@article{Heuermann2004, author = {Heuermann, Holger}, title = {A Synthesis Technique for Mono- and Mixed-Mode Symmetrical Filter}, series = {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}, journal = {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}, publisher = {Horizon House Publ}, address = {London}, isbn = {1-580-53992-0}, pages = {309 -- 312}, year = {2004}, language = {en} } @article{HeuermannRumiantsevSchott2004, author = {Heuermann, Holger and Rumiantsev, A. and Schott, S.}, title = {Advanced on-wafer multiport calibration methods for mono- and mixed-mode device characterization}, series = {On wafer characterization : 63rd ARFTG conference digest, spring 2004, 11 June 2004, Fort Worth, TX / Automatic RF Techniques Group. [Conference chair: John Cable. Publication chair: J. G. Burns]}, journal = {On wafer characterization : 63rd ARFTG conference digest, spring 2004, 11 June 2004, Fort Worth, TX / Automatic RF Techniques Group. [Conference chair: John Cable. Publication chair: J. G. Burns]}, publisher = {IEEE Operations Center}, address = {Piscataway, NJ}, isbn = {0-7803-8371-0}, pages = {91 -- 96}, year = {2004}, language = {en} } @inproceedings{HeuermannSadeghfamFinger2013, author = {Heuermann, Holger and Sadeghfam, Arash and Finger, Torsten}, title = {Alternative ignition system based on microwave plasma}, series = {Advanced ignition systems for gasoline engines : [Vortr{\"a}ge der 1st International Conference Advanced Ignition Systems for Gasoline Engines - 1. Internationale Tagung Z{\"u}ndsysteme f{\"u}r Ottomotoren, 12.-13. November 2012, Berlin]}, booktitle = {Advanced ignition systems for gasoline engines : [Vortr{\"a}ge der 1st International Conference Advanced Ignition Systems for Gasoline Engines - 1. Internationale Tagung Z{\"u}ndsysteme f{\"u}r Ottomotoren, 12.-13. November 2012, Berlin]}, publisher = {Expert-Verl.}, address = {Renningen}, organization = {International Conference Advanced Ignition Systems for Gasoline Engines <1, 2012, Berlin>}, isbn = {9783816931904}, pages = {95 -- 103}, year = {2013}, language = {en} } @inproceedings{HarzheimHeuermannMarso2016, author = {Harzheim, Thomas and Heuermann, Holger and Marso, Michel}, title = {An Adaptive Biasing Method for SRD Comb Generators}, series = {2016 German Microwave Conference (GeMiC)}, booktitle = {2016 German Microwave Conference (GeMiC)}, publisher = {IEEE}, doi = {10.1109/GEMIC.2016.7461613}, pages = {289 -- 292}, year = {2016}, language = {en} } @inproceedings{HeuermannSadeghfam2016, author = {Heuermann, Holger and Sadeghfam, Arash}, title = {Analog Amplitude-Locked Loop Circuit to Support RF Energy Solutions}, series = {IEEE MTT-S International Microwave Symposium Digest}, booktitle = {IEEE MTT-S International Microwave Symposium Digest}, isbn = {978-150900698-4}, doi = {10.1109/MWSYM.2016.7540092}, pages = {4 Seiten}, year = {2016}, language = {de} } @article{HoffmannUhlCeblinetal.2022, author = {Hoffmann, Andreas and Uhl, Matthias and Ceblin, Maximilian and Rohrbach, Felix and Bansmann, Joachim and Mallah, Marcel and Heuermann, Holger and Jacob, Timo and Kuehne, Alexander J.C.}, title = {Atmospheric pressure plasma-jet treatment of PAN-nonwovens—carbonization of nanofiber electrodes}, series = {C - Journal of Carbon Research}, volume = {8}, journal = {C - Journal of Carbon Research}, number = {3}, publisher = {MDPI}, address = {Basel}, issn = {2311-5629}, doi = {10.3390/c8030033}, pages = {8 Seiten}, year = {2022}, abstract = {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.}, language = {en} } @article{HoffmannRohrbachUhletal.2022, author = {Hoffmann, Andreas and Rohrbach, Felix and Uhl, Matthias and Ceblin, Maximilian and Bauer, Thomas and Mallah, Marcel and Jacob, Timo and Heuermann, Holger and Kuehne, Alexander J. C.