Study Of Radio Wave Propagation Research Articles

Comparative analysis between ERA5 reanalysis data and MRR observation data at different altitudes for fall velocity and liquid water content

Continuous measurements of rainfall parameters are required for radio planning and flood management among others. However, due to the dearth of requisite infrastructure and expertise within the region, it is usually necessary to use satellite and reanalysis data. In this study, the performance of ECMWF ERA5 data in providing fall velocity (W) and liquid water content (LWC) estimates at different altitudes was compared with measurements from a ground-based Micro Rain Radar in a tropical location. Results obtained showed correlation values of 0.60–0.94 and 0.16–0.93 for fall velocity and liquid water content, respectively. The performance of ERA5 was found to decrease with altitude. In general, the results show the sufficient reliability of the ERA-5 reanalysis data for the two parameters on vertical scales. Therefore, it can be inferred that the ERA-5 data are reliable in estimating the average LWC and W, especially on a vertical scale for both hydrological and radio wave propagation studies.

Variable Step Size Solution of Standard Parabolic Equation in Complex Environment

Aiming at the problem that it is difficult to balance the accuracy and velocity of the fixed-step solution of standard parabolic equation in the study of radio wave propagation in a wide range of complex environments, a variable-step solution method of standard parabolic equation is proposed. Firstly, after deducing the relationship between the error of SSFT solution and step size, frequency and other factors; And the basic selection range of step size for SPE variable step size solution is given. Secondly, the action mechanism of different environmental factors and the requirement of changing trend for step size are expounded through simulation, and the complex environment of SPE application is classified according to the requirement of error. Finally, the method is used to simulate the characteristics of the typical complex environment. The simulation results show that the method can save up to 71.4% of the time compared with the fixed-step method of parabolic equation under the condition of ensuring the calculation accuracy. The reliability and efficiency of the proposed method are verified, and the calculation efficiency of the parabolic equation radio wave prediction can be greatly improved. Therefore, the parabolic equation method with variable step size can ensure the accuracy of calculation, reduce the memory and time required for calculation, greatly improves the efficiency of calculation, and has practical significance in the application of real-time prediction of electromagnetic wave propagation in a wide range of complex environments.

A Novel Method for Prediction of Attenuation of Millimeter Waves by Fog and Smoke

Terrestrial radio wave link faces various challenges like attenuation caused by gases, water vapor and other weather phenomenon like rain, storms, snow, fog, cloud etc. These challenges are responsible for absorption and diffusion of energy. Another kind of obstacles observed by the radio waves on terrestrial path is vegetation, lamppost, grills and other urban constructions. Different phenomenon is studied under these conditions like reflection, diffraction, refraction, scattering, depolarization etc. In case of millimeter waves various propagation studies has been performed under different scenarios. More propagation studies are needed to be done especially for fog. In this paper radio wave propagation studies are performed for fog using proposed fog model and results are compared with the other model proposed in the Literature. Another propagation study is performed for smoke which is unique of its kind. This study indicates that even smoke can causes attenuation for millimeter wave frequencies.

Preface to the special issue on the Alphasat Aldo Paraboni propagation experiment

Preface to the special issue on the Alphasat Aldo Paraboni propagation experiment

Variable Step Size Technique for the Parabolic Equation in Complex Environmental Conditions

In this paper, a variable step size method for the PE (Parabolic Equation) is proposed to solve the problem of low computational efficiency in the study of radio wave propagation at a large range of complex environments. Firstly, the relationship between the error and the step size, the frequency and other factors of the SSFT (Split-Step Fourier Transform) solution in the standard atmosphere is deduced, and then the basic selection range of the step size is given for the variable step size method. Secondly, the action mechanism of different environmental factors and the requirement of changing trend for step size are expounded through simulation, and the complex environment of PE application is classified according to the requirement of error. Finally, the electric wave characteristics of typical complex environment are advanced by the method. The simulation results show that compared with the small step method, the variable step size method of the PE can reduce the horizontal sampling point by 55.9% and the calculation time by 69.6% when the accuracy is close to the small step method, and the variable step size method is more accurate than the fixed large size step method. Therefore, the variable step size on the PE can not only ensure the accuracy of calculation, but also reduce the memory and time required, which greatly improves the reliability and efficiency. Moreover, it is suitable for solving the problem of the radio wave propagation in complex environment.

