TY - JOUR A1 - Heuermann, Holger A1 - Graf, W. T1 - Direkte on-wafer-Messung des Wellenwiderstandes einer Mikrostreifenleitung JF - Kleinheubacher Berichte : Vorträge und Berichte der gemeinsamen Tagung des U.R.S.I.-Landesausschusses in der Bundesrepublik Deutschland / Hrsg.: Deutsche Telekom AG. 41. 1998 (1998) Y1 - 1998 ER - TY - JOUR A1 - Heuermann, Holger A1 - Graf, W. T1 - Direkte Messung der Dispersion des Wellenwiderstandes einer Mikrostreifenleitung JF - Kleinheubacher Berichte : Vorträge und Berichte der gemeinsamen Tagung des U.R.S.I.-Landesausschusses in der Bundesrepublik Deutschland / Hrsg.: Deutsche Telekom AG. 40. 1997 (1997) Y1 - 1997 ER - TY - JOUR A1 - Schopp, Christoph A1 - Rohrbach, Felix A1 - Langer, Luc A1 - Heuermann, Holger T1 - Detection of welding wire length by active S11 measurement JF - IEEE Transactions on Plasma Science N2 - A novel method to determine the extruded length of a metallic wire for a directed energy deposition (DED) process using a microwave (MW) plasma jet with a straight-through wire feed is presented. The method is based on the relative comparison of the measured frequency response obtained by the large-signal scattering parameter (Hot-S) technique. In the practical working range, repeatability of less than 6% for a nonactive plasma and 9% for the active plasma state is found. Measurements are conducted with a focus on a simple solution to decrease the processing time and reduce the integration time of the process into the existing hardware. It is shown that monitoring a single frequency for magnitude and phase changes is sufficient to achieve good accuracy. A combination of different measurement values to determine the length is possible. The applicability to different diameter of the same material is shown as well as a contact detection of the wire and metallic substrate. KW - Circuit simulation KW - Hot S-parameter KW - Modeling KW - Plasma KW - Plasma diagnostics Y1 - 2024 U6 - http://dx.doi.org/10.1109/TPS.2024.3356659 SN - 0093-3813 (Print) SN - 1939-9375 (Online) IS - Early Access SP - 1 EP - 6 PB - IEEE ER - TY - CHAP A1 - Sadeghfam, Arash A1 - Sadeghi-Ahangar, A. A1 - Elgamal, Abdelrahman A1 - Heuermann, Holger T1 - Design and Development of a Novel Self-Igniting Microwave Plasma Jet for Industrial Applications T2 - IEEE MTT-S International Microwave Symposium Digest Y1 - 2019 SN - 978-172811309-8 SP - 63 EP - 66 ER - TY - CHAP A1 - Elgamal, Abdelrahman A1 - Heuermann, Holger T1 - Design and Development of a Hot S-Parameter Measurement System for Plasma and Magnetron Applications T2 - 2020 German Microwave Conference (GeMiC), Cottbus, Germany, 2020 Y1 - 2020 SN - 978-3-9820397-1-8 SP - 124 EP - 127 ER - TY - CHAP A1 - Stephan, Achim A1 - Heuermann, Holger A1 - Prantner, Michael T1 - Cutting human tissue with novel atmospheric-pressure microwave plasma jet T2 - 46th European Microwave Conference (EuMC) Y1 - 2016 SN - 978-2-87487-043-9 U6 - http://dx.doi.org/10.1109/EuMC.2016.7824490 SP - 902 EP - 905 PB - IEEE ER - TY - JOUR A1 - Heuermann, Holger A1 - Peters, N. A1 - Schmitz, T. A1 - Sadeghfam, Arash T1 - Concept of Balanced Antennas with Load-Invariant Base Impedance Using a Two Element LC-Coupler. Peters, N., Schmitz, Th., Sadeghfam, A., Heuermann, H. JF - Proceedings of the European microwave association : journal of the European microwave association Y1 - 2005 SP - 117 EP - 122 PB - PLUS CY - Pisa ER - TY - JOUR A1 - Holtrup, S. A1 - Sadeghfam, Arash A1 - Heuermann, Holger