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Satellite, fifth generation (5G), and sixth generation (6G) mobile communication systems operating at micro- and millimeter wave frequencies are an essential pillar in advanced network architectures for high-throughput low latency services. The decisive factors for this current development were the significant technological advances accomplished over the last two decades, which meanwhile enable highly integrated, feature-rich, and cost-effective realizations of complete phased array transceiver topologies. Motivated through the today's trend for heterogeneous constellation types to provide truly global coverage, this contribution reviews the current state-of-the-art of electronically steerable antennas for terrestrial and non-terrestrial communication systems up to 100 GHz. First, the potential benefits and limitations of the most relevant technologies are contrasted and put into context with recent system architectures for adaptive beamforming. Their operating principles along with various experimental implementation and achievements providing advanced capabilities such as multi-band/multi-beam operation, polarization agility, and wide-angle scanning are thoroughly presented. Particular emphasis is laid on the review of direct radiating arrays, quasi-optical antenna configurations, and metasurface-based antennas., publishedVersion

In this work, a novel multi-feed synthesis for holographic leaky-wave (LW) antennas is presented that considers the angular dependence of each pixel structure. This approach of combining multiple single-beam holograms minimizes the impedance error w.r.t. each individual impedance hologram. A multi-feed antenna with two feeding points at 20GHz is fabricated and measured using this new design methodology. The simulation and measurement results show a good agreement. The fabricated LW antenna has a gain of 21.7 dBi and 22.1 dBi and a side lobe level (SLL) of 9.0 dB and 9.6 dB for both feeds., acceptedVersion

Zivile Drohnen finden privat wie auch kommerziell zunehmend Verwendung und werden beispielsweise von Sicherheitsbehörden, als Lieferdrohne oder zur Inspektionen von schwer zugänglichen Objekten genutzt. Für einen benutzerfreundlichen und sicheren Betrieb greifen moderne Drohnen auf eine Vielzahl von Sensoren zurück. Aktuelle Systeme nutzen satellitengestützte Positionsbestimmung, barometrische Höhenmessung und zur Detektion der Umgebung Infrarot-, Ultraschall- und Kamerasensoren. Diese Arbeit stellt Untersuchungen zur Anwendung von hochauflösenden Radarsensoren an Drohnen als Altimeter, für die Kollisionsvermeidung und für die Kartierung der Umgebung vor. Radar-Altimeter können gegenüber der barometrischen Höhenmessung die Flughöhe über Grund messen und weitere nützliche Informationen, wie etwa das Vorhandensein von Vegetation, bereitstellen. Basierend auf durchgeführte Untersuchungen zur Detektion von Vegetation, zur Notwendigkeit eines Gimbals, zur Nutzung als Landeradar sowie Frequenz- und Bandbreitenbetrachtungen werden mehrere Konzepte und Umsetzung vorgestellt und die Vorteile gegenüber den aktuellen Sensoren gezeigt. Bei der zwei- und dreidimensionalen Umfelderkennung werden neben der Entfernung und der Geschwindigkeit zusätzlich die Raumwinkel Azimut und Elevation gemessen. Hierfür wurde ein mehrkanaliger Radarsensor mit austauschbarem Antennen-Front-End entwickelt, an dem je nach Anforderung unterschiedliche Antennensysteme montiert werden können. Mit hoher Entfernungs- und Geschwindigkeitsauflösung sowie einem großen Sichtbereich konnte bei der zweidimensionalen Umfelderkennung gezeigt werden, dass die Detektion von stationären, bewegten und schwachen Zielen, z.B. kleine Drohnen oder feine Teile der Vegetation möglich ist. Die direkte Geschwindigkeitsmessung als Alleinstellungsmerkmal der Radarsensorik konnte zudem genutzt werden, um aus der Zielantwort die Eigenbewegung der Drohne zu bestimmen. Um unter Berücksichtigung der limitierten Nutzlast von Drohnen bei der dreidimensionalen Umfelderkennung beide Raumwinkel mit hoher Trennfähigkeit und großem Sichtbereich abzudecken, wurde ein ausgedünntes Antennensystem mit niedriger Kanalanzahl entworfen. Das für die einzelnen Kanäle verwendete Antennenelement sowie die Optimierung des Antennensystems werden detailliert beschrieben und messtechnisch validiert. Für die Erstellung von Karten der Umgebung zur Selbstlokalisierung oder Wegplanung werden an Drohnen häufig zusätzlich Lidarsensoren montiert. Es konnte gezeigt werden, dass mit den Daten des bildgebenden Radarsensors für die Umfelderkennung hochauflösende zwei- und dreidimensionale Radarkarten erstellt werden können. Untersuchungen zur Genauigkeit der Radarkarten zeigen, dass die Kenntnis der Position der Drohne und nicht der Radarsensor ausschlaggebend ist. In Hinblick auf die limitierte Nutzlast von Drohnen konnte selbst mit den satellitengestützten Positionsdaten der genutzten Drohne ohne zusätzlichen Lidarsensor Karten der Umgebung mit einer Genauigkeit von 0,5m erstellt werden. Die in dieser Arbeit gewonnen Erkenntnisse zeigen, dass Radarsensoren einen großen Beitrag für den sicheren Betrieb von Drohnen leisten und neue Anwendungsmöglichkeiten für Drohnen bieten können.

