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Author

Henning Mextorf

Bio: Henning Mextorf is an academic researcher from University of Kiel. The author has contributed to research in topics: Power dividers and directional couplers & Dielectric. The author has an hindex of 7, co-authored 17 publications receiving 121 citations.

Papers
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Proceedings ArticleDOI
07 Jun 2009
TL;DR: In this paper, the authors present an approach for the systematic design of reconfigurable quadrature directional couplers using even-odd analysis of four-ports with two-fold symmetry four eigenreflections are derived.
Abstract: This paper presents an approach for the systematic design of reconfigurable quadrature directional couplers. From even-odd-analysis of four-ports with two-fold symmetry four eigenreflections are derived. The scattering-parameters are linear combinations of them. The eigenreflections can be positioned deliberately with tuning reactances to create directional couplers which are reconfigurable in coupling ratio, operating frequency or the arrangement of the output ports. Two exemplary couplers, a LC-bridge and a modified branchline-coupler, are presented and measurement results are shown. Directional couplers with adjustable coupling ratio can also be created with cascaded couplers and additional phase shifters or discontinuities. A compact directional coupler using this principle is presented together with measurement results.

17 citations

Proceedings ArticleDOI
01 Oct 2008
TL;DR: In this paper, the authors present a systematic approach for the design of directional couplers with tunable coupling strength, which maintain the properties of perfect impedance match and isolation over the whole tuning range.
Abstract: This paper presents a systematic approach for the design of directional couplers with tunable coupling strength, which maintain the properties of perfect impedance match and isolation over the whole tuning range. The devised method is based on eigenreflections and requires the synthesis of one-ports. This can be carried out with the help of graphical presentations in the Smith chart, thus fostering intuition in finding new circuit structures. The method is theoretically demonstrated by the development of a novel tunable LC-coupler or Maxwell bridge and a tunable proximity coupler. An experimental realization of the Maxwell bridge yields a tunable coupling ratio between 2 dB and 20 dB while maintaining excellent return loss and isolation.

15 citations

Proceedings ArticleDOI
17 Jun 2012
TL;DR: In this paper, an UWB time domain transmission system for free-space moisture measurements is presented, which is capable of transmitting UWB signals having a bandwidth of several gigahertz which illuminate the samples.
Abstract: This paper presents an UWB time domain transmission system for free-space moisture measurements. The system is capable of transmitting UWB signals having a bandwidth of several gigahertz which illuminate the samples. The size of the samples is in the range of some of the transmitted wavelengths and is smaller than the antennas' footprints. The scattered pulses are collected by an array of receiving antennas. The received signals can be sampled instantaneously with just one receiving channel and a special combiner, which adds a time shift to each antenna path in order to separate the signals in time. Multivariate calibration is applied in order to develop a statistical model for the moisture content of the samples. An accuracy for the determination of the moisture content of 0.61% is achieved while the range of moisture is varied from 1.7% to 20%.

12 citations

Journal ArticleDOI
TL;DR: A novel method for the free-space characterization and shape recognition of dielectric objects using multivariate calibration methods and linear discriminant analysis is presented, separating the objects into geometrical classes independent of all other varied parameters.
Abstract: This paper presents a novel method for the free-space characterization and shape recognition of dielectric objects using multivariate calibration methods and linear discriminant analysis. The dimensions of the variously shaped objects are comparable with some of the transmitted wavelengths of the ultra-wideband (UWB) time-domain pulses used. A system illuminating the objects under test by a subnanosecond UWB pulse has been built. An array of receiving antennas receives the scattered pulses that contain information about the shape, the size, and the dielectric or related material properties of the objects. Multivariate analysis is applied to separate geometric effects from those due to the dielectric properties. Results are shown for two measurement series determining the amount of carbon and weight or the dielectric constant of the objects under test, independent of their shape, size, and orientation. Furthermore, a classification algorithm is applied, separating the objects into geometrical classes independent of all other varied parameters.

12 citations

Proceedings Article
14 Mar 2011
TL;DR: In this article, the authors presented the analysis and development of compact cascaded directional couplers with continuously tuneable coupling ratios, where the general approach of cascading two quadrature DDCs and discontinuities in the connecting branches is analyzed.
Abstract: This paper presents the analysis and development of compact cascaded directional couplers with continuously tuneable coupling ratios. The general approach of cascading two quadrature directional couplers and discontinuities in the connecting branches is analyzed. Two suggested compact individual couplers are analyzed using even-odd-analysis. Two proposed cascaded networks are composed of only 50Ω transmission lines, two variable capacitance diodes and either four capacitors or one capacitor and one inductor. DC supply and decoupling is needed additionally. Prototypes of the two-fold and the one-fold symmetrical network were fabricated and the measurement results are shown.

