Analysis Of Radio Wave Propagation Research Articles

Radio wave propagation analysis with dominant path model using MIMO antenna element for vehicular base station application

AbstractA low-profile slant ±45° polarized antenna for a 4G/5G base station with a dominant path wave propagation model (DPM) is reported in this paper. For dual-polarization and wide impedance bandwidth, the two dipole radiators are crisscrossed and a square metallic ring is integrated with the dipole arms and screwed with the four shorting vias. The antenna operates in Band 40/41/42/43 with strong isolation and low ECC (Envelop Correlation Coefficient). Fabricated antenna results show that the predicted wideband antenna has 13.38% bandwidth in 4G, which is Band 40/41, and 29.33% bandwidth in 5G sub-6 GHz Band 42/43. The antenna has a consistent radiation pattern, a 40 dB XPD (Cross Pol Discrimination), and a beam width of 69.5° ±1.5° in the entire frequency band. Three base station sites were explored to deploy the radiation pattern of a dual-polarized antenna in the 3D EM (Electromagnetic Analysis) tool. To evaluate signal quality, strength, radio network planning, and wave propagation analysis by analyzing antenna performance in real-time scenarios with 64 and 256 QAM (Quadrature Amplitude Modulation) techniques. For the proposed four-stream MIMO (Multiple-Input-Multiple-Output) antenna arrangement at deployed cell sites for 4G/5G base station applications, the maximum downlink and uplink data rates are 3.826/2.8 Mbps and 1044/800 Mbps respectively.

A prediction method for electromagnetic interference of large aperture radio telescope

<p indent=0mm>The ongoing Qi Tai Radio Telescope (QTT) which is a steerable 110-m aperture radio telescope has a very high sensitivity of signal detection, thus any weak noise will affect its efficient operation. We proposed a prediction method to lower the electromagnetic interference in the radio quiet zone of QTT site. Firstly, based on the topographic data and topographic features of radio quiet zone of the QTT site, we analyzed the applicability of the existing radio wave propagation model and chosen Longley-Rice and Two-Ray model as the algorithm of the radio wave propagation model of the QTT. By the simulation analysis of radio wave propagation, we got the path loss of the potential interference point when they reached the QTT feed aperture. Secondly, the interference level limits at the position of potential interference point were calculated by combining the QTT feed aperture interference level limits and antenna side lobe gains, and its influence on the radio telescope was predicted and analyzed by combining with the field environment. Finally, the typical village electronic equipment and <sc>35 kV </sc>power supply engineering in the QTT restricted area were analyzed by using this method, and the solutions were also proposed correspondingly.

Lessons Learned Using a Physics-Based Macromodel for Analysis of Radio Wave Propagation in Wireless Transmission

This paper summarizes the lessons learned using a physics-based macromodel in studying electromagnetic wave propagation over an imperfectly conducting ground in cellular wireless communication. First, it has been observed that the path loss exponent is independent of the nature of the ground parameters inside the cell of interest. Second, the electrical parameters of the environment have little effect on the path loss exponent in the cellular band. Third, it is observed that lowering the base station antenna toward the ground provides a stronger signal in the near field within the cell of interest. Furthermore, tilting the transmitting antenna toward the sky enhances the signal strength. Tilting the antenna toward the ground increases the signal strength but, in addition, enhances the interference pattern and, hence, is not a good solution. A typical path loss inside the cell is 30 dB per decade of distance, and outside the cell, it increases to 40 dB per decade. By bringing the antenna closer to the ground and then tilting it toward the sky, a good nonintuitive solution is provided. In such scenarios, a path loss of 20 dB per decade for some components of the field, the lowest possible, can be achieved for certain orientations and deployment of the base station antenna. In addition, it is shown that operating an antenna inside a metallic box eliminates its radiation capabilities and, hence, has no physical meaning even though it is claimed in the contemporary literature that it simulates a rich multipath environment. Finally, a note on the proper interpretation of the term channel capacity and its implications is delineated.

Supercomputing-Enabled First-Principles Analysis of Radio Wave Propagation in Urban Environments

Wireless communications are expected to take place in increasingly complicated scenarios, such as dense urban, forest, tunnel, and other cluttered environments. A key emerging challenge is to understand the physics and characteristics of wave propagation in these environments, which is critical for the analysis, design, and application of advanced mobile and wireless communication systems. In this paper, we present a full-wave field-based computational methodology for radio wave propagation in complex urban environments. Both transmitting/receiving antennas and propagation environments are modeled by first-principles calculations. A system-level, large scene analysis is enabled by the scalable, ultraparallel algorithms on the emerging high-performance computing platforms. The proposed computational framework is verified and validated with semianalytical models and representative measurements.

