Eight-Port Wideband MIMO Antenna for Sub-6 GHz 5G Base Stations

[EN] An eight-port wide-band multiple-input multiple-output (MIMO) antenna is presented for base stations applications. The antenna is composed by four unit cells (2×2) separated by a cross-shaped isolating block with a total size of 220×220×28 mm ` (2.42¿×2.42¿×0.3¿ , at central frequency f=fc=3.3 GHz). The unit cell is defined by a square cavity-backed antenna fed with two I-shaped crossed dipoles. The antenna provides 8 independent ports with 21.5 dB of minimum isolation and an impedance bandwidth (S11<¿10dB) of 97% ranging at 1.8-5 GHz. Results show an efficiency higher than 87%, unidirectional radiation patterns and low envelope correlation coefficient. The geometry of the antenna is suitable for scaling this design to a massive MIMO system with the replication of the proposed antenna.This work has been supported by the Spanish Ministry of Science and Innovation (Ministerio de Ciencia e Innovacion) under project PID2019-107885GB-C32.Molins-Benlliure, J.; Cabedo Fabres, M.; Antonino Daviu, E.; Ferrando Bataller, M. (2021). Eight-Port Wideband MIMO Antenna for Sub-6 GHz 5G Base Stations. IEEE. 839-840. https://doi.org/10.1109/APS/URSI47566.2021.970472883984

Contributions to the design of broadband antennas and arrays for base stations for the new generation of mobile communication systems

El objetivo de esta tesis es el diseño de antenas y arrays de banda ancha para estaciones base en las nuevas generaciones de comunicaciones móviles. Los nuevos retos en los sistemas de comunicación tales como el aumento de dispositivos conectados y el Internet de las cosas (IoT), conlleva la aparición de nuevas generaciones de telefonía. Para hacer frente a ese desafío se necesitan nuevas estrategias para optimizar el espectro, aumentar el ancho de banda y las velocidades de transmisión. Aunque algunas técnicas son aumentar la frecuencia de trabajo desarrollando celdas más pequeñas y rápidas, esta tesis se centra en el otro enfoque, extender las bandas de frecuencia utilizadas en la actualidad. Este enfoque tiene algunas ventajas como una mayor penetración ofreciendo mejor cobertura en zonas aisladas, así como la coexistencia de las futuras redes 5G con los estándares 3G y 4G actuales. En una primera parte, se presentan diseños de elementos de antenas planares cumpliendo con los nuevos requisitos. La antena está diseñada y fabricada de una forma rentable y asequible, presentando una topología compacta y completamente plana. La idea principal para la consecución de los objetivos es la inclusión de dipolos acoplados incluidos dentro de la propia antena de forma antipodal para conseguir un diseño compacto y un patrón de radiación estable en toda la banda de funcionamiento. El diseño compacto y de doble polarización se logra en un elemento que trabaja en todo el ancho de banda frecuencial entre 1.427 y 2.69 GHz, la banda que aquí se presenta como Banda Ultra Ancha Extendida (ExtUWB). En segundo lugar, se desarrolla un estudio de diferentes formas de planos de masa o re ectores en el campo cercano del elemento. La inclusi ón de un plano de masa es necesaria para eliminar la radiación trasera y dar forma al haz de radiación para obtener una antena directiva con el ancho de haz deseado que permanezca estable dentro de toda la banda de trabajo. El punto clave a tratar es que el plano de masa o re ector al ser colocado en el campo cercano del elemento produce perturbaciones en el mismo, tanto en la adaptación como en su diagrama de radiación. A continuación, se propone la combinación de dos elementos para cubrir las dos bandas requeridas. El elemento ExtUWB para la banda 1,42 a 2,69 GHz se integra con nuevos elementos para la banda 690 a 960 MHz. Se estudia la integración de los elementos de ambas bandas en un mismo espacio físico para desarrollar una antena de estación base que proporcione cobertura en las dos bandas de forma conjunta. Finalmente, se propone la combinación de elementos en con guraciones de array para las nuevas bandas de 5G con el propósito de ser utilizados como estaciones base. La inclusión en array permite lograr diferentes propósitos: aumentar la directividad, cumplir con los requisitos generales de las estaciones base y obtener exibilidad para diferentes con guraciones de arrays. Se proponen distintos arrays con diferentes objetivos, estos arrays son con gurables para ser utilizados como estaciones base clásicas, pero también formando un nuevo sistema innovador de Massive MIMO con propiedades de haz orientable que no se ha presentado para la banda L hasta ahora.The objective of this thesis is the design of broadband antennas and arrays for base stations for the new generations of mobile communications. The new challenges in the communication systems such as the increase of connected devices, the amount of smart products, and the Internet of Things (IoT), has brought the arrival of new 5G systems. To deal with that challenge, new mobile communication systems need new strategies for optimizing the spectrum, increase the bandwidth and the data rates as it is required. Although some techniques are to increase the working frequency and develop faster and smaller cells, this thesis is focused on the other coliving approach, which is to extend the nowadays mobile communication operating bands. That approach has some advantages as higher penetration with deeper coverage, and the coexistence of future 5G networks with the existing standards. Firstly, some designs of planar antenna element following the new requirements are presented. The antenna is designed and manufactured in a cost-effective and affordable way presenting a compact and fully planar topology. The main idea to obtain the objectives is the inclusion of active embedded dipoles in the antipodal part of the antenna itself to achieve a compact design and a stable radiation pattern within the wide frequency band of operation. Compactness and dual polarized performance is achieved for working in the whole frequency bandwidth between 1.427 and 2.69 GHz, the band that is presented here as the Extended Ultrawideband (ExtUWB). Secondly, a study of different ground plane shapes or reflectors in the element near field is developed. A ground plane is needed to remove the back radiation and shape the radiation beam to obtain a directive antenna with the desired beamwidth that remains stable within the broadband frequency band. The key point to deal with is that the ground plane or reflector placed in the element near field disturbs both the matching and the radiation. Thirdly, the combination of two elements to cover both required bands is proposed. The ExtUWB element for the band 1.42 to 2.69 GHz is integrated with new elements for the band 690 to 960 MHz. Integration of both band elements in the same physical space for developing the base station antenna providing dual band coverage is studied. Finally, the combination of elements in array configurations is proposed for the new 5G bands with the purpose of been used as base stations. It allows to accomplish different goals: increasing the directivity, fufilling the overall base station requirements, and obtaining flexibility for different array configurations. Different arrays are proposed with different objectives, those arrays are configurable for being used as classical base stations, but also as a new innovative system of Massive MIMO with beamsteering properties that has not been presented for the L-band till now.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Carlos del Río Bocio.- Secretario: Luis Emilio García Castillo.- Vocal: David González Ovejer

