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For the first time, the ionic polymer metal composite (IPMC) actuator is integrated with a RFID (Radio-Frequency Identification) tag antenna for achieving frequency reconfiguration in the UHF (Ultra-High-Frequency) band. Here, the IPMC movable flap serves as an actuator that can effectively tune the tag resonant frequency. By applying a 2-layer crenellated structure and employing a surface patterned electrode for restraining back relaxation, the deflection of the IPMC actuator can be significantly improved. The IPMC actuator can move in two directions, enabling two-degree frequency tuning. Numerical and experimental data confirm that the tip displacement of the IPMC actuator can be enhanced up to 266% with the use of the 2-layer crenellated structure. The IPMC actuator allows the resonant frequency of the tag antenna to be tuned back by as much as 35 MHz, after deviating due to placing on an unintended object. UHF RFID application is also performed using a portable commercial RFID reader. Good frequency reconfiguration and broad tuning range, along with far read distances, have been achieved with our tunable UHF RFID tag antenna.

Large-distance communications beyond a few meters is challenging for Terahertz (THz) signals because of high spreading loss and absorption in the media. The smart antenna concept used for RF antennas to improve the signal-to-interference/noise level can be extended to these THz antennas. Out of the two types of implementations of this concept, viz. (i) adaptive array and (ii) switched-beam antenna, this paper presents the switched-beam nanoantenna for the THz wave region. Based on the Yagi-Uda antenna concept, switched-beam graphene nanoantennas over silicon dioxide (SiO2) substrate is proposed in this paper. In one case (Antenna-I), the antenna is able to switch the beam in ± 90o directions, whereas in the other case (Antenna-II), the switching directions are 0o, ± 90o, 180o. This pattern reconfigurability can also be observed over a frequency range leading to simultaneous pattern and frequency reconfigurable nature of the nanoantenna. The reconfigurability is obtained by changing the graphene conductivity through its chemical potential. Due to plasmonic wave propagation in graphene at THz, the proposed graphene nanoantenna resonates at a sub-wavelength scale. Design aspects and the working principle of switched-beam graphene plasmonic nanoantennas in the THz region are discussed in this paper.

Adaptive signal processing sensor arrays, known also as smart antennas .The smart antenna adaptive algorithms achieve the best weight vector for beam forming by iterative means. The Least Mean Square (LMS) algorithm, is an adaptive algorithm .LMS incorporates an iterative procedure that makes successive corrections to the weight vector in the direction of the negative of the gradient vector which eventually leads to the minimum mean square error. Beam forming is directly determined by the two factors. The performance of the traditional LMS algorithm for different parameters is analysed in this paper. This algorithm can be applied to beam forming with the software Matlab. The result obtain can achieve faster convergence and lower steady state error. The algorithms can be simulated in MATLAB 7.10 version. 1. INTRODUCTON Throughout the world, there is significant research and development on smart antennas for wireless systems. This is because smart antennas have tremendous potential to enhance the performance of future generation wireless systems as evidenced by the antennas' recent deployment in many systems. There are two basic types of smart antennas.The first type is the phased array or multibeam antenna, which consists of either a number of fixed beams with one beam turned on towards the desired signal or a single beam (formed by phase adjustment only) that is steered toward the desired signal. The other type is the adaptive antenna array is an array of multiple antenna elements, with the received signals weighted and combined to maximize the desired signal to interference plus noise power ratio. This essentially puts a main beam in the direction of the desired signal and nulls in the direction of the interference. A smart antenna is therefore a phased or adaptive array that adjusts to the environment. That is, for the adaptive array, the beam pattern changes as the desired user and the interference move; and for the phased array the beam is steered or different beams are selected as the desired user moves. Nearly every company the WTEC panel visited is doing significant work in smartantennas. Indeed, some companies placed strong emphasis on this research. In particular, researchers at NEC and NTT stated that they felt that smart antenna technology was the most important technology for fourth generation cellular systems. Researchers at Filtronics and other companies agreed that smart antenna technology was one of the key technologies for fourth generation systems. A smart antenna system at the base station of a cellular mobile system is depicted in Fig 1. It consists of a uniform linear antenna array for which the current amplitudes are adjusted by a set of complex weights using an adaptive beamforming algorithm. The adaptive beamforming algorithm optimizes the array output beam pattern such that maximum radiated power is produced in the directions of desired mobile users and deep nulls are generated in the directions of undesired signals representing co-channel interference from mobile users in adjacent cells.