A1 - Awakowicz, P. T1 - Characterization and optimization technique for microwave-driven high-intensity discharge lamps using hot S-parameters JF - IEEE transactions on microwave theories and techniques N2 - High-intensity discharge lamps can be driven by radio-frequency signals in the ISM frequency band at 2.45 GHz, using a matching network to transform the impedance of the plasma to the source impedance. To achieve an optimal operating condition, a good characterization of the lamp in terms of radio frequency equivalent circuits under operating conditions is necessary, enabling the design of an efficient matching network. This paper presents the characterization technique for such lamps and presents the design of the required matching network. For the characterization, a high-intensity discharge lamp was driven by a monofrequent large signal at 2.45 GHz, whereas a frequency sweep over 300 MHz was performed across this signal to measure so-called small-signal hot S-parameters using a vector network analyzer. These parameters are then used as an equivalent load in a circuit simulator to design an appropriate matching network. Using the measured data as a black-box model in the simulation results in a quick and efficient method to simulate and design efficient matching networks in spite of the complex plasma behavior. Furthermore, photometric analysis of high-intensity discharge lamps are carried out, comparing microwave operation to conventional operation. Y1 - 2014 U6 - http://dx.doi.org/10.1109/TMTT.2014.2342652 SN - 0018-9480 VL - 62 IS - 10 SP - 2471 EP - 2480 PB - IEEE CY - New York ER - TY - JOUR A1 - Schopp, Christoph A1 - Doll, Timo A1 - Gräser, Ulrich A1 - Harzheim, Thomas A1 - Heuermann, Holger A1 - Kling, Rainer A1 - Marso, Michael T1 - Capacitively Coupled High-Pressure Lamp Using Coaxial Line Networks JF - IEEE Transactions on Microwave Theory and Techniques N2 - This paper describes the development of a capacitively coupled high-pressure lamp with input power between 20 and 43 W at 2.45 GHz, using a coaxial line network. Compared with other electrodeless lamp systems, no cavity has to be used and a reduction in the input power is achieved. Therefore, this lamp is an alternative to the halogen incandescent lamp for domestic lighting. To serve the demands of domestic lighting, the filling of the lamp is optimized over all other resulting requirements, such as high efficacy at low induced powers and fast startups. A workflow to develop RF-driven plasma applications is presented, which makes use of the hot S-parameter technique. Descriptions of the fitting process inside a circuit and FEM simulator are given. Results of the combined ignition and operation network from simulations and measurements are compared. An initial prototype is built and measurements of the lamp's lighting properties are presented along with an investigation of the efficacy optimizations using large signal amplitude modulation. With this lamp, an efficacy of 135 lmW -1 is achieved. Y1 - 2016 U6 - http://dx.doi.org/10.1109/TMTT.2016.2600326 SN - 0018-9480 VL - 64 IS - 10 SP - 3363 EP - 3368 PB - IEEE CY - New York, NY ER - TY - JOUR A1 - Heuermann, Holger T1 - Calibration procedures with series impedances and unknown lines simplify on-wafer measurements JF - IEEE transactions on microwave theory and techniques : MTT ; a publication of the IEEE Microwave Theory and Techniques Society. 