Numerical study of radio wave propagation in clear air acoustic scatterer

Numerical study of radio wave propagation in clear air acoustic scatterer

Indoor channel characterization studies for V-band gigabit wireless communications using dielectric-loaded exponentially tapered slot antenna

Demands for very high-speed wireless communication access is rapidly growing with respect to the increasing data rates for the use of rich multimedia content in various applications of defense, enterprise, industrial, and public domains. To serve these gigabit fidelity (Gi-Fi) uses for various wireless applications, millimeter wave (MmW) wireless technology with huge bandwidth in licensed/unlicensed bands is triggering boundless avenues. In this research, the concept of substrate-integrated waveguide (SIW) and exponentially tapered slot (ETS) antenna are used together design a high-gain, efficient planar dielectric-loaded antenna for MmW-based Gi-Fi wireless communications using unlicensed 60 GHz band in the MmW family. The SIW is used to feed the antenna and a dielectric is utilized increasing the gain. The dielectric-loaded ETS antenna and compact SIW feed are fabricated on a single substrate, resulting in low cost and easy fabrication utilizing printed circuit board process. The measured gain of single-element antenna is 11.4 dB, with radiation efficiency of 96.84% at 60 GHz. Then indoor radio wave propagation studies are carried out using elliptically dielectric-loaded ETS antenna with radio frequency measurement equipment to measure and model propagation channels at 60 GHz. The attained simulations are compared with the experimental results.

Indoor radio link characterization studies for millimeter wave wireless communications utilizing dielectric-loaded exponentially tapered slot antenna

A trend that is pragmatic in today’s wireless communications is the demand for the supportof increasing data rates over short distances. Through the last decade, ample knowledge about the 60 GHz millimeter wave (MmW) channel has been gathered and different architectures have been analyzed to develop MmW communication systems for commercial applications. The usage of MmW frequencies is perceived as a resilient entrant for realizing future, gigabit wireless communications as it offer vast bandwidths for short-range indoor communications. In this work, the MmW antenna solutions for exponentially tapered slot (ETS) antenna using substrate integrated waveguide (SIW) technology and indoor radio wave propagations are studied at 60 GHz for wireless communications. The SIW is used to feed the antenna, and a dielectric loading is utilized in front of the antenna to increase the gain. The antenna with elliptical-shaped dielectric loaded is fabricated using printed circuit board process. The measurement results are compared with simulated results. Then, the indoor short-range radio wave propagation study is carried out using ETS antenna with RF measurement equipment to measure and model propagation channels at 60 GHz. The attained simulations are compared to the experimental results.

A DECOMPOSITION METHOD FOR COMPUTING RADIOWAVE PROPAGATION LOSS USING THREE-DIMENSIONAL PARABOLIC EQUATION

The parabolic equation (PE) method is widely used in radiowave propagation predictions. It has the advantages of high efficiency and stability, but it will lead to greater predicting errors in some situations, because the effects of transverse terrain gradients are not modeled. This problem can be solved by extending the 2D PE to the three-dimensional (3D) PE. However, the computing efficiency will degrade because of large scale matrix operations. In this paper, a new method is presented, in which the 3D PE is decomposed into two 2D PEs. It increases the computational efficiency and accuracy effectively. To verify the capability of the proposed method in radiowave propagation prediction, an experiment platform was set up. The computational results using this new method are compared with the experimental and Method of Moment (MoM) numerical computational results. Good agreements are achieved in the comparison. The study of radiowave propagation under complex environments is vitally important for improving the effective signal coverage in wireless communication and television broadcasting with plenty of urban buildings as well as mountainous terrains. It presents a big challenge due to the multiple wave propagation mechanisms involving the line of sight, diffraction and scattering propagation and the characteristic of large scale computation. The major issues refer to how to keep the computational accuracy and conducting the large scale computation at the same time. To meet the request for large scale computation of actual engineering problems, the modified empirical formulas are often used for analysis and computation with the drawback of poor computational accuracy, and the variance of the predicted propagation loss is generally 2 to 5 dB for the flat terrain, but for the complex terrain, the variance of the predicted propagation loss is usually about 5 to 10 dB. Many computational methods have been developed to improve the predicted accuracy. The commonly used methods are geometric diffraction methods, path integration methods and FDTD. It is hard to meet the requirement of engineering computation because these methods are computationally expensive and require high data accuracy of the terrain database at the same time (1). The Parabolic Equation (PE) method is a computational method for radiowave propagation loss besides the full wave method and ray tracing method, and has become a research focus. The PE method has high potential in radiowave propagation of mobile communication and broadcasting and television signal coverage as it can not only deal with complex terrain boundary conditions accurately, but also deal with complex atmosphere waveguide structure. Compared with the full wave method, the PE method deals with an unidirectional wave propagation, in which the equation can be solved by the step marching method in the propagation direction. The PE method can reduce the computational complexity of the full wave equation.

