T. Zwick

Karlsruhe Institute of Technology, Carlsruhe, Baden-Württemberg, Germany

Are you T. Zwick?

Claim your profile

Publications (331)172.43 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: A modification of the classical orthogonal frequency division multiplexing signals is discussed that allows for the creation of a set of perfectly orthogonal transmit signals sharing the same bandwidth. These signals can be employed for performing radar measurements with multiple transmitters being simultaneously active, for example, in radar networks or multi-input multi-output radar applications. Since all the signals of the individual transmitters occupy the full available bandwidth, no deterioration of the achievable range resolution occurs. This study comprises both the theoretical considerations as well as the verification simulations and measurements. A particular focus is on the requirements regarding the frequency and time synchronisation of the individual signals and their impact on the achievable performance. The influence of possible Doppler shifts is also considered. Finally, a performance comparison with classical code-based multiple user access techniques is provided. The achieved results demonstrate that the proposed multi-carrier waveforms clearly outperform the classical code-based approach under realistic assumptions of synchronisation accuracy.
    IET Radar Sonar ? Navigation 03/2013; 7(3):261-269. · 1.03 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Silicon-organic hybrid (SOH) devices combine silicon waveguides with a number of specialized materials, ranging from third-order optically-nonlinear molecules to second-order nonlinear polymers and liquid-crystals. Second-order nonlinear materials allow building high-speed and low-voltage electro-optic modulators, which are key components for future silicon-based photonics transceivers. We report on a 90 GHz bandwidth phase modulator, and on a 56 Gbit/s QPSK experiment using an IQ Pockels effect modulator. By using liquid-crystal claddings instead, we show experimentally that phase shifters with record-low power consumption and ultra-low voltage-length product of VπL = 0.06 Vmm. Secondorder nonlinear materials, moreover, allow creating nonlinear waveguides for sum- or difference-frequency generation, and for lowest-noise optical parametric amplification. These processes are exploited for a large variety of applications, like in the emerging field of on-chip generation of mid-IR wavelengths, where pump powers are significantly smaller compared to equivalent devices using third-order nonlinear materials. In this work, we present the first SOH waveguide design suited for second-order nonlinear processes. We predict for our device an amplification of 14 dB/cm assuming a conservative χ(2)-nonlinearity of 230 pm/V and a CW pump power as low as 20 dBm.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2013; · 0.20 Impact Factor
  • Source
    Wireless Sensors and Sensor Networks (WiSNet), 2013 IEEE Topical Conference on; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper three versions of a variable gain amplifier (VGA) monolithic millimetre-wave integrated circuit (MMIC) are presented. They make use of 100 nm gate-length AlGaN/GaN-based high electron mobility transistors (HEMTs) grown on SiC. The MMICs operate in the 75 to 110 GHz band and have a centre-frequency of 94 GHz. Different phase compensation techniques, which are proposed in literature are applied and their suitability for millimetre-wave (mmW) frequency application is evaluated. We propose an additional phase compensation means leading to our best VGA version providing a gain tuning range from −17.2 to 7 dB with a phase variation of only 12.6 °.
    Microwave Symposium Digest (IMS), 2013 IEEE MTT-S International; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: For submillimeter-wave generation we present an active six-fold frequency multiplier circuit operating with an average output power of −16 dBm without post amplification and a measured output frequency range from 580 to 625 GHz. The S-MMIC is realized in a metamorphic HEMT technology with 35 nm gate-length for convenient multifunctional circuit integration.
    Microwave Symposium Digest (IMS), 2013 IEEE MTT-S International; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: A novel dielectric resonator (DR) resonant frequency tuning concept implemented, for the first time, in a micro-electro-mechanical-systems (MEMS) “Lithography, Electroplating and Molding” (LIGA) process, is presented. The complete system, except for the DR, is manufactured in the LIGA process. A description of the structure, consisting of a transmission line-DR system, coupled with a metallic Mach-Zenhder-Interferometer (MZI), is given. Simulation results, which show the resonance frequency tuning, the low Q-factor-reduction and first measurements with manufactured samples, as proof of concept, are included.
    Microwave Integrated Circuits Conference (EuMIC), 2013 European; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper demonstrates the feasibility of impedance transforming lumped-distributed branchline couplers (LDBC) at millimeter-wave frequencies. Simulation and measurement results of a W-band 50 Ω to 18 Ω transforming coupler are compared and show a good agreement. The LDBC has a relative bandwidth of 42% (65 GHz-100 GHz) and an insertion loss of about 1 dB at 80 GHz. A balanced power amplifier is presented employing the designed hybrid coupler to demonstrate the overall performance.