Research and verification for an improved two‐way parabolic equation method in obstacle environment

An improved two-way parabolic equation (2WPE) method for predicting radio wave propagation in obstacle environment is proposed. Classical 2WPE is mainly utilised for calculating radio propagation under irregular terrain by taking the undulating ground and obstacles as a whole, which yields calculation precision is very limited by the terrain inclination. In order to address the above problems, according to the principle of domain decomposition, by dividing the obstacles and the ground into different zones, 2WPE can be improved to calculate the fields in obstacle environment. With the improved 2WPE, the real phases of both the forward and backward waves can be retrieved when a radio wave entering and leaving the obstacles, and the total field can be obtained by superposition of forward and backward waves. After that, method of moments (MoM) is applied to verify the accuracy of the improved 2WPE in the short distance. In the simulation, the equivalent source model is used to unify the initial field or source settings of 2WPE and MoM to improve the verification precision. The accuracy and superiority of the improved 2WPE are proved, which lays a foundation for the analysis of radio wave propagation in the more complex environment.

Radiowave Propagation Analysis With a Bidirectional 3-D Vector Parabolic Equation Method

A 3-D bidirectional solution to the parabolic approximation of the wave equation is investigated by using a vector field representation. The backward propagating wave is integrated to the classical parabolic equation approach, which represents the forward propagating wave. Propagation over flat terrain in the presence of knife-edges is considered as well as over irregular terrain consisting of hills modeled by the succession of knife-edges. At each knife-edge, appropriate boundary conditions are enforced, and the wave is partly reflected in the backward direction. The wave is marched in both directions by using the split-step algorithm. Different tests are conducted in order to analyze and validate the results obtained by the proposed algorithm. Comparisons with results from both, 2-D parabolic equation-based algorithm, and 3-D finite-difference time domain-based algorithm, are presented in this paper.

Analysis of Radio Wave Propagation in an Urban Environment and its Application to Initial Disaster Response Support

When disasters strike, it is important to quickly collect and analyze disaster-related information immediately after the event. We have suggested ZigBee and geographic information systems (GIS) technologies to resolve these problems and provide an effective communications system. In this paper, a method for the rapid setup of short-range wireless networks infrastructure, which estimates the radio wave propagation and optimizes the positions of transmitters is proposed. Our estimation method is experimentally verified, and it combines ray-tracing with preliminarily obtained statistical attenuation information, which allows us to consider different types of the land and its elevation. Thus, we can determine the effective ranges for radio communication for each potential location in the actual environment. This information is then used in our optimization procedure to reduce the number of transmitters needed to establish connections.

Analysis of radio wave propagation for ISM 2.4 GHz Wireless Sensor Networks in inhomogeneous vegetation environments.

The use of wireless networks has experienced exponential growth due to the improvements in terms of battery life and low consumption of the devices. However, it is compulsory to conduct previous radio propagation analysis when deploying a wireless sensor network. These studies are necessary to perform an estimation of the range coverage, in order to optimize the distance between devices in an actual network deployment. In this work, the radio channel characterization for ISM 2.4 GHz Wireless Sensor Networks (WSNs) in an inhomogeneous vegetation environment has been analyzed. This analysis allows designing environment monitoring tools based on ZigBee and WiFi where WSN and smartphones cooperate, providing rich and customized monitoring information to users in a friendly manner. The impact of topology as well as morphology of the environment is assessed by means of an in-house developed 3D Ray Launching code, to emulate the realistic operation in the framework of the scenario. Experimental results gathered from a measurement campaign conducted by deploying a ZigBee Wireless Sensor Network, are analyzed and compared with simulations in this paper. The scenario where this network is intended to operate is a combination of buildings and diverse vegetation species. To gain insight in the effects of radio propagation, a simplified vegetation model has been developed, considering the material parameters and simplified geometry embedded in the simulation scenario. An initial location-based application has been implemented in a real scenario, to test the functionality within a context aware scenario. The use of deterministic tools can aid to know the impact of the topological influence in the deployment of the optimal Wireless Sensor Network in terms of capacity, coverage and energy consumption, making the use of these systems attractive for multiple applications in inhomogeneous vegetation environments.

