors 18, no. 8 (2018): 2727. http://dx.doi.org/10.3390/s18082727.

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High-precision and fast relative positioning of a large number of mobile sensor nodes (MSNs) is crucial for smart industrial wireless sensor networks (SIWSNs). However, positioning multiple targets simultaneously in three-dimensional (3D) space has been less explored. In this paper, we propose a new approach, called Angle-of-Arrival (AOA) based Three-dimensional Multi-target Localization (ATML). The approach utilizes two anchor nodes (ANs) with antenna arrays to receive the spread spectrum signals broadcast by MSNs. We design a multi-target single-input-multiple-output (MT-SIMO) signal transmission scheme and a simple iterative maximum likelihood estimator (MLE) to estimate the 2D AOAs of multiple MSNs simultaneously. We further adopt the skew line theorem of 3D geometry to mitigate the AOA estimation errors in determining locations. We have conducted extensive simulations and also developed a testbed of the proposed ATML. The numerical and field experiment results have verified that the proposed ATML can locate multiple MSNs simultaneously with high accuracy and efficiency by exploiting the spread spectrum gain and antenna array gain. The ATML scheme does not require extra hardware or synchronization among nodes, and has good capability in mitigating interference and multipath effect in complicated industrial environments.

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Yang, Guang You, Xiong Gan, Tuo Zheng, and Zhi Yan Ma. "A Study on Energy Consumption Optimization for Cooperative Beamforming in Wireless Sensor Networks." Key Engineering Materials 620 (August 2014): 625–31. http://dx.doi.org/10.4028/www.scientific.net/kem.620.625.

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In wireless sensor networks where the volume and energy of nodes are limited by batteries, which are difficult or prohibitively expensive to replace or recharge in the most of its application scenarios, so improving energy efficiency has very important significance.Cooperative beamforming forms virtual antenna arrays by multiple adjacent wireless sensor nodes, which improves the signal strength at the receiver and reduces the energy consumption of the transmitter by multiplexing gain and interference management.In this paper, the problem of energy consumption optimization for cooperative beamforming in wireless sensor networks was studied. First, considering both amplifier energy consumption and circuit energy consumption,energy consumption models for both broadcast phase and cooperative beamforming phase was presented.Then,we propose a two-step optimization to minimize the total energy consumption by optimizing the modulation parameter and the number of cooperative nodes.We simulate the total energy consumption for various transmission distances,modulation parameters , path losses and the number of cooperative nodes.The numerical results show that,for different system parameters, selecting the optimal modulation parameter and the optimal number of cooperative nodes can reduce total energy consumption and improve energy efficiency.

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Pasolini, Gianni, Anna Guerra, Francesco Guidi, Nicolò Decarli, and Davide Dardari. "Crowd-Based Cognitive Perception of the Physical World: Towards the Internet of Senses." Sensors 20, no. 9 (2020): 2437. http://dx.doi.org/10.3390/s20092437.

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This paper introduces a possible architecture and discusses the research directions for the realization of the Cognitive Perceptual Internet (CPI), which is enabled by the convergence of wired and wireless communications, traditional sensor networks, mobile crowd-sensing, and machine learning techniques. The CPI concept stems from the fact that mobile devices, such as smartphones and wearables, are becoming an outstanding mean for zero-effort world-sensing and digitalization thanks to their pervasive diffusion and the increasing number of embedded sensors. Data collected by such devices provide unprecedented insights into the physical world that can be inferred through cognitive processes, thus originating a digital sixth sense. In this paper, we describe how the Internet can behave like a sensing brain, thus evolving into the Internet of Senses, with network-based cognitive perception and action capabilities built upon mobile crowd-sensing mechanisms. The new concept of hyper-map is envisioned as an efficient geo-referenced repository of knowledge about the physical world. Such knowledge is acquired and augmented through heterogeneous sensors, multi-user cooperation and distributed learning mechanisms. Furthermore, we indicate the possibility to accommodate proactive sensors, in addition to common reactive sensors such as cameras, antennas, thermometers and inertial measurement units, by exploiting massive antenna arrays at millimeter-waves to enhance mobile terminals perception capabilities as well as the range of new applications. Finally, we distillate some insights about the challenges arising in the realization of the CPI, corroborated by preliminary results, and we depict a futuristic scenario where the proposed Internet of Senses becomes true.

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Kucuk, Kerem, and Adnan Kavak. "Connectivity Analysis for Wireless Sensor Networks with Antenna Array Integrated Central Node." Wireless Personal Communications 72, no. 2 (2013): 1361–71. http://dx.doi.org/10.1007/s11277-013-1083-2.

