TY - CONF A1 - Glitzky, Carsten A1 - Rabe, Torsten A1 - Eberstein, Markus A1 - Schiller, Wolfgang Arno A1 - Töpfer, J. A1 - Barth, S. A1 - Kipka, A. T1 - LTCC-modules with integrated ferrite layers - Strategies for material development and co-sintering T2 - 2009 IMAPS/ACerS - 5th International Conference and Exhibition on Ceramic Interconnect and Ceramic Microsystems Technologies (CICMT) CY - Denver, Colorado, USA DA - 2009-04-21 KW - LTCC KW - Ferrite KW - Co-firing KW - Shrinkage KW - Coefficient of thermal expansion (CTE) PY - 2008 SN - 0-930815-83-1 SP - 000058 EP - 000063 AN - OPUS4-18926 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gaebler, A. A1 - Moessinger, A. A1 - Goelden, F. A1 - Manabe, A. A1 - Goebel, M. A1 - Follmann, R. A1 - Koether, D. A1 - Modes, C. A1 - Kipka, A. A1 - Deckelmann, M. A1 - Rabe, Torsten A1 - Schulz, Bärbel A1 - Kuchenbecker, Petra A1 - Lapanik, A. A1 - Mueller, S. A1 - Haase, W. A1 - Jakoby, R. T1 - Liquid crystal-reconfigurable antenna concepts for space applications at microwave and millimeter waves N2 - Novel approaches of tunable devices for millimeter wave applications based on liquid crystal (LC) are presented. In the first part of the paper, a novel concept of a tunable LC phase shifter realized in Low Temperature Cofired Ceramics technology is shown while the second part of the paper deals with a tunable high-gain antenna based on an LC tunable reflectarray. The reflectarray features continuously beam scanning in between ±25°. Also first investigations on radiation hardness of LCs are carried out, indicating that LCs might be suitable for space applications. KW - Tunable antenna KW - Phase shifter KW - Liquid crystal KW - LTCC PY - 2009 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-194273 DO - https://doi.org/10.1155/2009/876989 SN - 1687-5877 VL - 2009 IS - Article ID 876989 SP - 1 EP - 7 PB - Hindawi Publishing Corporation CY - New York, NY, USA AN - OPUS4-19427 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jost, M. A1 - Strunck, S. A1 - Heunisch, Andreas A1 - Wiens, A. A1 - Prasetiadi, A.E. A1 - Weickhmann, C. A1 - Schulz, Bärbel A1 - Quibeldey, M. A1 - Karabey, O.H. A1 - Rabe, Torsten A1 - Follmann, R. A1 - Koether, D. A1 - Jakoby, R. T1 - Continuously tuneable liquid crystal based stripline phase shifter realised in LTCC technology N2 - This work presents the design, fabrication and measurements of a low temperature cofired ceramic (LTCC) integrated liquid crystal (LC) phase shifter. The effective permittivity of the phase shifter and therefore its differential phase shift can be tuned continuously by orienting the LC directors with electric fields. The phase-shift demonstrator is designed for Ka-band frequencies around 30 GHz and represents a stripline filled with LC, embedded inside an LTCC multilayer structure, which provides a space-qualified and hermetically-sealed LC cavity within an RF-capable material system. The total length of the device is 37 mm while the phase shifting LC section has a length of 14.6 mm. At 30 GHz it exhibits a differential phase shift of 60° with an insertion loss around 6 dB, resulting in a figure of merit around 10°/dB. An advantage is that the insertion loss is nearly independent of the tuning state of the LC. The response time of the phase shifter, depending on the desired LC orientation, is between 62 ms and 37 s. T2 - EuMC 2015 - 45th European microwave conference CY - Paris, France DA - 07.09.2015 PY - 2015 SN - 978-2-87487-039-2 SP - 1260 EP - 1263 AN - OPUS4-35268 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strunck, S. A1 - Gaebler, A. A1 - Karabey, O.H. A1 - Heunisch, Andreas A1 - Schulz, Bärbel A1 - Rabe, Torsten A1 - Follmann, R. A1 - Kassner, J. A1 - Koether, D. A1 - Manabe, A. A1 - Jakoby, R. T1 - Reliability study of a tunable ka-band SIW-phase shifter based on liquid crystal in LTCC-technology N2 - A tunable substrate-integrated waveguide phase shifter using low-temperature co-fired ceramic (LTCC)-technology is presented in this paper. By changing the effective permittivity in the liquid crystal (LC)-filled waveguide, the differential phase can be tuned continuously. This is achieved by means of an analog signal applied to the electrodes, surrounding the LC. The design allows for precise tuning of the differential phase, which is proven with a Monte Carlo measurement resulting in phase errors of less than 3° at 28 GHz. Besides that, the ambient temperature dependency of the module is shown. The phase shifter has a high integration level and can be included into a complete and lightweight single-phased array antenna module. The phase shifter is realized with a high level of integration which is available through the multilayer process of the LTCC. It has a length of 50 and provides a differential phase shift of more than 360° at 28 GHz. The figure of merit for tunable phase shifters is >40°/dB. KW - Passive components and circuits KW - New and emerging technologies and materials PY - 2014 DO - https://doi.org/10.1017/S175907871400083X SN - 1759-0787 SN - 1759-0795 SP - 1 EP - 7 PB - Cambridge Univ. Press CY - Cambridge AN - OPUS4-31198 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Matz, R. A1 - Rabe, Torsten A1 - Töpfer, J. A1 - Ziesche, S. T1 - Circuit-Board-Integrated Transformers Design and Manufacture N2 - Transformers couple two sections of a circuit by electromagnetic induction. They are widely used to either transform alternating voltage levels or to transmit power or signals across galvanic isolation. Both of these functions are essential for the operation of sensors and controllers. Covering all aspects from idea to circuit performance and from design to manufacture, this paper presents the first comprehensive description of the making of miniaturized, rugged, up-to-100W transformers for embedding into multilayer circuit boards. For circular coils, the well-manageable Ampere-Laplace law is shown to yield reliable designs, predicting correctly the performance of manufactured hardware. This enables fast design without lengthy finite element modelling. In the low-power linear regime, basic relations describe how the device’s characteristics evolve from the material properties and device structure. While scattering Parameters are useful for the analysis of isolated transformers with their intrinsic parasitics, the interaction with the components of the final circuit and the aspects of power and efficiency are addressed by chain matrixes. While these design rules are similar for multilayer boards of different material (like epoxy, Teflon, ceramics), the manufacturing of ceramic board transformers is considered here in detail. Low-temperature-cofired ceramic (LTCC) boards being sintered at 900 °C are particularly suited for harsh environments with chemical or thermal stress as frequently found at sensor positions. The transformer performance usually benefits from or even requires an integrated ceramic core of higher permeability, a ferrite, to shape the magnetic flux. Methods to sinter ferrites inside a dielectric ceramic multilayerandto measure their performance are therefore described in detail.Asthe sintering behaviour of dielectricandmagnetic ceramics differs considerably, their simultaneous sintering is challenging.However, the sintering temperatures of the usefulMnZnand NiZnCu ferrites can be lowered to that of the dielectric material with only moderate loss of permeability by glass additives. Furthermore, thermal mismatch between materials causes catastrophic failure or at least stress and loss of magnetic performance during cooling to room temperature after sintering. This is avoidable by either adjusting the thermal expansion coefficient of the ferrite or by enclosing the ferrite between stressreleasing separation layers.We present the state of the art in materials development according to the first approach as well as fully functional devices made with the second technique. Other applications not directly addressed but well related to this work are characterized by low load resistance in relation to the coil resistance of the transformer. Efficient power transmission then requires that technological solutions are applied to achieve the lowest possible resistive loss inside the coils by an enlarged conductor cross-section. As this is particularly challenging for LTCC boards, a technique is discussed to fabricate conductor traces with a thickness larger than their width. KW - Multilayer ceramic technology KW - LTCC KW - Transformer PY - 2020 DO - https://doi.org/10.4416/JCST2019-00071 SN - 2190-9385 VL - 11 IS - 1 SP - 44 EP - 61 PB - Göller Verlag CY - Baden-Baden AN - OPUS4-50751 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Herrmann, Ralf A1 - Rabe, J. A1 - Marx, S. ED - Baeßler, Matthias ED - Möller, G. ED - Rogge, Andreas ED - Schiefelbein, N. T1 - Datenmanagement und –analyse von kontinuierlichen Datenströmen bei Offshore Windparks N2 - Mit der Errichtung und der Inbetriebnahme des Windpark alpha ventus wurden umfangreiche Messungen an den Tragstrukturen und den Umgebungsparametern durchgeführt. Im Projekt Gigawind life wurde im TP1 ein Datenmanagementsystem zur kontinuierlichen und periodisch fortgeführten Datenauswertung für große Datenbestände (Big Data) entworfen und realisiert. Anhand von Performanceuntersuchungen konnte eine Verkürzung der Rechenzeit um den Faktor 10 in einem Rechencluster erreicht werden. Unter Anwendung einer Datenpipeline nach dem Publish/Subscribe Prinzip wird eine skalierbare Datenschnittstelle für Monitoringdaten vorgeschlagen. T2 - Messen im Bauwesen 2018 CY - Berlin, Germany DA - 13.11.2018 KW - Datenmanagement KW - Big Data KW - Windenergie PY - 2018 SN - 978-3-9818564-1-5 VL - 2018/1 SP - 89 EP - 98 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-46918 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rabe, U. A1 - Pudovikov, S. A1 - Herrmann, H.