5G RAN architecture based on analog radio-over-fiber fronthaul over UDWDM-PON and phased array fed reflector antennas

This manuscript introduces a 5G radio access network architecture concept based on ultra-dense wavelength division multiplexing (UDWDM) and incorporating an optical fronthaul network that uses a novel wireless antenna system for radio frequency transmission and reception. A ring topology is proposed where optical signals travel within the 5G UDWDM passive optical networks and millimeter waves are generated in the optical line terminals by optical heterodyning. The wireless transmission of the millimeter waves is conducted by an innovative phased array fed reflector antenna approach for mobile communications that grants high antenna gain due to highly focused radiation characteristics, as well as multiplexing gain by multiple beam generation. Furthermore, beam steering is provided by a radio frequency analog beamformer network. Finally, implementation options synthesizing the total system are discussed

Wideband Dual-Polarized Multiple Beam-Forming Antenna Arrays

© 1963-2012 IEEE. Wideband multibeam antenna arrays based on three-beam Butler matrices are presented in this paper. The proposed beam-forming arrays are particularly suited to increasing the capacity of 4G long-term evolution (LTE) base stations. Although dual-polarized arrays are widely used in LTE base stations, analog beam-forming arrays have not been realized before, due to the huge challenge of achieving wide operating bandwidth and stable array patterns. To tackle these problems, for the first time, we present a novel wideband multiple beam-forming antenna array based on Butler matrices. The described beam-forming networks produce three beams but the methods are applicable to larger networks. The essential part of the beam-forming array is a wideband three-beam Butler matrix, which comprises quadrature couplers and fixed wideband phase shifters. Wideband quadrature and phase shifters are developed using striplines, which provide the required power levels and phase differences at the outputs. To achieve the correct beamwidth and to obtain the required level of crossover between adjacent beams, beam-forming networks consisting of augmented three-beam Butler matrices using power dividers are presented to expand the number of output ports from three to five or six. Dual-polarized, three-beam antenna arrays with five and six elements covering LTE band are developed. Prototypes comprising beam-forming networks and arrays are tested according to LTE base station specification. The test results show close agreement with the simulation ones and compliance with LTE requirements. The designs presented are applicable to a wide range of wideband multibeam arrays

