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

A Novel Compact Quadruple-Band Indoor Base Station Antenna for 2G/3G/4G/5G Systems

This paper presents a quadruple-band indoor base station antenna for 2G/3G/4G/5G mobile communications, which covers multiple frequency bands of 0.8 - 0.96 GHz, 1.7 - 2.7 GHz, 3.3 - 3.8 GHz and 4.8 - 5.8 GHz and has a compact size with its overall dimensions of 204 × 175 × 39 mm 3 . The lower frequency bands over 0.8 - 0.96 GHz and 1.7 - 2.7 GHz are achieved through the combination of an asymmetrical dipole antenna and parasitic patches. A stepped-impedance feeding structure is used to improve the impedance matching of the dipole antenna over these two frequency bands. Meanwhile, the feeding structure also introduces an extra resonant frequency band of 3.3 - 3.8 GHz. By adding an additional small T-shaped patch, the higher resonant frequency band at 5 GHz is obtained. The parallel surrogate model-assisted hybrid differential evolution for antenna optimization (PSADEA) is employed to optimize the overall quadruple-band performance. We have fabricated and tested the final optimized antenna whose average gain is about 5.4 dBi at 0.8 - 0.96 GHz, 8.1 dBi at 1.7 - 2.7 GHz, 8.5 dBi at 3.3 - 3.8 GHz and 8.1 dBi at 4.8 - 5.0 GHz respectively. The proposed antenna has high efficiency and is of low cost and low profile, which makes it an excellent candidate for 2G/3G/4G/5G base station antenna systems

A Wideband Base Station Antenna Element with Stable Radiation Pattern and Reduced Beam Squint

© 2017 IEEE. This paper presents the design procedure, optimization strategy, theoretical analysis, and experimental results of a wideband dual-polarized base station antenna element with superior performance. The proposed antenna element consists of four electric folded dipoles arranged in an octagon shape that are excited simultaneously for each polarization. It provides ±45° slant-polarized radiation that meets all the requirements for base station antenna elements, including stable radiation patterns, low cross polarization level, high port-to-port isolation, and excellent matching across the wide band. The problem of beam squint for beam-tilted arrays is discussed and it is found that the geometry of this element serves to reduce beam squint. Experimental results show that this element has a wide bandwidth of 46.4% from 1.69 to 2.71 GHz with ≥15-dB return loss and 9.8 ± 0.9-dBi gain. Across this wide band, the variations of the half-power-beamwidths of the two polarizations are all within 66.5° ± 5.5°, the port-to-port isolation is >28 dB, the cross-polarization discrimination is >25 dB, and most importantly, the beam squint is <4° with a maximum 10° down-tilt

Suppression of Cross-Band Scattering in Multiband Antenna Arrays

© 1963-2012 IEEE. This paper presents a novel method of suppressing cross-band scattering in dual-band dual-polarized antenna arrays. The method involves introducing chokes into low-band (LB) elements to suppress high-band (HB) scattering currents. The experimental results show that by inserting LB-pass HB-stop chokes into LB radiators, suppression of induced HB currents on the LB elements is achieved. This greatly reduces the pattern distortion of the HB array caused by the presence of LB elements. The array considered is configured as two columns of HB antennas operating from 1.71 to 2.28 GHz interleaved with a single column of LB antennas operating from 0.82 to 1.0 GHz. The realized array with choked LB element has stable and symmetrical radiation in both HB and LB

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

A Review on 5G Sub-6 GHz Base Station Antenna Design Challenges

Modern wireless networks such as 5G require multiband MIMO-supported Base Station Antennas. As a result, antennas have multiple ports to support a range of frequency bands leading to multiple arrays within one compact antenna enclosure. The close proximity of the arrays results in significant scattering degrading pattern performance of each band while coupling between arrays leads to degradation in return loss and port-to-port isolations. Different design techniques are adopted in the literature to overcome such challenges. This paper provides a classification of challenges in BSA design and a cohesive list of design techniques adopted in the literature to overcome such challenges.</jats:p