    Microwave Integrated Circuits Conference (EuMIC), 2013 European; 01/2013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, a stripline-fed slot antenna for implanted devices is proposed. The antenna is characterized for the Industrial, Scientific and Medical Radio (ISM) band and applied to be implanted in muscle layer of the human body. Double-layered structure with slot both on top and bottom side of the antenna is used. The stripline-feed prevents the loss along the feed line regarding the in-body application and allows very high radiation efficiency. A miniaturization technology is applied by using a meandered line for the radiator connected with the stripline. The simulation and measured results show that the antenna with a small size of 12.5×14.7 mm2 features very good impedance matching in operational frequency band and a relative bandwidth of 16.9%, which indicates a high potential of this antenna for biomedical applications.
    Radar Conference 2013, IET International; 01/2013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents an integrated mixed-signal 120GHz FMCW/CW radar chipset in a 0.13μm SiGe BiCMOS technology. It features on-chip MMW built-in-self-test (BIST) circuits, a harmonic transceiver, software linearization (SWL) circuits and a digital interface. This chipset has been tested in a low-cost package, where the antennas are integrated. Above 100GHz, our transceiver has achieved state-ofthe-art integration level and receiver linearity, and DC power consumption.
    Solid-State Circuits Conference Digest of Technical Papers (ISSCC), 2013 IEEE International; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: The handling of the radio channel is an important aspect that determines the working capability of a mobile communication system. Since the channel behavior is influenced by the environment, which leads to a different behavior in different environments, the antenna design (synthesis) becomes environment dependent (time-variant) as well. In this paper, a capacity maximizing approach to design automotive antenna systems for time-variant channels based on the approach of sampling antennas is presented. Real world constraints such as the available space, transmit power, the number and arrangement of the antennas are taken into account. Besides the theory, different examples for optimizing Single-Input-Single-Output (SISO) and 2×2 Multiple-Input-Multiple-Output (MIMO) systems for Car-to-Car (C2C) communication will be presented and compared. In total up to 16 possible antenna locations on the vehicle are considered and compared. A three-dimensional ray-tracing tool calculates the communication channels used for this synthesis approach. The results show that directive antenna elements, which focus in ± driving direction, can be used to increase the capacity particular in safety-critical C2C scenarios.
    Antennas and Propagation (EuCAP), 2013 7th European Conference on; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: A packaging solution for single-chip millimeter-wave transceivers is presented. It integrates an antenna into the lid of the chip package. Multi-layer organic materials are used as antenna substrate. A prototype demonstrates the feasibility of the packaging process and the antenna performance. It consists of three parts: A package base; a MMIC dummy that allows measuring the antenna including the flip chip interconnect; and a 122-GHz grid array antenna. The complete antenna-in-package prototype is measured using a probe based measurement system.
    Antennas and Propagation (EuCAP), 2013 7th European Conference on; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: A millimeter-wave holographic antenna array is presented. The combination of the holographic antenna principle with the phased array technology allows a beam steering functionality in two dimensions. The presented holographic antenna belongs to the leaky-wave antennas and can be described by Floquet's theorem. After a review about the theoretical aspects of holographic antennas, the paper focuses on possibilities to improve the beam scanning range. The presented simulation results of the developed antenna with Yagi-Uda-Feed on Alumina are verified by measurements.
    Antenna Technology (iWAT), 2013 International Workshop on; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: Indoor navigation using inertial sensors with additional radio-signal support is considered in this paper. The experimental results of data fusion between a navigation system, based on inertial measurement unit (IMU) and impulse-based UWB localization system, are presented. The IMU is additionally supported by a pedestrian step length estimations, barometer and electronic compass. The Ultra-Wideband part consists of receiver, carried by the person, and access points distributed in the scenario. The focus of the paper is put on hardware implementation and choice of the optimal data fusion technique. The presented results indicate the clear benefit of tightly coupled navigation filter, where the time differences of arrival of UWB signals are directly processed, without prior calculation of the localization solution.
    Robotics and Automation (ICRA), 2013 IEEE International Conference on; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a basic model to estimate the operating distance of frequency modulated (FM) radars in the presence of FM interference. A function is provided to draw the equipotential lines for given S/I values in the frequency domain as a function of the spatial distribution of targets and interferers. The paper further includes a description of the gain versus deterministic interference. Conclusions are that smaller radar targets can be masked by other radars or that targets could mask themselves if they are equipped with a radar. The latter happens from a distance called Target Self-Masking Distance (TSMD).