Various methods have been proposed to control the electromagnetic fields in the near-or far-field region, one of which is to use antenna arrays. This paper reviews a technique, called the method of maximum power transmission efficiency (MMPTE), for the design of antenna arrays and wireless power transmission (WPT) systems. The method is motivated by the fact that all wireless systems aim to maximize the power transmission efficiency (PTE) between the transmitter and receiver and the PTE can thus be considered as a performance index for the design of WPT system and antenna as well. The MMPTE makes use of the PTE as the performance index to be optimized, and reduces a field synthesis problem into a circuit analysis problem, and is therefore easy to master and implement. It overcomes all the challenges associated with conventional array design methods, and is applicable to the design of any type of antenna array in any environment. This paper summarizes the basic theory of MMPTE and demonstrates MMPTE through a number of near- and far-field applications, including focused antennas, smart antennas, shaped beam antennas, end-fire antennas, multi-beam antennas, polarization-reconfigurable antennas, and wireless power transmission systems.

5G evolution in the mobile telecommunication is an emerging technology which achieves the data rate of about 10 Gbps. In order to achieve such a super speed data increased bandwidth with high frequency waveform is required. Massive Multiple Input Multiple Output Beam forming (BF) is a technique which is used to develop the 5G system and Millimeter (mm) wave is used to provide higher frequency. Conventional BF can provide the Channel State Information (CSI) to end terminals but adaptive BF cannot provide CSI. But adaptive BF is highly efficient for changing their behavior according to the requirement of the channel. In such a hybrid BF technology can be used to implement 5G technology which uses both analog and digital BF technology to transmit and receive the signal without distortion. The major challenge in the implementation of 5G technology is to find out the best beamforming technique. This paper deals with the performance of various beamforming techniques for implementing 5G technology.

This paper presents a resilient localization scheme for wireless sensor networks (WSNs). It suits well in estimation of node position under a corrupted radio environment. Position computation is based on information of angle-of-arrivals (AoA) and references obtained from a few mobile anchors. In the network, anchors are equipped with smart antennas and global positioning system receivers. They broadcast signals in a synchronous and periodic fashion. The neighboring nodes having the signals with received signal strength values above a prescribed threshold level, respond with their respective IDs. Anchors evaluate AoA information from these signals using estimation of signal parameters via rotational invariance technique (ESPRIT) algorithm. Next, they forward beacon messages, containing their references and estimated angles, to the corresponding nodes and move along random trajectories. After receiving three sets of such data, at least, nodes can initiate selective segregation of the inconsistent position estimations. Simulation results attaining higher degree of localization accuracy validate its competency over the existing schemes.

In this work, a novel antenna structure has been proposed, which consists of multiple sub-array features i.e., a field selectable beam (90°, 180°, 270°, and 360°) and the choice of gain (11.16, 14.59 and 17.25 dBi) that can be easily adapted to cater for the dynamic scenarios in the transportation environment. The sub-arrays were designed using the microstrip patch antenna (MPA) concept with capacitive feed and dual substrate stacked up configuration for superior operating bandwidth covering the entire 802.11ac (5.17 to 5.85 GHz Industrial Scientific and Medical (ISM) band), in addition to the extended coverage for 4.92 to 4.98 GHz licensed band with narrow azimuth beamwidth of 24°. The sub-array was designed, simulated and experimentally evaluated and the beamforming results revealed that the antenna structure can be integrated with beamforming concepts to provide an enhanced wireless link between the ground base station and the mobile terminals that allows beam steering to focus on the targeted direction and null the interference directions with small beam width. It is expected that the proposed configurable gain/beam beamforming antenna array will further reduce the deployment cost and enhance the anti-interference performance by two-fold, and shall bring the user experience in the transportation market to the next level.