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Hotte, David, Romain Siragusa, Yvan Duroc, and Smail Tedjini. "A Concept of Pressure Sensor Based on Slotted Waveguide Antenna Array for Passive MMID Sensor Networks." IEEE Sensors Journal 16, no. 14 (2016): 5583–87. http://dx.doi.org/10.1109/jsen.2016.2571665.

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Zhang, Jin, Shuai Zhang, Xianqi Lin, Yong Fan, and Gert Pedersen. "3D Radiation Pattern Reconfigurable Phased Array for Transmission Angle Sensing in 5G Mobile Communication." Sensors 18, no. 12 (2018): 4204. http://dx.doi.org/10.3390/s18124204.

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This paper proposes a 3D radiation pattern reconfigurable antenna (RPRA) and a reconfigurable phased array (RPA) for 5G mobile communication. The antenna and array are working at 28 GHz, which is selected as a 5G communication band in many countries. The proposed phased array will be applied as sensors to find out the optimal transmitting–receiving angle in a randomly changed cellular wireless scenarios. The RPRA and RPA are fed by Substrate Integrated Waveguide (SIW) and have three switchable radiation modes: Broadside 1, Broadside 2 and Endfire. The three modes correspond to three different radiation patterns and each of them covers a different area in the Azimuth plane. An eight-element phased array constructed by the proposed RPRA, which is able to switch beam in Azimuth plane and scan in the Elevation plane, is also presented in this paper. The proposed RPA is able to provide much higher spatial coverage than the conventional phased arrays and without additional feeding and phase shifting networks. The beam switching is realized by the PIN diodes. The proposed antenna and array have planer structures and require small clearance on the ground plane which makes them compatible with mobile phones. The simulations show good performance for both RPRA and RPA.

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Mustuzhar Gilani, Syed Mushhad, Muhammad Tamur Sultan, Zeng Shuai, and Asif Kabir. "Long Range Backhaul Microwave Connectivity in Wireless Sensor Networks via a New Antenna Designed for ISM 2.4 GHz Band." International Journal of Antennas and Propagation 2020 (April 25, 2020): 1–14. http://dx.doi.org/10.1155/2020/1789612.

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This study aimed to explore a metallic striped grid array planar antenna, analyze it numerically in terms of its parameters, and optimize it for best performance. It may be an appropriate candidate for long-range point-to-point connectivity in wireless sensor networks. Antenna gain and frequency impedance bandwidth are two important performance parameters. For an efficient antenna, its gain should be high while maintaining operating bandwidth wide enough to accommodate the entire frequency range for which it has been designed. Concurrently, antenna size should also be small. In this study, antenna dimensions were kept as small as possible without compromising its performance. Its dimensions were 300 mm × 210 mm × 9.9 mm, which made it compact and miniature. It had a maximum gain of 16.72 dB at 2.45 GHz and maximum frequency impedance bandwidth of 7.68% relative to 50 Ω. It operated across a frequency band ranging from 2.38 GHz to 2.57 GHz, encapsulating the entire ISM 2.4 GHz band. Its radiation efficiency remained above 93% in this band with a maximum of 98.5% at 2.45 GHz. Moreover, it also had narrow HPBWs in horizontal and vertical planes having values of 18.52° and 31.25°, respectively.

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Oh, Semyoung, and Daejin Park. "Low-Power Beam-Switching Technique for Power-Efficient Collaborative IoT Edge Devices." Applied Sciences 11, no. 4 (2021): 1608. http://dx.doi.org/10.3390/app11041608.

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Collaborative beamforming (CB) enables uplink transmission in a wireless sensor network (WSN) composed of sensors (nodes) and far-away access points (APs). It can also be applied to the case where the sensors are equipped with beam-switching structures (BSSs). However, as the antenna arrays of the BSSs are randomly headed due to the irregular mounting surface, some sensors form beams that do not illuminate a desired AP and waste their limited energy. Therefore, to resolve this problem, it is required to switch the beams toward the desired AP. While an exhaustive search can provide the globally optimal combination, a greedy search (GS) is utilized to solve this optimization problem efficiently. Simulation and experimental results verify that under certain conditions the proposed algorithm can drive the sensors to switch their beams properly and increase the received signal-to-noise ratio (SNR) significantly with low computational complexity and energy consumption.

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Erdogan, Ayhan, Vedat Coskun, and Adnan Kavak. "The Sectoral Sweeper Scheme for Wireless Sensor Networks: Adaptive Antenna Array Based Sensor Node Management and Location Estimation." Wireless Personal Communications 39, no. 4 (2006): 415–33. http://dx.doi.org/10.1007/s11277-006-9058-1.

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Miyamoto, R. Y., K. M. K. H. Leong, Seong-Sik Jeon, Yuanxun Wang, Yongxi Qian, and T. Itoh. "Digital wireless sensor server using an adaptive smart-antenna/retrodirective array." IEEE Transactions on Vehicular Technology 52, no. 5 (2003): 1181–88. http://dx.doi.org/10.1109/tvt.2003.816610.