Interview

Hiroya Tanaka from Toyota Central Research and Development Laboratories in Japan talks about the work behind the paper ‘Memristance enhancement by external voltage source’ on page 1446. Hiroya Tanaka I was engaged in the research of mobile antennas and radio wave propagation analysis during my Ph.D. Afterwards, I joined Toyota Central Research and Development Laboratories, Inc.. A lot of electric and electrical components are used in recent vehicles for energy management and advanced control. My current interests are nano-structured electromagnetic devices, nonlinear circuit elements and electromagnetic compatibility management for automotive applications. The result reported in the Electronics Letters paper is an output from the current research activity. An amazing finding has been reported by Professor M. Di Ventra's group. They have indicated that memristance is enhanced by white noise due to the nonlinear phenomenon of stochastic resonance. In our Letter, an alternative approach for the enhancement is proposed. The proposed circuit uses an external voltage source instead of white noise. The external voltage source has higher amplitude and frequency than the original signal. The numerical analysis reveals the increase of the memristance. Moreover, the current-voltage characteristic of the original signal is modulated by the external voltage source and then the hysteresis characteristic is enlarged. In our approach, the memristance is enhanced by the external voltage source instead of the white noise. The white noise level is tuned by temperature variation. On the other hand, the amplitude and frequency of external voltage source can be arbitrarily and easily tuned. Therefore, the proposed system is suitable for circuit implementation. The results in our Letter indicate that the memristance enhancement and hysteresis loop can be engineered by modulating memristance. In the past two decades, the role of fluctuation in system enhancement has been discussed in the context of nonlinear physics. One of the famous phenomena is ‘stochastic resonance’, which is induced by noise. The other example is ‘vibrational resonance.’ In this scheme, the noise is replaced by a periodic signal. The proposed system is included in the scheme of the vibrational resonance. The nonlinear physics based on the fluctuation has been applied to the field of signal processing. Various applications have been theoretically investigated, such as signal detection, imaging and wireless communication. The memristors are among interesting nonlinear circuit elements. Therefore, we have explored the possibility of memristors. Adequate parameters of the external voltage source – the amplitude, frequency and relative phase – should be set to maximise the memristance enhancement. In our Letter, the optimum parameters are determined numerically. Optimum condition of the external voltage source is strongly desired for maximising the circuit performance in the viewpoint of design. In the next step, I will derive the framework of designing the effective external voltage source. I am currently analysing the time response of memristance in the circuit using the external voltage source. The optimum condition of memristance enhancement circuit using external voltage source will be discussed in a later publication. The scheme of stochastic and vibrational resonance has often been discussed theoretically. And then the great enhancement of signal processing performance has been reported. However, to the best of our knowledge, there has been no successful example in practical applications. This is because the applied fluctuation should be controlled adaptively following the environment to maximise the signal processing performance. In addition, the memristive devices giving the maximum enhancement of the system performance should be developed. We have a big challenge in applying the interesting nonlinear physics to the real-world applications. Various schemes of memristive devices have been investigated theoretically and experimentally. Those include not only memristors but also memcapacitors and meminductors. Combinations of memristive systems with fundamental circuit elements will bring novel functions and advantages into the current analogue and digital circuit. Various applications of memristive devices have been investigated, such as digital memory, logic, neuromorphic circuits, learning circuit and programmable circuits. The memristive devices will be put into these practical applications in the near future.

Parametric Study and Validation of a UTD-PO Multiple-Cylinder Diffraction Solution Through Measurements at 60 GHz

A uniform theory of diffraction (UTD)-physical optics (PO) formulation for multiple-cylinder diffraction analysis is compared with measurements performed at 60 GHz. Thus, the influence of the variation of parameters, such as: the number of cylinders considered, the radius of curvature, the distance from the transmitter to the array of rounded obstacles, and the polarization is analyzed both theoretically and experimentally. The good agreement shown between the predicted and measured results validates such a theoretical solution for the analysis of radiowave propagation when multiple-diffraction over cylindrical surfaces has to be considered.

FDTD Analysis of Radio Wave Propagation at Intersection Surrounded by Concrete Block Walls in Residential Area for Inter-Vehicle Communications Using 720MHz Band

An inter-vehicle communication system for the 720MHz band that is designed to prevent car crashes at intersections has recently been proposed in Japan. This paper presents an analysis of the propagation characteristics of an intersection surrounded by concrete block walls in a residential area. The propagation characteristics were analyzed for the first time using the finite-difference time-domain (FDTD) method. We investigated the influence of wall thickness and source locations on the propagation characteristics. The results of our investigation showed that the most commonly used wall thickness and source locations do not strongly affect propagation loss. Furthermore, we analyzed the power delay profile and delay spread by taking into consideration the structure of the concrete block walls.

Analysis of radio wave propagation in Lagos environs

Various research studies have been carried out by different researchers on the behaviour of radio wave within different environment under different environmental and geographical conditions. The models derived are specific for the respective environment. To validate the model, field measurements were carried out at different locations within Epe town and its environs. The measurements system consist of live radio base stations transmitting at 900MHz and 1800MHz. Downlink signal strength level data were collected using drive test exercise consisting of test mobile phones, TEMS investigating software, MapInfo and Google earth. The respective path loss values were estimated and compared with existing model like OkumuraHata model for rural, suburban and urban areas. The result indicated an appreciable consistency with the empirical models except for rural areas.

