Echoes from meteor trails can be analysed to derive diffusion coefficient and thereafter estimates of neutral temperatures, typically around 90km altitude. The method entails some assumptions and, usually, use of model pressures. Even so, variations in derived temperatures have been assumed to be representative and indicators of other mesospheric processes. However, we now find that the observed variations

The construction of the background covariance matrix is an important component of ionospheric data assimilation algorithms, such as Ionospheric Data Assimilation Four‐Dimensional (IDA4D). It is a matrix that describes the correlations between all the grid points in the model domain and determines the transition from the data‐driven to model‐driven regions. The vertical component of this matrix also

Spatio‐temporal variability of ionosphere poses a major challenge in characterization of observable parameters, critical frequency of F2 layer (foF2), maximum ionization height (hmF2), Total Electron Content (TEC) and slab thickness. The nature of the multi‐scale space‐time variability of ionosphere can be modeled as a random field. In this study, as a first step in random field modeling of the trend

The Embrace Magnetometer Network (Embrace MagNet) uses a series of magnetometers over South America to monitor the Earth’s space environment and to study space weather. One of the common techniques used to study the effects of the magnetic disturbances in the globe is through the Quiet Day Curve (QDC) of the geomagnetic field components. These types of QDC are calculated based on geomagnetic field

While several mm‐wave and sub‐THz frequency bands are being proposed for next generation wireless systems to meet the increasing traffic demand, the electromagnetic properties of many common use materials at those frequencies still need to be determined. The evaluation of such properties is important for the design and deployment of future wireless networks. Recently, a simple method based on Fabry‐Pérot

In recent years, high‐speed railway and subway are being built rapidly in China. Tunnel scenario is a major scenario in some of the high‐speed railways and most of the subways. Channel characteristic is the decisive condition of wireless communication system design in tunnel. The availability of multiple‐input multiple‐output (MIMO) in tunnel is an important issue in the next generation communication

In this paper a novelty Massive Multiple Input Multiple Output (MIMO) channel model based on the birth‐and‐death process of multipath clusters is proposed. First, Massive MIMO measurements are conducted in typical outdoSor scenarios with the bandwidth of 100 MHz at frequencies of 1.4725 and 6 GHz, respectively, following with the investigation of radio propagation characteristics over antenna array

Ultrahigh frequency wireless signals are mainly influenced by the geomorphological environment during the transmission process, resulting in fading channels, especially in mountainous regions. The experiment was conducted in the Karst landform of Guizhou Province, China, in order to explore fading distribution characteristics for mainly analyzing electro magnetic compatibility (EMC) specialties between

The information of atmospheric attenuation at Ka‐band is important during rain and clear air condition. In this paper, Ka‐band attenuation data obtained from radiometric measurements at Kolkata, India (22°034′E, 88°022′N) have been presented. The role of water vapor is examined in determining the behavior of atmospheric attenuation during and without rain condition at 22.24, 26.24, and 31.4 GHz frequencies

We consider propagation of surface Transverse Electric (TE) waves in a rod filled with nonlinear metamaterial medium. The problem is reduced to the analysis of a nonlinear integral equation with a kernel in the form of the Green function of an auxiliary boundary value problem on an interval. The existence of propagating nonlinear surface TE waves for the chosen nonlinearity (Kerr law) is proved using

No abstract is available for this article.

Nearly 200 hours of observing with the Murchison Widefield Array (MWA) radio telescope during the Galactic and Extra‐galactic All‐sky MWA (GLEAM) survey were used to assemble images of ionospheric structure. These images cover a nearly 50°‐wide area on the sky at a cadence of 10 minutes over many 5‐7 hours‐long observing runs. They are generated by tracking the apparent motions of ~200‐‐800 cosmic

Streams of the particle ejected from the sun and the extreme space weather conditions like storms, high‐speed streamers (HSSs), interplanetary coronal mass ejections (ICMEs), corotating interaction regions (CIRs) and Interplanetary Shocks (IS) termed as geomagnetic storms have massive influence in the climate and component of the Earth’s upper atmosphere such as total electron content (TEC). The Study

Millimeter wave (mmWave) based massive multiple‐input multiple‐output (MIMO) beamforming technology is one of the key technologies in the fifth generation (5G) network. In this paper, we apply mmWave to high‐speed railway (HSR) communication scenario to meet its increasingly growing demands for tremendous data rate and reliable mobile services. The HSR mmWave communication system uses a control/user

