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Microwave Conference (GeMIC), 2011 German

Date 14-16 March 2011

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Displaying Results 1 - 25 of 89
  • Dispersion analysis of periodic structures by solving corresponding excitation problems

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (380 KB) |  | HTML iconHTML  

    Dispersion analysis of periodic structures with complicated material distributions is conventionally performed by solving eigenproblems where a unit cell with periodic boundary conditions is appropriately discretized and an algebraic eigenproblem solver is applied to the resulting linear equation system. In this paper, the same discretization models are employed but the solution of an algebraic eigenproblem is avoided. In contrast, the equation system is solved for an appropriately designed excitation and the dispersion behaviour is obtained from the resonance behaviour of the solution. This solution procedure is often much more robust than algebraic eigenproblem solutions and provides for particular physical insight into the problems. View full abstract»

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  • Stochastic electromagnetic fields

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (148 KB) |  | HTML iconHTML  

    A method for numerical simulation of noisy electromagnetic fields is presented. Stochastic electromagnetic fields are described by correlation spectra. A complete description of stochastic electromagnetic fields is given by the autocorrelation spectrum of each field variable and the cross correlation spectra of field variables at distinct points of observation. The auto and cross correlation spectra of the are computed from the auto-and cross correlation spectra of the source distribution. Network methods are introduced for the efficient solution of stochastic electromagnetic field problems. View full abstract»

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  • Surface impedances for planar conductors in volume discretization methods without frequency limitations

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (323 KB) |  | HTML iconHTML  

    Surface impedance boundary conditions (SIBC) for lossy metal layers are presented that are not limited to the frequency range in which a metal layer is thicker than several skin depth. A metal layer is considered as a TEM transmission line so that the SIBCs can be obtained as the input impedances of an open ended and a short circuited transmission line, respectively. The SIBCs are verified for a MMIC microstrip line and a coplanar waveguide. View full abstract»

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  • Design of a 120 W balanced GaN Doherty power amplifier

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (212 KB) |  | HTML iconHTML  

    In this paper the design of a high power balanced Doherty power amplifier (PAs) will be reported. The Doherty PA was designed to achieve high average efficiency for digitally modulated signals with high peak to average power ratio (PAR) used in third (3G) and fourth (4G) generation systems. To achieve high efficiency up to 6 dB output power back-off (OPBO), a combined design technique of uneven power divider and use of unsymmetrical devices has been considered. At same time in order to improve its linearity and higher power capability a balanced structure, which combines two identical Doherty amplifiers has been proposed. For demonstration, a 120 W Doherty PA has been implemented to operate at 2.5 GHz. A drain efficiency of 57% (48% power added efficiency (PAE)) has been measured at its maximum output power of 50.8 dBm. Efficiency of more than 40% at the 6 dB output power back-off has been also measured. Moreover, the Doherty PA has been characterized using two-tone signal of 10 MHz spacing which resulted in a third order inter modulation ratio of -35 dBc at the 8.5 dB output power back-off level. View full abstract»

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  • An 8 W GaAs Class-AB amplifier for operation in envelope tracking systems

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (212 KB) |  | HTML iconHTML  

    In this paper an 8 W GaAs HEMT power amplifier for operation in envelope tracking systems is presented. The application targeted is UMTS downlink operation with a peak-to-average ratio of about 7 dB. By varying the drain bias voltage between 5 V and 12 V the compression point can be shifted in the required area. Power-added efficiency is more than 45 % in this area and above 52% in the area of average output power of a UMTS signal. Gain can be kept above 14 dB in this operation mode with a variation of 3 dB. View full abstract»

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  • Efficiency improvement for RF power amplifiers by employing harmonic injection at the input

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (230 KB) |  | HTML iconHTML  

    This paper presents the experimental analysis of the injection of harmonic signals at the gate of a RF power transistor. The harmonic injection leads to an optimized shape of the waveforms at the inner transistor resulting in an improvement of the efficiency performance. A triplexer, allowing injecting the second as well as the third harmonic into the transistor is designed for these experiments, although in the present work only the second harmonic is used. At 2.6 GHz, the experimental results show that for a 25 W GaN HEMT RF power device, the drain efficiency can be improved by up to 6%. View full abstract»