}, title = {Atmospheric pressure plasma-jet treatment of polyacrylonitrile-nonwovens—Stabilization and roll-to-roll processing}, series = {Journal of Applied Polymer Science}, volume = {139}, journal = {Journal of Applied Polymer Science}, number = {37}, publisher = {Wiley}, issn = {0021-8995 (Print)}, doi = {10.1002/app.52887}, pages = {1 -- 9}, year = {2022}, abstract = {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.}, language = {en} } @article{HeuermannStolleSchiek1995, author = {Heuermann, Holger and Stolle, Reinhard and Schiek, Burkhard}, title = {Auswertemethoden zur Praezisions-Entfernungsmessung mit FMCW-Systemen und deren Anwendung im Mikrowellenbereich}, series = {tm - Technisches Messen. 62. 1995 (1995), H. 2}, journal = {tm - Technisches Messen. 62. 1995 (1995), H. 2}, pages = {66 -- 73}, year = {1995}, language = {de} } @article{HeuermannErkens2004, author = {Heuermann, Holger and Erkens, Holger}, title = {Blocking structures for mixed-mode systems. / Erkens, Holger ; Heuermann, Holger}, series = {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}, journal = {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}, publisher = {Horizon House Publ.}, address = {London}, isbn = {1-580-53992-0}, pages = {297 -- 300}, year = {2004}, language = {en} } @misc{HeuermannHueningWache2018, author = {Heuermann, Holger and H{\"u}ning, Felix and Wache, Franz-Josef}, title = {Bussystem sowie Kommunikationsverfahren}, year = {2018}, abstract = {Die Erfindung betrifft ein Bussystem enthaltend Busleitungen, an denen eine Anzahl von Busteilnehmern {\"u}ber 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 Zwischenbr{\"u}ckeneinheit anschließt, die mindestens zwei Sender-/Empf{\"a}nger-Paare enthaltend jeweils einen Sender und einen Empf{\"a}nger aufweist, wobei der Sender einen Senderoszillator, eine Amplituden- und/oder Phasen- und/oder Frequenzmodulator sowie eine Antenne aufweist und wobei der Empf{\"a}nger einen Mischer aufweisenden Demodulator sowie eine Antenne aufweist, wobei ein erstes Sender-/Empf{\"a}nger-Paar {\"u}ber eine Funkschnittstelle mit dem zweiten Sender-/Empf{\"a}nger-Paar miteinander gekoppelt sind.}, language = {de} } @article{Heuermann2008, author = {Heuermann, Holger}, title = {Calibration of a Network Analyzer Without a Thru Connection for Nonlinear and Multiport Measurements}, series = {IEEE Transactions on Microwave Theory and Techniques. 56 (2008), H. 11, 1}, journal = {IEEE Transactions on Microwave Theory and Techniques. 56 (2008), H. 11, 1}, isbn = {0018-9480}, pages = {2505 -- 2510}, year = {2008}, language = {en} } @article{HeuermannSchiek1994, author = {Heuermann, Holger and Schiek, Burkhard}, title = {Calibration of network analyser measurements with leakage errors}, series = {Electronics letters. 30 (1994), H. 1}, journal = {Electronics letters. 30 (1994), H. 1}, isbn = {0013-5194}, pages = {52 -- 53}, year = {1994}, language = {en} } @article{Heuermann1999, author = {Heuermann, Holger}, title = {Calibration procedures with series impedances and unknown lines simplify on-wafer measurements}, series = {IEEE transactions on microwave theory and techniques : MTT ; a publication of the IEEE Microwave Theory and Techniques Society. 47 (1999), H. 1}, journal = {IEEE transactions on microwave theory and techniques : MTT ; a publication of the IEEE Microwave Theory and Techniques Society. 