Antenna Orientation Research Articles

Stochastic Estimation of Orientation Parameters of an Antenna Complex based on Strapdown Inertial System Measurements

The problem of high-precision determination of the spatial orientation of the antennas of radio complexes located on high-rise masts of various designs is considered. It is established that the methods currently used, based on measurements of satellite navigation systems and autonomous measurements of strapdown inertial orientation systems, do not provide the required accuracy in solving the problem. It is shown that the low accuracy of existing methods is due to both weak noise immunity of information processing algorithms and the lack of the ability to take into account the dynamic properties of orientation parameters measured under conditions of high intensity interference, the properties of which, as a rule, are not taken into account. A dynamic algorithm is proposed for estimating the stochastic orientation parameters of the antenna of a radio complex, which is invariant to the nature of the movement of the mast base and provides stability and the required estimation accuracy under general assumptions about the nature of the interference of the sensitive elements of the strapdown inertial orientation system. The Rodrigue–Hamilton parameter vector was used as the observed state vector – the antenna orientation parameter vector – and the vector of measurements of the angular velocity sensors of the strapdown inertial system was used as the observation vector for it. The instrumentation of the strapdown inertial system includes three accelerometers and three angular velocity sensors located orthogonally at the center of mass of the antenna. Based on the obtained non-linear stochastic equations for the dynamics of the change in the parameter vector of the current orientation of the strapdown inertial orientation system on a moving base and the equations of their observation, a stochastic model of measurement signals for sensitive elements of the strapdown inertial orientation system, a non-linear (generalized) Kalman filter is constructed that provides the desired solution to the problem of estimating the parameters of the current antenna orientation on a perturbed base. We present the results of a numerical experiment and a conclusion about the possibility of using a fi lter to solve the problem of operational orientation of antennas of radio engineering complexes using medium- and high-precision strapdown inertial orientation systems and without correction over a long time.

Characterization of path loss model for wireless communication channel modelling

PurposeWireless communication channel provides a wide area of applications in the field of communication, distributed sensor network and so on. The prominence of the wireless communication channel is because of its robust nature and the sustainability for the precise ranging and the localization. The precision and accuracy of the wireless communication channel largely depend on the localization. The development of the wireless communication channel with improved benefits needs the accurate channel model.Design/methodology/approachThis paper characterizes the tangential path loss model in the WINNER based wireless communication channel model. The measurements taken in the WINNER channel model are compared with the tangential path loss characterized WINNER Channel model.FindingsThe model operates well over the varying antenna orientations, measurement condition and the propagation condition. The proposed tangential path loss model is performing well over the various outdoor scenarios.Originality/valueThe proposed characterization shows change in the small-scale parameters (SSP), such as power, delay, angle of arrival and angle of departure as well as the large-scale parameters (LSP), such as RMS delay spread, shadowing, path loss and Ricean factor associated with the model.

Dielectric resonator based multiport antenna system with multi-diversity and built-in decoupling mechanism

In this article, an eight-element, sixteen port dielectric resonator (DR) based double sided multi-port antenna is presented, which supports the unique dual-directional pattern diversity feature. The orientation of the double-sided dielectric resonator antenna (DRA) is one of the novel features of the proposed antenna. Four cylindrical dielectric resonator antennas (cDRAs) are placed at the top of the substrate, and each top cDRA is excited with the help of two orthogonally placed coplanar waveguide (CPW) fed conformal microstrip lines. In the same manner, the other four cDRAs are placed at the bottom of the substrate, and each cDRA is fed via conformal strip lines. The proposed antenna works in between 5.4 GHz and 6.0 GHz. Several isolation techniques (polarization diversity, pattern diversity, and separation between the antenna elements) within the antenna elements are approached to improve the antenna performance. As a result, without using any isolation improvement technique, the proposed structure achieves 17 dB of isolation between the ports, which makes the proposed radiator unique. The similarity in simulated and experimental outcomes confirms that the designed 16-port multi-port antenna system is suitable for Wireless LAN applications.