    Radar Conference (EuRAD), 2013 European; 01/2013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: 1. Introduction Ultra-wideband (UWB) radio sensor networks promise interesting perspectives for emitter and object position localization, object identification and imaging of environments in short range scenarios. Their fundamental advantage comes from the huge bandwidth which could be up to several GHz depending on the national regulation rules. Consequently, UWB technology allows unprecedented spatial resolution in the geo-localization of active UWB radio devices and high resolution in the detection, localization and tracking of passive objects. With the lower frequencies (< 100 Hz) involved in the UWB spectrum, looking into or through non-metallic materials and objects becomes feasible. This is of major importance for applications like indoor navigation and surveillance, object recognition and imaging, through wall detection and tracking of persons, ground penetrating reconnaissance, wall structure analysis, etc. UWB sensors preserve their advantages -high accuracy and robust operation- even in complicated, multipath rich propagation environments. Compared to optical sensors, UWB radar sensors maintain their capability and performance in situation where optical sensors collapse. They can even produce useful results in non-LOS (non-Line of Sight) situations by taking advantage of multipath. Despite the excellent range resolution capabilities of UWB radar sensors, detection and localization performance can be significantly improved by the cooperation between spatially distributed nodes of a sensor network. This allows robust localization even in the case of partly obscured links. Moreover, distributed sensor nodes can acquire comprehensive knowledge of the structure of an unknown environment and construct an electromagnetic image which is related to the relative sensor-to-sensor node coordinate system. Distributed observation allows the robust detection and localization of passive objects and the identification of certain features of objects such as shape, material composition, dynamic parameters, and time-variant behavior. This all makes UWB a promising basis for the ©2013 Malz et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Chapter 9 2 Will-be-set-by-IN-TECH autonomous navigation of mobile sensor nodes, such as maneuverable robots- in an unknown environment that may arise as a result of an emergency situation. The objective of the CoLOR project (Cooperative Localization and Object Recognition in Autonomous UWB Sensor Networks) was to develop and demonstrate new principles for localization, navigation and object recognition in distributed sensor networks based on UWB radio technology. The application scenario of the CoLOR project is described by mobile and deployable sensor nodes cooperating in an unknown or even hostile indoor environment without any supporting infrastructure as it may occur in emergency situations such as fire disasters, earthquakes or terror attacks. In this case, UWB can be used to identify hazardous situations such as broken walls, locate buried-alive persons, roughly check the integrity of building constructions, detect and track victims, etc. In this scenario, it is assumed that optical cameras and other sensors cannot be used. Data fusion of optical image information and UWB radar was not in the scope of this project. x y Figure 1. CoLOR scenario. A possible scenario is shown in Fig. 1. The unknown environment is first explored by autonomous robots that deploy fixed nodes at certain positions. Those nodes being able of transmitting and receiving shall play the role as anchor nodes. They span a local coordinate system and should be placed at "strategic" positions, i.e. they span a large volume and ensure a complete illumination of the environment. Moving nodes will localize themselves relative to this anchor node reference. Moreover, when moving they collect information about the structure of the environment by receiving reflected waves. This way, they build an "electromagnetic image" of the environment and recognize basic building structures ("landmarks"). Step by step a map of the environment is built which can be used as another reference for navigation. This procedure is already well known from autonomous robot navigation as SLAM (Simultaneous Localization and Mapping). However, here we do not consider optical methods but UWB to recognize the feature vector. If there are solitary objects, the moving sensor may scrutinize shape and material composition by circling around. Other objects like humans may walk around and create time-variant reflections that identify their 180 Ultra-Wideband Radio Technologies for Communications, Localization and Sensor Applications Cooperative Localization and Object Recognition in Autonomous UWB Sensor Networks 3 moving trajectory. Humans and animals may also reveal themselves by time variant features resulting from vital functions such as breathing. The organization of this chapter is as follows. Section 2.1 describes the architecture of the sensor network and basic parameters of UWB sensor nodes that we used to achieve our objectives. Section 2.2 specifies the simulated test scenario that was applied for the development of the localization and imaging algorithms. Simulated data allowed us to develop algorithms in parallel to the demonstrator, which is presented in Section 2.3. The demonstrator was used to assess performance and to evaluate the developed data extraction algorithms in realistic scenarios. The algorithms were developed and evaluated using data obtained from the UWB wave propagation simulator described in Section 3. Within the CoLOR project algorithms were developed for: the cooperative localization of sensor nodes, see Section 4, the evaluation of sensor network topology, see Section 5, simultaneous localization and map building, see Section 6, object parameter estimation, see Section 7, imaging of environment, see Section 8 and the detection and localization of moving objects, see Section 9. Special attention was given to algorithms that promise real-time capability.