This paper presents the equatorial ionospheric response to 11 strong‐to‐severe geomagnetic storms that occurred during the period 2000–2005, the declining phase of the Solar Cycle 23. The analysis has been performed using the global ion density plots of the Defense Meteorological Satellite Program (DMSP). Observations show that for about 91% of the cases, postsunset equatorial irregularities occurred

The zero‐order integral equation method (IEM) and the second‐order IEM were introduced to simulate the high‐altitude electromagnetic pulse (HEMP) in our former reports, where the planar gamma radiation model and the point gamma radiation model were utilized, respectively. Herein, the equation of the IEM is analyzed and simplified, after which the fifth‐order method is introduced. Several asymmetric

Anomalous propagation conditions may cause multipath fading and strong signal enhancement on terrestrial line of sight links or interference on transhorizon paths. In detecting this conditions, spatial distribution of vertical refractivity gradient and ducting index were estimated across Nigeria using atmospheric data obtained from Era5 archive of European Centre for Medium‐Range Weather Forecasts

This paper presents 3–4 and 38–40 GHz wideband channel characteristics for industrial internet‐of‐things (IIoT) scenario based on measurements. The channel measurement equipment applied in the measurements consists of a programmable vector network analyzer and necessary auxiliaries. An extensive amount of data in line‐of‐sight (LoS) and non‐line‐of‐sight (NLoS) scenarios is collected with omnidirectional

No abstract is available for this article.

For various precise navigational applications using Indian NavIC system, it is imperative to have an accurate estimation of the ionospheric line‐of‐sight total electron content (TEC). In dual frequency TEC estimation from code and carrier phase measurements, the error is mainly caused by the satellite and receiver differential instrumental biases, which can be several TEC units. The reason for the

GPS amplitude and phase scintillations in terms of the index S4 and σϕ and the corresponding losses of lock in signal have been studied with consequent errors in receiver positions for the whole month of March 2014 from Calcutta situated near the northern crest of the equatorial ionization anomaly (EIA). The impact of phase and amplitude scintillations is found to be different on GPS satellites in

Horizontal phase speeds for a medium‐scale traveling ionospheric disturbance (TID) are calculated from three different atmospheric gravity wave (AGW) dispersion relations using vertical phase speeds derived from vertical ionograms measured by a single ionosonde. Observed heights from a network of four ionosondes in southern New Mexico provide the measured phase velocities. Horizontal phase speeds calculated

In this paper, first, energy detection (ED) based spectrum sensing inorthogonal frequency division multiplexing (OFDM) system using National Instrument (NI) Universal Software Radio Peripheral (USRP) 2942R software defined radio platform has been implemented. It is observed that in practical scenario ED scheme gives poor performance at low gain (G) values. To overcome the shortcomings of energy detection

This study mainly focuses on the prediction of the variability of the vertical total electron content (VTEC) and validation of the new versions of the International Reference Ionosphere (IRI 2016), IRI extended to the plasmasphere (IRI‐Plas 2017), and NeQuick 2 models over the equatorial anomaly region during 2013–2018. The Global Positioning System (GPS)‐derived VTEC data inferred from the South American

A multiuser full‐duplex (FD) two‐wayrelaying system is considered with decode‐and‐forward relaying protocol. All nodes are assumed to have FD abilities, and residual self‐interference (RSI) at each node is modeled as a Rician‐distributed random variable. Based on the availability of channel state information (CSI) at the relay node, different scheduling schemes are adopted and investigated in terms

One of the newly launched satellite navigation systems is the Indian Regional Navigation Satellite System (IRNSS) operating at L5 and S band and providing position determining with an accuracy of 10 m over the Indian subcontinent and 1,500 km beyond. Collocation of this constellation, containing three geostationary and four geosynchronous satellites, with GPS over a common ionospheric volume at certain

Like any other system relying on transionospheric propagation, Global Navigation Satellite System (GNSS) Radio Occultation (GNSS‐RO) is affected by ionospheric conditions during measurements. Regions of plasma irregularities in F region create abrupt gradients in the distribution of ionized particles. Radio signals propagated through such regions suffer from constructive and destructive contributions

Turbulence in the atmosphere plays a vital role in controlling the surface, lower and upper tropospheric dynamics. Here, we have utilized a newly installed Aryabhatta Research Institute of Observational Sciences (ARIES) Stratosphere Troposphere (ST) radar at the high‐altitude subtropical site in the central Himalayan region (Nainital, 29.4°N, 79.5°E, 1793 m above mean sea level) for the first ever

This paper presents the global three‐dimensional morphology and seasonal variation of the scintillation index at E‐layer altitudes varying from 70 to 140 km. An attempt is conducted to analyze the scintillation distribution in different latitude bins and to explore solar and geomagnetic activity‐dependent characteristic of E‐layer scintillations. The scintillation index is derived from the signal‐to‐noise