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Li, Qingyu, Keren Dai, Xiaofeng Wang, Yu Zhang, He Zhang, and Defu Jiang. "Low-Complexity Failed Element Diagnosis for Radar-Communication mmWave Antenna Array with Low SNR." Electronics 8, no. 8 (2019): 904. http://dx.doi.org/10.3390/electronics8080904.

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The millimeter-wave (mmWave) antenna array plays an important role in the excellent performance of wireless sensors networks (WSN) or unmanned aerial vehicle (UAV) clusters. However, the array elements are easily damaged in its harsh working environment but hard to be repaired or exchanged timely, resulting in a serious decline in the beamforming performance. Thus, accurate self-diagnosis of the failed elements is of great importance. In previous studies, there are still significant difficulties for large-scale arrays under extremely low SNR. In this paper, a diagnosis algorithm with low complexity and high reliability for the failed elements is proposed, which is based on a joint decision of communication signal and sensing echoes. Compared with the previous studies, the complexity of the algorithm is reduced by the construction of low-dimensional feature vectors for classification, the decoupling of the degree of arrival (DOA) estimation and the failed pattern diagnosis, with the help of the sub-array division. Simulation results show that, under an ultra-low SNR of −12.5 dB for communication signals and −16 dB for sensing echoes, an accurate self-diagnosis with a block error rate lower than 8% can be realized. The study in this paper will effectively promote the long-term and reliable operation of the mmWave antenna array in WSN, UAV clusters and other similar fields.

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Wang, Yurong, Aijun Liu, Kui Xu, and Xiaochen Xia. "Energy and Information Beamforming in Airborne Massive MIMO System for Wireless Powered Communications." Sensors 18, no. 10 (2018): 3540. http://dx.doi.org/10.3390/s18103540.

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Energy supply and information backhaul are critical problems for wireless sensor networks deployed in remote places with poor infrastructure. To deal with these problems, this paper proposes an airborne massive multiple-input multiple-output (MIMO) system for wireless energy transfer (WET) and information transmission. An air platform (AP) equipped with a two-dimensional rectangular antenna array is employed to broadcast energy and provide wireless access for ground sensors. By exploiting the statistical property of air-terrestrial MIMO channels, the energy and information beamformers are jointly designed to maximize the average received signal-to-interference-plus-noise ratio (SINR), which gives rise to a statistical max-SINR beamforming scheme. The scheme does not rely on the instantaneous channel state information, but still requires large numbers of RF chains at AP. To deal with this problem, a heuristic strongest-path energy and information beamforming scheme is proposed, which can be implemented in the analog-domain with low computational and hardware complexity. The analysis of the relation between the two schemes reveals that, with proper sensor scheduling, the strongest-path beamforming is equivalent to the statistical max-SINR beamforming when the number of AP antennas tends to infinity. Using the asymptotic approximation of average received SINR at AP, the system parameters, including transmit power, number of active antennas of AP and duration of WET phase, are optimized jointly to maximize the system energy efficiency. The simulation results demonstrate that the proposed schemes achieve a good tradeoff between system performance and complexity.

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Wang, Haiyue, Lianwen Deng, Heng Luo, Junsa Du, Daohan Zhou, and Shengxiang Huang. "Microwave Wireless Power Transfer System Based on a Frequency Reconfigurable Microstrip Patch Antenna Array." Energies 14, no. 2 (2021): 415. http://dx.doi.org/10.3390/en14020415.

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The microwave wireless power transfer (MWPT) technology has found a variety of applications in consumer electronics, medical implants and sensor networks. Here, instead of a magnetic resonant coupling wireless power transfer (MRCWPT) system, a novel MWPT system based on a frequency reconfigurable (covering the S-band and C-band) microstrip patch antenna array is proposed for the first time. By switching the bias voltage-dependent capacitance value of the varactor diode between the larger main microstrip patch and the smaller side microstrip patch, the working frequency band of the MWPT system can be switched between the S-band and the C-band. Specifically, the operated frequencies of the antenna array vary continuously within a wide range from 3.41 to 3.96 GHz and 5.7 to 6.3 GHz. For the adjustable range of frequencies, the return loss of the antenna array is less than −15 dB at the resonant frequency. The gain of the frequency reconfigurable antenna array is above 6 dBi at different working frequencies. Simulation results verified by experimental results have shown that power transfer efficiency (PTE) of the MWPT system stays above 20% at different frequencies. Also, when the antenna array works at the resonant frequency of 3.64 GHz, the PTE of the MWPT system is 25%, 20.5%, and 10.3% at the distances of 20 mm, 40 mm, and 80 mm, respectively. The MWPT system can be used to power the receiver at different frequencies, which has great application prospects and market demand opportunities.