9 citations


Cited by
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Journal ArticleDOI
TL;DR: This paper describes the design and realization of a 5.6-GHz ultrawide-bandwidth-based position measurement system that achieves centimeter-level accuracy in an indoor environment based on asynchronous modulated pulse round-trip time measurements.
Abstract: This paper describes the design and realization of a 5.6-GHz ultrawide-bandwidth-based position measurement system. The system was entirely made using off-the-shelf components and achieves centimeter-level accuracy in an indoor environment. It is based on asynchronous modulated pulse round-trip time measurements. Both system level and realization details are described along with experimental results including estimates of measurement uncertainties.

79 citations

Journal ArticleDOI
TL;DR: A highly reconfigurable radio frequency patch hybrid coupler with a simple topology is presented for the first time and tunable coupling coefficient can be implemented by changing the capacitance.
Abstract: A highly reconfigurable radio frequency patch hybrid coupler with a simple topology is presented for the first time. Due to the introduction of lumped equivalent circuit and flexibility of varactor loaded patterned ground plane, the complex reconfigurability in port arrangement and coupling coefficient can be implemented. Varying the capacitance across different planes allows the electronic switching between different operating modes of the patch hybrid coupler. When the auxiliary patch and patterned ground plane is placed closer to the two output ports, tunable coupling coefficient can also be implemented by changing the capacitance. This results in wide band reconfigurability for the coupling coefficient range. For demonstration purposes, a patch hybrid coupler operating at 2.4 GHz is designed and measured to validate the port reconfigurable concept. Also, a patch hybrid coupler with tunable coupling coefficient operating at 3.5 GHz is designed, fabricated, and measured. This circuit gives a reconfigurable coupling coefficient ranging from -4.2 to -10 dB while maintaining good performance.

61 citations

Journal ArticleDOI
TL;DR: In this article, a reconfigurable quadrature hybrid coupler and a tunable low-loss reflective-type phase shifter built using the Cavendish Kinetics RF microelectromechanical systems switched capacitor devices are presented.
Abstract: This paper presents the design, fabrication, and measurement of a reconfigurable quadrature hybrid coupler and a tunable low-loss reflective-type phase shifter built using the Cavendish Kinetics RF microelectromechanical systems switched capacitor devices. The quadrature coupler tunes from 1.5 to 2.2 GHz with 20–50-MHz steps, and $> {\hbox {20-dB}}$ reflection and isolation. The phase shifter covers 360 $^{\circ } $ at 2.0 GHz with an insertion loss of ${\hbox {2.0}} \pm {\hbox {0.5}}~{\hbox {dB}}$ at different phase states. The linearity measurements show that these devices can handle up to 5 W of input power at 1.8–2.2 GHz with an input third-order intercept point $( {\rm IIP}_{3}) > 44~{{\hbox {dBm}}}$ over all phase states. The measured second and third harmonic components are $ at 30 dBm of RF input power. The application areas are in-phase shifters for micro and pico base-stations in the 1.7–2.3-GHz range.

57 citations

Journal ArticleDOI
TL;DR: In this paper, a highly reconfigurable, low power, and compact directional coupler is presented, which uses varactors and novel active inductors to achieve wide tuning ranges of operating frequencies and coupling coefficients.
Abstract: This paper presents a highly reconfigurable, low-power, and compact directional coupler. The coupler uses varactors and novel active inductors to achieve wide tuning ranges of operating frequencies and coupling coefficients. The use of a low-pass circuit architecture with only two inductors minimizes chip area, power consumption, and noise. The coupler is implemented in a 0.13-μm CMOS process. It occupies an area of 350 μm× 340 μm and consumes 40 mW or less power. The obtained 1-dB compression point is -3.2 dBm, and the measured noise figure is ~ 23 dB. These parameters compare favorably with previously published reconfigurable couplers. The measured coupling coefficient can be tuned from 1.3 to 9.0 dB at 4 GHz with 32 dB or better isolation and 15 dB or better return loss. The operating center frequency can be tuned from 2.0 to 6.0 GHz for a nominal 3-dB operation. These results agree with theoretical predictions and simulations reasonably well.

51 citations

Journal ArticleDOI
TL;DR: In this paper, a varactor-based coupler structure was proposed for reconfigurable operating frequency, power-dividing ratio, and coupler to/from crossover responses.
Abstract: This paper proposes a varactor-based coupler structure that allows for reconfigurable operating frequency, power-dividing ratio, and coupler to/from crossover responses. Particularly, this coupler can theoretically realize perfect impedance matching and port isolation at all tuning states. The coupler analysis, design equations, and design graphs were conducted, given, and discussed in detail. For demonstration purposes, two prototypes were experimentally developed and characterized. The first quadrature coupler demonstrates a frequency-tuning range from 0.632 to 1.5 GHz with a constant power-dividing ratio of −3 dB, 20-dB isolation, and >14-dB return loss. In the second prototype, for the phase error 19 dB, the power-dividing ratio was tuned from −6.4 to 20.5 dB at 1 GHz, yielding a 26.9-dB tuning range and crossover characteristics at low bias voltages. Measured and simulated results are in good agreement.

36 citations