Super Dual Auroral Radar Network (SuperDARN) radars operate in a coordinated but monostatic configuration whereby high‐frequency (HF) signals scattered from ionospheric density irregularities or from the surface of the Earth return to the transmitting radar where Doppler parameters are then acquired. A bistatic arrangement has been developed for SuperDARN radars in which HF signals transmitted from

In the fifth generation (5G) wireless communication, high‐speed railway (HSR) communication is one of the most challenging scenarios. By adopting massive multi‐input multioutput (mMIMO) technology in HSR communication, the design of the underlying communication system becomes more challenging. Some new channel characteristics must be studied, such as nonstationarity in space, time, and frequency domains

In this paper, we present a novel improved wind driven optimization (IWDO) for transmit beamforming of phased array radar, which is assumed as a multiple constraints optimization problem. Firstly, the emitted signal model and objective functions of optimization with constraints are presented. Secondly, all air parcels are divided into feasible and infeasible parcels, then the target function and constraint

The MAVEN Radio Occultation Science Experiment (ROSE) generates vertical profiles of electron density in the ionosphere of Mars from two‐way, single‐frequency radio occultation observations. Here we develop methods for generating vertical profiles of ionospheric electron density from frequency residuals obtained from such observations. We show that the relevant set of equations can be closed for ionospheric

This paper investigated variations of quiet time ionospheric irregularities over the African equatorial ionization anomaly using the rate of change of total electron content index. Irregularities were quantified in terms of percentage occurrence and examined along with parameter of the anomaly, mainly its strength and the asymmetry of the crests as well as equatorial electric field derived from the

Global navigation satellite system (GNSS) precise positioning performance will be strongly affected under severe ionospheric anomaly conditions. The combination of multi‐GNSS can increase the available observations and improve the geometry of continuously tracked satellites. This paper focuses on assessing the positioning performance with the combination of Global Positioning System (GPS), Global'naya

A total of 17 SURA‐China Seismo‐Electromagnetic Satellite (CSES) experiments in 2018 have been summarized and analyzed in multiple parameters detected in the topside ionosphere at altitude of 507 km from CSES. Most of them were fulfilled with underdense heating condition, and no any artificial density duct had been detected onboard CSES, but some plasma perturbations were actually observed in lower

No abstract is available for this article.

The expected magnitude of extralow‐frequency (ELF) electromagnetic response in the upper ionosphere to ground large‐scale power transmission lines at low Earth orbit (LEO) is modeled. The full‐wave system of Maxwell's equations is numerically solved in a realistic ionosphere whose parameters have been reconstructed with the use of the International Reference Ionosphere (IRI) model. We have calculated

In this paper, we describe an improved technique for using the backscattered phase from meteor radar echo measurements just prior to the specular point (t0) to calculate meteor speeds and their uncertainty. Our method, which builds on earlier work of Cervera et al. (1997, https://doi.org/10.1029/96RS03638), scans possible speeds in the Fresnel distance‐time domain with a dynamic, sliding window and

Weak target detection based on fractal analysis under rada sea clutter background is an open problem. The existing methods, using single fractal dimension and Hurst exponent in time domain or Fourier domain, are not applicable under low signal‐to‐clutter ratio (SCR) conditions. Since autoregressive (AR) spectrum has the advantage of high‐frequency resolution over the Fourier spectrum in sea clutter

Transport theory is used to calculate the intensity of a wave propagating though a trunk‐dominated forest. The trunks are replaced by parallel infinitely long dielectric cylinders, and a vertically polarized plane wave is normally incident on the layer of these randomly distribution parallel cylinders. The problem can be reduced to a two‐dimensional transport problem that can be solved by the eigenvalue

In this paper, an ultra‐wideband (UWB) monopole antenna with penta‐notched rejection characteristics is proposed. The first three rejected bands, 2.6 GHz (LTE band), 4.0 GHz (C‐band satellite downlink), and 8.0 GHz (X‐band satellite uplink), are obtained using two fork‐shaped slots embedded on the radiating patch, respectively. However, additional two notched frequencies for 5.5 GHz (WLAN band) and

No abstract is available for this article.

