Experimental investigation of adaptive impedance matching for a MIMO terminal with CMOS SOI tuners

It is well known that user proximity introduces absorption and impedance mismatch losses that severely degrade multiple-input multiple-output (MIMO) performance of handset antennas. In this work, we experimentally verified the potential of adaptive impedance matching (AIM) to mitigate user interaction effects and identified the main AIM gain mechanism in realistic systems. A practical setup including custom-designed CMOS silicon-on-insulator (SOI) impedance tuners implemented on a MIMO handset was measured in three propagation environments and 10 real user scenarios. The results indicate that AIM can improve MIMO capacity by up to 42% equivalent to 3.5 dB of multiplexing efficiency (ME) gain. Taking into account the measured losses of 1 dB in the integrated tuners, the maximum net ME gain is 2.5 dB suggesting applicability in practical systems. Variations in ME gains of up to 1.5 dB for different hand-grip styles were mainly due to differences in impedance mismatch and tuner loss distribution. The study also confirmed earlier results on the significant differences in mismatch and absorption between phantoms and real users, in which the phantoms underestimated user effects and therefore AIM gains. Finally, propagation environments of different angular spreads were found to give only minor ME gain variations

Antennit metallikuorisissa matkapuhelimissa

This master’s thesis studies the effects of a slotless, continuous metal cover of a mobile terminal on the performance of its antennas. Additionally, LTE MIMO antennas are designed together with GPS and Wi-Fi antennas. The cellular antennas should operate on 704–960MHz and 1.71–2.69 GHz with at least 30% efficiency, and the other antennas at 1.575 GHz, 2.4 GHz, and 5 GHz bands with 40% efficiency. The topic is studied by completing electromagnetic simulations. The used model of the mobile phone is much more accurate than the ones used in earlier studies. The simulations focus on the antenna structures, locations, and sizes, as well as feeding of them. Additionally, matching circuits are investigated, and designed for each antenna. The effect of the metal cover is studied with several test cases, each of which focuses on one parameter, e.g. a dimension, location, or feed of the antenna. The first simulations are done with a simple model, and a concept for the cellular antennas is constructed on the basis of the obtained results. The final simulations are completed, and the antennas optimized with the accurate model. The proposed structure consists of three closely located, strongly coupling elements. The cellular antennas are at distinct ends of the device, and integrated into the side metals. GPS and Wi-Fi antennas are also integrated into the sides, and placed in the area between the ends of the phone. The main challenge due to the metal-cover is obtaining sufficient and wideband matching. Regardless the challenging environment, all the designed antennas fulfill their requirements. Based on the results, achieving a good antenna performance in a metal-covered phone is not impossible.Tässä diplomityössä tutkitaan matkapuhelimen yhtenäisen metallikuoren vaikutusta antennien suorituskykyyn. Työssä suunnitellaan myös LTE-taajuuksilla toimiva MIMO-antenni sekä GPS- ja Wi-Fi-antennit. Matkapuhelinantennien tulee toimia taajuuksilla 704–960MHz ja 1.71–2.69 GHz vähintään 30 % hyötysuhteella. Vastaavasti muiden antennien taajuuskaistat ovat 1.575 GHz, 2.4 GHz ja 5 GHz tavoitehyötysuhteen ollessa 40 %. Tutkimus suoritetaan sähkömagneettisilla simulaatioilla. Työssä käytettävä puhelimen simulointimalli on paljon realistisempi kuin aiemmissa tutkimuksissa käytetyt mallit. Simuloinnit keskittyvät antennirakenteisiin sekä niiden sijainteihin, kokoihin ja syöttötapoihin. Lisäksi jokaiselle antennille suunnitellaan sovituspiiri. Metallikuoren vaikutusta tutkitaan useilla eri testeillä, joista jokainen keskittyy yhteen parametriin kuten antennin mittoihin, sijaintiin tai syöttöön. Työ aloitetaan yksinkertaisella simulointimallilla, ja näiden testien perusteella valitaan puhelinantennirakenne. Lopulliset testit ja antennien optimointi tehdään tarkalla mallilla. Esitetty rakenne koostuu kolmesta lähekkäin olevasta ja voimakkaasti kytkevästä antennielementistä. Puhelinantennit sijaitsevat laitteen eri päissä ja ovat osa puhelimen sivuissa olevaa metallirengasta. GPS- sekä Wi-Fi-antennit ovat myös osa metallirengasta ja sijaitsevat laitteen päätyjen väliin jäävällä alueella. Suurin metallikuoresta aiheutuva haaste on riittävän hyvän ja laajakaistaisen sovitustason saavuttaminen. Vaikeasta ympäristöstä huolimatta suunnitellut antennit täyttävät asetetut suorituskykytavoitteet. Tulosten perusteella on mahdollista suunnitella hyvin toimivat antennit metallikuoriseen puhelimeen