In-port-plug transmission line design of the ITER plasma position reflectometer

This work describes the microwave design of the transmission line housed in the in-port-plug region of the ITER plasma position reflectometer (PPR). The design of the components of the in-port-plug reflectometers (located in equatorial port-plug 10 (EPP10) and in upper-port-plug 01 (UPP01)) is presented. Using a 3D ray tracing code, the spatial position and optimum orientation angles of each set of emission and detection antennas were determined. A feasible path was then created from the obtained antenna positions and orientations to the primary vacuum window. Oversized tall waveguides were chosen to reduce ohmic losses. Due to space constraints in the ITER crowded environment, bends in oversized waveguides were unavoidable, and thus mode conversion was produced. To keep mode conversion losses at bay, hyperbolic secant curvature bends had to be used whenever possible. However, E-plane bends in tall waveguides proved to be especially critical, making it necessary to employ other approaches when higher bending angles were needed. Mode conversion results were obtained by evaluating the mode coupling equations. Ohmic losses have also been computed and their results compared with commercial simulators, obtaining a perfect agreement.

A high gain and wideband on-chip hybrid plasmonic V-shaped nano-antenna

In this paper, a wideband hybrid plasmonic V-shaped nano-antenna is proposed based on coupled hybrid plasmonic waveguide (CHPW) feeding to increase the surface plasmon propagation length. The CHPW specifications are investigated analytically and numerically to obtain the dispersion relation and propagation length using the genetic algorithm and the finite element method, respectively. Moreover, the proposed V-shaped nano-antenna, with a fractional bandwidth of ∼86% and a maximum efficiency of 98%, is able to receive/transmit optical signals at three telecommunication wavelengths of 850, 1310, and 1550 nm with high realized gains of 10.5, 9.39, and 9.05 dB, respectively. The shape of the radiation pattern, with a main lobe along the antenna axis, makes this antenna appropriate for point-to-point connections in inter- or intra-chip optical wireless links and networks, which is studied comprehensively in this article. Furthermore, to obtain a high optical power signal and tune the antenna orientation, the performance of the antenna is investigated with two different types of array structure, single row and square, and its applications for energy harvesting and beam steering are studied. The fabrication feasibility of the nano-antenna is realizable based on complementary metal-oxide-semiconductor technology.

Impact of Field Polarization on Radiated Emission Characterization in an Open TEM Cell

This article presents a comprehensive study of the influence of electromagnetic (EM) field polarization on radiated emission characterization in an open transverse EM (TEM) cell, which is usually neither considered in the measurement process nor clearly identified. It also takes into account the influence of the operating frequency with respect to the higher order mode cutoff frequency of the cell, the latter being generally unknown to the experimenter. Commonly used 433-MHz (LoRa) and 2.4-GHz (Wi-Fi) antennas were placed inside an open TEM cell in different orientations in order to investigate the impact of the antenna polarization. For antennas parallel to the septum, a 1.6–8.6-dB difference in power levels collected by the cell (corresponding to a 31%–86% underestimation), for different polarizations, depending on the operating frequency being below or above the higher order mode cutoff frequency, was obtained between orthogonal orientations due to reduction in $E$ - and (mainly) $H$ -field levels, leading to significant uncertainty on power levels. For the 2.4-GHz antenna perpendicular to the septum, the power level was highly dependent on both the antenna orientation and location along the cell’s axes, being more dependent along the main axis. This clearly demonstrates that the physical phenomena due to the polarization of the radiating element and the cell’s dominant mode frequency must be characterized and estimated, in addition to the generally known tangential $H$ -field coupling to integrated circuit pins or printed circuit board (PCB) traces. This leads to an update of best practices of IEC 61000-4-20 or IEC 61967-2 emission testing.

Characteristic analysis of wireless local area network's received signal strength indication in indoor positioning

The indoor positioning method based on received signal strength indication (RSSI) ranging is a lack of systematic quantitative research on the factors affecting the characteristics of indoor RSSI, which affect the accuracy of positioning. This paper quantitatively analyzes the characteristics of the 2.4 GHz RSSI collected in indoor scenes from the following four aspects: antenna orientation of the receiver, type of wireless network interface card (NIC) of the receiver, time period of the data measurement and height difference between the transmitting and receiving antenna. The experimental results show that: (i) the RSSI value measured is the strongest when the antenna of the receiver is vertically oriented to the antenna of the transmitter, while the weakest when the antenna is vertically back-facing and the difference between the strongest signal and the weakest signal is 20-25% at the same test point; (ii) the wider the measurement range of NIC, the more conducive to data collection; (iii) the distribution of RSSI signals generated by an access point at a fixed position is inconsistent with time; (iv) when the height of receiving antenna is 0.5 m different from each other, the path loss index of ranging model produces a deviation of about 10%.