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Lonkeng, Alban Doumtsop, and Jie Zhuang. "Two-Dimensional DOA Estimation Using Arbitrary Arrays for Massive MIMO Systems." International Journal of Antennas and Propagation 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/6794920.

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With the quick advancement of wireless communication networks, the need for massive multiple-input-multiple-output (MIMO) to offer adequate network capacity has turned out to be apparent. As a portion of array signal processing, direction-of-arrival (DOA) estimation is of indispensable significance to acquire directional data of sources and to empower the 3D beamforming. In this paper, the performance of DOA estimation for massive MIMO systems is analyzed and compared using a low-complexity algorithm. To be exact, the 2D Fourier domain line search (FDLS) MUSIC algorithm is studied to mutually estimate elevation and azimuth angle, and arbitrary array geometry is utilized to represent massive MIMO systems. To avoid the computational burden in estimating the data covariance matrix and its eigenvalue decomposition (EVD) due to the large-scale sensors involved in massive MIMO systems, the reduced-dimension data matrix is applied on the signals received by the array. The performance is examined and contrasted with the 2D MUSIC algorithm for different types of antenna configuration. Finally, the array resolution is selected to investigate the performance of elevation and azimuth estimation. The effectiveness and advantage of the proposed technique have been proven by detailed simulations for different types of MIMO array configuration.

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Fedorov, Vladimir M., Mikhail V. Efanov, Vasiliy Ye Ostashev, Vladimir P. Tarakanov, and Aleksander V. Ul’yanov. "Antenna Array with TEM-Horn for Radiation of High-Power Ultra Short Electromagnetic Pulses." Electronics 10, no. 9 (2021): 1011. http://dx.doi.org/10.3390/electronics10091011.

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An antenna array with short shielded transverse electromagnetic horns (S-TEM-horns) for emitting high-power radiation of ultra-short electromagnetic pulses (USEMP) has been created and researched. The antenna unit consists of an ultra-wideband antenna array with four S-TEM horns, with each connected to a two-wire HF transmission line, and these four lines are connected to an antenna feeder. This feeder is connected to a semiconductor generator with the following parameters: a 50 Ohm connector, 10–100 kV high-voltage monopolar pulses, a rise time of about 0.1 ns, FWHM = 0.2–1 ns, and pulse repetition rates of 1–100 kHz. The antenna array was designed and optimized to achieve a high efficiency of about 100% for the antenna aperture by using a 2 × 2 array with S-TEM-horns, with shielding rectangular plates for the return current. The transient responses were studied by simulation using the electromagnetic 3D code “KARAT” at the time domain and experimentally with the use of our stripline sensor for measurement of the impulse electrical field with a 0.03 ns rise time and a 7 ns duration at the traveling wave. The radiators were emitting USEMP waves with a hyperband frequency spectrum of 0.1–6 GHz. The radiation with an amplitude of 5–30 kV/m of the E-field strength at a distance of up to 20 m was successfully applied to test the electronics for immunity to electromagnetic interference.

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Ali, Muhsin, Bilal A. Khawaja, Muhammed Mustaqim, and Munir A. Tarar. "U-Slot microstrip patch antenna array for dual band operation in next generation wireless sensor network." International Journal of Sensor Networks 14, no. 4 (2013): 218. http://dx.doi.org/10.1504/ijsnet.2013.059078.

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Yasin, M., and Pervez Akhtar. "Convergence analysis of Bessel beamformer and its comparison with LMS in adaptive array system." COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 34, no. 3 (2015): 952–61. http://dx.doi.org/10.1108/compel-07-2014-0184.

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Purpose – The purpose of this paper is to analyze the convergence performance of Bessel beamformer, based on the design steps of least mean square (LMS) algorithm, can be named as Bessel LMS (BLMS) algorithm. Its performance is compared in adaptive environment with LMS in terms of two important performance parameters, namely; convergence and mean square error. The proposed BLMS algorithm is implemented on digital signal processor along with antenna array to make it smart in wireless sensor networks. Design/methodology/approach – Convergence analysis is theoretically developed and verified through MatLab Software. Findings – Theoretical model is verified through simulation and its results are shown in the provided table. Originality/value – The theoretical model can obtain validation from well-known result of Wiener filter theory through principle of orthogonality.

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Kim, Young-Jun, Gunhark Noh, Han Lim Lee, and Sungwook Yu. "Dual-Polarized Multi-Channel 24 GHz Radar Sensor Antenna for High Channel-to-Channel Isolation." Sensors 20, no. 18 (2020): 5233. http://dx.doi.org/10.3390/s20185233.

