Optimal Antenna Configuration Research Articles

Parasitic Loaded Shorting Pin Based Compact Multi-slot LoRa Antenna for Military Application

In this paper, work on a compact multi-slot patch antenna with a parasitic load and shorting-pin has been presented for its use in long range (LoRa) defense applications. Initially the antenna is designed and simulated using HFSS and a parametric study has been carried out for achieving an optimized antenna configuration. This is followed by the fabrication of antenna prototype based on the optimal performances obtained from the simulated results. Further, the return loss along with free space co-polar and cross-polar radiation pattern measurements has been carried out for the fabricated antenna. The experimental results show a good comparison with that of the simulated one. The proposed antenna resonates at an operating frequency of 866 MHz, providing a -10 dB bandwidth from 856 MHz-877 MHz, which covers the wireless standard used for LoRa technology. Finally, a comparative analysis of the proposed antenna with the recently reported works is presented.

Extracting mud invasion information using borehole radar — A numerical study

In hydrocarbon drilling, mud filtrate penetrates permeable formations and alters the pore fluid characteristics in the immediate vicinity of the borehole. Typically, the prevailing in situ pore fluids are displaced by the invading mud filtrate, which leads to gradually changing distributions of the fluid and electrical properties. Understanding this invasion process is crucial for the interpretation of logging data and associated reservoir evaluations. Conventional logging methods tend to be inadequate for this purpose as their resolution is too low. We find that invasion depth can be determined from borehole radar data using an optimized antenna configuration and time-lapse measurements. A series of parametric sensitivity analyses provide information about the effects of variations of the rock and fluid properties on the identification and extraction of borehole radar signals reflected from the invasion front. Our results suggest that by embedding the radar antennas in cavities filled with an absorbing dielectric material, it is possible to minimize the interference arising from the metal components of the logging tool. In the simulated reservoir scenario, a time-lapse measurement mode with a time interval of at least 6 h can reliably extract the radar signals reflected from the invasion front, and the proposed borehole radar has a lateral detection range from 0.15 to 1 m. A comprehensive range of parametric sensitivity analyses indicates that the signals reflected from the invasion front are principally influenced by oil viscosity, porosity, and mud and formation water salinity, as well as by molecular diffusion coefficient and cementation exponent. These properties and parameters should be carefully explored and assessed when applying borehole radar to evaluate mud invasion information in a reservoir environment.

Design and Analysis of High-Capacity MIMO System in Line-of-Sight Communication.

The phase of the channel matrix elements has a significant impact on channel capacity in a mobile multiple-input multiple-output (MIMO) communication system, notably in line-of-sight (LoS) communication. In this paper, the general expression for the phase of the channel matrix at maximum channel capacity is determined. Moreover, the optimal antenna configuration of the 2 × 2 and 3 × 3 transceiver antenna array is realized for LoS communication, providing methods for optimal antenna placement, which can be used in short-range LoS communication and non-scattering environment communication, such as coupling train communication and inter-satellite communication. Simulation results show that the 2 × 2 rectangular antenna array is more suitable for the communication of coupling trains, while the 3 × 3 circular arc antenna array is more suitable for virtual coupling trains according to antenna configurations. Moreover, the 2 × 2 antenna rectangular configuration proposed in this paper has reached the optimal channel in inter-satellite communication, which lays a foundation for the deployment of communication systems.

High Data Transfer Rate Spatial Division Multiplexing for Short Range non-Line-of-Sight Ultraviolet Optical Transmission

To overcome the inherent bandwidth limitation of non-line-of-sight (NLOS) ultraviolet communication (UVC) channel, a novel space division multiplexing (SDM) framework based on non-coplanar rotation angle is established. The influence of SDM structure parameters on inter-channel interference (ICI) is studied to obtain the optimal antenna configuration. And a Gaussian approximate distribution (GAD) signal detection model is presented, which simplifies the calculation of the Bit error rate (BER) of the Photon multiplier tube (PMT) reception and is suitable for complex ICI analysis. Furthermore, a low ICI scheme based on the relationship between BER and the interference factor is proposed to increase the data transmission rate or reduce the alignment configuration. As a result, the maximum data rate increases to 34 Mbps, or the alignment demand decreases by 33.33% at most. Moreover, these analysis results and techniques can be applied to other NLOS scattering optical wireless communication systems.

