Antenna Techniques Research Articles

Ergodic Capacity for Evaluation of Mobile System Performance

In this research the performance of 5G mobile system is evaluated through the Ergodic capacity metric. Today, in an­­y wireless communication system, many parameters have a significant role on system performance. Three main parameters are of concern here; the source power, number of antennas, and transmitter-receiver distance. User equipment’s (UEs) with equal and non-equal powers are used to evaluate the system performance in addition to using different antenna techniques to demonstrate the differences between SISO, MIMO, and massive MIMO. Using two mobile stations (MS) with different distances from the base station (BS), resulted in showing how using massive MIMO system will improve the performance than the standard SISO and MIMO techniques, under Rayleigh fading channel. Using MATLAB as a simulation tool it was found that the ergodic channel capacity enhance by increasing the power of the source and the base station antenna and it behaves in an opposite way with distance.

Golden Coded GFDM for 5G Communication

The 5th Generation (5G) of wireless communication will be heterogeneous to support various traffic types and applications. Generalized Frequency Division Multiplexing (GFDM) is a 5G non-orthogonal waveform contender that offers scalable and spectrally compliant air interface which addresses the needs of 5G requirements. To aid the demand of high-capacity and reliable transmission, multiple antenna techniques are relied upon. In this work, the 5G modulation scheme GFDM is combined with a full rate Space–Time Block Code (STBC) with nonvanishing determinant called Golden Codes to exploit the diversity to the fullest. The proposed work is implemented in a real-time SDR test-bed called Wireless Open Access Research Platform (WARP). The proposed work is compared with 4G OFDM modulation in both Golden Coded and Uncoded case. The performance is assessed in terms of BER and Capacity/Bandwidth resolution. From the investigations, it is seen that the BER performance of Golden Coded GFDM outperforms the Uncoded GFDM by 3 dB SNR gain and attains a near-equal performance as OFDM. Also, it is evident from the analysis that, there is a 3.5 bps/Hz gain in capacity when compared to OFDM.

Study on improvement of the performance parameters of a novel 0.41\u20130.47 THz on-chip antenna based on metasurface concept realized on 50\xa0\u03bcm GaAs-layer

A feasibility study is presented on the performance parameters of a novel on-chip antenna based on metasurface technology at terahertz band. The proposed metasurface on-chip antenna is constructed on an electrically thin high-permittivity gallium arsenide (GaAs) substrate layer. Metasurface is implemented by engraving slot-lines on an array of 11 × 11 circular patches fabricated on the top layer of the GaAs substrate and metallic via-holes implemented in the central patch of each row constituting the array, which connects the patch to the leaky-wave open-ended feeding slot-lines running underneath the patches. The slot-lines are connected to each other with a slit. A waveguide port is used to excite the array via slot-lines that couple the electromagnetic energy to the patches. The metasurface on-chip antenna is shown to exhibit an average measured gain in excess of 10 dBi and radiation efficiency above 60% over a wide frequency range from 0.41 to 0.47 THz, which is significant development over other on-chip antenna techniques reported to date. Dimensions of the antenna are 8.6 × 8.6 × 0.0503 mm3. The results show that the proposed GaAs-based metasurface on-chip antenna is viable for applications in terahertz integrated circuits.

Directional modulation method to increase the capacity of confidential messages over broadcast channels

This study investigates information and secrecy capacity over broadcast channels through the use of directional modulation. The authors develop and demonstrate the utility of an antenna array control technique that provides communication devices with enhanced information and secrecy capacity by time-varying the array steering vectors using a novel beam control method. They show that an increase in the achievable capacity in a broadcast communication system beyond the currently-accepted Sato bound is possible by using the time domain of array steering vectors as an additional degree of freedom. Furthermore, they increase the overall secrecy capacity of the system by spatially restricting the successful reception of signals. In practical terms, this results in higher-rate, confidential messages for multiple devices for a given power constraint. They present simulation results of the array steering technique showing that direction-dependent modulation can provide broadcast channel capacity and secrecy capacity exceeding theoretical bounds for conventional, static coding techniques. They further describe an experiment and share measured results that corroborate the simulated results at the physical layer and provide insight into the proposed method.

