In this thesis, an LTE/WWAN planar loop antenna for tablet computer with a compact size of 75 ¡Ñ 12 mm2 is presented. The planar loop antenna comprises a printed loop strip and a patch monopole encircled therein. By embedding a printed distributed inductor in the loop strip, whose effect is similar to a chip inductor, a parallel resonant mode is generated owing to the contributed inductance of the distributed inductor and the contributed capacitance of the coupling between the loop strip and the patch monopole. The parallel resonant mode leads to increase input resistance of the 0.5-wavelength loop mode at the high-frequency tail and a zero reactance nearby the original resonance of the 0.5-wavelength loop mode, thereby resulting in a dual-resonance excitation to greatly enhance the bandwidth of the antenna¡¦s lower band for the LTE700/GSM850/900 operation. In addition, the patch monopole, which performs not only as a coupling feed but also an efficient radiator, provides a 0.25-wavelength resonant mode to combine with a higher-order resonant mode contributed by the printed loop strip to form the antenna¡¦s upper band to cover the GSM1800/1900/UMTS/LTE2300/2500 operation. Further, the required distance between the antenna and the testing flat phantom to meet the 1-g body SAR requirement of 1.6 W/kg is discussed. A comparison of the body SAR value of the planar loop antenna and the bent loop antenna is also discussed.

The proliferation of modern wireless networks increases demand for high capacity and throughput in order to provide faster, more robust, efficient and broadband services to end users. Mobile WiMAX and LTE are examples of such networks in which for some cases they have exposed limited connectivity due to harsh environment. Relay stations are preferred to overcome problems of weak or no access for such network devices, that are placed in specific positions to maintain high quality of data transfer at low cost and provide the required connectivity anywhere anytime. These stations should be equipped with an antenna system capable of establishing communication between base station (backhaul link) and end users (access link). This thesis focuses on the design and development of a new antenna system that is suitable for a relay-based wireless network. Planar geometries of microstrip patch antennas are utilized. The antenna system comprises two antenna modules: a new design of a single antenna for access link and a new design of an antenna array for backhaul link realization. Both antenna specifications are compatible with the IEEE802.16j protocol standard. Hence, relay station should be capable of pointing its radiation pattern to the base station antenna, thus to achieve the desired radiation pattern of the relay station, a new beam-forming module is proposed, designed and developed to generate the proper radiation pattern. The beam-forming module incorporating digital phase shifters and attenuator chips is fabricated and tested. The optimization process using the Least Mean Square (LMS) algorithm is considered in this study to assign the proper phase and amplitude that is necessary to each radiation element excitation current, to produce the desired steered radiation pattern. A comprehensive study on the coupling effects for several relative positions between two new backhaul and access link antenna elements is performed. Two new antenna configurations for coupling reduction are tested and the simulated and measured results in terms of antenna radiation performances were compared and commented.

Les antennes à pointage électronique présentent des avantages significatifs dans les systèmes de communication sans fil. Malgré cela elles ne sont toujours pas implantées dans l'industrie automobile. En effet, l'espace limité et le toit en grande partie métallique freinent l’utilisation de ces aériens dans ce contexte contraint. De nombreux défis restent à relever pour concevoir un système efficace, peu encombrant, faible coût et permettant de rayonner sur 360°. L’objectif de cette thèse est donc la mise au point d’une antenne à balayage électronique pour application automobile fonctionnant dans la bande LTE. Un système de «type MIMO » est proposé. Une antenne à résonateur diélectrique efficace, multi-bandes et efficace est conçue selon une procédure de développement spécifique. Un déphaseur accordable est également mis au point et réalisé. Il utilise des commutateurs et un condensateur variable. Un déphasage de 360 degrés est obtenu, le dispositif est commandé électriquement. L’antenne et le déphaseur sont ensuite associés dans un système complet fonctionnant dans la bande LTE. Celui-ci utilise deux antennes identiques, une seule étant alimentée. Ce système complet est mesuré seul et sur le véhicule. Les résultats obtenus sont prometteurs et permettent d’envisager, moyennant quelques améliorations, une exploitation industrielle. Les études menées pour aboutir à ce dispositif sont détaillées dans le manuscrit. / Even though beam steering technology has significant advantages in wireless communication systems, it is still not implemented in the automotive industry. Indeed, the limited space and the large metal sheet on the rooftop are the challenges for such system. This thesis is focused on the design of the LTE beam steering antenna based on a MIMO system for an automotive environment. An appropriate multiband, efficient and compact Dielectric Resonator Antenna is conceived using a specific development procedure. Also, a tunable phase shifter is designed and realized with switches and a variable capacitor. It has 360 degrees phase shift and can be electrically controlled. The proposed DRA and phase shifter are integrated in a global antenna system for automotive application in the LTE band. We finally propose a MIMO system with an active beam steering radiation pattern. It is very compact and can be implemented on the vehicle rooftop. Using the proposed phase shifter, a beam steering antenna is obtained with a global coverage close to 360� for the antenna alone or on the vehicle. Measurements are made in the using context of the antenna. Finally, the developed system is, with some improvement, powerful for powerful enough for "commercial" automotive applications. The studies carried out to develop this antenna are detailed in this manuscript.