In this paper, a smart antenna array based on the image-aware technique that can automatically switch its beam to track users is proposed. Mobilenet, a deep neural network (DNN), is utilized to find the users' position information from images; it is trained using the collected dataset, and the parameters are optimized. The modified DNN is then implanted into a miniaturized embedded system RK3399. To obtain beam switchable radiation, a 2×2 microstrip patch antenna array with a 4×4 Butler feeding matrix is designed in the 2.4 GHz ISM band. Then, the RK3399 is compactly integrated with the patch antenna array, and a microcamera is used as the eye of the antenna to capture the environment information. A series of measurements of the received power and error vector magnitude (EVM) are performed in a real indoor scenario to verify the design. The results agree well with the expected results and show that the design is capable of guaranteeing communication quality and improving energy efficiency, making this technique a good candidate for indoor wireless applications.

In the smart antenna system, the transmit and receive (T/R) module is one of the core components as it accounts for nearly 45% of the overall smart antenna system cost. Due to the high implementation cost of the T/R module, the literature was mainly centered around the military and satellite radar applications. However, over the years, the cost of the T/R module has been reduced drastically by leveraging on the advanced manufacturing technology, volume production pricing and adaptation of the commercially available off-the-shelf components, as a result, the adoption of the T/R module in commercial and industrial application become possible. In this work, we have proposed a commercially affordable T/R module that operates in 4.9-5.9 GHz band for commercial and industrial applications. The T/R module was designed, calibrated, and characterized for use in the beamforming smart antenna system. The design process including the circuit, schematic and printed circuit board (PCB) were highlighted. The proposed recursive calibration process managed to correct the phase error to ±1° and amplitude error to ±0.2 dB. In addition, the amplitude distribution of 0.5-1-1-0.5 combination has successfully suppressed the side-lobe level (SLL) to -28.7 dB for 0°, -22.71 dB for ±20° and -12.77 dB for ±40° beam steering. This work is aimed to promote the adoption of the T/R module into the commercial and industrial applications such as public or government infrastructure.

In the recent years, Mobile Ad-Hoc Wireless Networks (MANET) have played a key role in communication system. It is a self-configured and infrastructure-less network. It is used in different application areas like disaster recovery operations, hospitals and agricultural sectors. However, there are a lot of problems that limit the performances of this network for significantly achieving its roles in different areas. To overcome these problems, this paper enhances the performances of MANET in wireless communication system by adapting smart antenna in Ad-hoc On-Demand Distance Vector (AODV) routing protocol combining with multiple network interfaces. The improved new version AODV utilizing directional antenna and multiple network interface compared with Omni-directional antenna is evaluated based on simulations, which was done with the Network Simulator version two (NS2). Through this study, we found out that directional antennas integrating with multiple network interface throughput and end to end delays always outperform Omni-directional antennas in both random and grid scenarios for AODV routing protocol. In high communication paths and long communication distances also directional antennas have significant improvements in contrast to traditional Omni-directional antennas. Finally, we recommend that for increasing throughput and decreasing end to end delay utilizing directional antennas and multiple network interfaces in MANET technology improve the performances of the wireless communication system.

Smart antenna system has been studied extensively for the fifth generation of wireless communication systems, because it has made a system better performance of higher capacity and coverage as well as of power-saving. The present paper introduces a design of planar microstrip patch antenna array for a smart mobile system operating at 28 GHz. The present smart antenna has an adaptive radiation pattern that adjusts its main beam automatically to the desired direction by following the signal environment. This is based on the processing of an algorithm called the Least Mean Square (LMS) resulting in a change in the magnitude and phase of the feeding current for each element in the antenna array. From the obtained results, the main beam can be steered 180 degrees in the phi (azimuth) plane at a constant theta (elevation) angle. The planar antenna array was designed and simulated using CST Microwave Studio and MATLAB software that is used to find the required exciting current for each element. It is found that the antenna bandwidth is greater than 1 GHz while its gain is about 21 dB.

This paper presents a pentagonal array composed of ten elements for operation at 5.8 GHz. The proposed device operates in circular polarization exploiting the sequential rotation architecture applied to five pair of disc-based patch elements. A pentagonal sub-array is well-suited to be packed in icosahedral arrangement, which in turn is the ideal shape for smart antennas with wide angle spatial coverage. A single layer via-less prototype is simulated on a FR408 substrate. A realized gain up to 11.6dBi with a polarization purity exceeding 30 dB at 5.8 GHz is observed.