The International Reference Ionosphere 2012 – a model of international collaboration

The International Reference Ionosphere (IRI) project was established jointly by the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) in the late sixties with the goal to develop an international standard for the specification of plasma parameters in the Earth’s ionosphere. COSPAR needed such a specification for the evaluation of environmental effects on spacecraft and experiments in space, and URSI for radiowave propagation studies and applications. At the request of COSPAR and URSI, IRI was developed as a data-based model to avoid the uncertainty of theory-based models which are only as good as the evolving theoretical understanding. Being based on most of the available and reliable observations of the ionospheric plasma from the ground and from space, IRI describes monthly averages of electron density, electron temperature, ion temperature, ion composition, and several additional parameters in the altitude range from 60 km to 2000 km. A working group of about 50 international ionospheric experts is in charge of developing and improving the IRI model. Over time as new data became available and new modeling techniques emerged, steadily improved editions of the IRI model have been published. This paper gives a brief history of the IRI project and describes the latest version of the model, IRI-2012. It also briefly discusses efforts to develop a real-time IRI model. The IRI homepage is at http://IRImodel.org.

A Comparative Study of Radio Wave Propagation Over the Earth Due to a Vertical Electric Dipole

A comparative study of the electromagnetic field excited by a vertical electric dipole on the Earth is presented. Four sets of formulas for both the planar Earth model and the spherical Earth model (of large radius) are compared to find out their valid ranges. Numerical computations are also carried out specifically for a three-layered Earth model. For the planar Earth model, when both the source and observation points are on the surface, and the planar Earth covered with a thick-enough dielectric layer, the method by Zhang is more accurate; while for the fields above the surface and the thin-enough dielectric layer, the method by King and Sandler is more accurate. However, the hybrid of the trapped surface wave and the lateral wave were exhibited in the curves in, but they were not shown in the curves. Numerical calculation also shows that the amplitude of the trapped surface wave attenuates as rho <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1/2</sup> in the rho direction as expected. However, the lateral wave given by does not exhibit rho <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> decay in the rho direction. For the layered spherical Earth model, the exact series summation, which serves as an exact solution to the classic problem, is computed and compared with the residue series. Numerical results show that the residue series gives a good approximation to the field, but the smooth curve illustrates that the hybrid effect due to the trapped surface wave and the lateral wave was ignored in literature. The field strength of the trapped surface wave decreases with the dielectric layer thickness and is affected by the curvature of the Earth. The exact series shows the oscillation of the field caused by the hybrid effects, which can be considered as the dielectric resonance between the upper and lower dielectric interfaces when it is guided to propagate, but none of the other three approximations can depict the effects.

Pseudoreciprocity in a disturbed nonisotropic medium and its application to radio wave propagation

Reciprocity is an important result of electromagnetism that breaks down in the case of a nonisotropic media. For such media, however, there exist pseudoreciprocity results for which the pseudoreciprocal fields have different, but related, permittivity and permeability tensors. It is shown that these results can be readily extended to take account of disturbances in the medium of one of the pseudoreciprocal fields. These extensions are used to develop algorithms for radio wave propagation and, in particular, algorithms for the study of propagation through disturbed nonisotropic media. The ionosphere is an example of such a medium, and the algorithms are demonstrated through their application to the study of radio wave propagation through a traveling ionospheric disturbance.

Multiple quasi-parabolic presentation of the IRI profile

The paper describes the representation of any given density profile with multiple quasi-parabolic (QP) segments and the technique is applied to IRI profiles. An optimization method is introduced that automatically finds the segment boundaries and minimizes the number of segments for a specified fitting accuracy. This representation of the profiles makes it possible to use analytical ray tracing techniques for ionospheric radio wave propagation studies. The Lowell Digisondes now provide the multiple QP profiles in real time as an additional output.

Worst-month rain statistics for radiowave propagation study in Malaysia

A study of the worst-month rainfall rate statistics for the Malaysian environment is presented. Rain rate data with 1 min integration time were collected in the Universiti Teknologi Malaysia and the Universiti Sains Malaysia. The relationship between the worst month and the yearly probabilities is presented and the ITU-R model verified. For better precision, new values are proposed for the parameters Q/sub 1/ and /spl beta/ in Malaysia.

