A technique for MIMO antenna design with flexible element number and pattern diversity

This paper presents a new technique for designing Multiple Input Multiple (MIMO) Output antennas having pattern diversity. Massive MIMO is expected to form part of 5G communications and will require antennas having a very large number of elements. However, due to the size limitation, it is highly challenging to preserve high isolation between the ports. Pattern diversity technique are also highly desirable and can facilitate MIMO system with diversity gain. However, achieving that within a compact antenna with the limited space between the elements is also challenging. In this paper a technique is introduce and applied to 4-element and 6-element MIMO antennas. This technique can improve the isolation between the ports and it also yields pattern diversity for MIMO antennas with various numbers of elements. The technique is verified via experimental measurement

A Highly Integrated MIMO Antenna UnitA Highly Integrated MIMO Antenna Unit A: Differential/Common Mode Design

Abstract—A novel concept of antenna design, termed as differential/common mode (DM/CM) design, is proposed to achieve highly integrated multi-input multi-output (MIMO) antenna unit in mobile terminals. The inspiration comes from a dipole fed by a differential line which can be considered as a differential mode (DM) feed. What will happen if the DM feed is transformed into a common mode (CM) feed? Some interesting features are found in this research. By symmetrically placing one DM antenna and one CM antenna together, a DM/CM antenna can be achieved. Benefitting from the coupling cancellation of anti-phase currents and the different distributions of the radiation currents, a DM/CM antenna can obtain high isolation and complementary patterns, even if the radiators of the DM and CM antennas are overlapped. Therefore, good MIMO performance can be realized in a very compact volume. To validate the concept, a miniaturized DM/CM antenna unit is designed for mobile phones. 24.2 dB isolation and complementary patterns are achieved in the dimension of 0.330λ0×0.058λ0×0.019λ0 at 3.5 GHz. One 8×8 MIMO antenna array is constructed by using four DM/CM antenna units and shows good overall performance. The proposed concept of DM/CM design may also be promising for other applications that need high isolation between closely-packed antenna elements and wide-angle pattern coverage

Design and construction of a 4G mobile network antenna

En aquest projecte es presenta el disseny i la construcció d'una antena de telefonia per a cobertura de 4G, on s'ha pres com a base les investigacions realitzades per Aykut Cihangir en el paper titulat "Integration of Resonant and Non-Resonant Antennas for Coverage of 4G LTE bands in Handheld Terminals". El principal objectiu d'aquesta investigació i desenvolupament és doncs validar els resultats obtinguts en el paper de referència i així buscar millorar el disseny proposant nous mètodes i formes geomètriques de les parts que componen l'antena total. Cal ressaltar que en el disseny de l'antena, donat els requeriments en ample de banda i nivells de reflexió, es fa indispensable desenvolupar xarxes d'adaptació que permetin millorar el funcionament i contribueixin a incrementar la radiació i disminuir les pèrdues per reactàncies en les freqüències de funcionament desitjades. Finalment, l'antena s'ha fabricat sense xarxa d'adaptació, i s'han realitzat les proves amb l'analitzador de xarxes, comparant els resultats obtinguts en la realitat amb aquells que van resultar de les simulacions en el programari.En este proyecto se presenta el diseño y la construcción de una antena de telefonía para cobertura de 4G, donde se ha tomado como base las investigaciones realizadas por Aykut Cihangir en el paper titulado "Integration of Resonant and Non-Resonant Antennas for Coverage of 4G LTE Bands in Handheld Terminals". El principal objetivo de esta investigación y desarrollo es pues validar los resultados obtenidos en el paper de referencia y así buscar mejorar el diseño proponiendo nuevos métodos y formas geométricas de las partes que componen la antena total. Cabe resaltar que en el diseño de la antena, dado los requerimientos en ancho de banda y niveles de reflexión, se hace indispensable desarrollar redes de adaptación que permitan mejorar el funcionamiento y contribuyan a incrementar la radiación y disminuir las pérdidas por reactancias en las frecuencias de funcionamiento deseadas. Finalmente, la antena se ha fabricado sin red de adaptación, y se han realizado las pruebas con el analizador de redes, comparando los resultados obtenidos en la realidad con aquellos que resultaron de las simulaciones en el software.In this project, the design and construction of an antenna for 4G mobile communications coverage is proposed, which has been based on the research performed by Aykut Cihangir in the paper named "Integration of Resonant and Non-Resonant Antennas for Coverage of 4G LTE Bands in Handheld Terminals". The main objective of this research and development is thus to validate the results obtained in the paper of reference and to seek for an improvement on the design by proposing new methods and geometrical modifications of the parts of the overall antenna. It should be noted that in the design of the antenna -given the requirements of the bandwidth and levels of reflection- it is necessary to develop matching networks so as to improve the antenna's performance and to help to increase the radiation and to decrease the reactance's losses in the desired frequencies. Finally, the antenna has been manufactured without matching network and, has been tested with the network analyser, comparing the results obtained in real performance against those resulting from the simulations in software