In the last decades, the development of efficient antennas for wireless power transfer applications has gained great attention from researchers worldwide and has become a vital research topic. In this paper, we propose the optimum design and implementation in microstrip technology of a switched beam smart antenna alimented by a 4x4 butler matrix (BM) for a microwave wireless power transmission system (MPT) at 5.8 GHz. The proposed smart antenna consists of a four linear microstrip patch antenna array and a 4x4 butler matrix beamforming network. It was able to form and steer four orthogonal beams in the four directions (±39°, and ±15°). Furthermore, it exhibited a high gain of 17.98 dB and good simulated and measured return losses. The design, optimization and simulation of the smart antenna components were performed using advanced design system (ADS).

Steerable directional antennas are increasingly utilised to improve the overall performance of the traditional wireless sensor networks. Steerable directional antenna based networking solutions increase the network capacity by providing a longer range of transmission and reduced interference as compared to networking solutions with omni-directional antennas. However, the use of smart antennas requires complex algorithms and such algorithms may not be easily leveraged in low power Internet of Things (IoT) networks. This study presents mechanisms for integrating low complexity smart antenna solutions into IETF 6TiSCH protocol with the aim of creating scalable and reliable industrial IoT networks. The solution defines extensions to MAC layer and scheduling mechanisms of IETF 6TiSCH protocol to enable its seamless integration with low complexity steerable smart antennas. The results of this study show that smart antenna enabled 6TiSCH protocol stack outperforms the legacy 6TiSCH stack in terms of data delivery performance especially in high density scenarios.

The coronavirus disease 2019 (COVID-19) that broke out on December 2019 spread speedily throughout the world, resulting in serious economic problems and increasing the mortality rate. Preceding research illustrated that one of the main routes for the spread of COVID-19 is respiratory aerosol transmission, where the generation of the droplets is created by coughing, sneezing, breathing, and speaking. Therefore, innovative control methods are necessity needed to manage the epidemic. Microwave has been extensively applied to inactivate microorganisms like viruses in many different media. The previous techniques were applied in the laboratory just to virus samples. In this proposal, we use the microwave radiation to inactivate the airborne viruses in the ambient air inside the rooms of hospitals and clinics. The main contribution of this paper is to design a compact antenna array using smart antenna techniques to cover the room with uniform microwave power. It is taken into account that the radiated power is under the standard safety levels.

IETF 6TiSCH standard aims to create reliable, deterministic, and low-power networks by scheduling bandwidth resources in time and frequency domains. The main emphasis of 6TiSCH protocol is that it creates Internet of things (IoT) networks with a deterministic and controllable delay. However, many of its benefits are tied to the ability of the 6TiSCH scheduler to optimally distribute radio resources among wireless nodes which may not be possible when the number of frequency resources are limited and several other wireless technologies share the same frequency band (e.g., WiFi, Bluetooth and IEEE 802.15.4). Here the integration of a low-complexity directional antenna system with IETF 6TiSCH protocol is investigated with the aim of creating a 6TiSCH solution with higher spatial reuse. 6TiSCH nodes equipped with such smart directional antennas can schedule bandwidth resources not only in time and frequency domain but also in spatial (space) domain.

Efficient wireless backhaul networks using IEEE 802.11ac WiFi systems equipped with phased array antennas are proposed and implemented. The implemented backhaul system is composed of a commercial IEEE 802.11ac chipset, field programmable gate array, and smart antenna, i.e., phased array antennas. To select the best beam direction and maximize the throughput performance, a path-finding algorithm, which is based on the received signal strength and an interpolation method, is proposed. The smart wireless backhaul (SWB) can reduce the time of the initial installation and provide stable quality of service under various channel conditions. In addition, the proposed SWB includes a scheduling scheme with a new queue structure to support a point-to-multipoint network topology. The feasibility and various applications of the proposed SWB are also demonstrated by performing field tests. The implementation and field tests show the potential for wireless backhaul enabling small-cell networks.