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This article presents a dual-polarized, high gain multi-beam and high T/Rx channel-to-channel isolation antenna module for 24 GHz sensor applications. The proposed antenna is configured to support 2-Tx and 2-Rx channels with a pair of vertically polarized (VP) radiation pattern and a pair of horizontally polarized (HP) radiation pattern. Further, each linearly polarized T/Rx antenna is configured by 2 × 4 array with a multi-layer integrated feed network, resulting in four sets of 2 × 4 array antennas fabricated within a single printed circuit board (PCB). Since multiple RF channels must be ensured with minimal interference, high antenna-to-antenna, including Tx-to-Tx, Rx-to-Rx, and Tx-to-Rx port isolations in the proposed antenna are achieved by multi-layered feed network and four sets of T-shaped magnetic walls. To verify the performance of the proposed structure, a 2-Tx and 2-Rx antenna module was fabricated at 24 GHz. The fabricated antenna showed a measured maximum 10-dB impedance bandwidth of 3.9% with a maximum measured gain of 11.7 dBi, considering both Tx and Rx. Further, the measured channel-to-channel isolations were always better than 35.6 dB at 24 GHz.

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Yang, Zhening, Alexandru Takacs, Samuel Charlot, and Daniela Dragomirescu. "Flexible substrate technology for millimeter wave wireless power transmission." Wireless Power Transfer 3, no. 1 (2016): 24–33. http://dx.doi.org/10.1017/wpt.2015.21.

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In this paper, a technology based on thin flexible polyimide substrate (Kapton) to develop antennas for millimeter wave wireless power transmission is presented. Firstly, we characterize the Kapton polyimide (relative permittivity and loss tangent) using a ring resonator method up to V band. A 60 GHz patch antenna is designed, fabricated, and measured to validate our technology. Crossed-dipoles array antennas at Kuband and K band for energy harvesting are also designed, fabricated, and measured. Then a prototype of crossed-slot dipole antenna at V band is proposed. Finally, a resistivity characterization of Au bump used in flip-chip packaging is done, which leads us one step further toward aheterogeneous integration on flexible substrate of different components for Wireless Sensor Network nodes.

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Karampatea and Siakavara. "Synthesis of Rectenna for Powering Micro-Watt Sensors by Harvesting Ambient RF Signals' Power." Electronics 8, no. 10 (2019): 1108. http://dx.doi.org/10.3390/electronics8101108.

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In the article, a dual and wide band antenna array suitable for RF rectenna applications was synthesized and global rectenna systems are presented. The array consists of two bowtie-shaped patches, printed on the one side of a dielectric slab (FR4). Οn the other side of the slab, an aperture-textured metallic ground layer, is printed. Examples of full-wave rectifiers connected, through matching networks, to the antenna elements and forming integrated rectenna systems for radio-frequency (RF) power harvesting at 868 MHz, from 920 to 960 MHz and at 1.8 GHz, are presented. Statistical results over frequency and the directions of arrival (DoAs) of incoming waves were received showing, at the rectifier, mean direct current (DC) voltage of 580 mV, and mean power of 58 μW, for circularly polarized waves of field intensity of 1.8 V/m. The DC voltage can reach 800 mV, the power 120 μW and the efficiency 68% when the waves come from DoAs of maximum antenna’s gain. Due to the wideband performance of the antenna, it could be used at various frequency slots as long as the matching network’s operation frequency is changed. Thus the proposed rectennas could be suitable for energizing low-power sensors or at least to charge their batteries.

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Nguyen, Nhu Huan, Thi Duyen Bui, Anh Dung Le, et al. "A Novel Wideband Circularly Polarized Antenna for RF Energy Harvesting in Wireless Sensor Nodes." International Journal of Antennas and Propagation 2018 (2018): 1–9. http://dx.doi.org/10.1155/2018/1692018.

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A novel wideband circularly polarized antenna array using sequential rotation feeding network is presented in this paper. The proposed antenna array has a relative bandwidth of 38.7% at frequencies from 5.05 GHz to 7.45 GHz with a highest gain of 12 dBi at 6 GHz. A corresponding left-handed metamaterial is designed in order to increase antenna gain without significantly affecting its polarization characteristics. The wideband circularly polarized antenna with 2.4 GHz of bandwidth is a promising solution for wireless communication system such as tracking or wireless energy harvesting from Wi-Fi signal based on IEEE 802.11ac standard or future 5G cellular. A potential application of this antenna as a receiving antenna for RF-DC device to obtain DC power for a wireless sensor node from Wi-Fi signal is shown.

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Meng, Shan, Xin Dai, Bicheng Xiao, Yimin Zhou, Yumei Li, and Chong Gao. "Deep learning–based fifth-generation millimeter-wave communication channel tracking for unmanned aerial vehicle Internet of things networks." International Journal of Distributed Sensor Networks 15, no. 8 (2019): 155014771986588. http://dx.doi.org/10.1177/1550147719865882.