47 (1999), H. 1}, isbn = {0018-9480}, pages = {1 -- 5}, year = {1999}, language = {en} } @article{SchoppDollGraeseretal.2016, author = {Schopp, Christoph and Doll, Timo and Gr{\"a}ser, Ulrich and Harzheim, Thomas and Heuermann, Holger and Kling, Rainer and Marso, Michael}, title = {Capacitively Coupled High-Pressure Lamp Using Coaxial Line Networks}, series = {IEEE Transactions on Microwave Theory and Techniques}, volume = {64}, journal = {IEEE Transactions on Microwave Theory and Techniques}, number = {10}, publisher = {IEEE}, address = {New York, NY}, issn = {0018-9480}, doi = {10.1109/TMTT.2016.2600326}, pages = {3363 -- 3368}, year = {2016}, abstract = {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.}, language = {en} } @article{HoltrupSadeghfamHeuermannetal.2014, author = {Holtrup, S. and Sadeghfam, Arash and Heuermann, Holger and Awakowicz, P.}, title = {Characterization and optimization technique for microwave-driven high-intensity discharge lamps using hot S-parameters}, series = {IEEE transactions on microwave theories and techniques}, volume = {62}, journal = {IEEE transactions on microwave theories and techniques}, number = {10}, publisher = {IEEE}, address = {New York}, issn = {0018-9480}, doi = {10.1109/TMTT.2014.2342652}, pages = {2471 -- 2480}, year = {2014}, abstract = {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.}, language = {en} } @article{HeuermannPetersSchmitzetal.2005, author = {Heuermann, Holger and Peters, N. and Schmitz, T. and Sadeghfam, Arash}, title = {Concept of Balanced Antennas with Load-Invariant Base Impedance Using a Two Element LC-Coupler. Peters, N., Schmitz, Th., Sadeghfam, A., Heuermann, H.}, series = {Proceedings of the European microwave association : journal of the European microwave association}, journal = {Proceedings of the European microwave association : journal of the European microwave association}, publisher = {PLUS}, address = {Pisa}, pages = {117 -- 122}, year = {2005}, language = {en} } @inproceedings{StephanHeuermannPrantner2016, author = {Stephan, Achim and Heuermann, Holger and Prantner, Michael}, title = {Cutting human tissue with novel atmospheric-pressure microwave plasma jet}, series = {46th European Microwave Conference (EuMC)}, booktitle = {46th European Microwave Conference (EuMC)}, publisher = {IEEE}, isbn = {978-2-87487-043-9}, doi = {10.1109/EuMC.2016.7824490}, pages = {902 -- 905}, year = {2016}, language = {en} } @inproceedings{ElgamalHeuermann2020, author = {Elgamal, Abdelrahman and Heuermann, Holger}, title = {Design and Development of a Hot S-Parameter Measurement System for Plasma and Magnetron Applications}, series = {2020 German Microwave Conference (GeMiC), Cottbus, Germany, 2020}, booktitle = {2020 German Microwave Conference (GeMiC), Cottbus, Germany, 2020}, isbn = {978-3-9820397-1-8}, pages = {124 -- 127}, year = {2020}, language = {en} } @inproceedings{SadeghfamSadeghiAhangarElgamaletal.2019, author = {Sadeghfam, Arash and Sadeghi-Ahangar, A. and Elgamal, Abdelrahman and Heuermann, Holger}, title = {Design and Development of a Novel Self-Igniting Microwave Plasma Jet for Industrial Applications}, series = {IEEE MTT-S International Microwave Symposium Digest}, booktitle = {IEEE MTT-S International Microwave Symposium Digest}, isbn = {978-172811309-8}, pages = {63 -- 66}, year = {2019}, language = {en} } @article{SchoppRohrbachLangeretal.2024, author = {Schopp, Christoph and Rohrbach, Felix and Langer, Luc and Heuermann, Holger}, title = {Detection of welding wire length by active S11 measurement}, series = {IEEE Transactions on Plasma Science}, journal = {IEEE Transactions on Plasma Science}, number = {Early Access}, publisher = {IEEE}, issn = {0093-3813 (Print)}, doi = {10.1109/TPS.2024.3356659}, pages = {1 -- 6}, year = {2024}, abstract = {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.}, language = {en} }