Antenna Configuration Method for RF Measurement Based on DOPs in Satellite Formation Flying

Radio frequency (RF) measurement technology provides a relative navigation solution that can be of great importance to have significant potential for application to the satellite groups. With the development of the RF relative measurement sensors, it is found that the antenna configuration of the sensors affects the precision of relative position and attitude measurement. This study proposes improvements to the precision of the sensors by the virtue of the optimal antenna configuration. Furthermore, the concept of dilution of precision (DOP) is extended to the RF relative measurement sensors, and a new dilution called IDOP is proposed as a benchmark to determine the precision of relative position and attitude measurement in engineering applications of the space mission. In order to select the optimal antenna configuration in real time in a scene where the intersatellite position and attitude change dynamically, this study presents an optimal antenna configuration selection strategy and models the antenna configuration selection as a combinatorial optimization problem. Furthermore, the genetic algorithm (GA) with two encoding mechanisms is proposed to solve this problem. Finally, numerical results are presented to verify the robustness.

Impact of Non-Typical Antenna Configurations on Higher Order Sectored Sites in Ultra Dense Networks

The site densification and higher order sectorization are the two well-known possible ways of increasing the system capacity. However, to take the full advantage of these techniques they should be implemented with optimum antenna configuration. The target of this paper is to highlight the gain of using an optimized antenna configuration for 3-, and 6-sector sites in achieving a better quality (SINR) and capacity. Generally, a 3-sector site is deployed with 65° HPBW antenna; however, it was observed that for ultra-dense networks i.e. 100 m to 250 m ISD distance 3-sector site gives better result with 32° HPBW antenna. Similarly, performance of 6-sector site was found better with 16° HPBW antenna at small ISDs, whereas at large intersite distances the 32° HPBW antenna was found to be a preferred choice. It was observed that spectral efficiency of the cell degrades with site densification and higher order sectorization, but the overall capacity of a system improves due to more number of sectors and cells.

Photonic Terahertz-Wave Generation Using Slot-Antenna-Integrated Uni-Traveling-Carrier Photodiodes

Widely frequency-tunable terahertz-wave generation with enhanced output power was investigated using slot-antenna-integrated uni-traveling-carrier photodiodes (UTC-PDs). Based on numerical analysis, the optimum antenna configuration for simultaneously attaining increased output power and relatively broad bandwidth was determined. Slot-antenna-integrated UTC-PDs (short- and long-slot) and a broadband bowtie-antenna-integrated UTC-PD were fabricated and analyzed by comparing their characteristics. The slot-antenna-integrated UTC-PDs exhibited two to three times larger output power at their resonant peak frequencies than that of the bowtie-antenna-integrated UTC-PD. Output-power enhancement was attained at frequencies from 900 GHz to 1.6 THz for the short-slot device and from 350 to 850 GHz for the long-slot device, and these characteristics were in good agreement with the numerical analysis. The typical output power obtained was 3.5 μW for the short-slot device at 1.25 THz and 28 μW for the long-slot device at 700 GHz both for a photocurrent of 10 mA with a bias voltage of -0.4 V.

BER performance of an MRT‐HQAM system over Rayleigh fading channels

Hierarchical quadrature amplitude modulation (HQAM) allows for transmission of multiple classes of data (such as voice, video and file transfer), provides flexibility in terms of coverage area and allows for network upgrades while maintaining backwards compatibility. However, the addition of hierarchical layers leads to higher-order modulation schemes which make the system increasingly susceptible to noise and fading. To mitigate fading while maintaining backwards compatibility, maximum ratio transmission (MRT) is incorporated into the HQAM system to maximise signal-to-noise ratio for a given number of diversity branches. This study presents a theoretical bit error rate (BER) performance analysis of an MRT enhanced HQAM (MRT-HQAM) system in Rayleigh fading. The BER performance gains of the proposed system over single-input–single-output and single-input–multiple-output HQAM systems are shown. The HQAM hierarchical modulation parameter is varied and the effects are presented. Furthermore, the authors present the effects of varying the number of antennas on the transmitting and receiving ends and discuss the optimal antenna configuration. The theoretical BER expressions used in the performance analysis are verified using simulation results.