47 (1999), H. 1 Y1 - 1999 SN - 0018-9480 SP - 1 EP - 5 ER - TY - JOUR A1 - Heuermann, Holger A1 - Schiek, Burkhard T1 - Calibration of network analyser measurements with leakage errors JF - Electronics letters. 30 (1994), H. 1 Y1 - 1994 SN - 0013-5194 SP - 52 EP - 53 ER - TY - JOUR A1 - Heuermann, Holger T1 - Calibration of a Network Analyzer Without a Thru Connection for Nonlinear and Multiport Measurements JF - IEEE Transactions on Microwave Theory and Techniques. 56 (2008), H. 11, 1 Y1 - 2008 SN - 0018-9480 SP - 2505 EP - 2510 ER - TY - PAT A1 - Heuermann, Holger A1 - Hüning, Felix A1 - Wache, Franz-Josef T1 - Bussystem sowie Kommunikationsverfahren N2 - Die Erfindung betrifft ein Bussystem enthaltend Busleitungen, an denen eine Anzahl von Busteilnehmern über einen Transceiver anschließbar sind, wobei der Transceiver eine bidirektionale Kommunikation zwischen mindestens zwei Busteilnehmern bewirkt, wobei auf einer busabgewandten Seite des Transceivers sich an denselben eine Zwischenbrückeneinheit anschließt, die mindestens zwei Sender-/Empfänger-Paare enthaltend jeweils einen Sender und einen Empfänger aufweist, wobei der Sender einen Senderoszillator, eine Amplituden- und/oder Phasen- und/oder Frequenzmodulator sowie eine Antenne aufweist und wobei der Empfänger einen Mischer aufweisenden Demodulator sowie eine Antenne aufweist, wobei ein erstes Sender-/Empfänger-Paar über eine Funkschnittstelle mit dem zweiten Sender-/Empfänger-Paar miteinander gekoppelt sind. Y1 - 2018 N1 - Patent WO002018046055A1 ER - TY - JOUR A1 - Heuermann, Holger A1 - Erkens, Holger T1 - Blocking structures for mixed-mode systems. / Erkens, Holger ; Heuermann, Holger JF - Conference proceedings : Tuesday 12th, Wednesday 13th and Thursday 14th October, [RAI International Exhibition and Congress Centre, Amsterdam ; part of European Microwave Week 2004] / EuMA, European Microwave Association. Vol. 1 Y1 - 2004 SN - 1-580-53992-0 N1 - European Microwave Conference ; (34, 2004, Amsterdam) ; European Microwave Week ; (7, 2004, Amsterdam) SP - 297 EP - 300 PB - Horizon House Publ. CY - London ER - TY - JOUR A1 - Heuermann, Holger A1 - Stolle, Reinhard A1 - Schiek, Burkhard T1 - Auswertemethoden zur Praezisions-Entfernungsmessung mit FMCW-Systemen und deren Anwendung im Mikrowellenbereich JF - tm - Technisches Messen. 62. 1995 (1995), H. 2 Y1 - 1995 SP - 66 EP - 73 ER - TY - JOUR A1 - Hoffmann, Andreas A1 - Rohrbach, Felix A1 - Uhl, Matthias A1 - Ceblin, Maximilian A1 - Bauer, Thomas A1 - Mallah, Marcel A1 - Jacob, Timo A1 - Heuermann, Holger A1 - Kuehne, Alexander J. C. T1 - Atmospheric pressure plasma-jet treatment of polyacrylonitrile-nonwovens—Stabilization and roll-to-roll processing JF - Journal of Applied Polymer Science N2 - Carbon nanofiber nonwovens represent a powerful class of materials with prospective application in filtration technology or as electrodes with high surface area in batteries, fuel cells, and supercapacitors. While new precursor-to-carbon conversion processes have been explored to overcome productivity restrictions for carbon fiber tows, alternatives for the two-step thermal conversion of polyacrylonitrile precursors into carbon fiber nonwovens are absent. In this work, we develop a continuous roll-to-roll stabilization process using an atmospheric pressure microwave plasma jet. We explore the influence of various plasma-jet parameters on the morphology of the nonwoven and compare the stabilized nonwoven to thermally stabilized samples using scanning electron microscopy, differential scanning calorimetry, and