Propagation measurements and analysis for high-speed railway cutting scenario

Presented is the statistical analysis of radio wave propagation in a high-speed railway cutting scenario, derived from 930 MHz measurements taken along the ‘Zhengzhou-Xi'an’ high-speed railway of China. The crown width and bottom width of the cutting are well-covered by the proposed models. The Ricean distribution offers a good fit and the K-factor is found to be lognormal, with a mean value of 1.88 dB and standard deviation of 3.29 dB.

UTD-PO Formulation for the Multiple-Diffraction of Spherical Waves by an Array of Multimodeled Obstacles

A hybrid uniform theory of diffraction-physical optics (UTD-PO) solution for the analysis of the multiple-diffraction of spherical waves caused by an array of obstacles, which have been modeled by different shapes, is hereby presented. The formulation, validated with measurements from technical literature, does not need to incorporate high-order diffraction terms (slope diffraction) thanks to a recursive relation, therefore producing an easier, faster solution-when compared with other methods-that, at the same time, achieves accurate results. Such results can be applied in radiowave propagation analysis when multiple-diffraction over obstacles with quite different shapes has to be considered.

Educational Software for Project and Analysis of Radiowave Propagation

In this work, we illustrated the development of an Educational Software for Project and Analysis of Radiowave Propagation (SEPAR). This software is composed by tools to project links radiowave-based and a tutorial with theoretical elements of electromagnetic waves propagation. In the radiowave design are considered the propagation losses, atmospheric effect, fading, modulation, relief and antennas characteristics. The software was utilized at radiowave design course and the observed results showed that the software is a strong tool to learning and motivation the student's autonomy. It was observed that after supplied the first theoretical concepts the students start to use the software intuitively and could consolidate the illustrated concepts.

A Hybrid UTD-PO Solution for Multiple-Cylinder Diffraction Analysis Assuming Spherical-Wave Incidence

A modified hybrid uniform theory of diffraction-physical optics formulation for the analysis of the multiple diffraction caused by an array of cylinders, assuming spherical-wave incidence, is hereby presented. The solution, validated with numerical data from technical literature, is mathematically less complex and computationally more efficient-particularly for a large number of cylinders-than other existing methods, due to the fact that high-order diffraction terms (slope diffraction) are not considered, without such lack of terms barely entailing any loss in accuracy. Results can be applied in radiowave propagation analysis when multiple diffraction over rounded obstacles has to be considered.

Rigorous coupled-wave analysis of radio wave propagation through periodic building structures

The transmission and reflection characteristics of a periodic wall structure are studied by a rigorous coupled-wave analysis (RCWA) method. The presented method solves the reflection and transmission coefficients for an electromagnetic plane wave, obliquely incident onto a periodic multilayer building structure. Simulation findings are compared with those obtained by other researchers. The transmission and reflection properties of concrete block and reinforced concrete walls are also analyzed. The good agreement of the simulation results with previous published results validates the recommended RCWA method.

Educational software tool based on a geographical information system (GIS) for radio wave propagation analysis

A tool is presented to evaluate and represent path loss, delay-spread, and the direction of arrival in graph form of each contribution considered in the propagation over buildings in urban scenarios. A geographical information system (GIS) and a ray-tracing technique are used in order to facilitate the understanding of the main propagation mechanisms in a more realistic environment, and the fields are evaluated using geometrical optics (GO) and the uniform theory of diffraction (UTD). This tool may be used to illustrate the influence of the propagation environment on radio wave parameters to telecommunications engineering students.

FVTD analysis of radiowave propagation in two-dimensional tunnels with arbitrary bending angle

FVTD analysis of radiowave propagation in two-dimensional tunnels with arbitrary bending angle

Analysis of radiowave propagation in a four-layered anisotropic forest environment

Propagation of electromagnetic waves in forest environments is examined in which both the transmitting and receiving points are located in the trunk layer of a four-layered anisotropic forest model. This propagation model considers the forest as a horizontally stratified, anisotropic media of canopy and trunk, bounded by ground below and air above. The electromagnetic fields are obtained using dyadic Green's functions in their eigenfunction expansion forms for an anisotropic four-layered geometry. Analytical results are found for the fields, which consist primarily of three wave modes: a direct wave, multiply reflected waves, and lateral waves. These field constituents are compared, and their domains of preponderance are calculated; it is found that the lateral wave plays a major role in communication at large distances. Radio losses for typical forest are calculated to illustrate numerical application of the forest model.