Antenna System Design for 5G and Beyond – A Modal Approach

Antennas are one of the key components that empower a new generation of wireless technologies, such as 5G and new radar systems. It has been shown that antenna design strategies based on modal theories represent a powerful systematic approach to design practical antenna systems with high performance. In this thesis, several innovative multi-antenna systems are proposed for wireless applications in different frequency bands: from sub-6 GHz to millimeter-wave (mm-wave) bands. The thesis consists of an overview (Part I) and six scientific papers published in peer-reviewed international journals (Part II). Part I provides the overall framework of the thesis work: It presents the background and motivation for the problems at hand, the fundamental modal theories utilized to address these problems, as well as subject-specific research challenges. Brief conclusions and future outlook are also provided. The included papers of Part II can be divided into two tracks with different 5G and beyond wireless applications, both aiming for higher data rates.In the first track, Papers [I] to [IV] investigate different aspects of antenna system design for smart-phone application. Since Long Term Evolution (LTE) (so-called 3.5G) was deployed in 2009, mobile communication systems have utilized multiple-input multiple-output antenna technology (MIMO) technology to increase the spectral efficiency of the transmission channel and provide higher data rates in existing and new sub-6 GHz bands. However, MIMO requires multi-antennas at both the base stations and the user equipment (mainly smartphones) and it is very challenging to implement sub-6 GHz multi-antennas within the limited space of smartphones. This points to the need for innovative design strategies. The theory of characteristic modes (TCM) is one type of modal theory in the antenna community, which has been shown to be a versatile tool to analyze the inherent resonance properties of an arbitrarily shaped radiating structure. Characteristic modes (CMs) have the useful property of their fields being orthogonal over both the source region and the sphere at infinity. This property makes TCM uniquely suited for electrically compact MIMO antenna design.In the second track, Papers [V]-[VI] investigate new integrated antenna arrays and subarrays for the two wireless applications, which are both implemented in a higher part of the mm-wave frequency range (i.e. E-band). Furthermore, a newly developed high resolution multi-layer “Any-Layer” PCB technology is investigated to realize antenna-in-package solutions for these mmwave antenna system designs. High gain and high efficiency antennas are essential for high-speed wireless point-to-point communication systems. To meet these requirements, Paper [V] proposes directive multilayer substrate integrated waveguide (SIW) cavity-backed slot antenna array and subarray. As a background, the microwave community has already shown the benefits of modal theory in the design and analysis of closed structures like waveguides and cavities. Higher-order cavity modes are used in the antenna array design process to facilitate lower loss, simpler feeding network, and lower sensitivity to fabrication errors, which are favorable for E-band communication systems. However, waveguide/cavity modes are confined to fields within the guided media and can only help to design special types of antennas that contain those structures. As an example of the versatility of TCM, Paper [VI] shows that apart from smartphone antenna designs proposed in Papers [I]-[IV], TCM can alsobe used to find the desirable modes of the linear antenna arrays. Furthermore, apart from E-band communications, the proposed series-fed patch array topology in Paper [VI] is a good candidate for application in 79 GHz MIMO automotive radar due to its low cost, compact size, ability to suppress surface waves, as well as relatively wide impedance and flat-gain bandwidths