Application specific, lightweight yet high strength materials always remain in large demand to the aerospace engineers. Poly-ether-ether-ketone (PEEK) is a unique polymer which has low density, high glass transition temperature, and stability at an ultra-high vacuum condition. In addition, high compliance of PEEK and ease of vacuum forming facilitate the development of complex geometric shapes. In this research, we have investigated the suitability of PEEK material for parabolic antenna structure under space environment conditions. We have carried out rigorous space qualification tests on various categories of PEEK material. With the promising experimental results, we have developed a 450 mm diameter prime focal C-band Antenna. The parabolic antenna is made up of PEEK material, and it is supported on the curved ribs made up of PEEK CA30 material. The developed antenna setup is further installed for far-field radiation testing in a Compact Antenna Test Facility (CATF) in the anechoic chamber. Simultaneously, RF simulations are carried out using CST software. The simulated and measured far-field radiation patterns show close agreements. Thereafter, thermal analysis of the developed antenna and the effect of thermal expansion on radiation far-field are discussed. The developed antenna is very promising to be used in the future space missions.

This letter shows that the position of a source inside an electromagnetic bandgap material determines how the emission is shaped and focused. Two degenerate electromagnetic configurations, allowed by a square lattice at a given frequency, can be selectively excited by placing the feeding point in specific locations within the building block of the periodic structure. In this way, the radiated energy can be directed toward defined focusing directions, without need to change the lattice and its dispersion diagram. A practical application, where embedded emitters selectively drive single lattice modes, is presented, showing that such a mechanism may open the way to important uses in the microwave domain, e.g., for cell splitting, smart antennas, and multiple-input-multiple-output technology, as well as in terahertz communications and optical applications.

Current 4G - the fourth-generation wireless communication, which exists in most countries represents an advance of the previous 3 generation wireless communication. However, there are some challenges and limitations, associated with an explosion of wireless devices, which cannot be accommodated by 4G. Increasing the proliferation of smart devices, the development of new multimedia applications and growing demand for high data rates are among the main problems of the existing 4G system. As a solution, the wireless system designers have started research on the fifth-generation wireless systems. 5G will be the paradigm shift that could provide with ultra-high data rate, low latency, increase of the base station capacity and improved quality of services. This paper will be the review of the changes through the evolution of existing cellular networks toward 5G. There will be represented a comprehensive study associated with 5G, requirements for 5G, its advantages, and challenges. We will explain the architecture changes – radio access network (RAN), air interfaces, smart antennas, cloud RAN and HetNet. Furthermore, there will be discussed about physical layer technologies, which include new channel modes estimation, new antenna design, and MIMO technologies. Also, we will discuss the MAC layer protocols. We will look at three kinds of technologies: heterogeneous networks, massive multiple-input, and output, millimeter-wave. Finally, there will be explained the applications, supported by 5G, new features, various possibilities, and predictions.

The development of Directional Medium Access Control (DMAC) strategies that allow to enhance the limitations due to the use of omnidirectional antennas in Mobile ad Hoc Networks (MANET), introduces several issues that need to be properly addressed such as the Deafness problem. The use of Smart Antenna Systems (SAS) along with Directional Request To Send (DRTS) and Directional Clear To Send (DCTS) could be not sufficient to mitigate the Deafness. In this regard, a sectorized antenna approach together with a frame scheduling mechanism can improve the overall MAC performance while limiting the Deafness; however, the employment of scheduling algorithms without priority such as the Round Robin could limit the network performance especially in terms of Packet Delivery Ratio (PDR) and fairness. For this reason, we propose two approaches: the A-MSDU (Aggregation MAC Service Data Unit) MAC and a WRR (Weighted Round Robin) MAC that could allow to overcome the limitations of the Round Robin scheme applied at MAC layer in order to have an high efficiency in the overall resource allocation. More specifically, obtained results show that, through the use of frame aggregation, it is possible to considerably reduce issues implied by Round Robin such as time slice and network overhead; WRR approach, instead, is able to enhance the overall network fairness by reducing the number of collisions provided by a directional MAC based on Round Robin scheduling; this aspect translates into higher PDR performance compared to Round Robin approach.