Antenna Optimization for Decode-and-Forward Relay in Magnetic Induction Communications

Magnetic Induction (MI) communication is effective in underground tunnels for emergency rescue vehicle due to the small-size antenna. It can highly benefit from a cooperative decode-and-forward (DF) relay to achieve a higher data rate. However, its channel gain is extremely position-and-orientation-selective. The unreachable space increases the complexity of the antenna deployment. To find the best antenna position and orientation (PO) of the relay achieving the higher data rate, this paper formulates the optimization problem of the relay MI antenna PO with tunnel constraints. To solve the problem more quickly, we propose to use geometric modeling to eliminate the tunnel constraints and develop a random-search algorithm achieving a fast convergence and excellent global search ability. Simulations show that the proposed algorithm can quickly converge to one optimum which signifies a noticeable improvement of data rate for vehicle MI systems with weak signals.

Orientation-selective elliptic optical vortex array

We propose an orientation-selective elliptic optical vortex array (OS-EOVA). Using multicoordinate (namely, polar, Cartesian, and elliptic) transformations, three kinds of operations applied on optical vortex elements (including location, rotation, and stretching) were executed to obtain the desired orientation in the observed plane. Then, exploiting the reverse design technique, the above-mentioned operations were mapped onto the initial execution plane via Fourier transform. Based on this, 1D and 2D OS-EOVAs were generated experimentally and the existence of optical vortices was verified. Specific OS-EOVAs were designed, possessing antenna array orientation as well as radial and azimuthal orientation. Compared to existing OVAs, the OS-EOVA provides an additional modulated dimension, i.e., orientation. This technique will open up some potential applications, such as complex manipulation of multiparticle systems and fabrication of micromaterials with orientation.

Stochastic evaluation of orientation parameters for an antenna complex using strapdown inertial system measurements

When solving the problem of high-precision spatial orientation of antennas of radio engineering complexes placed on high-rise masts of various designs, one of the main tasks is to increase the accuracy of their angular orientation in the conditions of inevitable disturbances of the mast base (due to wind disturbances, operation of various units, etc.) and interference of measurement of antenna orientation parameters by various measuring systems. Currently used methods based on measurements of satellite navigation systems and autonomous measurements of attitude and heading reference system do not provide the required accuracy for solving the problem of antenna orientation, located on a highly dynamic mobile base. This circumstance is due both to the weak noise immunity of algorithms of information processing and the inability of accounting for the dynamic properties of orientation parameters measured also in the presence of noise of high intensity, whose properties also usually are not taken into account. In this regard, the article considers a dynamic algorithm for estimating the stochastic parameters of the antenna orientation of the radio engineering complexes, invariant to the nature of the movement of the mast base and providing stability and the required accuracy of the evaluation under the most general assumptions about the nature of interference of the sensing elements attitude and heading reference system. As the observed state vector – the vector of antenna orientation parameters, the vector of Rodriguez–Hamilton parameters is used, and as the vector of observation of it – the vector of measurements of angular velocity sensors of a strapdown inertial system, which consists of three accelerometers and three angular velocity sensors located orthogonally in the center of mass of the antenna. Based on the nonlinear stochastic equations of dynamics of change of the vector of parameters of the current orientation attitude and heading reference system on the moving base and stochastic models of the measuring signals sensing elements attitude and heading reference system, a non-linear (generalized) Kalman filter, providing the desired solution of the problem of estimation of the parameters of the current orientation of the antenna on the perturbed basis, was built. The results of the numerical experiment allow us to conclude that it can be used to solve the problem of operational orientation of radio engineering complexes antennas placed on masts, using medium-and high-precision attitude and heading reference system without correction for a long time.