Optimal Antenna Deployment for Multiuser MIMO Systems Based on Random Matrix Theory

This paper investigates the issues on optimal antenna deployment at a base station to maximize downlink ergodic sum-rate capacity. We analyze the ergodic sum-rate capacity of a multiuser multiple-input–multiple-output (MIMO) system using random matrix theory, and the analysis reveals that such a capacity depends largely on the deployed antenna structure. Moreover, we have found an optimal antenna configuration based on the proposed particle swarm optimization (PSO) algorithm to maximize the ergodic sum-rate capacity. The theoretical results on downlink ergodic sum-rate capacity match simulation results very well, validating the accuracy of the theoretical analysis. The simulation results show that the proposed optimal antenna configuration offers the largest downlink sum-rate capacity with the best bit error rate (BER) performance compared with uniform linear arrays (ULAs) and uniform circular arrays (UCAs). It is concluded that the optimal antenna coordinates can be predetermined before deploying the antennas in a given base station.

Outage Performance of Optimal Relay Selection and Adaptive Antenna Configuration in Bidirectional Full-Duplex Amplify-and-Forward Relay Network

In this paper, outage performance of an optimal relay selection and adaptive antenna configuration in a bi-directional full duplex amplify-and-forward relay network is proposed. In the proposed network, based on the instantaneous channel state information (CSI), transmit and receive antenna configurations are adaptively selected at each AF relay node. The optimally chosen relay node and its adaptive antenna configuration will be active in the information exchange between the source nodes to improve the Signal to Interference plus Noise Ratio (SINR). Analytical expressions are derived for the end-to-end outage probability of the proposed network in Rayleigh fading environment. Although the self-interference at the full duplex relay node restricts the performance of the full duplex network despite the antenna configuration. The results reveal that the outage performance of the proposed network is better than the full duplex (FD) and half duplex (HD).

Joint relay antenna and precoding selection for K‐user MIMO Y channels with physical‐layer network coding

SummaryIn this paper, we focus on physical‐layer network coding (PNC) used in multiple‐input multiple‐output (MIMO) Y channels, where K users simultaneously exchange messages with each other via a shared relay. For MIMO‐PNC, signal space alignment for network coding (SSA‐NC) is a promising precoding method and can achieve K(K‐1) degrees of freedom if certain conditions can be satisfied. An important one is that the number of relay antennas is less than twice of the user antennas, that is, the dimensionality constraint of SSA‐NC. In this paper, we focus on a particular scenario where the dimensionality constraint is not satisfied. In order to resolve this problem, we develop a scheme of jointly selecting relay antennas and precoding vectors. In particular, a novel precoding and detection method is presented to alleviate the interference caused by simultaneous transmissions. Through analyzing the symbol error rate performance of MIMO‐PNC, we establish the relationship between the achievable flow diversity gain and the optimal number of the antennas, and a precoding selection method is designed under a given relay antenna configuration. Finally, we propose a joint scheme to select the optimal relay antenna configuration and precoding vectors. Numerical results demonstrate that the presented scheme can effectively support MIMO‐PNC in various scenarios. Copyright © 2015 John Wiley & Sons, Ltd.

Design of a ferrite rod antenna for harvesting energy from medium wave broadcast signals

Radio frequency (RF) energy harvesting is an emerging technology that has the potential to eliminate the need for batteries and reduce maintenance costs of sensing applications. The antenna is one of the critical components that determines its performance and while antenna design has been well researched for the purpose of communication, the design for RF energy harvesting applications has not been widely addressed. The authors present an optimised design for such an antenna for harvesting energy from medium wave broadcast transmis- sions. They derive and use a model for computing the optimal antenna configuration given application requirements on output voltage and power, material costs and physical dimensions. Design requirements for powering autonomous smart meters have been considered. The pro- posed approach was used to obtain the antenna configuration that is able to deliver 1 mW of power to 1 kΩ load at a distance of up to 9 km, sufficient to replace batteries on low-power sensing applications. Measurements using a prototype device have been used to verify the authors simulations.