By using the multibeam smart antennas (MBSAs), the nodes can form a high-throughput wireless mesh network with concurrent packet delivery in multiple directions. In this paper, a novel medium access control (MAC) scheme is designed for multibeam airborne mesh networks. It has the following two features: First, IEEE 802.11-compatible, interference-minimized channel access via a special two-layer MAC architecture, where the upper-layer MAC supports the concurrent multibeam transmission/reception, and the lower-layer MAC takes advantage of MBSAs; second, adjustment of the parameters of the two MAC layers to support different mission priorities in airborne networks, including the allocation of time slots in the upper layer. The simulation results demonstrate the superior performance of our proposed multibeam MAC protocols.

With the increasing demand for high speed reliable communications, smart antennas, such as the Butler Matrix array, can be used to develop a system that increases the performance of a wireless system. The Butler matrix is a switched beam array system which can produce orthogonal uniform beams. The main objective is to improve the efficiency of the power in a 90-degree bend. Also, the double-mitered bend is particularly interesting since it provides a substantially lower reflection coefficient and a lower value of S12 at a frequency of 2.4 GHz compared to an unmitered one. Therefore, this paper describes an optimum design using a double-mitered method with a 2 × 2 and a 4 × 4 Butler Matrix array, operating at 2.4 GHz which is used in wireless systems with an FR4 substrate.

The features of the use of finite waveguide antenna arrays in the structure of modern smart antenna systems are considered. The paper deals with the problem of diffraction of an electromagnetic wave on a finite waveguide antenna array scanning in the E-plane. Antenna array consists of five radiating elements. The open ends of the waveguides are surrounded by a metal screen. The resonator coupling region was chosen as matching elements. The solution of the problem is carried out by the integral equation method on the basis of the selection of overlapping regions. The problem reduces to solving the Fredholm integral equation of the second kind. An array of infinitely thin plates and that of waveguides with a finite wall thickness are considered. The main regularities for choosing the optimal geometric dimensions of the antenna array are established. Studies were carried out for arrays with a number of elements from five to fifteen. The analysis of edge effects in the final antenna array is carried out. It is shown that the introduction of a resonator region into a five-element lattice makes it possible to expand the sector of the radiation angles and avoid the effect of blinding. It is shown that this statement is valid not only for five-element lattices, but also for arrays with a large number of radiating elements. The radiation patterns are calculated. The coefficients of mutual coupling in an array with five elements are investigated. General recommendations for choosing optimal sizes of the resonator coupling region of radiators are considered.

This work proposes the use of the Particle Swarm Optimization method (PSO) to maximize the main beam of an intelligent, switched array of four Yagi-Uda antennas. The antenna feeds, amplitude and phase, are the PSO input variables, which not only maximizes the main lobe for a given direction, but also minimizes all secondary ones. The MATLAB software is used to make the simulations. Radiation patterns are here produced, which show that PSO is efficient for maximizing lobes in the range from 0° to 180°. Suggestion of an arrangement for a 360° coverage around the array is also presented.

Machine Learning Algorithms (MLA) have revolutionized many eras in the recent past. MLA has started to simplify the data world with its revolutionary methodologies. Use of MLA for Smart Antenna Arrays (SAA) has been the need of the hour to enhance the system performance of SAA. The combination of MLA and SAA can have diverse usefulness in the Internet of Things (IoT) applications. This paper has provided a brief survey on the use of MLA for SAA for IoT applications in many fields. As the highly interconnected world of IoT needs many optimization, stringent analysis and advanced prediction methods MLA for SAA can be a good solution to counter the challenges faced by SAA of the IoT.

Due to the multiple possibilities in wavefront manipulation, reconfigurable metasurfaces have attracted considerable interests. In this work, a two-dimensional reconfigurable reflective metasurface integrating varactor diodes is proposed for an operation in the microwave domain. The reconfigurability mechanism enables to control the electromagnetic response of each meta-atom individually by an elaborately designed voltage bias system. Both simulations and measurements are carried out to evaluate and validate the design of the tunable metasurface. Owing to the individual control and high-efficiency characteristics, the reconfigurable metasurface can easily pave the way to applications in multi-frequency and/or multi-functional wireless power transmission, lenses, complex beam generation and smart antennas.