Computational modeling of the curing of a frame of an inflatable satellite antenna in near-earth orbit

Temperature analysis of a new technological process, curing of prepregs in near-earth orbit, is performed via computational modeling. The problem arose in connection with the currently discussed possibility of using inflatable antennas for small space satellites. Inflatable antennas have a number of advantages over classic extendable metal antennas. However, in order to ensure the continuous operation of inflatable antennas, it is necessary that they acquire rigidity over time and cease to depend on the pressure of air in them. This can be achieved using a frame made of an orbital-curable prepreg. This idea requires experimental justification and analysis by means of computational modeling. In this work, only one of the aspects (temperature effect) of the in-orbit curing technological process is considered. The creation of special equipment for heating prepregs in the satellite body is undesirable because it will increase weight and sizes of a satellite. However, the natural heating of structural elements in space can be due to the radiation emitted from the Sun and the Earth. Numerical experiments demonstrate that the required curing temperature can be achieved in the case when, instead of a simple prepreg frame, use is made of the frame on which a thin layer of copper is deposited. Temperature distributions in the structure during its rotation are examined. Analysis of the results yields time intervals at which the antenna orientation with respect to the solar flux direction should be changed in order to obtain the required temperatures, striving to achieve curing of all elements of the frame in a small number of revolutions around the Earth, that is, as long as a high gas pressure remains in the inflatable antenna.

Ray-Based Modeling of Directional Millimeter-Wave V2V Transmissions in Highway Scenarios

Due to the need for larger bandwidth, future mobile networks may primarily operate over millimeter-wave (mmWave) bands. In this regard, one of the central research topics today is mmWave channel modeling. However, highly mobile vehicle-to-vehicle (V2V) mmWave channels pose an open question because conducting measurements may be challenging in this environment. The existing publications on mmWave V2V channel modeling consider line-of-sight (LoS) or single-blocker scenarios. Accordingly, the impact of interference from adjacent vehicles is not taken into account. Conventional analytical models suggest that path loss (PL) strikes equally in all directions whereas measurements are inherently directional, especially in the case of mmWave propagation. Recently, it was proposed to synthesize the omnidirectional PL from directional measurements. However, with this method, the resulting PL is underestimated. Moreover, theoretical models assume that vehicular transceivers follow a certain predetermined distribution, which may not be accurate in real-world scenarios. Several works take into account the directionality of an antenna pattern when the antenna orientation is known. However, the effects of reflection, diffraction, and transmission through obstacles are not considered. One way to avoid these limitations is to use ray-based simulations. However, the ray-launching (RL) approach does not specify any criteria for the directionality of the antenna patterns. Assuming omnidirectional PL appears impractical for mmWave transmission where directional communication is crucial to combat high PL. In this paper, we propose an approach for synthesizing directional PL based on extensive RL modeling. For the obtained directional and omnidirectional PL, we parametrize the close-in (CI) and float-intercept (FI) channel models. As a result of our modeling, from 0.1 to 2.7 for the LoS and from 0.1 to 2.6 for the non-LoS (NLoS) higher PL exponent is observed as compared to the omnidirectional case.

UAV-Based Antenna Measurements for Polarimetric Weather Radars: Probe Analysis

One of the principal challenges in the calibration of polarimetric weather radars is achieving the strict requirements in the measurement of the antenna radiation pattern of the system; e.g., a co-polarization mismatch of at most 0.1 dB, and cross-polarization levels less than approximately −40 dB are highly desirable. In a UAV-based antenna pattern measurement system, the radiation characteristics of the probe antenna can be adversely affected by scattering off of the UAV platform itself, and by the relative orientation of the probe antenna with respect to the UAV frame. It is hypothesized that such extraneous reflections depend on the type of antenna used as a probe, and in this context, a more directive probe antenna (i.e., with low back lobe radiation) would be necessary to achieve the required measurement accuracy for weather radar applications. This work studies the effect of UAV and probe antenna interaction for different types of antennas through EM simulations, and this is validated with chamber measurements. For the patch array antenna under study, co-polarization mismatch levels of approximately 0.13 and 0.05 dB, and maximum cross-polarization levels of −37 and −34 dB, are achieved at boresight in measurements and simulations, respectively, which can be improved to meet the requirements with a careful selection of the gimbal operating angle range.