Optimum antenna configuration in MIMO systems: a differential evolution based approach

AbstractIn this paper, we address the problem of determining the optimum antenna configuration for a multi‐input multi‐output (MIMO) system at any given signal‐to‐noise ratio (SNR). We used two‐level differential evolution (DE) algorithm that finds both an appropriate expression among a set of candidate expressions within the list of the optimization software used, and the parameter values (coefficients) belonging to the selected expression. The results of the proposed expression are compared with the results of high SNR approximation, asymptotic approach and optimum antenna number ratios. It is shown that the numerical outcomes produced by the new expression exhibit very good agreement with the optimum antenna number ratios, and this agreement is almost independent of the specific value of SNR. Copyright © 2010 John Wiley & Sons, Ltd.

Measurement of Distributed Antenna Systems at 2.4 GHz in a Realistic Subway Tunnel Environment

Accurate characterization of the radio channel in tunnels is of great importance for new signaling and train control communications systems. To model this environment, measurements have been taken at 2.4 GHz in a real environment in Madrid subway. The measurements were carried out with four base station transmitters installed in a 2-km tunnel and using a mobile receiver installed on a standard train. First, with an optimum antenna configuration, all the propagation characteristics of a complex subway environment, including near shadowing, path loss, shadow fading, fast fading, level crossing rate (LCR), and average fade duration (AFD), have been measured and computed. Thereafter, comparisons of propagation characteristics in a double-track tunnel (9.8-m width) and a single-track tunnel (4.8-m width) have been made. Finally, all the measurement results have been shown in a complete table for accurate statistical modeling.

Virtual Drive: A Complete V2X Communication and Radar System Simulator for Optimization of Multiple Antenna Systems

Vehicle-to-X (V2X) communication as well as automotive radar are fast growing areas of consumer interest. This gives rise to a challenge to a well-working communication systems in handling the V2X radio channel. The two most important components influencing the channel are the antennas and the fast changing environment, resulting in a time-variant behavior of the channel. Therefore, finding the optimal antenna configuration to ensure the best performance is a difficult task. A possible solution is the employment of measurement campaigns, but they are expensive, time consuming, and provide no repeatability. An alternative approach, based on simulations, is presented in this article. This tool, called “Virtual Drive,” consists of an environment and a traffic model and calculates the multipath propagation with a 3D ray-tracing tool. This combination yields a “virtual drive” through arbitrary scenarios and allows for the optimization of antenna configurations that are to be investigated. The different components of the Virtual Drive are described and the accuracy of the software tool is examined by a comparison with measurements. Finally, the manifold capabilities of such a software tool are demonstrated using the example of vehicular antenna optimization for cars and of radar system optimization.

Combined diversity and multiplexing for multiple-input multiple-output system with cochannel interference

A multiple-input multiple-output (MIMO) system that combines diversity and multiplexing is proposed for multi-cellular networks with cochannel interference. In the proposed MIMO system, the data stream is divided into multiple substreams, and each substream is transmitted and received over multiple antenna elements. Because of having both the advantages provided by diversity and multiplexing, the proposed MIMO system can gain larger throughput than the scheme with either diversity or multiplexing solely being employed. We propose an algorithm to find the optimum antenna configuration that maximises the throughput of the proposed MIMO system. We also propose a power control algorithm for the proposed MIMO system such that the interference is decreased and the throughput can be increased. In addition, the time division multiple access scheme and a scheduling algorithm are proposed to mitigate the interference in one time slot so that the throughput of the proposed MIMO system can be further increased.