The capability for actual measurements—not just simulations—of the dynamical behavior of THz electromagnetic waves, including interactions with prevalent 3D objects, has become increasingly important not only for developments of various THz devices, but also for reliable evaluation of electromagnetic compatibility. We have obtained real-time visualizations of the spatial evolution of THz electromagnetic waves interacting with a single metal micro-helix. After the micro-helix is stimulated by a broadband pico-second pulse of THz electromagnetic waves, two types of anisotropic re-emissions can occur following overall inductive current oscillations in the micro-helix. They propagate in orthogonally crossed directions with different THz frequency spectra. This unique radiative feature can be very useful for the development of a smart antenna with broadband multiplexing/demultiplexing ability and directional adaptivity. In this way, we have demonstrated that our advanced measurement techniques can lead to the development of novel functional THz devices., 微小金属らせんとテラヘルツ光との相互作用を可視化 --次世代超高速移動通信などにおける高性能アンテナへ応用--. 京都大学プレスリリース. 2021-02-09.

In various fields such as the 5G antenna system and satellite communication system, there is a growing demand to develop a smart antenna with a frequency selective or beamforming function within a limited space. While antennas utilizing mechanical, electronic, and material characteristics are being studied, a method of having tunable frequency characteristics by applying a liquid crystal material with dielectric anisotropy to a planar patch antenna is proposed. In resonance mode, the design method for using only the minimum amount of expensive liquid crystals is systematically arranged while maximizing the amount of change in the operating frequency of the antenna by considering the electric field distribution on the surface of the patch antenna. Furthermore, to increase the dielectric anisotropy of the liquid crystal, the liquid crystal must be aligned. Simultaneously, in cases where the cell gap of the liquid crystal exceeds 100 μm, the alignment force is weakened. While compensating for this shortcoming, securing the radiation characteristics of the antenna is proposed, and simulations are performed.

Wireless technology is growing rapidly in today’s era. It is very crucial to design and develop smart antenna structure which could resonate for multiple frequency bands. In this paper, the Dielectric Resonator Antenna (DRA) array has been successfully designed for multiband applications. The presented array resonates at 1.85 GHz, 5.13 GHz, 9 GHz and 14.24 GHz frequencies with the peak gain values of 1.20 dBi, 2.66 dBi, 3.91 dBi, 6.6 dBi and 2.05 dBi respectively. The microstrip line feed is utilised as feeding technique where the width of microstrip line is optimised to achieve adequate antenna resonance. The alumina ceramic has been utilised as DRA material having the relative permittivity of 9.3. The FR4 material is used as a substrate above which the dielectric resonator blocks have been formed. The overall size of the antenna is 50 x 40 mm2. There a close match between simulated results and measured results which shows proposed structure potential for GSM 1800 (1.81 GHz), WLAN (5.13 GHz), Radar (9 GHz), Direct Broadcast Satellite (12.5-15 GHz) applications

Security is the major concern in wireless sensor networks. To reduce security threats in WSNs physical layer, each node could be designed with an antenna which forms a MIMO communication system. This research work proposed a novel and effective solution to enhance the security of WSN. The sensor node at the transmitter side are used to transmit the beamforming signal to the receiver while few nodes are used to create artificial noise to jam the eavesdropper. Beamforming is used in WSNs for effective communication which enhances the received signal to noise ratio (SNR) at the receiver side. Based on beamforming, smart antennas are modified to switch the direction and adjusts the transmitted power and phase through intermediate relay nodes and constructively it is used in the destination side to combine the signal. This new beamforming technique needs the information about the channel for security concern in these relay system of destination as well as an eavesdropper. For physical layer security beamforming area along with schemes such as amplify and forward relays, decode and forward relays and also co-operative jamming relays where adopted, to confuse the eavesdropper. Two channels are used in the experimental model such as main/legitimate channel, which is used between the relay node and destination node, and the other one is the wiretap channel which is used between the intermediate relay node and the eavesdropper.