A hybrid thin film multilayer antenna for automotive radar is presented in this work. A 2×8 aperture coupled stacked patch antenna array is realized on a single layer printed circuit board (PCB) using a novel thin film based approach. Using a compact 180 ◦ phase difference power divider, inter-element spacing in a 2×2 sub-array is reduced. Measurement results show a 19% (67.9–82.5 GHz) impedance bandwidth and a wideband broadside radiation pattern, with a maximum gain of 15.4 dBi realized gain at 72 GHz. The presented antenna compares favorably with other multilayer PCB antennas in terms of performance, with the advantage of simpler manufacturing and robust design. The antenna can be employed in mid-range automotive radar applications., acceptedVersion

Radar sensors are an integral part of driver assistance systems. The performance of modern automotive radar sensors can be improved by incorporating multilayer wideband antennas in these systems. In this thesis, such wideband multilayer antenna array concepts for automotive radar sensors operating in the frequency range 76--81 GHz are investigated. The first two concepts investigated are based on a conventional multilayer PCB. A variable width grid array antenna is used for both designs, with the feed network being the difference between both concepts. For the first design, a two substrate layer PCB is used. The second design employs a three substrate layer PCB. A novel hybrid approach to design multilayer antennas is then introduced. Multilayer antennas are designed using single layer PCB and multilayer thin films attached to the PCB. The single layer PCB houses the complete feed network, whereas the radiating elements are realized on multilayer thin films. Two antenna concepts are presented as examples of this approach. The first is an aperture coupled stacked patch (ACSP) antenna array fed by a grounded coplanar waveguide (GCPW) feed network. A novel compact power divider is included in the feed network to reduce inter-element distance. The second concept is based on a novel antenna element, namely the stacked grid antenna (SGA). Feed networks with three different transmission line types are realized, namely the SIW, GCPW and MS, to create antenna arrays with the SGA to show the flexibility of antenna design. A comparison between the multilayer PCB approach and the hybrid thin film approach is then performed, using the investigated designs as the basis. The comparison shows that both approaches have their benefits. In terms of aperture efficiency, multilayer PCB antennas can achieve better results due to a completely buried feed network. However, it is shown that the hybrid thin film approach achieves similar wideband antenna performance as the conventional multilayer PCB approach, with added benefits of simple design, low cost manufacturing and increased robustness.