PERANCANGAN DAN REALISASI ANTENA MIKROSTRIP MIMO BOWTIE 4X4 PADA FREKUENSI 1,8 GHz UNTUK APLIKASI LTE

ABSTRAK Perkembangan zaman dan meningkatnya kebutuhan teknologi telekomunikasi di Indonesia, mendorong pemerintah dan operator bekerjasama dalam mewujudkan jaringan LTE yang direalisasikan mulai tahun 2014. Di Indonesia yang umumnya menggunakan teknologi GSM, jaringan LTE juga diimplementasikan pada frekuensi 1,8 GHz. Untuk meningkatkan kualitas dan kapasitas sistem komunikasi LTE digunakan teknologi MIMO. Teknologi MIMO (Multiple Input Multiple Output) merupakan sistem komunikasi dengan menggunakan multi antena baik disisi transmitter maupun receiver. Dengan teknologi MIMO, empat antena mikrostrip direalisasikan supaya dihasilkan data rate yang lebih tinggi. Pada tugas akhir ini dirancang dan direalisasikan antena mikrostrip MIMO Bowtie 4x4 untuk aplikasi pada teknologi LTE pada frekuensi 1,88 GHz dengan gain ? 3 dBi dan bandwidth ? 50 MHz. Dari hasil pengukuran, didapatkan bandwidth yang memenuhi syarat VSWR <1,6. Bandwidth ? 70 MHz pada semua antena. Gain pada antena pertama 3,62 dBi, pada antena kedua 3,67 dBi, pada antena ketiga 3,60 dBi, dan pada antena keempat 3,50 dBi. Pola radiasi yang dihasilkan ketika simulasi dan pengukuran adalah bidireksional. Polarisasi yang dihasilkan ketika simulasi dan pengukuran adalah elips. Berdasarkan frekuensi, bandwidth, gain, dan dimensi antena yang dihasilkan, maka antena ini dapat digunakan sebagai antena pada mini BTS untuk teknologi LTE. Kata kunci: Antena Mikrostrip Bowtie, MIMO, LT

Characterization and Enhancement of Antenna System Performance in Compact MIMO Terminals

Co-band multiple-antenna implementation in compact user terminals is necessary for harvesting the full potential of diversity and multiple-input multiple-output (MIMO) technology in cellular communication systems. The recent worldwide deployment of Long Term Evolution (LTE), which requires the use of MIMO technology in the downlink, adds to the urgency of achieving both practical and optimal multiple-antenna systems in user terminals. Contrary to conventional understanding, an optimal multiple-antenna implementation does not only involve the design and placement of antenna elements in the terminals, but extends beyond the antenna elements and common antenna parameters to comprise interactions with the near field user and the propagation environment. Moreover, these interactions are non-static, which implies that the multiple-antenna system must adapt to the prevailing overall communication channel in order to assure the highest performance gains. This doctoral thesis aims to address several key issues in optimal multiple-antenna system design for compact multi-band MIMO terminals, with the first half (Papers I to III) focusing on the performance characterization of such terminals in the presence of user interaction and propagation channel, under the challenging constraint that the terminals are compact. The second half of the thesis (Papers IV to VI) considers two performance enhancement approaches suitable for compact MIMO terminals in realistic usage conditions. In particular, the potential benefits of harmonizing compact multiple-antenna systems with the propagation channel and user influence are determined with respect to reconfigurability in antenna patterns and impedance matching circuits. In Paper I, the diversity performance of internal multiple antennas with multi-band coverage in a mock-up with the size of a typical mobile handset is investigated in different user interaction scenarios. For comparison, a second mock-up with only one multi-band antenna is also evaluated in the same user cases. An ideal uniform propagation environment is assumed. The performance at frequency bands below and above 1 GHz are presented and analyzed in detail. Paper II extends the study in Paper I by evaluating the single-input multiple-output (SIMO) and MIMO capacity performance of the same antenna prototypes under the same user interaction scenarios and propagation environment. In Paper III, the impacts of gain imbalance and antenna separation on the throughput performance of a dual-dipole configuration are studied at frequencies below and above 1 GHz in a repeatable dynamic multi-path environment, using a live HSPA network. Since the compactness of a user terminal has implications on the antenna separation and gain imbalance of the multiple antennas, the focus is to gain knowledge on how these two factors affect the end user experience in practice. In Paper IV, three simple dual-antenna topologies implemented in compact smart phone prototypes of identical form factors are evaluated in MIMO channel measurements in noise-limited and interference-limited urban scenarios. Each dual-antenna topology is intentionally designed to provide a distinct set of antenna patterns. The goal is to investigate the potential of antenna system design as one of the key performance differentiators in real terminal implementations. Paper V extends the work in Paper IV by introducing user interaction to the same MIMO channel measurement setup. Furthermore, the focus of this paper is on the evaluation of both the average and local channel performances and their potential enhancements. Finally, Paper VI ascertains the potential capacity gains of applying uncoupled adaptive matching to a compact dual-antenna terminal in an indoor office environment, under a realistic user scenario. The performance gains are evaluated by means of extensive MIMO channel measurements at frequency bands below and above 1 GHz

Design and Measurement-Based Evaluation of Multi-Antenna Mobile Terminals for LTE 3500 MHz Band