Interactive Visual Optimization and Analysis for RFID Benchmarking

Radio frequency identification (RFID) is a powerful automatic remote identification technique that has wide applications. To facilitate RFID deployment, an RFID benchmarking instrument called aGate has been invented to identify the strengths and weaknesses of different RFID technologies in various environments. However, the data acquired by aGate are usually complex time varying multidimensional 3D volumetric data, which are extremely challenging for engineers to analyze. In this paper, we introduce a set of visualization techniques, namely, parallel coordinate plots, orientation plots, a visual history mechanism, and a 3D spatial viewer, to help RFID engineers analyze benchmark data visually and intuitively. With the techniques, we further introduce two workflow procedures (a visual optimization procedure for finding the optimum reader antenna configuration and a visual analysis procedure for comparing the performance and identifying the flaws of RFID devices) for the RFID benchmarking, with focus on the performance analysis of the aGate system. The usefulness and usability of the system are demonstrated in the user evaluation.

Optimizing antenna configuration for MIMO systems with imperfect channel estimation

We study the optimal antenna configuration (i.e. number of transmit and receive antennas) for multiple-input multiple-output systems in pilot-symbol-assisted modulation schemes with imperfect channel estimation. We assume block flat-fading channels and focus on a practical range of high signal-to-noise ratio. An ergodic capacity lower bound is used as the objective function to be maximized. We analytically study the capacity gain from adding extra antennas to the transmitter or to the receiver in two different scenarios. Our numerical results show that the optimal antenna configuration under imperfect channel estimation can be significantly different from that under perfect channel estimation assumption. In addition, we investigate the capacity gain from optimizing antenna configuration and find that the gain can be larger than that achieved by optimizing transmit power over pilot and data symbols, particularly for large block lengths.

Detecting the Rise and Fall of 21 cm Fluctuations with the Murchison Widefield Array

We forecast the sensitivity with which the Murchison Widefield Array (MWA) can measure the 21 cm power spectrum of cosmic hydrogen. The MWA is sensitive to roughly a decade in scale (wavenumbers of -->k ~ 0.1-1 h Mpc−1). This amounts primarily to constraints on two numbers: the amplitude and the slope of the 21 cm power spectrum on the scales probed. We find, however, that the redshift evolution in these quantities can yield important information about reionization. We examine a range of theoretical models, spanning uncertainties in the nature of the ionizing sources and the abundance of minihalos during reionization. Although the power spectrum differs substantially among these models, a generic prediction is that the amplitude of the 21 cm power spectrum on MWA scales ( -->k ~ 0.4 h Mpc−1) peaks near the epoch when the intergalactic medium (IGM) is 50% ionized. Moreover, the slope of the 21 cm power spectrum flattens as the ionization fraction increases and the sizes of the H II regions grow. With regards to detection sensitivity, we show that the optimal MWA antenna configuration for power spectrum measurements would pack all 500 antenna tiles as closely as possible in a compact core. Detecting the characteristic redshift evolution of our models will help to confirm that observed 21 cm fluctuations originate from the IGM, and not from foregrounds, and will provide an indirect constraint on the evolution of the volume-filling factor of H II regions during reionization. After two years of observations, the MWA can constrain the filling factor at an epoch when --> ~ 0.5 to within roughly ± -->δ ~ 0.1 at 2 σ confidence.

Optimizing Wireless LAN for Longwall Coal Mine Automation

A significant development in underground longwall coal mining automation has been achieved with the successful implementation of wireless LAN (WLAN) technology for communication on a longwall shearer. WIreless-FIdelity (Wi-Fi) was selected to meet the bandwidth requirements of the underground data network, and several configurations were installed on operating longwalls to evaluate their performance. Although these efforts demonstrated the feasibility of using WLAN technology in longwall operation, it was clear that new research and development was required in order to establish optimal full-face coverage. By undertaking an accurate characterization of the target environment, it has been possible to achieve great improvements in WLAN performance over a nominal Wi-Fi installation. This paper discusses the impact of Fresnel zone obstructions and multipath effects on radio frequency propagation and reports an optimal antenna and system configuration. Many of the lessons learned in the longwall case are immediately applicable to other underground mining operations, particularly wherever there is a high degree of obstruction from mining equipment