There is a growing demand for collaborative robots in order to improve the ef���ciency of industrial processes and to push Industry 4.0 forward. The challenge for these robots is the compliance of the safety regulations to protect human workers from injuries. Therefore, a large number of sensors for the close range (several centimeters up to some meters) around the robot are needed. For a protective cover around the robotic arms all sensors must cooperate and process their information together. This paper presents a close range proximity sensor based on a 160-GHz radar MMIC with a transition to two ���exible dielectric waveguides. On the low-loss waveguides, leaky-wave antennas with a large ���eld of view are distributed. This reduces the number of sensors and achieves a coverage area for one sensor of more than 2200 cm�� for a distance of 30 cm. For distances below 30 cm the sensor has blind areas. However, the expected extended targets like body parts can still be detected and the proximity sensor will stop the robot in the danger area. Additionally, the ���exible waveguide offers the possibility to place the antennas almost arbitrarily around the robotic arm. For a single target scenario it is even possible to determine the target position by multilateration with only one receive channel., publishedVersion

Radar sensors are crucial components of advanced driver assistance systems. In order to cope with the future requirements of highly automated and autonomous driving, today’s automotive radar sensors performance needs to be improved. This dissertation addresses the design and development of robust mm-wave antenna systems suitable for automotive radar applications. This study presents a microstrip antenna array with wideband and stable radiation performance. It proposes also an optimization strategy for finding the position of transmitting and receiving antennas in a MIMO radar while taking the angular resolution requirements into consideration. Finally, it analyzes the problem of the integration of the radar sensor in the vehicle and introduces the use of low-RCS antenna arrays to mitigate the multiple reflections between the bumper of the car and the radar sensor, when the latter is hidden integrated in the vehicle. Some low-RCS antenna designs are proposed and discussed.

A novel concept for a holographic antenna-in-package (AiP) is presented enabling the seamless integration of high gain antennas at millimeter wave frequencies. The antenna is based on a holographic impedance approach stimulating a leaky wave mode at 150 GHz. Since the antenna structure is placed on top of the glass package, a large antenna aperture with high angular beam width and efficiency were achieved. The surface wave launcher (SWL) of the antenna connected to the integrated active circuitry is designed in a very compact fashion using a vertical through-glass-via (TGV) and solder balls. The performance of the proposed holographic antenna package has been investigated by an analytic model and full wave simulations. The measurement results of the antenna prototype on glass using anisotropic unit cells show excellent agreement to the simulated values. A maximum gain of 24.7 dBi, a sidelobe level of 15 dB, and a 3 dB-beam width of 4.7�� are achieved. The measured 3D-radiation pattern shows a highly directive pattern in all cuts., acceptedVersion

Integrated antennas are a crucial component in the development of high-performance, fully-integrated transceiver chips. However, due to the small size of integrated antennas and their complicated contacting fixtures, existing measurement setups cannot be used for their characterization. Therefore, new approaches must be investigated to obtain reliable and accurate measurement results and thus to make optimized on-chip antenna designs possible. This work addresses the challenges of measuring integrated antennas at mm-wave frequencies. It introduces a robotic measurement setup to accurately determine the radiation properties of on-chip antennas and quantifies the achievable measurement accuracy through an in-depth uncertainty analysis. The study also analyzes post-processing techniques to mitigate severe distortions that occur in the measurement environment.

In dieser Arbeit werden Methoden zur Erzeugung von TE₀- und TM₀-Oberflächenwellen für die Anwendung in mmW-Leckwellenantennen nach dem holografischen Prinzip vorgestellt und untersucht. Ziel ist dabei, die Integrierbarkeit der Oberflächenwellenerzeuger in mmW-Systeme zu vereinfachen und gleichzeitig die Abstrahleigenschaften der Leckwellenantennen zu verbessern.

A hybrid thin film multilayer antenna for automotive radar is presented in this work. A 2×8 aperture coupled stacked patch antenna array is realized on a single layer printed circuit board (PCB) using a novel thin film based approach. Using a compact 180 ◦ phase difference power divider, inter-element spacing in a 2×2 sub-array is reduced. Measurement results show a 19% (67.9–82.5 GHz) impedance bandwidth and a wideband broadside radiation pattern, with a maximum gain of 15.4 dBi realized gain at 72 GHz. The antenna can be employed in mid-range automotive radar applications., acceptedVersion

Automotive radars are one of the key sensor technologies to develop reliable fully-automated cars. They are usually installed behind the bumper of the vehicle and therefore, multiple reflections can occur. The multiple reflections can be mitigated with the use of low-RCS (radar cross-section) antenna arrays. This paper presents the design of a complex low-RCS multiple antenna system that mimics a typical MIMO (multiple-input multiple-output) configuration. A prototype has been developed and tested. Approximately 17 dB of RCS reduction has been experimentally achieved. The measurement results show that the use of such a low-RCS antenna system can successfully reduce the amplitude of multiple reflections.