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  • Transponder and reader concept for a HF locating system

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (823 KB) |  | HTML iconHTML  

    This paper presents a low-frequency local positioning system operating at 13.56 MHz. With a wavelength of around 22 m the system operates in the near field. The phase shift between a CW signal generated at the base station and the response generated in a transponder is measured. The transponder is using the novel switched injection locked oscillator concept (SILO). Measurement results show that the proposed concept allows for robust indoor ranging with an uncertainty in the decimeter-range. The system is aiming at short range indoor localization problems, where a measurement through a crowd of people is required. Indoor navigation or information systems e.g. in museums, public buildings or fairs are possible applications. View full abstract»

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  • Triggering UMTS user equipment inter-RAT cell reselection using noise jammers

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (595 KB) |  | HTML iconHTML  

    In this work a strategy for triggering an interradio access technology cell reselection in UMTS user equipment is proposed. All mobile devices within the effective range of a transmitter radiating a noise-like RF signal on the UMTS downlink frequency bands are forced to leave the UMTS cells and camp on non-UMTS cells, such as e.g., GSM. This allows to use a GSM based localization technique even in areas with UMTS coverage. In contrast to classical RF communication jammers which focus on disrupting the communication link, our exclusive goal is to trigger the inter-RAT cell reselection to GSM. In particular we estimate the necessary jammer RF power by examining the cell reselection procedure running in the user equipment (UE) and using some exemplary geographical scenarios. We use a hardware system to proof the results. View full abstract»

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  • A high accuracy Direction-Of-Arrival and Misalignment Angle Detector

    Page(s): 1 - 3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (611 KB) |  | HTML iconHTML  

    High-precision Direction-Of-Arrival measurements are often a challenge. The need to accurately detect the angle of incidence of an incoming electromagnetic wave with respect to a reference geometrical axis is very important for automotive and security applications. Furthermore, the ability to measure a misalignment angle of a transmitting antenna in respect to a reference is a task required by countless industrial applications. A high accuracy angle-detection system is hereby presented and measurement results from a prototype detecting a 24 GHz source are shown. View full abstract»

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  • Doppler estimation in an OFDM joint radar and communication system

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (564 KB) |  | HTML iconHTML  

    In this paper a processing algorithm that allows for estimating the velocity of multiple reflecting objects with standard OFDM communication signals is discussed. This algorithm does not require any specific coding of the transmit data. The technique can be used in combination with a range estimation algorithm in order to implement active radar sensing functions into a communication system for vehicular applications. Simulation and measurement results which prove the operability of the developed algorithm are presented. View full abstract»

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  • Particle swarm optimization of minimum-redundancy MIMO arrays

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (128 KB) |  | HTML iconHTML  

    Minimum-redundancy multiple-input multiple-output (MR-MIMO) antenna arrays - a class of thinned arrays - are introduced. The concepts of convolution array and correlation array are used for data processing required for radar applications but also for optimization of the element distribution in such arrays. An upper bound for the achievable thinning rate is estimated. Particle swarm optimization (PSO) is applied to optimize the element distribution of some linear, monostatic MR-MIMO arrays with up to 12 elements. View full abstract»

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  • Dispersion engineering: How to design a miniature coaxial low-pass

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (157 KB) |  | HTML iconHTML  

    In this paper we present a new filter topology for the design of a shortened low-pass filter. We develop a rapid prototyping scheme based on equivalent circuit theory to predict the dispersion of the TEM mode in a periodic structure. This allows us to tune the cutoff frequency of the filter and its stopband. Additionally, the lightweight model is used for the pre-design in terms of steepness and matching. After further optimizations, two cardinal setups are investigated with respect to their high-power capability. View full abstract»

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  • LTCC-Integrated Evanescent Mode Cavity filters at X- to K-band

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (835 KB) |  | HTML iconHTML  

    Evanescent Mode Cavity filters with different center frequencies (10 GHz, 15 GHz and 20 GHz) were designed in Low Temperature Co-fired Ceramics (LTCC) technology as Substrate Integrated Waveguide (SIW) components. The achieved 3dB bandwidths are between 421 MHz for the 10 GHz EMC-filter and 617 MHz for the 20 GHz EMC-filter. The minimal insertion loss is between -1.72dB for the 10 GHz EMC-filter and -2.43dB for the 20 GHz EMC-filter. These filters show also a size reduction of more than 50% compare to standard cavity filters, while still have a similar Q-factor. View full abstract»

