scholarly journals Performance Analysis of Spatially Correlated Cylindrical Antenna Array for 3D Massive MIMO

2020 ◽  
Vol 12 (6) ◽  
pp. 1-10
Author(s):  
Patrick Danuor ◽  
Emmanuel Ampoma Affum
Keyword(s):  
Antenna Array ◽  
Antenna Arrays ◽  
Massive Mimo ◽  
Electromagnetic Waves ◽  
Three Dimensional ◽  
Correlation Coefficients ◽  
Spatially Correlated ◽  
Cylindrical Antenna ◽  
Student’S T ◽  
Von Mises

The spectral efficiency of three-dimensional (3D) massive MIMO is impaired due to the spatial correlation (SC) between closed-spaced elements of antenna arrays (AAs). This paper investigates the impacts of arbitrary Q-power variations of the Power Cosine distribution for a precise characterization of the SC. This is done by presenting mathematical expressions characterizing the SC of cylindrical antenna array (CAA) regarding Student's -t, Von Mises and Cosine distributions, for the direction of arrival (DoA) of the electromagnetic waves impinging on the receiving antenna. Unlike the Student's -t and Von Mises distribution, our outcome recorded huge mismatch between theoretical and simulation correlation coefficients for arbitrary Q-power values above ten (10) which also reduced the downlink channel capacity. The practical relevance is that even though higher Q-power values are the key parameters for system performance, meticulous selection of arbitrary Q-power values above ten (10) is essential to minimize errors regarding channel modelling.

scholarly journals Spatial Correlation for DoA Characterization Using Von Mises, Cosine, and Gaussian Distributions

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Wamberto J. L. Queiroz ◽  
Francisco Madeiro ◽  
Waslon Terllizzie A. Lopes ◽  
Marcelo S. Alencar
Keyword(s):  
Spatial Correlation ◽  
Antenna Arrays ◽  
Electromagnetic Waves ◽  
Mutual Coupling ◽  
Coupling Effect ◽  
Exact Expression ◽  
Von Mises Distribution ◽  
Angle Of Arrival ◽  
Gaussian Distributions ◽  
Von Mises

This paper presents mathematical expressions for the spatial correlation between elements of linear and circular antenna arrays, considering cosine, Gaussian, and Von Mises distributions, for the direction of arrival (DoA) of the electromagnetic waves at the receiver antenna. The expressions obtained for the Von Mises distribution can include or not the mutual coupling effect between the elements and are simpler than those obtained for the cosine and the Gaussian distributions of the angle of arrival. The Von Mises distribution produces spatial correlation expressions in terms of Bessel and trigonometric functions. An exact expression for the spatial correlation, taking into account the mutual coupling, for the circular and linear arrays and an arbitrary number of elements are presented. It can be verified, by numerical evaluation of the expressions, that the coupling between the elements correlates the electromagnetic field, and a separation of half wavelength could not be enough to decorrelate them.

scholarly journals 3D Antenna Characterization for WPT Applications

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4461
Author(s):  
Marina Jordão ◽  
Diogo Pires ◽  
Daniel Belo ◽  
Pedro Pinho ◽  
Nuno Borges Carvalho
Keyword(s):  
Antenna Array ◽  
Antenna Arrays ◽  
Power Transmission ◽  
3D Structure ◽  
Three Dimensional ◽  
Experimental Results ◽  
Antenna Design ◽  
Wireless Power ◽  
Characterization Technique ◽  
Specific Direction

The main goal of this paper is to present a three-dimensional (3D) antenna array to improve the performance of wireless power transmission (WPT) systems, as well as its characterization with over-the-air (OTA) multi-sine techniques. The 3D antenna consists of 15 antenna elements attached to an alternative 3D structure, allowing energy to be transmitted to all azimuth directions at different elevation angles without moving. The OTA multi-sine characterization technique was first utilized to identify issues in antenna arrays. However, in this work, the technique is used to identify which elements of the 3D antenna should operate to transmit the energy in a specific direction. Besides, the 3D antenna design description and its characterization are performed to authenticate its operation. Since 3D antennas are an advantage in WPT applications, the antenna is evaluated in a real WPT scenario to power an RF–DC converter, and experimental results are presented.