The Prototype Incoherent Scatter Radar System of Nanchang University

The incoherent scattering radar (ISR) is the only ground device on Earth that can detect the parameters of the ionospheric plasma because of its large detection range, high detection accuracy, and high spatial resolution. The prototype ISR system of Nanchang University has been completed now. Compared to the existing ISR systems in the world, which have a high radio frequency (RF) power and antenna array, high power consumption, expensive equipment operation, and maintenance costs, the radar has the advantages of low power consumption, low cost, and modularity. This radar system uses novel techniques of software-defined radio (SDR) and active phased array antennas to detect changes in the ionosphere. This article introduces the system design and antenna array of the software-defined radar prototype. The built-in radar transmitting and receiving equipment and specific radar parameters are described in detail and the radar detection results under different detection conditions are presented.

Planar Feeding Techniques for Wearable Textile Antennas

Feeding techniques for textile antennas are of crucial importance to simultaneously address mechanical requirements of robustness while maintaining high RF performance. To assist in determining which planar feeding mechanism is best suited for textile antennas, a dedicated study of various planar feeding mechanisms is undertaken as one of the main aims of this article. Two of the most prominent techniques, namely the inset and proximity-coupled methods, are investigated on a quarter-wave patch, with particular attention to their suitability for various substrate thicknesses. It is shown that neither technique is suitable beyond a substrate thickness of $0.03\lambda _{0}$ . Consequently, a new textile feeding technique is proposed that blends aspects of the inset and proximity-coupled feeding techniques and represents the main contribution of this article. It is shown that this new feeding mechanism can serve as viable planar textile replacement for a coaxial probe feeding mechanism up to the substrate thicknesses of $0.05\lambda _{0}$ .

Signal interference‐based selectivity‐enhancement technique for omnidirectional monopole antenna

AbstractA compact monopole antenna with enhanced selectivity is designed based on circular disk monopole antenna and signal interference technique (SIT). It is composed of a circular disk monopole and a SIT‐based filtering structure consisting of two pairs of short‐circuited edge coupled stubs loaded on the feeding line. When the filtering structure is just loaded the feeding line, a filtering monopole antenna is obtained. A prototype is constructed, assembled, and tested. The measured results agree well with simulated one.

A Novel Random Access Framework for Uplink Cellular IoT: Non-Orthogonal Preambles and Multi-Antennas

Traditionally, even though the base station (BS) is equipped with multiple antennas, it has not been able to apply antenna technique such as an uplink multi-user multiple-input multiple-output (MU-MIMO) during the random access (RA) procedure due to the contention feature of the RA. To overcome such limitation, this letter proposes a novel RA framework leveraging both non-orthogonal preambles and multi-antenna technique. In our proposed framework, the non-orthogonal preambles effectively increase the total amount of contention resources, i.e., RA preambles, and thus the occurrence of preamble collisions can be significantly reduced. Accordingly, the BS can take an opportunity to exploit an uplink MU-MIMO even in the contention-based RA procedure under the belief that the contention may be resolved. We mathematically analyze the proposed framework in terms of packet collision probability and resource efficiency. Analysis and simulation results reveal that our proposed framework is able to accommodate more internet-of-things (IoT) devices in a resource-efficient way, compared to the conventional one.

Reconfigurable Antennas: Switching Techniques—A Survey

Due to the fast development of wireless communication technology, reconfigurable antennas with multimode and cognitive radio operation in modern wireless applications with a high-data rate have drawn very close attention from researchers. Reconfigurable antennas can provide various functions in operating frequency, beam pattern, polarization, etc. The dynamic tuning can be achieved by manipulating a certain switching mechanism through controlling electronic, mechanical, physical or optical switches. Among them, electronic switches are the most popular in constituting reconfigurable antennas due to their efficiency, reliability and ease of integrating with microwave circuitry. In this paper, we review different implementation techniques for reconfigurable antennas. Different types of effective implementation techniques have been investigated to be used in various wireless communication systems such as satellite, multiple-input multiple-output (MIMO), mobile terminals and cognitive radio communications. Characteristics and fundamental properties of the reconfigurable antennas are investigated.

DESIGN OF RAT-RACE BASED RETRO-DIRECTIVE ARRAYS FOR SUB 6GHZBAND

Due to the large available capacity in Radio frequency spectrum from 30GHz to 300GHz is allocated for millimeter communications (mm Wave). It has been attracting significant attention from industry and academic purpose .To meet very large growth in data and connectivity for tomorrow’s innovations mmwave systems has been designed. Fast beaming tracking and security are important factors for the development of communication technology. A Retro directive antenna (RDA) technique has been attenuated to one way of improving security. It has the interesting property of instinctive responding to an incoming signal location without any information about the direction of source. The purpose of the proposed system is to design a Rat race coupler which acts as a Retro directive mode in ANSYS. The resonant frequency of the coupler is 2.4 GHz. The Proposed Rat race couplers have been devised using the Glass Epoxy substrate (FR4) with dielectric constant (er = 4.4). S parameters, radiation pattern, insertion and isolation losses are obtained from ANSYS software.