On the Usefulness of the Generalised Additive Model for Mean Path Loss Estimation in Body Area Networks

In this article, the usefulness of the Generalised Additive Model for mean path loss estimation in Body Area Networks is investigated. The research concerns a narrow-band indoor off-body network operating at 2.45 GHz, being based on measurements performed with four different users. The mean path loss is modelled as a sum of four components that depend on path length, antenna orientation angle, absolute difference between transmitting and receiving antenna heights and relative polarisation of both antennas. It is proved that the Generalised Additive Model allows for mean path loss estimation with a higher accuracy in comparison with Linear Regression. The obtained mean error is 0 dB, the root mean square error is 5.52 dB and the adjusted coefficient of determination is 61.2%.

ПРИМЕНЕНИЕ МЕТОДА «КОНЕЧНОГО ПОВОРОТА И СМЕЩЕНИЯ» В УПРАВЛЕНИИ ПАРАБОЛИЧЕСКОЙ АНТЕННОЙ

The article deals with the application of the "finite rotation and displacement" method (FRDM) which can find the desired values of the generalized coordinates for the control system of a parabolic antenna. The special manipulator of a sequential structure with sufficient rigidity is used to control the parabolic antenna. The rigidity of this manipulator is ensured by use of links in the form of spherical shells and bearings located along the perimeter of each shell in the rotation plane of each link. It allows to optimally place the material of the manipulator's design and to obtain sufficient rigidity with minimal weight. The manipulator consists of four links connected by fifth class kinematic pairs with an arbitrary inclination of the axes. For this task the antenna's orientation is important without taking into account the small displacement of its position during the process of its orientation. The FRDM method provides both orientation and position. It is based on determining the precise and optimal iterative steps for each degree of mobility, providing maximum approximation to the specified orientation parameters of the parabolic antenna. According to the method's algorithm, the software is developed consisting of subprograms for organizing a general solution of the inverse kinematics for an arbitrary number of links and a particular one for a manipulator in the form of source data. The initial data are the vector model of the manipulator, the values of the structural constraints of the generalized coordinates, and the characteristics of kinematic pairs by type and class

The complexity of symmetric connectivity in directional wireless sensor networks

In this paper, we investigate the Antenna Orientation (AO) and Antenna Orientation and Power Assignment (AOPA) problems concerning symmetric connectivity in Directional Wireless Sensor Networks (DWSNs) where each sensor node is equipped with $$ 2 \le k \le 5$$ directional antennas having beam-width $$\theta \ge 0$$. The AO problem for DWSNs is closely related with the well-known Euclidean Degree-Bounded Minimum Bottleneck Spanning Tree (EBMBST) problem where different cases for the degree bound have been studied. While current works on DWSNs focus on solving each case of k ($$=2,3,4$$) separately, we propose a uniform approach for the AO problem that yields constant-factor approximation algorithms for the AO as well as the EBMBST problem where the degree bound is between 2 and 4. Our method achieves the same constant factors. For the AOPA problem, to the best of our knowledge, our paper provides the first results concerning this problem. We show that the problem is NP-hard when $$2 \le k \le 4$$. We also establish the first constant-factor approximation algorithms for the problem. Finally, we perform some simulations to understand the practical performance of our algorithms.

Electromagnetic wave propagation based upon spectral-element methodology in dispersive and attenuating media

SUMMARYWe build on mathematical equivalences between Maxwell’s wave equations for an electromagnetic medium and elastic seismic wave equations. This allows us to readily model Maxwell’s wave propagation in the spectral-element codes SPECFEM2D and SPECFEM3D, written for acoustic, viscoelastic and poroelastic seismic wave propagation, providing the ability to handle complex geometries, inherent to finite-element methods and retaining the strength of exponential convergence and accuracy due to the use of high-degree polynomials to interpolate field functions on the elements, characteristic to spectral-element methods (SEMs). Attenuation and dispersion processes related to the frequency dependence of dielectric permittivity and conductivity are also included using a Zener model, similar to shear attenuation in viscoelastic media or viscous diffusion in poroelastic media, and a Kelvin–Voigt model, respectively. Ability to account for anisotropic media is also discussed. Here, we limit ourselves to certain dielectric permittivity tensor geometries, in order to conserve a diagonal mass matrix after discretization of the system of equations. Doing so, simulation of Maxwell’s wave equations in the radar frequency range based on SEM can be solved using explicit time integration schemes well suited for parallel computation. We validate our formulation with analytical solutions. In 2-D, our implementation allows for the modelling of both a transverse magnetic (TM) mode, suitable for surface based reflection ground penetration radar type of applications, and a transverse electric (TE) mode more suitable for crosshole and vertical radar profiling setups. Two 2-D examples are designed to demonstrated the use of the TM and TE modes. A 3-D example is also presented, which allows for the full TEM solution, different antenna orientations, and out-of-plane variations in material properties.