Millimeter-wave (mm-wave) automotive radars are typically installed behind the car fascia. However, the placement behind the bumper can cause multiple reflections, which may lead to a wrong estimation of the direction of arrival (DoA) of the target. The use of low-RCS (radar cross-section) antennas can mitigate them. This work presents the characterization of a mm-wave frequency-modulated continuous-wave (FMCW) MIMO (multiple-input multiple-output) radar equipped with a low-RCS antenna systems. The measurement results demonstrate that such an antenna configuration can reduce the angular error in the DoA estimation and increase the robustness of the system., acceptedVersion

MIMO radar systems create a large virtual aperture to enhance the angular resolution. As a multiplexing scheme often the time-division multiplexing (TDM) procedure is chosen. The drawbacks are a reduced maximal unambiguously detectable Doppler frequency and the need to correct a phase error in angle estimation for relative radial velocities. To overcome these disadvantages a multiplexing scheme is proposed which uses different chirp rates. Every transmitting antenna is active at the same time but can be distinguished due to the different slopes of the frequency ramps., acceptedVersion

In this dissertation, the operation of dual-linear polarized antennas is considered in order to provide ideal performance suited for several applications including polarimetric synthetic aperture radar (SAR), wireless and satellite communications. The underlying objectives realized in this work are reported as design realizations of dual-linear polarized antennas with low cross polarization patterns and high isolation between ports that employ special properties of the electromagnetic metamaterial (MTM) structures. Some of these key properties appear as negative permittivity, negative permeability, negative refractive index, and antiparallel nature of the phase velocity and the group velocity. The antenna design is carried out at two frequencies, 5.5 GHz and 10 GHz, and key physical issues that affect the operation of dual-linear polarization operation antennas are treated in light of electromagnetic MTM properties. It’s well known that a dual linear polarized antenna poses a big challenges such as cross polarization patterns and high mutual coupling between two input ports. Therefore, these drawbacks are key topic that receive significant attention in literature which reports on how to mitigate these drawbacks, however, at the expense of complexity of the antenna structures. The MTM structures have received considerable coverage in antenna research for obtaining size reduction, directivity enhancement, and beam steering. For this purpose, different MTMs structures are chosen in this thesis for achieving additional improvements, while keeping the antenna design as simple as possible, something which is very difficult to accomplish using conventional design methods.:Chapter 1: Introduction Chapter 2: Dual linear Polarization Antennas and Arrays Chapter 3: Fundamental Theory of Metamaterials Chapter 4: Metamaterial Structures Design-Methodology Chapter 5: Design of Dual Linear Polarization Using CRLH-TL Metamaterial Line Feed Chapter 6: Cross Polarization Discrimination Enhancement of a Dual Linear Polarization Antenna Using Split Ring Resonator Chapter 7: Antenna Array Design Chapter 8: Conclusions and Future Work In der folgenden Dissertation wird der Einsatz von zweifach linear polarisierten Antennen zur idealen Ausführung von verschiedenen Anwendungen, einschließlich von polarimetrischen Synthetic Aperture Radar (SAR), kabellose und satellitengestützte Kommunikation, diskutiert. Die Ziele dieser Arbeit werden dargestellt durch die Gestaltung von zweifach linear polarisierten Antennen mit gering Kreuz-Polarisationsmustern und die starke Isolation zwischen den Ports durch die einzigartigen Eigenschaften der Strukturen des elektromagnetischen Metamaterials (electromagnetic metamaterial; MTM). Einige dieser Eigenschaften treten als negative Permittivität, negative Permeabilität, negativer Brechungsindex und als antiparallel Richtungen (Gegenvektor) der Phasen-und Gruppengeschwindigkeit auf. Somit wird die Antennengestaltung auf zwei Frequenzen übertragen, 5,5GHz und 10 GHz, und die Ausführung der zweifach linearen Polarisation wird durch die elektromagnetischen Eigenschaften des MTM illustriert. Weil die Kreuzpolarisationsmuster und starke gegenseitige Koppelung zwischen zwei Input-Ports bei einer zweifach linear polarisierten Antenne große Schwierigkeiten bereiten, werden diese im Großteil der Fachliteratur als Schwerpunkte gesetzt, was zu einer Milderung der Nachteile führte, jedoch dafür die Komplexität der Antennenstruktur zunahm. Die Vielfalt an MTM ist ein bedeutender Teil im Bereich der Antennenforschung einschließlich der Größenverkleinerung, der Verbesserung der Richtcharakteristik und der Strahlensteuerung. Für diesen Zweck werden in dieser Dissertation verschiedenste MTM Strukturen ausgewählt um weitere Verbesserungen der Antennenstruktur zu ermöglichen und gleichzeitig die Einfachheit der Struktur zu bewahren, was mit konventionellen Gestaltungsmethoden nur schwer zu erreichen ist.:Chapter 1: Introduction Chapter 2: Dual linear Polarization Antennas and Arrays Chapter 3: Fundamental Theory of Metamaterials Chapter 4: Metamaterial Structures Design-Methodology Chapter 5: Design of Dual Linear Polarization Using CRLH-TL Metamaterial Line Feed Chapter 6: Cross Polarization Discrimination Enhancement of a Dual Linear Polarization Antenna Using Split Ring Resonator Chapter 7: Antenna Array Design Chapter 8: Conclusions and Future Work