Comments on "An asymptotic high-frequency analysis of the radiation by a source on a perfectly conducting convex cylinder with an impedance surface patch" [with reply

The authors of the above named paper (see ibid., vol.36, no.10, p.1407-17, 1988) suggest that previous work on mixed-path radio ground wave theory is less general than their asymptotic analysis. The commenter clarifies the similarities to and differences from the earlier radiowave propagation studies, which span a period of several decades, and discusses the role of the Elliott mode in such problems. He also draws attention to the similarity of their eq.(12) to the generalized attenuation function in ground wave theory. In replying, Ersoy and Pathak note that for certain cases eq.(12) should be replaced by a more general expression, and they discuss in turn several other points raised by the commenter.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Radio wave propagation and acoustic sounding

Radio wave propagation of the decimetric and centimetric waves depends to a large extent on the boundary layer meteorological conditions which give rise to severe fadings, very often due to multipath propagation. Sodar is one of the inexpensive remote sensing techniques which can be employed to probe the boundary layer structure. In the paper a historical perspective has been given of the simultaneously conducted studies on radio waves and sodar at various places. The radio meteorological information needed for propagation studies has been clearly spelt out and conditions of a ray path especially in the presence of a ducting layer have been defined as giving rise to fading or signal enhancement conditions. Finally the potential of the sodar studies to obtain information about the boundary layer phenomena has been stressed, clearly spelling out the use of acoustic sounding in radio wave propagation studies.

A microcomputer-based real-time data system for radio wave propagation studies

A microcomputer-based real-time data system has been implemented and tested for data collection and processing. The paper presents the main system components, together with special features tailored for radio propagation studies. The computer system is designed to control a data acquisition system (DAS) and to perform other data processing functions. The system is built using Hewlett-Packard hardware: the low-cost HP9825 microcomputer together with the HP3497 automatic data acquisition and control system. The main features of the system are: (i) Menu-driven system, (ii) user friendly interactive operation, (iii) optimized tape utilization and DAS scanning speed, (iv) on-line help facility. The paper starts by introducing the system layout and then describes the system hardware, which includes the microcomputer, the data acquisition system and the various sensors. System design is then presented with emphasis on tape and speed optimization. It is hoped that the present paper will be useful for engineers and scientists planning environmental, meteorological and engineering studies involving real-time data acquisition.

Satellite Communications in Japan

This paper describes recent research and development of satellite communication technology in Japan together with the future prospects. Newly developed earth station facilities for both commercial and experimental purposes are described first. New satellite communication systems, such as STAR, SMAX, TTT, SSB-PM, and SSRA, which originated and/or have been studied extensively in Japan, are described briefly. Recent developments of microwave and millimeter-wave antennas, parametric amplifiers, high-power tubes, etc., are surveyed. Brief descriptions are also given of radio-wave propagation studies and development plans for Japanese communication satellites.

Electron Collision Frequency in the F-region of the Ionosphere

EXPERIMENTAL measurements of the collision frequency of electrons in the lower ionosphere have been made by a variety of ground-based and rocket techniques. In general there is good agreement up to about 100 km between these and values calculated from atmospheric properties and laboratory measurements of electron collision cross-sections (see, for example, ref. 1). Above 100 km, as Thrane and Piggott have pointed out, however, there are significant difficulties in providing reliable estimates of the collisional frequency and, in particular, there seems to be some considerable discrepancy between calculated values based on the variation of atmospheric pressure with height and experimental values based on ground-based radio wave propagation studies. We have recently re-examined the problem of determining the collision frequency at levels above the E-layer and in this report we outline an approach based on simultaneous absorption and h′(f) measurements.

Gross Errors in Height Indication from Pulsed Radar Altimeters Operating over Thick Ice or Snow

Errors reported in 1946 by aircraft pilots using pulsed radar altimeters over Antarctic ice, coupled wih results of radio-wave propagation studies in both polar areas (1946-1955), led to measurements of the electrical characteristics of thick ice at high and ultra-high frequencies. These measurements produced information relative to dielectric constants, loss factors, scattering, and interface reflection data that subsequently permitted successful radio-wave penetration measurements in continental ice to depth of several hundred feet in both the Antarctic and the Arctic (1958-1960). Results indicated clearly that low-flying pilots relying on pulsed 440-Mc altimeters in poor visibility over thick ice can be fatally misled by errors inherent in these instruments. The paper presents recent data obtained by the Signal Corps pertinent to radio-wave transparency of thick ice and snow.