Multi-Band Small Antennas for Mobile Terminals

The thesis presents several novel ideas of designing electrically small antennas for mobile terminals such as mobile phones. As the fifth generation wireless systems (5G) is coming soon, radio signals at sub 6 GHz and millimetre-wave (mmWave) frequencies will be employed in mobile communication. In this thesis, the author concentrates on the antennas at sub 6 GHz, because the signals at sub 6 GHz will still play an important role in 5G mobile communication due to the advantage of signal penetration through buildings. The research areas consist of main antenna and multi-input multi-output (MIMO) antenna technology including decoupling techniques and MIMO antenna unit. First, a novel six-mode loop antenna as a main antenna is proposed for mobile phones. Loop antennas offer better user experience than monopole antennas, inverted-F antennas (IFA), and planar inverted-F antennas (PIFA) because of the unique balanced modes (1?, 2?, ...). However, the balanced modes also cause narrower bandwidth of loop antennas. In order to overcome the bandwidth problem, how to reach the upper limit of the existing operating modes and how to create more modes are explored. A novel monopole/dipole parasitic element, which operates at an unbalanced monopole-like 0.25? mode and a balanced dipole-like 0.5? mode, is firstly proposed. In order to validate the concept, one prototype with the dimension of 75×10×5 mm3 is designed, fabricated, and measured. The antenna is able to cover 660-1100 MHz, 1710-3020 MHz, 3370-3900 MHz, and 5150-5850 MHz, which is wide enough for almost all the service of mobile telecommunication systems. Then, a multimode decoupling technique is proposed for wideband/multiband isolation enhancement in compact volume. Although decoupling techniques have been researched for many years, multimode decoupling technique remains a great challenge for mobile terminals. One difficulty in achieving multi decoupling modes is that the operating modes of closely-packed decoupling elements have very strong mutual effect, which makes the tuning complicated and even unfeasible. Thus, in physical principle, a novel idea of achieving the stability of the boundary conditions of decoupling elements is proposed to solve the mutual effect problem; in physical structure, a metal boundary is adopted to realize the stability. One distinguished feature of the proposed technique is that the independent tuning characteristic can be maintained even if the number of decoupling elements increases. Therefore, wideband/multiband high isolation can be achieved by isolating multi decoupling elements. To validate the concept, two case studies are given. In a quad-mode decoupling design, the isolation is enhanced from 12.7 dB to > 21 dB within 22.0% bandwidth by using a 0.295?0×0.059?0×0.007?0 decoupling structure. Finally, a novel principle, namely differential/common mode (DM/CM) design, is proposed to achieve highly integrated MIMO antenna unit in mobile terminals. The inspiration comes from a dipole fed by a differential line which can be considered as differential mode (DM) feed. What will happen if the DM feed is transformed into a common mode (CM) feed? Some interesting features are found in the research. By symmetrically placing one DM antenna and one CM antenna together, a DM/CM antenna can be achieved. Benefitting from the coupling cancellation of anti-phase currents and the different distributions of the radiation currents, a DM/CM antenna can obtain high isolation and complementary patterns, even if the radiators of the DM and CM antennas are overlapped. Therefore, good MIMO performance can be realized in a very compact volume. To validate the concept, a miniaturized DM/CM antenna unit is designed for mobile phones. 24.2 dB isolation and complementary patterns are achieved in the dimension of 0.330?0×0.058?0×0.019?0. One 8×8 MIMO antenna array is constructed by using four DM/CM antenna units and shows good overall performance. The proposed idea of DM/CM design may be promising for other applications that need high isolation and wide-angle pattern coverage