Feeding integrated antennas during a measurement requires special feeding structures. Due to the small antenna dimensions, these feeding structures are often much bigger than the antenna under test (AUT) itself and with chip sizes of around 1 mm2, the achievable separation between antenna and feed is limited. Wafer probes have to be used to feed the AUT during passive antenna measurements and present a large reflective surface in close proximity to the AUT. Reflections from the wafer probe cause interference on the measurement surface and distort the results. The same is true for active antenna measurements, where bondwires and the package can have a significant effect on the radiated fields. The fragility and size of the components do not allow to reduce reflections with absorbers, which is why modal filtering was used in this paper to mitigate undesired reflections and improve the measurement result through postprocessing. Two issues that limit the performance of the algorithm are discussed, namely, phase center inaccuracies of the AUT and a limited measurement surface. It is shown that modal filtering is applicable to integrated antenna measurements at frequencies over 100 GHz and that a significant improvement in the measured radiation pattern can be achieved. Furthermore, it is shown that the postprocessed results make it possible to measure the directivity of integrated antennas, despite strong probe reflections., acceptedVersion

Due to various error sources, accurate integrated antenna measurements can be difficult to achieve. This study analyses the accuracy of a measurement set-up for radiation pattern (RP), directivity and gain measurements. The main sources of uncertainty are pointed out and the overall achievable accuracy is determined. The expanded uncertainty budgets for RP, directivity and gain measurements are 0.2, 0.2 and 1.7 dB, respectively. Furthermore, the phase centre of the antenna under test (AUT) is calculated for a more accurate and faster antenna alignment. The standard deviation of the calculated phase centre position is 50 ��m on each axis., acceptedVersion

This work introduces a novel wireless approach for the data transmission within automotive battery management systems. The main target is the reduction of the wiring harness deployed in a battery. The characteristics of the wireless in-battery channel are investigated by means of measurements and software-based electromagnetic simulations. Different types of antennas and frequency bands are analyzed. The performance of the proposed system is evaluated by means of simulations and prototypes.