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Using unmanned aerial vehicle as movable base stations is a promising approach to enhance network coverage. Moreover, movable unmanned aerial vehicle–base stations can dynamically move to the target devices to expand the communication range as relays in the scenario of the Internet of things. In this article, we consider a communication system with movable unmanned aerial vehicle–base stations in millimeter-Wave. The movable unmanned aerial vehicle–base stations are equipped with antennas and multiple sensors for channel tracking. The cylindrical array antenna is mounted on the movable unmanned aerial vehicle–movable base stations, making the beam omnidirectional. Furthermore, the attitude estimation method using the deep neural network can replace the traditional attitude estimation method. The estimated unmanned aerial vehicle attitude information is combined with beamforming technology to realize a reliable communication link. Simulation experiments have been performed, and the results have verified the effectiveness of the proposed method.

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Grubert, J., J. Heyen, C. Metz, L. C. Stange, and A. F. Jacob. "Planar millimeter wave radar frontend for automotive applications." Advances in Radio Science 1 (May 5, 2003): 125–29. http://dx.doi.org/10.5194/ars-1-125-2003.

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Abstract. A fully integrated planar sensor for 77 GHz automotive applications is presented. The frontend consists of a transceiver multichip module and an electronically steerable microstrip patch array. The antenna feed network is based on a modified Rotman-lens and connected to the array in a multilayer approach offering higher integration. Furthermore, the frontend comprises a phase lock loop to allow proper frequency-modulated continuous wave (FMCW) radar operation. The latest experimental results verify the functionality of this advanced frontend design featuring automatic cruise control, precrash sensing and cut-in detection. These promising radar measurements give reason to a detailed theoretical investigation of system performance. Employing commercially available MMIC various circuit topologies are compared based on signal-tonoise considerations. Different scenarios for both sequential and parallel lobing hint to more advanced sensor designs and better performance. These improvements strongly depend on the availability of suitable MMIC and reliable packaging technologies. Within our present approach possible future MMIC developments are already considered and, thus, can be easily adapted by the flexible frontend design. Es wird ein integrierter planarer Sensor für 77 GHz Radaranwendungen vorgestellt. Das Frontend besteht aus einem Sende- und Empfangs-Multi-Chip-Modul und einer elektronisch schwenkbaren Antenne. Das Speisenetzwerk der Antenne basiert auf einer modifizierten Rotman- Linse. Für eine kompakte Bauweise sind Antenne und Speisenetzwerk mehrlagig integriert. Weiterhin umfasst das Frontend eine Phasenregelschleife für eine präzise Steuerung des frequenzmodulierten Dauerstrichradars. Die aktuellen Messergebnisse bestätigen die Funktionalit¨at dieses neuartigen Frontend-Designs, das automatische Geschwindigkeitsregelung, Kollisionswarnung sowie Nahbereichsüberwachung ermöglicht. Die Qualität der Messergebnisse hat weiterführende theoretische Untersuchungen über die potenzielle Systemleistungsfähigkeit motiviert. Unter Berücksichtigung von kommerziell erhältlichenMMICs werden verschiedene Schaltungstopologien auf der Grundlage des Signal-Rausch-Verhältnisses verglichen. Sowohl für sequenzielle als auch für parallele Ansteuerung der Antennenkeulen wird eine deutliche Leistungssteigerung ermittelt. Diese Verbesserungen hängen maßgeblich von der Verfügbarkeit geeigneter MMICs und einer zuverlässigen Aufbau- und Verbindungstechnik ab. Das vorliegende Frontend-Konzept kann auf Grund seiner Flexibilität leicht an derlei zukünftige Entwicklungen angepasst werden.

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Sodré, Arismar Cerqueira, Igor Feliciano da Costa, Renan Alves dos Santos, Hugo Rodrigues Dias Filgueiras, and Danilo Henrique Spadoti. "Waveguide-Based Antenna Arrays for 5G Networks." International Journal of Antennas and Propagation 2018 (2018): 1–10. http://dx.doi.org/10.1155/2018/5472045.

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This work reports the development of two high-performance waveguide-based antenna arrays for 5G cellular networks, operating in the underutilized millimetre wave (mm-wave) frequency spectrum. Two different scenarios of mm-wave communications are proposed for illustrating the applicability of the proposed arrays, which provide specific radiation patterns, namely, 12 dBi gain omnidirectional coverage in the 28 GHz band and dual-band sectorial coverage using the 28 and 38 GHz bands with gain up to 15.6 dBi. Numerical and experimental results of the array reflection coefficient, radiation pattern, and gain have been shown in an excellent agreement.