Mutual Coupling Reduction Techniques for Multi-band Base Station Antennas

This dissertation proposes antenna design techniques which suppress mutual coupling in densely populated dual-polarized broadband multi-band base station antenna (BSA) arrays for improved radiation characteristics. Array face densification without the proposed techniques leads to undesirable interactions between arrays and radome cover. This research is supported by extensive full-wave electromagnetic simulations, characteristic mode analysis, equivalent circuit models, and array theory. The results are validated through measurements of the radiation patterns and scattering parameters of fabricated prototypes.Upon excitation of a mid-band (MB) array, an electrically long low-band (LB) parasitic, necessary for broadband matching of the baseline LB dipole, exhibits dipole-like induced currents which degrade the MB radiation patterns. The currents are suppressed through parallel plate series capacitance integrated along the length of the LB dipole arms to lower the dipole self-impedance, enabling broadband matching using an electrically short LB parasitic. The proposed technique improves MB radiation pattern symmetry, cross-polar radiation (CPR), sidelobe level, and gain. Upon excitation of the proposed LB dipole, the baseline MB dipole balun feed stems exhibit induced common mode currents, which radiate as electrically short monopoles over a conducting ground plane, that degrade the LB radiation characteristics. These currents are suppressed by integrating parallel plate series capacitance along the length of the balanced ports of the MB balun. The proposed balun improves the LB beamwidth stability, CPR, and gain stability. The proposed serially loaded LB dipole and MB dipole balun feed stem are implemented simultaneously in a six-foot BSA in which the system performance improvements are verified. Upon excitation of a high-band (HB) array in a tri-band array environment, the dielectric radome behaves as a partially reflecting surface. The reflected waves interfere with the HB excitation, resulting in significant boresight radiation attenuation in the upper part of the HB operating band. A Fabry-Perot cavity antenna (FPCA) operating in the second resonance mode (N=1) is proposed to improve this attenuation through increasing the boresight directivity. Upon HB excitation of the proposed FPCA, circular-disk MB parasitics, necessary for broadband matching of the neighboring MB array, exhibit dipole-like induced currents. The induced currents radiate as dipoles which reduce the HB half power beamwidth (HPBW) in the lower and middle part of the HB operating band. These currents are suppressed by introducing electrically thin radial slots in the baseline MB parasitic. The radial slots change the characteristic modes and lower their modal significance, which eliminates the secondary radiation sources. The proposed technique increases the HPBW in the lower and middle part of the HB operating band. These proposed design techniques provide new tools to antenna designers which allow for the densification of BSA arrays for use in next generation cellular networks, while minimizing radiation pattern degradation otherwise present in baseline BSA designs using existing techniques

Antenna Designs for 5G/IoT and Space Applications

This book is intended to shed some light on recent advances in antenna design for these new emerging applications and identify further research areas in this exciting field of communications technologies. Considering the specificity of the operational environment, e.g., huge distance, moving support (satellite), huge temperature drift, small dimension with respect to the distance, etc, antennas, are the fundamental device allowing to maintain a constant interoperability between ground station and satellite, or different satellites. High gain, stable (in temperature, and time) performances, long lifecycle are some of the requirements that necessitates special attention with respect to standard designs. The chapters of this book discuss various aspects of the above-mentioned list presenting the view of the authors. Some of the contributors are working strictly in the field (space), so they have a very targeted view on the subjects, while others with a more academic background, proposes futuristic solutions. We hope that interested reader, will find a fertile source of information, that combined with their interest/background will allow efficiently exploiting the combination of these two perspectives

The Design of Novel Pattern Reconfigurable Antennas for Mobile Networks

This research evaluates a beam reconfigurable basestation transceiver for cellular applications from both a systems and antenna design perspective. The novelty in this research is the investigation of an automatic azimuth beamwidth switching antenna, which can effectively respond to homogeneous traffic distribution in a cellular mobile network. The proposed technique which this antenna uses is azimuth beam switching which incorporates PIN diodes to provide a reconfigurable reflecting ground plane for a three sector antenna. Numerical systems analysis has been carried out on a hexagonal homogeneous cellular network to evaluate how this reconfigurable antenna can balance mean and cell edge capacity through azimuth beamwidth reconfiguration. The optimum azimuth beamwidth is identified as 60°, which achieves the best cell capacity, and by reconfiguring the azimuth beamwidth from 60° to 110°, the maximized capacity at the edges of the cell can be improved. The influence of mechanical tilt, inter site distance, path loss model and vicinity of the cell edge for this antenna are described. This research shows that a mean cell edge improvement from 15Mbit/s to 18Mbit/s is achievable when beamwidth reconfiguration is used, and that this improvement is consistent for cell sizes from 500m to 1500m. Results from a test of an as-manufactured reconfigurable antenna are presented here, and show similar results compared to simulations. To overcome network coverage deterioration at large antenna downtilt angles in a homogeneous cellular mobile network, different beam shaping techniques in the elevation plane, including antenna sidelobe suppressing and null filling, are discussed here. By filling up the first upper-side null for a 12-element antenna array, both the average cell edge and cell capacity can be improved. The application of this beam shaping pattern for a 12-element array is described here, for the purpose of optimising a specific cell within a mobile network which is shown below average coverage and/or capacity. By choosing a proper antenna downtilt angle for this specific cell, whilst keeping the optimum tilt angle for other cells in the network, the cell’s coverage/capacity can be increased without impacting too much on the performance of other surrounding cells. Lastly, the effects of number of antenna elements for a 60° azimuth beamwidth antenna array on the network coverage/capacity are discussed here. This research shows that, as a result of an increasing number of antenna elements in an elevation direction, network capacity can be increased along with the optimum tilt angle. This suggests that a high gain antenna array in a cellular mobile network can be potential for large site deployment and fewer installations

13th Annual Review of Progress in Applied Computational Electromagnetics at the Naval Postgraduate School, Monterey, CA, March 17-21, 1997, Conference Proceedings Volumes I & II

Includes Volumes 1 &