The increasing demand for radar sensors and the wide distribution of handheld communication devices push the development of low-cost components with a small form factor. One approach to achieve smaller, low-cost devices is the integration of the required components on a monolithic microwaveintegrated circuit (MMIC). At frequencies above 100 GHz, passive components are small enough to be integrated onto a chip, and the advances in semiconductor technology make it possible to build active components that can operate at millimeter (mm)-wave frequencies [1], [2]. The available bandwidths of several gigahertz at mm-wave frequencies offer high data rates for communication devices or high resolution for remote-sensing applications. By integrating the radio-frequency (RF) components and the antennas, lossy off-chip transitions can be avoided, thus limiting the required connections to the power supply and baseband signals., acceptedVersion

The results of integrated antenna measurements are often severely distorted by reflections from the measurement environment. In order to contact and feed passive integrated antennas wafer probes have to be used. Wafer probes are not only electrically large, but are also located in the immediate environment of the antenna under test (AUT) and reflect parts of the radiated signals. This causes significant distortions and erroneous results in radiation pattern, directivity, and gain measurements. Custom wafer probes have been used to reduce reflections for meaningful measurement results, but these special probes are difficult to fabricate and expensive. If the antenna is measured within an active system that generates the transmit signal, waver probes are not required to feed the AUT, but bond wires, circuit elements close to the antenna, and surface wave radiation still limit the achievable accuracy of the measurements. In this paper modal filtering is used to mitigate the influence of unwanted distortions in post-processing for both wafer probe and active antenna measurements. It is shown that modal filtering can be applied to integrated antenna measurements above 100GHz and that reflections from wafer probes, bond wires, and the PCB can be reduced significantly for passive and active antenna measurements, respectively., acceptedVersion

The goal of this work is the introduction of efficient antenna structures on the basis of the requirement of different microwave imaging methods; i.e. quantitative and qualitative microwave imaging techniques. Several criteria are proposed for the evaluation of single element antenna structures for application in microwave imaging systems. The performance of the proposed antennas are evaluated in simulation and measurement scenarios.

When measuring integrated antennas the signal has to be fed to the antennas with wafer probes. Wafer probes are commonly used to contact integrated circuits for on-chip measurements. As integrated radar and communication chips with radiating elements are a fairly recent development, the wafer probes were not optimized for size and reflective properties (characteristics which are important for antenna measurements), but rather for their return loss, insertion loss, and mechanical stability. This resulted in metal probes that are relatively large compared to the wavelength. In this paper, two probes are compared with regard to their performance in integrated antenna measurements. The first probe is a standard commercially available probe. The second one is a modified probe with an extended coaxial probe tip to increase the distance between probe and antenna, which decreases the distortion and reflection caused by the probe significantly., acceptedVersion

In this paper the design and the implementation of a cavity antenna array in PCB technology for automotive radar applications is presented. The array consists of four cavity antennas fed by a microstrip-line feeding network and H-shaped coupling apertures in the ground plane. Simulation and measurement results show that the proposed structure is a suitable candidate for the integration in automotive radar sensors., acceptedVersion

Vivaldi antennas are excellent radiating elements that provide high gain and wide bandwidth. However, due to their end-fire radiation pattern they are not suited for the integration in printed circuit board (PCB) technology, if a broadside radiation is required. This paper presents a modified Vivaldi antenna loaded with a periodic arrangement of metallic strips that allows to achieve a broadside radiation pattern. Good agreement is obtained between the full-wave simulation results and the experimental data in terms of impedance matching, gain and radiation pattern., acceptedVersion

For meaningful pattern measurements of integrated antennas the devices, which are required during the measurement process, need to be optimized to influence the measurement results as little as possible. In this paper the errors caused by reflections on the chuck are investigated and quantified. A plastic chuck was built to reduce sources of reflection and thus improve the overall accuracy of the setup. The new chuck causes less ripples over the scanning angle and over the frequency and therefore, increases the performance of the setup significantly., acceptedVersion

Recent decades have witnessed the rapid evolution of wireless sensing and communication systems aimed at the consumer market. The antenna is a key component in any of these systems, and the selection criteria for a commercial success include the antenna performance, size, weight, and cost.The printed reflectarray surfaces can be manufactured using simple and low-cost etching processes, especially when produced in large quantities. Several folded reflectarray are presented and compared. In addition, a novel dual-frequency folded reflectarray is designed and measured. At last, one planar lens antenna is introduce.