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Rahman, MuhibUr, Mahdi NaghshvarianJahromi, Seyed Mirjavadi, and Abdel Hamouda. "Bandwidth Enhancement and Frequency Scanning Array Antenna Using Novel UWB Filter Integration Technique for OFDM UWB Radar Applications in Wireless Vital Signs Monitoring." Sensors 18, no. 9 (2018): 3155. http://dx.doi.org/10.3390/s18093155.

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This paper presents the bandwidth enhancement and frequency scanning for fan beam array antenna utilizing novel technique of band-pass filter integration for wireless vital signs monitoring and vehicle navigation sensors. First, a fan beam array antenna comprising of a grounded coplanar waveguide (GCPW) radiating element, CPW fed line, and the grounded reflector is introduced which operate at a frequency band of 3.30 GHz and 3.50 GHz for WiMAX (World-wide Interoperability for Microwave Access) applications. An advantageous beam pattern is generated by the combination of a CPW feed network, non-parasitic grounded reflector, and non-planar GCPW array monopole antenna. Secondly, a miniaturized wide-band bandpass filter is developed using SCSRR (Semi-Complementary Split Ring Resonator) and DGS (Defective Ground Structures) operating at 3–8 GHz frequency band. Finally, the designed filter is integrated within the frequency scanning beam array antenna in a novel way to increase the impedance bandwidth as well as frequency scanning. The new frequency beam array antenna with integrated band-pass filter operate at 2.8 GHz to 6 GHz with a wide frequency scanning from the 50 to 125-degree range.

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Sundgren, H., I. Lundström, and H. Vollmer. "Chemical sensor arrays and abductive networks." Sensors and Actuators B: Chemical 9, no. 2 (1992): 127–31. http://dx.doi.org/10.1016/0925-4005(92)80205-c.

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Coetzee, Jacob Carl. "Dual-Frequency Decoupling Networks for Compact Antenna Arrays." International Journal of Microwave Science and Technology 2011 (March 17, 2011): 1–3. http://dx.doi.org/10.1155/2011/249647.

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Decoupling networks can alleviate the effects of mutual coupling in antenna arrays. Conventional decoupling networks can provide decoupled and matched ports at a single frequency. This paper describes dual-frequency decoupling which is achieved by using a network of series or parallel resonant circuits instead of single reactive elements.

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Großmann, Toni Dirk, Ricardo Decker, Steffen Kurth, Lothar Kroll, and Thomas Otto. "Reflection based Strain Sensing using Metamaterials." Technologies for Lightweight Structures (TLS) 3, no. 1 (2020): 25–33. http://dx.doi.org/10.21935/tls.v3i1.125.

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Resonator arrays of periodicially arranged electromagnetic sub-wavelength resonators show a strong frequency filter behaviour which can be controlled by the geometry, size and arrangement of the resonators. The use of several resonator arrays and their integration into a polymer matrix allows the realisation of metamaterials with a specific resonance behaviour. The resonance behaviour can be influenced by material and structural changes enabling a passive sensor function. The considered sensor approach based on metamaterials is investigated to enable structural health monitoring of lightweight structures. In the present case, a double-layer Jerusalem cross (JC) resonator array (RA) is integrated into a glass fibre reinforced plastic (GFRP) to analyse the change of the resonance behaviour under load (strain) using a reflection measurement. The CST (Computer Simulation Technology) Microwave Studio was used to model the resonator array for operation in the microwave frequency range between 15 GHz and 35 GHz as well as for the numerical analysis of the resonance behaviour under load. The numerical results were validated by a tensile test using a tensile test machine (type TIRATEST 28100, Tira GmbH) and by a reflection measurement using two standard gain horn antennas (type Standard Gain Horn Series 862, ARRA Inc) and a vector network analyser (type ZVA50, Rohde&Schwarz). The reflection measurement shows a reflection minimum at 28.6 GHz which moves to higher frequencies under load of the GFRP laminate. With the shift of the minimum, the quality factor decreases and the dip widens. The investigation shows that it is possible to provide a GFRP laminate with a specific electromagnetic behaviour by integrating resonator arrays. It is also shown that the specific electromagnetic behaviour can be influenced by structural changes and thus opens up the possibility of monitoring the condition of lightweight structures.

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Cole, Matthew C., and Paul J. Kenis. "Integrated Electrical Sensor Arrays in Microfluidic Networks." ECS Transactions 3, no. 10 (2019): 427–35. http://dx.doi.org/10.1149/1.2357282.

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Cole, Matthew C., and Paul J. A. Kenis. "Multiplexed electrical sensor arrays in microfluidic networks." Sensors and Actuators B: Chemical 136, no. 2 (2009): 350–58. http://dx.doi.org/10.1016/j.snb.2008.12.010.