Three-Dimensional Facial Characteristics of Caucasian Infants without Cleft and Correlation with Body Measurements

2004 ◽  
Vol 41 (6) ◽  
pp. 593-602 ◽  
Author(s):  
Jill E. White ◽  
Ashraf F. Ayoub ◽  
Marie-Therese Hosey ◽  
Mitchum Bock ◽  
Adrian Bowman ◽  
...  
Keyword(s):  
Sex Differences ◽  
Three Dimensional ◽  
Correlation Coefficients ◽  
Facial Asymmetry ◽  
Analysis Of Covariance ◽  
Body Measurements ◽  
Mouth Width ◽  
Student’S T ◽  
A Prospective Study ◽  
Facial Images

Objective The aim of this study was to characterize the soft tissue facial features of infants without cleft and to report on the correlation between these with weight, length, and head circumference. Design This was a prospective study using a noninvasive three-dimensional (3D) stereophotogrammetry (C3D) system to capture the images of the participants. Landmarks were identified on the 3D facial images. Means and SDs were derived for facial distances and angles. A facial asymmetry score was calculated for each image. Two sample Student's t tests, Pearson's correlation coefficients and analysis of covariance were used to ascertain any gender differences and determine whether these could be explained by weight differences. Participants Eighty-three infants, 41 boys and 42 girls, were captured at rest with their lips apart, at approximately 3 months of age. Results Significant sex differences, of 1 to 2 mm, were found in several facial dimensions, such as face height and nose width. The larger facial measurements correlated significantly with body measurements. Analysis of variance confirmed these differences could be explained by differences in weight. There were no sex differences in the nose/mouth width ratios or in any of the angles measured, suggesting that there may be little sex difference in shape. A slight degree of asymmetry in the faces of infants without cleft was detected. Conclusions Comparisons between noncleft controls and infants with cleft should take cognizance of normal age and sex variations in height and weight that occur among infants.

Effects of occlusal scheme on All-on-Four abutments, screws and prostheses: A three-dimensional finite element study

2020 ◽  
Author(s):  
Nurullah Türker ◽  
Hümeyra Tercanlı Alkış ◽  
Steven J Sadowsky ◽  
Ulviye Şebnem Büyükkaplan
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Good Prognosis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Group Function ◽  
Occlusal Contact ◽  
Maximum Deformation ◽  
Contact Points ◽  
Von Mises

An ideal occlusal scheme plays an important role in a good prognosis of All-on-Four applications, as it does for other implant therapies, due to the potential impact of occlusal loads on implant prosthetic components. The aim of the present three-dimensional (3D) finite element analysis (FEA) study was to investigate the stresses on abutments, screws and prostheses that are generated by occlusal loads via different occlusal schemes in the All-on-Four concept. Three-dimensional models of the maxilla, mandible, implants, implant substructures and prostheses were designed according to the All-on-Four concept. Forces were applied from the occlusal contact points formed in maximum intercuspation and eccentric movements in canine guidance occlusion (CGO), group function occlusion (GFO) and lingualized occlusion (LO). The von Mises stress values for abutment and screws and deformation values for prostheses were obtained and results were evaluated comparatively. It was observed that the stresses on screws and abutments were more evenly distributed in GFO. Maximum deformation values for prosthesis were observed in the CFO model for lateral movement both in the maxilla and mandible. Within the limits of the present study, GFO may be suggested to reduce stresses on screws, abutments and prostheses in the All-on-Four concept.

scholarly journals Full snapshot reconstruction in hybrid architecture antenna arrays

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Maria Trigka ◽  
Christos Mavrokefalidis ◽  
Kostas Berberidis
Keyword(s):  
Antenna Array ◽  
Antenna Arrays ◽  
Communication Systems ◽  
Linear Array ◽  
Research Work ◽  
Hybrid Architecture ◽  
Angle Of Arrival ◽  
Music Algorithm ◽  
Array Structures ◽  
Signal Sources

AbstractIn the context of this research work, we study the so-called problem of full snapshot reconstruction in hybrid antenna array structures that are utilized in mmWave communication systems. It enables the recovery of the snapshots that would have been obtained if a conventional (non-hybrid) uniform linear antenna array was employed. The problem is considered at the receiver side where the hybrid architecture exploits in a novel way the antenna elements of a uniform linear array. To this end, the recommended scheme is properly designed so as to be applicable to overlapping and non-overlapping architectures. Moreover, the full snapshot recoverability is addressed for two cases, namely for time-varying and constant signal sources. Simulation results are also presented to illustrate the consistency between the theoretically predicted behaviors and the simulated results, and the performance of the proposed scheme in terms angle-of-arrival estimation, when compared to the conventional MUSIC algorithm and a recently proposed hybrid version of MUSIC (H-MUSIC).

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