A Novel Azimuth Ambiguity Suppression Method for Spaceborne Dual-Channel SAR-GMTI

Azimuth ambiguity degrades the quality of synthetic aperture radar (SAR) images and leads to the increase of false alarm rate in ground moving target indication (GMTI). Due to the existing azimuth ambiguity, suppression methods do not remove the first-order ambiguity completely and ignore the ambiguity above first order as well, moving target detection is affected by residual ambiguity. Hence, a novel method to suppress first-order and higher order azimuth ambiguities for the dual-channel SAR/GMTI is proposed in this letter. First, the displaced phase center antenna (DPCA) technique is applied to suppress clutter. Then, estimate the local azimuth ambiguity-to-signal ratio (LAASR) to find out the area affected by ambiguity. Finally, an inpainting algorithm is improved to patch the ambiguity area. The proposed method can remove the ambiguity almost completely. Moreover, the method is verified using the GaoFen-3 SAR dual-channel complex image data, and the result shows that the false alarm of moving target detection is degraded without reducing the detection rate.

Інформаційне повідомлення

Information message:- 12th International Conference on Antenna Theory and Techniques (June 22-27, 2020);- XX International Propulsion Engineering Congress (September 8-13, 2020);- Scientific and practical student conference "Modern problems of engine building, energy and intellectual mechanics-2020" (May 19-20, 2020).

A Novel Dual-Band Binary Branch Fractal Bionic Antenna for Mobile Terminals

A novel two-iteration binary tree fractal bionic structure antenna is proposed for the third generation (3G), fourth generation (4G), WLAN, and Bluetooth wireless applications in the paper, which is based on the principles of conventional microstrip monopole antenna and resonant coupling technique, combined with the advantages of fractal geometry. A new fractal structure was presented for antenna radiator, similar to the tree in nature. The proposed antenna adapted two iterations on a fractal structure radiator, which covers mobile applications in two broad frequency bands with a bandwidth of 44.2% (1.85–2.9 GHz) for TD-SCDMA, WCDMA, CDMA2000, LTE33-41, and Bluetooth frequency bands, and 11.5% (4.9–5.5 GHz) for WLAN frequency band. The proposed antenna was fabricated on a G10/FR4 substrate with a dielectric constant of 4.4 and a size of 50 × 40 mm2. The good agreement between the measurement results and the simulation results validate that the proposed design approach meet the requirements for various wireless applications.

Intelligent Offloading Strategy Design for Relaying Mobile Edge Computing Networks

To support the application of IoT and smart city, high data-rate wireless transmission is required. To meet the demand of high data-rate, the techniques of multiple antennas and mobile edge computing (MEC) networks have been proposed in order to enhance the data transmission rate significantly. However, there still exist lots of challenges array signal processing assisted MEC networks. In this paper, we propose an intelligent framework of offloading strategy for MEC networks assisted by array signal processing, where one user with multiple antennas has some computational tasks. These tasks can be computed by the user itself which however has limited computational capability, or computed by the near-by computational access points (CAPs) which has a powerful computational capability at the cost of wireless transmission. We consider the system cost by jointly taking into account the computational price, the energy consumption and the latency. By minimizing the system cost, we propose an intelligent offloading strategy based on ant colony optimization (ACO) algorithm, where the ants randomly visit the CAPs in order to obtain the final results. To further enhance the MEC network performance, the array signal processing is utilized at the user, where either the maximum ratio transmission (MRT) or selection combining (SC) is used to assist the data transmission from the user to CAPs. Simulation results with MRT and SC are finally demonstrated to verify the effectiveness of the proposed ACO-based offloading strategy and array signal processing schemes.