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Natale, Corrado Di, Fabrizio A. M. Davide, Arnaldo D'Amico, Wolfgang Göpel, and Udo Weimar. "Sensor arrays calibration with enhanced neural networks." Sensors and Actuators B: Chemical 19, no. 1-3 (1994): 654–57. http://dx.doi.org/10.1016/0925-4005(93)01115-k.

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Wu, Zhihui, Bin Zhang, Fengzhong Qu, et al. "Precise-Orientation-Beamforming Scheme for Wireless Communications between Buoys." Mathematical Problems in Engineering 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/9860484.

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Utilizing wireless sensor network (WSN) to monitor the marine environment is one of the major techniques in oceanographic monitoring, and how to increase the limited communication distance between the buoys in WSN has become a hot research issue. In this paper, a new technique called precise-orientation-beamforming (POB) which uses the beamforming algorithm to increase the communication distance between buoys is presented. As was widely applied in the radar and sonar, the beamforming method was not used to extend the communication distance between buoys so far. The POB method overcomes the unstable position of buoys caused by waves by implementing the orientation filter. The whole process includes two steps: First, the real-time attitude of the antenna array is calculated by the orientation filter. With the known relative direction of the destination node to the antenna array, the second step is to control phased array antenna beamforming parameters, directing the beam at the destination node. The POB scheme has been simulated under the condition of regular waves. The results reveal that POB provides significant power gains and improves the distance between two communicating nodes effectively.

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Ayers, Joseph, Anthony Westphal, and Daniel Blustein. "A Conserved Neural Circuit-Based Architecture for Ambulatory and Undulatory Biomimetic Robots." Marine Technology Society Journal 45, no. 4 (2011): 147–52. http://dx.doi.org/10.4031/mtsj.45.4.17.

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AbstractThe adaptive capabilities of underwater organisms result from layered exteroceptive reflexes responding to gravity, impediment, and hydrodynamic and optical flow. In combination with taxic responses to point sources of sound or chemicals, these reflexes allow reactive autonomy in the most challenging of environments. We are developing a new generation of lobster and lamprey-based robots that operate under control by synaptic networks rather than algorithms. The networks, based on the command neuron, coordinating neuron, and central pattern generator architecture, code sensor input as labeled lines and activate shape memory alloy-based artificial muscles through a simple interface that couples excitation to contraction. We have completed the lamprey-based robot and are adapting this sensor, board, and actuator architecture to a new generation of the lobster-based robot. The networks are constructed from discrete time map-based neurons and synapses and are instantiated on the digital signal processing chip. A sensor board integrates inputs from a short baseline sonar array (for beacon tracking and supervisory control), accelerometer, a compass, antennae, and optionally chemosensors. Actuator control is mediated by pulse-width duty cycle coding generated by the electronic motor neurons and a comparator and power field-effect transistor (FET) system housed on low- and high-current driver boards. These circular boards are stacked in a tubular hull with the processor and batteries. This system can readily mimic the biomechanics of the model organisms by the addition of hydrodynamic control surfaces. The behavioral set results from chaining sequences of exteroceptive reflexes released by sensory feedback from the environment.

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Buttazzoni, Giulia, Fulvio Babich, Francesca Vatta, and Massimiliano Comisso. "Geometrical Synthesis of Sparse Antenna Arrays Using Compressive Sensing for 5G IoT Applications." Sensors 20, no. 2 (2020): 350. http://dx.doi.org/10.3390/s20020350.

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One of the main targets of the forthcoming fifth-generation (5G) cellular network will be the support of the communications for billions of sensors and actuators, so as to finally realize the Internet of things (IoT) paradigm. This pervasive scenario unavoidably requires the design of cheap antenna systems with beamforming capabilities for compensating the strong attenuations that characterize the millimeter-wave (mmWave) channel. To address this issue, this paper proposes an iterative algorithm for sparse antenna arrays that enables to derive the number of elements, their amplitudes, phases, and positions in the presence of constraints on the far-field pattern. The algorithm, which relies on the compressive sensing approach, is formulated by transforming the original nonconvex optimization problem into a convex one. To prove the suitability of the conceived solution for 5G IoT mmWave applications, numerical examples and comparisons with other existing methods are provided, considering synthesis problems with different pattern and aperture specifications.

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Vakula, Damera, and N. V. S. N. Sarma. "FAULT DIAGNOSIS OF PLANAR ANTENNA ARRAYS USING NEURAL NETWORKS." Progress In Electromagnetics Research M 6 (2009): 35–46. http://dx.doi.org/10.2528/pierm09011204.

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Sousa Júnior, W. M., and L. A. Silva. "Exploiting Heterogeneity in Ad Hoc networks with Antenna Arrays." Journal of Communication and Information Systems 19, no. 3 (2004): 74–80. http://dx.doi.org/10.14209/jcis.2004.13.

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Journal articles on the topic 'Sensor networks. Antenna arrays'

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