Thirty‐nine years of archived meteorological data measured at two stations located in the northern and southern parts of Quebec, Canada are used to estimate the surface refractivity and its dry and wet components. The results of the comparison of the obtained estimates showed that for all months the values of the dry component are higher in the northern part, whereas the values of the wet component

We show that Gaussian process regression (GPR) can be used to infer the electromagnetic (EM) duct height within the marine atmospheric boundary layer (MABL) from sparsely sampled propagation factors within the context of bistatic radars. We use GPR to calculate the posterior predictive distribution on the labels (i.e., duct height) from both noise‐free and noise‐contaminated array of propagation factors

This paper presents fast Fourier transform (FFT)‐based multiband spectrum sensing over multipath Rayleigh frequency selective fading channels in single input multiple output (SIMO) in‐band full‐duplex (FD) cognitive radio (CR) networks (FDCRNs) under residual self‐interference (RSI). In this work, first, multiband energy detection using Neyman Pearson criterion is proposed in FDCRNs under RSI, where

Equatorial Atmosphere Radar (EAR) is a very high frequency (VHF) Doppler radar with an active phased array antenna system operating at 47 MHz. It had originally been equipped with a single receiving channel system since its establishment in 2001 at the equator in Kototabang, West Sumatra, Indonesia (0.20°S, 100.32°E). Recent progress has enabled the implementation of a spaced antenna (SA) method on

This paper presents the climatology of stratospheric intrusion into the troposphere during the Indian Summer Monsoon (ISM) observed using the mesosphere‐stratosphere‐troposphere (MST) radar located at Gadanki (13.5°N, 79.2°E). The most significant and new observation is the presence of enhanced signal‐to‐noise ratio (SNR) of 3 dB and half‐power full spectral width of >0.2 m s−1 in the vicinity of tropopause

Discrete high‐density plasma structures in the Earth's ionosphere that convect across the polar cap from the dayside to nightside are known as polar cap patches. This high‐latitude phenomenon can interfere and disrupt satellite and high‐frequency (HF) communications when the associated sharp electron density gradients are encountered, and therefore, accurate modeling and forecasting of such events

LTE for Railways (LTE‐R) is a next‐generation communication network dedicated to railway services, enabling high‐speed, reliable, and intelligent communications to ensure safety and efficiency for rail passengers. The wireless channel between the train and the ground is a key challenge in network design and optimization. The high‐speed train (HST) and its surrounding scenarios bring nonstationarity

No abstract is available for this article.

Circular polarization ratio (CPR) was regarded as an important index for detecting water ice in the permanently shaded region (PSR) of the Moon poles. However, many studies have intuitively described that the double‐bounce scatte ring caused by dihedral consisting of rock facets and the lunar rough surface may yield high CPR. Under a large local incidence angle, single scattering is reduced. Double‐bounce

A feeding algorithm has been proposed for the excitation of the optimal electric current of Rayleigh quotient form optimization problems. Modal weighting coefficients of the corresponding generalized eigenvalue problem are calculated to form the correlation information between the desired and all other unwanted modes. Based on this information, multiple feeds are arranged to approximate the desired

Rainfall has an attenuation of backscatter coefficient of the sea surface and a change in the sea surface roughness, and these effects give rise to some errors in retrieving the sea surface wind speed, the significant wave height, and wave slope. It is meaningful to make considerable efforts to study the attenuation of radio waves caused by rainfall. In this article, a new model of analyzing the attenuation

The editors thank the 2019 peer reviewers

Zenith tropospheric delay (ZTD) is one of the main error sources in space geodetic techniques, such as Global Positioning System (GPS) and satellite altimetry. To qualitatively and quantitatively determine the most suitable model for Antarctica, we analyze the accuracy and applicability of nine models (UNB3m, EGNOS, GPT2 + Saastamoinen, GPT2w + Saastamoinen, GPT3 + Saastamoinen, GPT2 + Hopfield, GPT2w + Hopfield

In this work, by using the assumptions that wavelength is much smaller than charge separation distance of an electric dipole, which in turn is much smaller than a distance up to the point of observation, the new results for radiation of an electric dipole were obtained. These results generalize and extend the standard classical solution, and they indicate that under the above assumptions, the electric

No abstract is available for this article.

The accuracy of the fundamental electric quadrupolar constitutive relation used in the paper by Yaghjian and Silveirinha (2016, https://doi.org/10.1002/2016RS006066) is determined and used to improve upon the derivation of one of the boundary conditions for electric quadrupolar media. In addition, three typographical errors in the aforementioned paper are noted.

In recent decades, artificial intelligence has demonstrated successful applications in computer vision and natural language processing due to its breakthrough performance. In this paper, we propose a deep convolutional neural network (DCNN)‐based method, characterized by acoustic features, for FM broadcast monitoring. The results show that the proposed DCNN model trained with the FBank feature extracted