Today, people like to enjoy their life in a fast lifestyle and therefore, high speed wireless communication has become essential for delivering content and knowledge in the information age. This leads to a large demand for compact multiband or wideband antennas to prop up wireless communication devices such as cell phones, tablets, laptops, computers, and other related devices. Compact design permits more space to integrate other electronic components. In addition, a number of other requirements are remain exist such as antenna packaging, antennas on chip without compromising its performance while integrating in wireless devices. Therefore, designers propose different innovative approaches to reduce the complexities and difficulties in the design of wireless device. The aim of this book is to showcase latest R&D trends and novel methods in designing and analyzing broadband, multiband, and reconfigurable antennas for 5G and B5G mobile and wireless applications, as well as integrating in small volume wireless devices. This book provides theoretical and experimental approach to some extent which would be useful to the researchers, scientist, engineers, and senior students in the field of antenna engineering. This book also highlights unique design issues to help the reader as well to understand more advanced research.

This book is focused on wireless infrastructure deployment in modern transportation markets, where the wireless infrastructure co-exists with the existing structure. It details the challenges this deployment may face and explores the mitigation measures to overcome the challenges. The book proposes a smart antenna structure to overcome airspace congestion, which improves the overall wireless performance and deployment cost. With the combination of practical know-how and theoretical estimation, this book provides insight on how the modern smart antenna techniques that support most cutting-edge wireless technology can be adopted into the existing infrastructure whilst minimising the distraction to the existing system. This book is suitable for industrial and academic researchers, practising engineers within the field of smart antennae, and wireless infrastructure designers and developers.

Smart antenna (SA) systems result in higher capacity and broader coverage in wireless communications. Multiple-input multiple-output (MIMO) systems have resulted in higher capacity and reliability. The combination of these two systems (SA-MIMO) has advantages of both systems simultaneously. One drawback of multiple antenna systems is the high computational burden and hardware cost due to radio frequency (RF) chains. One remedy for this drawback and to reduce the number of RF chains is antenna selection in which the best subset of antennas is selected among the available large number of antennas. This paper proposes a joint user and transmit antenna selection strategy in the uplink SA-MIMO systems. First, the best subset of antennas is selected at each user on the transmit side. After that, the best user is selected to transmit the signal to the receiver. The simulation results show that how the proposed strategy results in a better performance without a need to increase the number of RF chains.

This study aims to support the communication network in the LoRa technology application in supporting the application of the IoT system. In Indonesia, LoRa technology is included in the communication technology based on low power wide area network (LPWAN) non-cellular by utilizing the unlicensed ISM band of 915 MHz. Generally, LoRa technology is widely used in research and industry. This paper designs a smart beam steering antenna at a frequency of 923 MHz in accordance with Indonesian regulations that can guarantee data quality reception on the LoRa system. The computation results of this smart antenna design has confirmed that it allows to steer the antenna beam direction into 360° full azimuthal coverage. The main lobe is altered for every 60° step. In terms of performance parameters, this antenna design exhibits a pretty good performance with Return Loss value ≤-10 dB, VSWR value

An optimized switched parasitic smart antenna (SPSA) 915 MHz that consists of 6 monopole parasitic wires encircled a single feeding monopole wire and configured on top of a 328 mm circular ground plane was manufactured and evaluated. SPSA prototype is initially designed to support the practical operation of a particular IoT based surveillance network within the university campus environment. In practical, the constructed antenna installed at a server station will continuously detect the particular active sensor node and maintain the connection and the data transfer between sensor node and the server. A slightly different switched beamforming technique deployed on the fully shielded cover seven monopole wires planar array by electronically setting-up 3 parasitic wires to be grounded and three other floating at the same time in order to point the power beam into a certain direction. Through the sequential variations of those wires set-up then the main lobe directions would be pointed to 6 different directions, i.e. 0°/360°, 60°, 120°, 180°, 240°, and 300°.

As of late, adapt antennas, with the capacity to transmit wave in more than one example and polarization, assume an incredible job in present-day media transmission frameworks. They can be utilized to improve framework increase and security, fulfill framework necessities, stay away from boisterous conditions, and adjust to nature adaptable. This paper depicts keen antennas that might be utilized on the airship. Two aviation bundles are noted in a more prominent component: a staged exhibit receiving wire with optical pillar shaping and a huge vibrating staged cluster radio wire with electronic pay strategies. In the supposition of this document, the radiation design conditions of antennas incorporate shaft heading, shape, and increase. These antennas have been all around connected for aviation and earthly applications, for example, dynamic situations, versatile bar checking, and various information different yield (MIMO) systems.