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  • Broadband matching of high-permittivity coatings with frequency selective surfaces

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1024 KB) |  | HTML iconHTML  

    Due to design restrictions, future automotive radar sensors within the 79GHz band need to be integrated behind painted, plastic fascia (e.g. a painted bumper) for advanced driver assistance systems. Reflections from the bumper, which is in the line-of-sight of the sensor, might lead to undesirable performance degradation. To reduce these reflections, impedance matching of multilayer structures with high permittivities (e.g. metallic paints) is necessary. Next to conventional matching techniques, frequency selective surfaces (FSS) can be freely designed to realize a matching layer. For four possible structures a bandwidth evaluation is shown. The measurement and simulation results revealed that for a bandwidth of 4 GHz, the proposed solution (single cross structure) outperforms state of the art matching techniques. View full abstract»

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  • A compact four-poles cross-coupled square open loop resonator diplexer

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (295 KB) |  | HTML iconHTML  

    In this paper, a compact four-poles cross-coupled square open loop resonator diplexer is proposed to develop the microstrip square open loop resonators bandpass filter. The filter is based upon a square open loop resonator consisting of two identical patches which is attached to the inner corner of the square open loop for size reduction. The compact miniaturized four poles square open loop resonators are used to design filters and a diplexer for IMT-2000 bands application. A prototype diplexer is designed at 1950 MHz and 2140 MHz. The diplexer channels are 3.07% and 2.8% fractional bandwidth. The measured insertion losses are about 3.0 dB for the two channels with better than 45 dB isolation. It is very useful for applications in the IMT-2000 mobile communication systems. View full abstract»

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  • Active learning method for external Q computation

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (483 KB) |  | HTML iconHTML  

    The external quality factor (Qext) of a resonator which represents the strength of the electromagnetic coupling between the resonant mode and the transmission mode of the feed line is an important parameter for designing microwave filters. Analytical computation of Qext needs exact determination of the field distribution around the coupling port. But the complexities of input/output ports in microwave/millimeter wave filters make this procedure completely complicated. In the case of some special resonators such as microstrip open loop resonators, lack of analytical solution for field distribution increases this complexity and results in time consuming full wave simulations. This paper proposes the use of active learning method (ALM) with ink drop spread (IDS) engine in computation of external quality factor of microstrip triangular open loop resonators (TOLR) in a vanishingly short time while keeping the accuracy. Using ALM based extracted Qext in the case of TOLR, a four pole chebychev bandpass filter was designed and fabricated. Very good agreement between the desired characteristics of the filter and the fabricated response shows the accuracy of the proposed approach. View full abstract»

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  • Combined lumped element network and transmission line model for wireless transmission links

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (619 KB) |  | HTML iconHTML  

    Multi-port models of wireless transmission links yield an accurate description of the physical properties of the transmission link. A systematic procedure for the generation of combined lumped element/delay line equivalent circuits for wireless transmission is described. Lumped element equivalent circuits provide compact models of distributed microwave circuits. The modeling of wireless transmission links exhibiting long signal propagation delay times, however yields equivalent circuits with a large number of lumped circuit elements. The number of circuit elements can be considerably reduced by including transmission line elements in the equivalent circuit model. As an example a wireless transmission link between monolithic integrated antennas is modeled. View full abstract»

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  • Enhanced investigations of 433 MHz-10 GHz time invariant wireless in-car communication channels

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (151 KB) |  | HTML iconHTML  

    This paper presents the results of frequency domain channel sounding of wireless in-car channels. Based on an extended measurement campaign different application-specific channels are characterized by channel gain, cumulative density functions and time dispersion parameters. The measurement sets are chosen for the freely disposable industrial, scientific and medical (ISM) frequency bands. Characteristic time-domain values are calculated from ultra-wideband (UWB) channel transfer functions exhibiting a frequency range of 433 MHz-10 GHz. Inside the drivers cabin both line-of-sight (LOS) and obstructed-line-of-sight (OLOS) radio links are considered. All parameters are derived from measurements using omni-directional antennas and can thus be applied to common channel models. View full abstract»