Antenna Tracking Techniques for Long Range Air-to-Ground Communication Systems Using a Monopulse Method

In this paper, we consider long range air-to-ground (AG) communication systems which support airborne platforms including unmanned aerial vehicles (UAVs) for real-time applications. In this system, we design tracking techniques for directional ground antennas which enable reliable AG communication regardless of dynamic maneuvers of the UAV. We apply a simple monopulse method and a fixed gain filtering algorithm to develop a single channel monopulse tracking system with an angular estimation filtering, which exploits a downlink signal without requiring a dedicated channel. Through the AG communication prototype and realistic flight tests, we evaluate the tracking accuracy performance at the distance of hundreds of kilometers and demonstrate the auto-tracking capability of the angular estimation filter. The flight test results show that the tracking accuracy of our proposed system is sufficient for long range transmission with a narrow beam antenna. Also, in the absence of the downlink signal, it is observed that the ground prototype can resume the monopulse tracking procedure, and successfully maintains the tracking accuracy.

Dynamic enhanced proximity coupling technique for antennas

Dynamic enhanced proximity coupling technique for antennas

Dynamic enhanced proximity coupling technique for antennas

Role of feeding is very important for the efficient operation of an antenna. Changes in the feeding structures improve (i) bandwidth (BW), (ii) return loss and (iii) impedance matching (IM). Common coaxial feeding produces low return loss and good IM, but it yields narrow BW. Proximity feeding increases BW and eliminates spurious radiation at the cost of high losses. Dynamic feeding attains low losses, good IM and narrow BW along with frequency reconfiguration (FR). This paper aims to produce broad BW and FR antenna with the help of Dynamic Enhanced Proximity Coupling (DEPC) technique. In this, a multiple substrate layer antenna with a patch in one layer and feed in another layer along with ascension of feed position produces a low loss, broad BW and FR antenna. The DEPC design, which is tested on rectangular patch and fractal structures, achieves improved current distribution and overall BW compared to other techniques.

Wideband Hybrid Precoding Using Time Modulated Arrays

Hybrid digital-analog precoding is a cost effective solution for transmitting over the large bandwidths and huge antenna arrays available in the millimeter wave frequency bands. In this work we focus on the transmission of wideband signals over hybrid precoders that utilize Time-Modulated Arrays in the analog domain. We consider analog precoders constructed with Single-Pole-Double-Throw switches which are both flexible and efficient. We pose two Orthogonal Frequency-Division Multiplexing symbol configurations to cope with the harmonic interference introduced by the Time-Modulated Array. One does not take advantage of the wireless channel frequency diversity and the other does. We optimize digital and analog precoders to maximize the achievable rate in both symbol configurations. Optimization takes into account the switching devices efficiency and the inherent losses of this antenna technique. Finally, we show the excellent performance obtained with the proposed approach, in terms of achievable rate, compared to that of conventional phased arrays.

Enabling Things To Talk in Heterogeneous Self-Organizing Networks—An Exhaustive Critique For IOT

The superstructure network in the Internet of Things (IoT) is an emerging network targeted to enable an ecosystem of smart applications and services. It connectsphysical resources and peopletogether with software, hence contribute to sustainable growth, provided it combines and guarantees trustand security for people and businesses. In this work we presented smart city viewpoint opt-in to the Firth Generation (5G) mobile networks. Both a framework and deployment are explored rigorously to assist and predicting robustness of IoT technologies and applications as a natural outcome of the Third Generation Partnership Project (3GPP) in general and LTE in particular. These technologies are compared on the basis of Air Interfaces and their Specifications i.e. Adaptive Modulation and Coding, Multiple Access Schemes and Multiple Antenna Techniques along with the evolution and comparison of the Network Architectures.

An Analyzing of Cross Layer Design for Implementing Adaptive Antenna Technique in Mobile Ad-Hoc Networks

Abstract A mobile ad-hoc network (MANET) uses an omni-directional antenna, which transmits and receives power from all directions, resulting in higher noise and interference. The interference effects can be minimized with the help of adaptive directional antennas. The proposed model for implementing adaptive antenna techniques in MANET is a cross layer design. Utilizing adaptive antennas, two nodes are able to communicate when both the transmitter’s and receiver’s unidirectional radiation beams are directing toward each other’s nodes. A cross layer methodology for dynamic topology control enables the interaction between medium access control layer and the routing layer for reaching the necessary quality of service (QoS) of various data packets. After the initialization of a network, the algorithm initially develops a topology and the routing techniques use this network topology to find out the route paths for data transmission. Later, based on the network scenario for ongoing transmissions and to obtain the necessary QoS, the topology gets altered by the topology control layer in order to obtain the optimized network with better performance. Simulation results show specifically, throughput and signal-to-noise ratio were increased by 33 % and 42 %, respectively.