Dynamic Capacity Enhancement using a Smart Antenna in Mobile Telecommunications Networks

This work describes an investigation into the performance of antennas for mobile base station applications and techniques for improving the coverage and capacity within a base station cell. The work starts by tracing the development of mobile systems, both in technical and commercial terms, from the earliest analogue systems to present day broadband systems and includes anticipated future developments. This is followed by an outline of how smart antenna systems can be utilised to improve cell coverage and capacity. A novel smart antenna system incorporating an array of slant ± 450 dual- polarised stacked patch elements four columns wide excited by a novel multi-beam forming and beam shaping network has been designed, simulated and implemented. It is found that for an ideal smart antenna array, four narrow overlapping beams, one wide “broadcast channel” beam and right and left shaped beams can be provided. Results are presented for the simulation of the smart antenna system using CST EM simulation software which inherently includes mutual coupling and the effects of a truncated ground plane on the element patterns. The results show some significant changes to the desired set of coverage patterns and various mutual coupling compensation techniques have been reviewed. An improved design technique has been developed for compensating the performance degrading effects of mutual coupling and finite ground plane dimensions in microstrip antenna arrays. The improved technique utilises combination of two previously known techniques: complex excitation weights compensation by inversion of the array mutual coupling scattering matrix and the incorporation of a WAIM (wide angle impedance matching) sheet. The technique has been applied to a novel multi-beam smart antenna array to demonstrate the efficacy of the technique by electromagnetic simulation. In addition, a demonstrator array has been constructed and tested which has yielded a positive conformation of the simulation results. For the developed demonstrator array which provides seven different beams, beams “footprints” have been predicted both for free space propagation and for urban propagation to evaluate the dynamic capacity performance of the smart antenna in a 3G mobile network. The results indicate that sector capacity can be dynamically tailored to user demand profiles by selection of the appropriate beam patterns provided by the novel smart antenna system

Dynamic capacity enhancement using a smart antenna in mobile telecommunications networks

This work describes an investigation into the performance of antennas for mobile base station applications and techniques for improving the coverage and capacity within a base station cell. The work starts by tracing the development of mobile systems, both in technical and commercial terms, from the earliest analogue systems to present day broadband systems and includes anticipated future developments. This is followed by an outline of how smart antenna systems can be utilised to improve cell coverage and capacity. A novel smart antenna system incorporating an array of slant ± 450 dual- polarised stacked patch elements four columns wide excited by a novel multi-beam forming and beam shaping network has been designed, simulated and implemented. It is found that for an ideal smart antenna array, four narrow overlapping beams, one wide “broadcast channel” beam and right and left shaped beams can be provided. Results are presented for the simulation of the smart antenna system using CST EM simulation software which inherently includes mutual coupling and the effects of a truncated ground plane on the element patterns. The results show some significant changes to the desired set of coverage patterns and various mutual coupling compensation techniques have been reviewed. An improved design technique has been developed for compensating the performance degrading effects of mutual coupling and finite ground plane dimensions in microstrip antenna arrays. The improved technique utilises combination of two previously known techniques: complex excitation weights compensation by inversion of the array mutual coupling scattering matrix and the incorporation of a WAIM (wide angle impedance matching) sheet. The technique has been applied to a novel multi-beam smart antenna array to demonstrate the efficacy of the technique by electromagnetic simulation. In addition, a demonstrator array has been constructed and tested which has yielded a positive conformation of the simulation results. For the developed demonstrator array which provides seven different beams, beams “footprints” have been predicted both for free space propagation and for urban propagation to evaluate the dynamic capacity performance of the smart antenna in a 3G mobile network. The results indicate that sector capacity can be dynamically tailored to user demand profiles by selection of the appropriate beam patterns provided by the novel smart antenna system.EThOS - Electronic Theses Online ServiceGBUnited Kingdo