This thesis primarily deals with the concept of designing an antenna based device to harvest energy from Radio Frequency (RF) and using the harvested energy to sense the available Long Term Evolution (LTE) network in order for the Internet of Things (IoT) devices to connect to the network for the purpose of transmitting and receiving data. Secondarily the importance of this project is targeting how to conserve battery power in an IoT device and extend it’s lifetime. Research in the field of energy harvesting has been going on for a long time. Most of the researches concentrate on harvesting significant amount of energy to power up an entire device and so no one has ever thought of using the harvested RF energy to sense the availability of LTE network. This method of using antenna to sense network requires only a small amount of harvested energy. Due to this reason the proposed design works for a very low input received signal strength indicator (RSSI) as well, unlike higer RSSI required for other applications. The proposed design has three major sub-parts such as the (i) Antenna for the purpose of receiving the available ambient radio frequency. (ii) Matching circuit for the purpose of maximum power transfer between the antenna and the rectifier circuit. Finally (iii) rectifier which is used to convert the AC voltage into DC voltage. The device then measures the obtained voltage through the Analog to Digital Converter (ADC) pin in the Micro-Controlling Unit (MCU) available with the attached IoT device. The MCU then maps the harvested voltage into the corresponding analog voltage.Depending on the set threshold voltage the MCU can then advice whether or not to connect to the LTE network. The design implements matching circuit for the two LTE bands that are primarily in use in the European region i.e., band 3, 8 that work in 915, 1800 MHz frequency region respectively. In this way we can identify in which band the device is harvesting energy. The matching circuit also acts as a bandpass filter. For the design and production of the entire harvester device one needs adequate knowledge in the field of RF and Antennas and a high level knowledge in the field of electronics in order to run Simulations and to design Printed Circuit Boards (PCBs). Advanced Design Software (ADS) has been used to run all the simulations and Altium software for the design of PCBs. The final prototype is presented along with the casing and tested on the field in practical scenario. Antenna test chambers were used to test the performance of the antennas being used for the design. The prototype harvests RF energy and indicates whether or not to connect to the LTE network with the help of light emitting diode (LED). The uniqueness of the device is that it can detect signals as low as -110 dBm, this has been set as the threshold for the purpose of sensing LTE networks. / Denna avhandling behandlar primärt konceptet att använda antenner för att hämta energi från RF och att använda den insamlade energin för att känna av det tillgängliga LTE-nätverket för att IoT-enheterna ska kunna ansluta till nätverket för syftet med att överföra och ta emot data. Sekundärt Målet med av detta projekt är att spara batteri i en IoT-enhet och förlänga dess livslängd. Forskning inom området energiskörd har pågått under lång tid nu. De flesta av undersökningarna koncentrerar sig på att skörda betydande mängder energi för att driva en hel enhet och så ingen har någonsin tänkt på att använda den avkända RF-energin för att känna av tillgängligheten för LTE-nätverket. Denna metod för att använda antenn för att känna av nätverk kräver endast en liten mängd skördad energi. På grund av denna anledning fungerar den föreslagna designen även för en mycket låg ingång RSSI, till skillnad från högre RSSI som krävs för andra applikationer. Den föreslagna designen har tre huvuddelar, såsom (i) antennen för att ta emot den tillgängliga omgivande radiofrekvensen. (ii) Matchningskrets för maximal effektöverföring mellan antennen och likriktarkretsen. Slutligen (iii) likriktaren som används för att omvandla AC-spänningen till DC-spänning. Enheten mäter sedan den erhållna spänningen genom ADC-stiftet i MCU som finns tillgänglig med den anslutna IoT-enheten. MCU mappar sedan den genererade spänningen till motsvarande analoga spänning. Beroende på den inställda tröskelspänningen kan MCU sedan ge råd om att ansluta till LTE-nätverket eller inte. Konstruktionen implementerar matchningskrets för de två LTE-banden som primärt används i den europeiska regionen vilka är band 3, 7 som arbetar i 915 respektive 1800 MHz frekvensområdet. På så sätt kan vi identifiera i vilket band enheten hämtar energi i. Matchningskretsen fungerar också som ett bandpassfilter. För design och produktion av hela insamlingsenheten behöver man adekvat kunskap inom området RF och antenner och en hög nivå kunskap inom elektronikområdet för att kunna köra simuleringar och designa PCBs.ADS har använts för att köra alla simuleringar och Altium-mjukvara för design av PCBs. Den slutliga prototypen presenteras tillsammans med höljet och testas på fältet i praktiskt scenario. Antenntestkammare användes för att testa prestandan hos antennerna som användes för konstruktionen. Prototypen skördar RF-energi och indikerar om man ska ansluta till LTE-nätverket eller inte med hjälp av blinkande LED.Det unika med enheten är att den kan upptäcka signaler så låga som - 110 dBm, detta har satts som tröskel för avkänning LTE nätverk.