Conception de systèmes multi-antennes multi-bandes pour terminaux mobiles LTE

Multiple antennas techniques are an interesting solution to increase throughput without increasing the bandwidth. This is an advantage in a context where the proliferation of users and services leads to a saturation of spectrum. However, the systems based on diversity raise new challenges for their integration into terminals. The work presented in this thesis is to consider jointly the performance of multi-antennas systems and integration into terminals constraints. Developed systems operate in two bands LTE: 790-862 MHz and 2.5-2.69 GHz, and cover also for some of them the upper part of the band TVWS (TVWhite Space): 700-790 MHz to provide cognitive radio applications. The first study is concentrated on designing an efficient system while maintaining a reasonable size. The proposed system is integrated into the terminals emerging in the market today such as mini-tablets, the tablet-phone hybrid or laptop. Very satisfactory performance in terms of bands and isolation are achieved. Aiming the size reduction, we propose an alternative compact system providing acceptable performances. For this purpose, three prototypes are proposed where the last could be integrated into a mobile phone. For all systems, we have evaluated the diversity performances in terms of correlation coefficient and Mean Effective Gain. It has been founded that the systems provide good diversity performances even if the terminal's position is changed during the communication. Moreover, the influence on the antennas performances with a presence of users is studied. The results show that these systems are suitable for LTE and can be used for MIMO wireless communications.Les techniques à base d’antennes multiples constituent une solution intéressante à l’augmentation du débit sans accroître la bande passante. Cependant, la conception de systèmes à base de diversité soulève de nouveaux défis quant à leur intégration au sein de terminaux à encombrement réduit. Le travail présenté consiste à prendre en compte conjointement les éléments déterminant les performances de communication multi-antennes et les contraintes d’intégration liées aux terminaux. Les systèmes développés fonctionnent dans deux bandes LTE: 790-862 MHz et 2.5-2.69 GHz; certains couvrent également la partie haute de la bande TVWS (TV White Space): 700-790 MHz afin d’offrir des applications de radio cognitive. Pour la première conception, la démarche consiste à obtenir un système performant sans rechercher, dans un premier temps une forte intégration. Néanmoins, le système proposé est intégrable dans des terminaux émergeant dans le marché actuel comme l’hybride téléphone-tablette. Des performances très satisfaisantes en termes de bandes et d’isolation sont atteintes. Ensuite, on privilégie la compacité du système tout en offrant des performances acceptables. Cette démarche permet la conception de trois prototypes, dont le dernier est intégrable dans un téléphone.D’autre part, l’influence de la présence d’un utilisateur mais également de l’intégration dans un terminal multimédia sur les performances des systèmes est étudiée. Enfin, les performances en diversité sont évaluées dans différentes configurations d’environnements. Les résultats ont montré que ces systèmes sont adaptés à la technologie LTE et offrent la possibilité d’établir des communications sans fil MIMO

MIMO antennas for mobile phone applications

Recent evolutions in wireless mobile communications have shown that by employing multiple inputs and multiple outputs (MIMO) technology at both the transmitter and receiver, both the wireless system capacity and reliability can be enhanced without the need for increasing the power transmitted or using more spectrum. Despite a considerable amount of research have been done on the design of MIMO and diversity handset antennas, the design of low profile, small footprint and multi-standard (wideband or multiband) diversity antennas on handset devices remains a challenging issue. Therefore, the purpose of this thesis is to present new antenna structures for handset MIMO and diversity applications. As the MIMO antenna design can be conducted either using multiple element antennas (MEA) or isolated mode antenna technology (IMAT), the work in this thesis is fallen in these two general design themes (areas). The first area under investigation concerns multiport antennas (IMAT antennas). It has the following two contributions: • A novel dual-feed water-based antenna is designed from a low cost liquid material with a very high dielectric constant (pure water ). The isolation between feeds is achieved by two back to back L-shaped ground plane strips. A prototype is made and the optimised diversity parameters are obtained, the results show that this design has a good diversity performance over the frequency range of 2.4 – 2.7 GHz. • A new and low profile (h = 3 mm) planar inverted-F antenna (PIFA) with a coplanar-feed is presented. It has a wideband response over the frequency range of 2.35 – 3.25 GHz. The design is based on a comparative study on the mutual coupling between different feed arrangements. As a result, the coplanar feed is employed in the proposed antenna; the polarization diversity is achieved by exciting two orthogonal radiation modes. The isolation between the feeds is achieved by an L-shaped ground plane slot. Both simulated and measured results demonstrate that the design is a very good candidate for mobile diversity and MIMO applications. The second investigation area concerns multiple element antenna (MEA) systems for wideband and multiband handset applications. It includes the following contributions: • Three antenna systems of the planar inverted-L (PILA) antenna (h = 5 mm) are employed for wideband handset diversity applications over the frequency range of 1.7 – 2.85 GHz: 1) The first design has a dual-element PILA in which both the pattern and spatial diversities are employed; one antenna element is located on the upper edge of the ground plane while the other is located on the lower edge. 2) The second design represents a more compact dual-element PILA antenna in which the two elements are placed on the same ground plane edge (collocated on the same edge). The antenna isolation is achieved using a parasitic decoupling element inserted between the two elements. A novel approach for the design of the parasitic decoupling element is proposed. It is based on stepped impedance resonator circuit theory. As a result, more space is saved with this design (footprint = 385 mm2) over the first design (footprint = 702 mm2). 3) The third design is a four-element PILA system in which two antenna pairs (one pair at the upper edge which the other pair is located on the lower edge on the system PCB). All the prototypes are made and evaluated; the results show excellent diversity performance over the applications in the frequency range of 1.7-2.7 GHz. • A dual-element hexa-band antenna is proposed for smartphone MIMO applications. It consists of two elements: a hexa-band metallic frame antenna and a hepta-band PILA antenna coupled with a meandered shorted strip as an internal antenna. The isolation is achieved due to the resulted orthogonal radiation patterns, especially, at 0.85 GHz. The optimized antenna is made and tested and the results show that this design covers a hexa-band and is particularly suitable for GSM850/ DCS1800/ PCS1900/ UMTS2100/ LTE2500/ LTE3600 smartphone applications