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  • Brune's synthesis of linear lossy distributed one-port and symmetric two-port microwave circuits

    Page(s): 1 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (133 KB) |  | HTML iconHTML  

    A systematic procedure for network modelling of lossy one-port and symmetric two-port microwave circuits is presented. We describe a systematic strategy for Brune's circuit synthesis of one-ports from positive real rational functions and its numerical implementation. Starting from numerical data obtained by measurement or from numerical full-wave simulation the rational function representation of Z- or Y-parameters is found using vector fitting procedure. Applying Brune's synthesis algorithm, a lumped element equivalent circuit is generated. View full abstract»

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  • Characterization and impedance matching of new high sensitive planar Schottky detector diodes

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (131 KB) |  | HTML iconHTML  

    New high sensitive zero-bias Schottky detector diodes with low junction capacitance and differential resistance are characterized by applying DC and S-parameter measurements in W-band. The extracted parameters provide an accurate RF model for circuit simulations to design and realize an impedance matching network at 90 GHz to avoid standing waves in a diode detector as an essential part of high sensitive direct detection receivers. View full abstract»

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  • Closed-form description of coupled microstrip line step discontinuities

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (582 KB) |  | HTML iconHTML  

    Symmetric coupled microstrip line step discontinuities are analyzed and modeled. Equivalent even and odd mode networks taking into account fringing field and current distribution effects are derived for the junction. A comprehensive four port description of the even and odd mode lumped components is set up. For a given substrate and frequency closed-form expressions are derived by curve-fitting data sets obtained from a systematic full-wave parameter study of a class of discontinuities. View full abstract»

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  • 110 GHz characterization of coplanar waveguides on GaN-on-Si substrates

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (236 KB) |  | HTML iconHTML  

    We characterize the microwave loss in coplanar waveguides (CPWs) on AlGaN/GaN HEMT buffer layers on high-resistivity silicon (HR-Si) substrates, up to 110 GHz. To our knowledge, this is the first broadband characterization of CPWs on GaN-on-Si. Conventional CPWs on commercially available AlGaN/GaN on HR-Si HEMT layers show a loss as low as 0.8 dB/mm at 110 GHz. Losses are further reduced by etching trenches between the CPW conductors, reaching 0.47 dB/mm at 110 GHz. The work shows that CPWs on GaN-on-Si exhibit performances comparable to those built on S.L InP, demonstrating the suitability of GaN-on-Si technology for mm-wave applications. View full abstract»

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  • Shunting yard management using millimeter wave radar

    Page(s): 1 - 3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (728 KB) |  | HTML iconHTML  

    Management of shunting yards is a highly responsible task and mainly done manually with visual inspection or at modern stations done with a highly sophisticated sensor technology. A few distributed radar sensors allow the permanent inspection of the rails and wagons under all weather conditions. The new concept is described and illustrated by measurement results. View full abstract»

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  • A 77 GHz near-field probe with integrated illuminating waveguide

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (331 KB) |  | HTML iconHTML  

    In this paper, a near-field probe with integrated illuminating waveguide for frequencies around 77 GHz is introduced. For such high frequencies, alignment of transmitter and receiver in the near-field measurement setup are difficult. So the purpose is integrating both devices into one setup for an easy and reproducible measurement procedure. The measurement probe is used in order to characterize individual patches on the surface of reflectarray antennas, placing the device a few millimeters above the antenna surface. This requires a high spatial resolution and a insignificant influence of the probe on the examined structure. The ability of the developed probe has been investigated in simulations and has been verified in near-field measurements at reflectarray structures for 77 GHz. View full abstract»

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  • Passive wireless temperature sensing with BST-based chipless transponder

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    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (603 KB) |  | HTML iconHTML  

    A passive wireless temperature sensor with identification capabilities based on a phase modulation scheme is discussed in this paper. The approach presented utilizes a pulse backscatter technique based on metamaterial transmission lines. The focus of the work is the material engineering for the temperature-sensitive element and its integration into a passive phase modulation circuit. The approach makes use of temperature-sensitive barium-strontium-titanate thick film capacitances. The discussed principle has been experimentally verified with a prototype. View full abstract»

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