Measurements of integrated antennas are often cumbersome and erroneous. Inaccuracies of the measurement setup, unknown material parameters, and metal parts in the immediate surrounding of the antenna under test (AUT) cause errors to the measured parameters. In order to be able to measure integrated antennas at frequencies beyond 100 GHz with high accuracy, a dedicated measurement setup was developed. For the quantification of the accuracy of the setup various measurements with different parameters were taken and their individual impact on the result was analyzed. On this basis the accuracy of measured antenna parameters like gain, directivity, and radiation pattern at 280 GHz was calculated as well as their sensitivity towards certain uncertainties in the measurement process., acceptedVersion

In this paper a detailed description of an automated mm-wave antenna measurement setup is given, and gain and directivity measurement results are shown for a standard gain horn antenna and an integrated antenna at 280 GHz. The setup comprises a vector network analyzer (VNA) with frequency converters for different frequency bands, a six degree of freedom industrial robot, and a controller that provides the interface and controls the measurements. This setup makes it possible to measure gain, directivity, radiated power, and efficiency of both waveguide fed and integrated chip antennas at frequencies between 60 GHz and 330GHz with high accuracy. Furthermore, the setup is highly configurable. Arbitrary trajectories on arbitrary planes around the AUT (antenna under test) can be measured quickly without having to change any hardware., acceptedVersion

In order to measure antenna properties precisely at frequencies above 100 GHz, elaborate measurement techniques are required. This is especially challenging for integrated antennas, as probes require a steady, rigid measurement setup to avoid damage. This paper introduces an antenna measurement setup that allows fast and reliable 3-dimensional antenna pattern measurements in a frequency range of 60 GHz to 330 GHz. The system consists of a probe station, a vector network analyzer (VNA) and an industrial robotic arm with six axes. The robot ensures highly repeatable and accurate measurements and allows high flexibility in terms of scan geometry and resolution. Using a probe station, this setup not only supports measurements of waveguide-fed antennas, but also integrated antennas. After explaining the basic setup, measurement results are shown to demonstrate the capability of the system., acceptedVersion

Core topics of the work are the vehicle access systems such as PAssive Start and Entry (PASE), Remote Keyless Entry (RKE) as well as Tyre Pressure Monitoring System (TPMS). Two goals are followed: the development of antennas and functionality analysis from RF (Radio Frequency) point of view and improvement of system parts. The overall objective of this work is to advance the state-of-the-art vehicular electromagnetic simulation taking into account the vehicle body and nearest surroundings.

Zukünftige drahtlose Kommunikationssysteme mit mehr als einer Antenne ("Multiple Input Multiple Output", MIMO) versprechen eine drastische Steigerung der übertragenen Datenrate. Diese Steigerung hängt aber stark von den Eigenschaften des Funkkanals ab, die in Simulationsmodellen passend abgebildet werden müssen. In dieser Arbeit wird ein neues MIMO-Kanalmodell entwickelt. Die Leistungsfähigkeit von bekannten MIMO-Techniken wird in Simulationen mit konventionellen Kanalmodellen und dem neu entwickelten ausgewertet. Die mögliche Leistungssteigerung durch MIMO-Techniken und deren Grenzen wird anhand des neuen Kanalmodells erläutert. Future radio communication systems with more than one antenna (Multiple Input Multiple Output, MIMO) promise to improve the data rate dramatically. This potential improvement depends strongly on the properties of the radio channel, which need to be modeled appropriately for simulation purposes. In this thesis, a new multi-antenna radio channel model will be developed. Commonly proposed MIMO techniques will be introduced and their performance will be simulated in conventional channel models and in the newly developed one. The possible performance improvement due to MIMO and its limitations will be explained using the new radio channel model.

A coherent system with two stepped frequency radar sensors separated by 1-2 m is presented in this paper for close-range imaging. Resolution is achieved via range resolution from the two different sensor positions, exploiting both monostatic and bistatic responses. A first test had been performed using a vector measurement equipment for an antenna measurement range as a radar simulator, and a mobile experimental system was built and tested, which included stationary and mobile targets.

A coherent system with two stepped frequency radar sensors separated by 1-2 m is presented for close range imaging. Resolution is achieved via range resolution from the two different sensor positions, exploiting both mono- and bistatic responses. First test had been made using vector measurement equipment for an antenna measurement range as radar simulator, and a mobile experimental system was built up and tested including stationary and mobile targets.