    Ultra-Wideband Radio Technologies for Communications, Localization and Sensor Applications, Edited by Reiner Thomaa, Reinhard H. Knoochel, Juurgen Sachs, Ingolf Willms, Thomas Zwick, 01/2013: chapter Cooperative Localization and Object Recognition in Autonomous UWB Sensor Networks; , ISBN: 978-953-51-0936-5
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper investigates a packaging solution for single chip applications at D-band frequencies. A broadband planar antenna is integrated in a LTCC based QFN package using a flip-chip interconnect to the MMIC dummy. Hence it is shown that a broadband millimeter wave flip-chip interconnect is realizable by a gold stud bump technology without the use of a subsequent matching network. Additionally the plastic lid has minimal influence to the overall performance of the Antenna in Package (AiP) which is shown by probe based measurements. The relative bandwidth is about 30 %, a high gain from 7 to 14 dBi is achieved in the frequency range from 120 – 170 GHz.
    Microwave Conference (EuMC), 2013 European; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: A packaging concept for a fully integrated millimeter-wave transceiver in a surface-mountable plastic package is presented. It integrates a Silicon Germanium chip with an off-chip antenna into a pre-molded air-cavity package. The chip and the antenna are interconnected by standard ball-stitch wire-bond technology. A 122-GHz antenna design is presented that allows integrating the antenna into a plastic chip package together with the semiconductor chip. Measurements of the antenna only, and of the antenna including the wire bond interconnect are given. Finally, a 116-GHz transmitter chip is integrated into a plastic package, together with a 116-GHz antenna. The radiation pattern of the integrated antenna is measured with a package lid, and with a dielectric lense that is used to focus the radiation pattern.
    Antenna Technology (iWAT), 2013 International Workshop on; 01/2013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Ultra-wideband (UWB) technology promises interesting perspectives for short range sensing. This paper presents UWB antennas that are used by an autonomous operating robot in order to demonstrate different localization, object identification and imaging applications in real scenarios. As the different algorithms need special antenna solutions, three types of UWB antennas are developed. Two of them are dual-polarized to allow the use of polarization diversity. Further, the antennas differ in radiation pattern and location of the phase center in order to meet the requirements given by the manifold applications. The used frequency band covers 3.5 to 10.5 GHz.
    Antenna Technology (iWAT), 2013 International Workshop on; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a 2-dimensional radar imaging concept using a MIMO OFDM-based radar, which can also estimate velocity at the same time for automotive radar purpose at 24 GHz. The transmit OFDM signal is designed in such a way that the multiple transmitters will only radiate at the subcarriers unique to itself while preserving the total bandwidth and thus the range resolution. The virtual antenna array concept is utilized to widen the basis of the antenna array with the least possible transmit-receive elements. Using beamforming techniques at the receiver together with novel radar processing techniques, the range, Doppler, and azimuth information for an arbitrary number of objects (relative to the number of antenna elements used in the antenna array) can be estimated through a simultaneous transmission.
    Radar Conference (EuRAD), 2013 European; 01/2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: In general, two-dimensional radar imaging applications, which require angular information in azimuth and elevation, use full planar antenna arrays. If orthogonally arranged transmit and receive arrays are used instead, the angular resolution equals that of a radar system using only a single antenna on the transmit and a full antenna array on the receiver side or vice-versa. This paper evaluates the influence of different antenna array configurations on the angular resolution capability by means of a 24GHz Digital Beamforming radar system. Besides the so-called inverted T-shaped antenna arrangement, various array geometries are discussed. Compared to the full planar antenna array the introduced geometries provide better angular resolution, while allowing for a highly reduced number of antennas, saving space and cost. Each presented antenna array is realized in hardware and the angular resolution capability is evaluated by means of a 24 GHz Digital Beamforming radar system.
    Radar Conference (EuRAD), 2013 European; 01/2013

Publication Stats

2k Citations
172.43 Total Impact Points

Institutions

  • 2008–2014
    • Karlsruhe Institute of Technology
      • Institute of High Frequency Technology and Electronics (IHE)
      Carlsruhe, Baden-Württemberg, Germany
  • 2009
    • Fraunhofer Institute for Applied Solid State Physics IAF
      Freiburg, Baden-Württemberg, Germany
    • Universidad Politécnica de Madrid
      • Departamento de Electromagnetismo y Teoría de Circuitos
      Madrid, Madrid, Spain
  • 2004
    • IBM
      Armonk, New York, United States
  • 2000
    • Technische Universität Ilmenau
      Stadt Ilmenau, Thuringia, Germany