Design of multi-element antennas for small mobile terminals operating at higher frequencies remains challenging despite smaller antenna dimension and possibility of achieving electrically large separation between them. In this paper, the importance of the type of radiating elements operating at 3400-3600 MHz and their locations on the terminal chassis are highlighted. An isotropic radiation pattern that receives incoming signals from arbitrary directions is obtained by combining the radiation patterns of multiple antennas with localized chassis current distribution. Four multiport antennas configurations with two- and eight-element antennas are designed and evaluated experimentally in indoor propagation environments. Our proposed designs of multi-element antennas provide the highest MIMO channel capacity compared to their counterparts using antennas with less localized chassis current distribution, even in the presence of user's hand

Miniaturization and evaluation methods of mobile terminal antenna structures

In recent years, the trend in the mobile communications market has been towards thinner and mechanically more complex terminal devices, which are able to operate in several wireless systems. Due to this development, miniaturization and performance enhancement of internal mobile terminal antennas have become major challenges for the industry of the field. Not only should an internal antenna be small in size and broadband, it must also be able to ensure reliable power transmission in a real multipath propagation environment. A well-known way to improve the reliability of a radio connection is to use multi-antenna reception in the mobile terminal. In multiple-input multiple-output (MIMO) systems, multiple antennas are additionally used at the base station. In both cases, fast and reliable methods are needed for the performance evaluation of multi-antenna terminals. In the first part of this thesis, the main benefits, drawbacks and applications of coupling element based mobile terminal antenna structures are studied, with special emphasis on antenna miniaturization. Optimum shaping and placement of capacitive coupling elements are first studied in this work. Next, it is demonstrated by simulations and measurements that the bandwidth-to-volume ratio of a mobile terminal antenna structure can be improved significantly by using optimized coupling elements instead of traditional self-resonant antenna elements. To facilitate the implementation of coupling element based multi-resonant antenna structures, a theoretical study on the dual-resonant impedance matching of non-resonant coupling elements is also presented. The feasibility of coupling elements for multi-band terminals is demonstrated with a novel quad-band GSM antenna, which consumes a total volume of only 0.7 cm3. Finally, a novel frequency tunable matching circuitry designed for non-resonant coupling elements is introduced. In this work, also the bandwidth, efficiency in talk position, and SAR (specific absorption rate) of mobile phone antennas are studied as a function of frequency over wide frequency band (0.6 GHz - 6 GHz) by applying the idea of coupling elements. The results show that below 3 GHz the three parameters are strongly affected by the resonant wavemodes of the chassis, whereas above 3 GHz, the wavemodes of the coupling element dominate. In addition to the above, the resonant wavemodes of the chassis of a clamshell phone are investigated in this work by using coupling elements. The results bring out several challenges, such as a non-radiating resonance, that an antenna designer may face with clamshell phones. The second part of this thesis concentrates on the performance evaluation of mobile terminal multi-antenna configurations. First, the accuracy of a novel measurement based antenna test bed (MEBAT) is thoroughly studied. After this, the performance of several mobile terminal multi-antenna configurations is systematically investigated using the MEBAT. The emphasis is kept on the power reception properties (effective array gain or EAG) of the multi-antenna configurations. An accurate and fast theoretical way of predicting the median EAG of an antenna configuration is proposed in the work. Based on a comprehensive analysis of the theoretical and empirical EAG results, guidelines for optimum radiation pattern characteristics of a multi-antenna configuration are given. Based on the eigenvalue dispersion and capacity results obtained in the studied MIMO environments, it is concluded