infrared spectroscopy. We show that stabilization with a non-equilibrium plasma-jet can be twice as productive as the conventional thermal stabilization in a convection furnace, while producing electrodes of comparable electrochemical performance. KW - batteries and fuel cells KW - electrospinning KW - fibers KW - irradiation KW - porous materials Y1 - 2022 U6 - http://dx.doi.org/10.1002/app.52887 SN - 0021-8995 (Print) SN - 1097-4628 (Online) N1 - Weitere Informationen: Bundesministerium für Bildung und Forschung, Fördernummer: 13XP5036E. Deutsche Forschungsgemeinschaft, Fördernummern: 390874152, 441209207, 327886311 VL - 139 IS - 37 SP - 1 EP - 9 PB - Wiley ER - TY - JOUR A1 - Hoffmann, Andreas A1 - Uhl, Matthias A1 - Ceblin, Maximilian A1 - Rohrbach, Felix A1 - Bansmann, Joachim A1 - Mallah, Marcel A1 - Heuermann, Holger A1 - Jacob, Timo A1 - Kuehne, Alexander J.C. T1 - Atmospheric pressure plasma-jet treatment of PAN-nonwovens—carbonization of nanofiber electrodes JF - C - Journal of Carbon Research N2 - Carbon nanofibers are produced from dielectric polymer precursors such as polyacrylonitrile (PAN). Carbonized nanofiber nonwovens show high surface area and good electrical conductivity, rendering these fiber materials interesting for application as electrodes in batteries, fuel cells, and supercapacitors. However, thermal processing is slow and costly, which is why new processing techniques have been explored for carbon fiber tows. Alternatives for the conversion of PAN-precursors into carbon fiber nonwovens are scarce. Here, we utilize an atmospheric pressure plasma jet to conduct carbonization of stabilized PAN nanofiber nonwovens. We explore the influence of various processing parameters on the conductivity and degree of carbonization of the converted nanofiber material. The precursor fibers are converted by plasma-jet treatment to carbon fiber nonwovens within seconds, by which they develop a rough surface making subsequent surface activation processes obsolete. The resulting carbon nanofiber nonwovens are applied as supercapacitor electrodes and examined by cyclic voltammetry and impedance spectroscopy. Nonwovens that are carbonized within 60 s show capacitances of up to 5 F g⁻¹. Y1 - 2022 U6 - http://dx.doi.org/10.3390/c8030033 SN - 2311-5629 N1 - This article belongs to the Collection "Nanoporous Carbon Materials for Advanced Technological Applications" VL - 8 IS - 3 PB - MDPI CY - Basel ER - TY - CHAP A1 - Heuermann, Holger A1 - Sadeghfam, Arash T1 - Analog Amplitude-Locked Loop Circuit to Support RF Energy Solutions T2 - IEEE MTT-S International Microwave Symposium Digest Y1 - 2016 SN - 978-150900698-4 U6 - http://dx.doi.org/10.1109/MWSYM.2016.7540092 ER - TY - CHAP A1 - Harzheim, Thomas A1 - Heuermann, Holger A1 - Marso, Michel T1 - An Adaptive Biasing Method for SRD Comb Generators T2 - 2016 German Microwave Conference (GeMiC) Y1 - 2016 U6 - http://dx.doi.org/10.1109/GEMIC.2016.7461613 N1 - GeMiC 2016 ; March 14–16, 2016, Bochum, Germany SP - 289 EP - 292 PB - IEEE ER - TY - CHAP A1 - Heuermann, Holger A1 - Sadeghfam, Arash A1 - Finger, Torsten T1 - Alternative ignition system based on microwave plasma T2 - Advanced ignition systems for gasoline engines : [Vorträge der 1st International Conference Advanced Ignition Systems for Gasoline Engines - 1. Internationale Tagung Zündsysteme für Ottomotoren, 12.-13. November 2012, Berlin] Y1 - 2013 SN - 9783816931904 SP - 95 EP - 103 PB - Expert-Verl. CY - Renningen ER -