A Polarimetric Coherence Method to Determine Ice Crystal Orientation Fabric From Radar Sounding: Application to the NEEM Ice Core Region

Ice crystal orientation fabric (COF) records information about past ice-sheet deformation and influences the present-day flow of ice. Polarimetric radar sounding provides a means to infer anisotropic COF patterns due to the associated birefringence of polar ice. Here, we develop a polarimetric coherence (phase-based) method to determine horizontal properties of the COF. The method utilizes the azimuth and depth dependence of the vertical gradient of the hhvv coherence phase to infer the dielectric principal axes and birefringence, which are then related to the second-order fabric orientation tensor. Specifically, under the assumption that one of the orientational eigenvectors is vertical, we can determine the horizontal eigenvectors and the difference between the horizontal eigenvalues (a measure of horizontal fabric asymmetry). The method exploits single-polarized data acquired with varying antenna orientation. It applies to ground-based “multi-polarization” surveys and is demonstrated using data acquired by Center for Remote Sensing of Ice Sheets (CReSIS) using Multi-Channel Coherent Radar Depth Sounder (MCRDS) from the North Greenland Eemian Ice Drilling (NEEM) ice core region in Greenland. The analysis is validated using a combination of polarimetric matrix backscatter simulations and comparison with COF data from the NEEM ice core. The results are consistent with a conventional model of ice deformation at an ice divide where a lateral tension component is present, with minor horizontal COF asymmetry and the greatest horizontal concentration of crystallographic axes orientated near parallel to the ice divide.

Effect of Antenna Deployment on Achievable Rate in Cooperative Magnetic Induction Communication

Magnetic Induction (MI) communication can be applied in some through-the-earth scenarios such as mines and underground rivers. To increase the transmission rate of MI communications, we propose a cooperative MI (CMI) scheme with an amplify-and-forward (AF) relay. Different from existing studies, we mainly focus on the relay with arbitrary antenna position and orientation (antenna deployment, AD). We derive the closed-form expression of CMI achievable data rate gain (CMG) for the relay and the closed-form expression of CMI channel bandwidth. Simulations reveal that a relay with appropriate AD could yield a significant increase in the achievable rate for MI systems.

RSS Indoor Localization Based on a Single Access Point.

This research work investigates how RSS information fusion from a single, multi-antenna access point (AP) can be used to perform device localization in indoor RSS based localization systems. The proposed approach demonstrates that different RSS values can be obtained by carefully modifying each AP antenna orientation and polarization, allowing the generation of unique, low correlation fingerprints, for the area of interest. Each AP antenna can be used to generate a set of fingerprint radiomaps for different antenna orientations and/or polarization. The RSS fingerprints generated from all antennas of the single AP can be then combined to create a multi-layer fingerprint radiomap. In order to select the optimum fingerprint layers in the multilayer radiomap the proposed methodology evaluates the obtained localization accuracy, for each fingerprint radio map combination, for various well-known deterministic and probabilistic algorithms (Weighted k-Nearest-Neighbor—WKNN and Minimum Mean Square Error—MMSE). The optimum candidate multi-layer radiomap is then examined by calculating the correlation level of each fingerprint pair by using the “Tolerance Based—Normal Probability Distribution (TBNPD)” algorithm. Both steps take place during the offline phase, and it is demonstrated that this approach results in selecting the optimum multi-layer fingerprint radiomap combination. The proposed approach can be used to provide localisation services in areas served only by a single AP.