that it may be difficult to affect the spatial multiplexing properties of a MIMO system by means of handset antenna design. The presented results indicate that a handset antenna designer should mainly focus on maximizing the EAG.Viime vuosina yleinen kehityssuunta matkaviestinmarkkinoilla on ollut kohti ohuempia ja mekaanisesti monimutkaisempia päätelaitteita, jotka kykenevät toimimaan useissa langattomissa järjestelmissä. Tämän kehityksen johdosta matkapuhelinten sisäisten antennien koon pienentäminen ja suorituskyvyn parantaminen ovat muodostuneet merkittäviksi haasteiksi alan teollisuudelle. Sen lisäksi, että sisäisen antennin tulee olla pienikokoinen ja laajakaistainen, tulee sen myös kyetä takaamaan luotettava tehonsiirto todellisessa monitie-etenemisympäristössä. Hyvin tunnettu tapa radioyhteyden luotettavuuden parantamiseksi on hyödyntää moniantennivastaanottoa matkapuhelimessa. Multiple-input multiple-output (MIMO)-järjestelmissä useita antenneja hyödynnetään lisäksi tukiasemassa. Kummassakin tapauksessa tarvitaan nopeita ja luotettavia menetelmiä matkapuhelinten moniantennirakenteiden suorituskyvyn arvioimiseksi. Työn ensimmäisessä osassa tutkitaan kytkentäelementteihin perustuvien antennirakenteiden tärkeimpiä hyötyjä, haittoja ja sovelluksia painottaen antennien koon pienentämistä. Työssä tutkitaan ensin kapasitiivisten kytkentäelementtien optimaalista muotoilua ja sijoittamista. Seuraavaksi osoitetaan simulaatioin ja mittauksin, että matkapuhelimen antennirakenteen kaistanleveys-tilavuus-suhdetta saadaan parannettua huomattavasti käyttämällä optimoituja kytkentäelementtejä perinteisten resonanssityyppisten antennielementtien sijaan. Kytkentäelementteihin perustuvien moniresonanssi antennirakenteiden toteuttamisen helpottamiseksi työssä esitetään myös teoreettinen tutkimus ei-resonoivien kytkentäelementtien sovittamisesta kaksoisresonanssiin. Kytkentäelementtien soveltuvuutta monitaajuuspäätelaitteisiin havainnollistetaan uudentyyppisellä nelitaajuus-GSM-antennilla, jonka kokonaistilavuus on ainoastaan 0.7 cm3. Lopuksi esitellään uudentyyppinen kytkentäelementeille suunniteltu taajuussäädettävä sovituspiiri. Tässä työssä tutkitaan myös matkapuhelinantennien kaistanleveyttä, hyötysuhdetta puheasennossa ja SAR- (specific absorption rate) arvoja taajuuden funktiona laajalla taajuuskaistalla (0.6 GHz - 6 GHz) hyödyntäen kytkentäelementtejä. Tulokset osoittavat, että 3 GHz:n alapuolella näihin kolmeen parametriin vaikuttavat vahvasti rungon resonoivat aaltomuodot, kun taas 3 GHz:n yläpuolella kytkentäelementin aaltomuodot dominoivat. Yllä olevan lisäksi työssä tutkitaan taitettavan puhelimen rungon resonoivia aaltomuotoja kytkentäelementtien avulla. Tulokset tuovat esille useita haasteita, kuten säteilemättömän resonanssin, joita antennisuunnittelija saattaa kohdata taitettavien puhelinten kanssa. Työn toinen osa keskittyy matkapuhelinten moniantennirakenteiden suorituskyvyn arviointiin. Ensin uudentyyppisen mittauksiin perustuvan antennien testialustan (MEBAT) tarkkuutta arvioidaan perusteellisesti. Tämän jälkeen useiden matkapuhelinten moniantennirakenteiden suorituskykyä tutkitaan järjestelmällisesti MEBATin avulla. Painotus on moniantennirakenteiden tehovastaanotto-ominaisuuksissa (effective array gain tai EAG). Työssä ehdotetaan tarkkaa ja nopeaa teoreettista tapaa antennirakenteen EAG:n mediaanin ennustamiseksi. Teoreettisten ja empiiristen EAG-tulosten perusteellisen analyysin pohjalta annetaan suosituksia moniantennijärjestelmän säteilykuvion optimaalisille ominaisuuksille. Tutkituissa MIMO-järjestelmissä saatujen ominaisarvohaje- ja kapasiteettitulosten perusteella tehdään johtopäätös, että matkapuhelimen antennisuunnittelun keinoin voi olla vaikeaa vaikuttaa MIMO-järjestelmän kykyyn muodostaa rinnakkaisia kanavia. Esitetyt tulokset ehdottavat, että matkapuhelimen antennisuunnittelijan tulisi pääasiassa keskittyä EAG:n maksimointiin.reviewe

人体・多重波相互作用影響下におけるウェアラブルアンテナのOver-The-Air設計方法論

富山大学・富理工博甲第120号・李鯤・2017/03/23富山大学201

IEEE Access Special Section: Antenna and Propagation for 5G and Beyond

5G is not just the next evolution of 4G technology; it is a paradigm shift. “5G and beyond” will enable bandwidth in excess of 100s of Mb/s with a latency of less than 1 ms, in addition to providing connectivity to billions of devices. The verticals of 5G and beyond are not limited to smart transportation, industrial IoT, eHealth, smart cities, and entertainment services, transforming the way humanity lives, works, and engages with its environment