-G. A1 - Wiggenhauser, H. A1 - Prabhakara, Prathik A1 - Niederleithinger, Ernst T1 - Using the Corner Reflection for Depth Evaluation of Surface Breaking Cracks in Concrete by Ultrasound N2 - The corner echo is a well-known effect in ultrasonic testing, which allows detection of surface breaking cracks with predominantly perpendicular orientation to the surface as, for example, corrosion cracks in metal pipes or shafts. This echo is formed by two planes, the surface of the crack and the surface which the crack breaks. It can also be classified as a half-skip method, since a reflection of the pulse occurs on the backwall before the reflection at the defect takes place. In combination with the diffraction from the crack tip, the corner echo also allows crack sizing. As shown in this paper, the corner reflection can be used in civil engineering for nondestructive inspection of concrete. Commercially available low frequency ultrasonic arrays with dry point contact sources generate SH transversal waves with sufficient divergence of the sound field in order to detect corner reflections. Ultrasonic line-scans and area-scans were acquired with a linear array on flat concrete specimens, and the data were reconstructed by the Synthetic aperture focusing technique. If the angles and the area of reconstruction are chosen accordingly, the corner echo reflection can be distinguished from other ultrasonic information. The corner echo can thus be used as a method for deciding whether a crack is a partial-depth crack or a full-depth crack and thus for obtaining a statement about crack depth. This paper presents corresponding experimental results obtained on concrete specimens with artificial test defects and cracks induced under controlled conditions. KW - Ultrasound KW - Crack depth KW - Concrete KW - Corner echo PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-574631 DO - https://doi.org/10.1007/s10921-023-00956-8 SN - 0195-9298 VL - 42 IS - 2 SP - 1 EP - 19 PB - Springer Nature AN - OPUS4-57463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mohammadifar, E. A1 - Ahmadi, V. A1 - Gholami, M.F. A1 - Oehrl, A. A1 - Kolyvushko, O. A1 - Nie, C. A1 - Donskyi, Ievgen A1 - Herziger, S. A1 - Radnik, Jörg A1 - Ludwig, K. A1 - Böttcher, C. A1 - Rabe, J.P. A1 - Osterrieder, K. A1 - Azab, W. A1 - Haag, R. A1 - Adeli, M. T1 - Graphene-Assisted Synthesis of 2D Polyglycerols as Innovative Platforms for Multivalent Virus Interactions N2 - 2D nanomaterials have garnered widespread attention in biomedicine and bioengineering due to their unique physicochemical properties. However, poor functionality, low solubility, intrinsic toxicity, and nonspecific interactions at biointerfaces have hampered their application in vivo. Here, biocompatible polyglycerol units are crosslinked in two dimensions using a graphene-assisted strategy leading to highly functional and water-soluble polyglycerols nanosheets with 263 ± 53 nm and 2.7 ± 0.2 nm average lateral size and thickness, respectively. A single-layer hyperbranched polyglycerol containing azide functional groups is covalently conjugated to the surface of a functional graphene template through pH-sensitive linkers. Then, lateral crosslinking of polyglycerol units is carried out by loading tripropargylamine on the surface of graphene followed by lifting off this reagent for an on-face click reaction. Subsequently, the polyglycerol nanosheets are detached from the surface of graphene by slight acidification and centrifugation and is sulfated to mimic heparin sulfate proteoglycans. To highlight the impact of the two-dimensionality of the synthesized polyglycerol sulfate nanosheets at nanobiointerfaces, their efficiency with respect to herpes Simplex virus type 1 and severe acute respiratory syndrome corona virus 2 inhibition is compared to their 3D nanogel analogs. Four times stronger in virus Inhibition suggests that 2D polyglycerols are superior to their current 3D counterparts.2D nanomaterials have garnered widespread attention in biomedicine and bioengineering due to their unique physicochemical properties. However, poor functionality, low solubility, intrinsic toxicity, and nonspecific interactions at biointerfaces have hampered their application in vivo. Here, biocompatible polyglycerol units are crosslinked in two dimensions using a graphene-assisted strategy leading to highly functional and water-soluble polyglycerols nanosheets with 263 ± 53 nm and 2.7 ± 0.2 nm average lateral size and thickness, respectively. A single-layer hyperbranched polyglycerol containing azide functional groups is covalently conjugated to the surface of a functional graphene template through pH-sensitive linkers. Then, lateral crosslinking of polyglycerol units is carried out by loading tripropargylamine on the surface of graphene followed by lifting off this reagent for an on-face click reaction. Subsequently, the polyglycerol nanosheets are detached from the surface of graphene by slight acidification and centrifugation and is sulfated to mimic heparin sulfate proteoglycans. To highlight the impact of the two-dimensionality of the synthesized polyglycerol sulfate nanosheets at nanobiointerfaces, their efficiency with respect to herpes Simplex virus type 1 and severe acute respiratory syndrome corona virus 2 inhibition is compared to their 3D nanogel analogs. Four times stronger in virus Inhibition suggests that 2D polyglycerols are superior to their current 3D counterparts. KW - 2D Materials KW - Graphene template KW - Multivalency KW - Polyglycerol KW - Virus inhibition PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-527726 DO - https://doi.org/10.1002/adfm.202009003 VL - 31 IS - 32 SP - 2009003 PB - Wiley VCH AN - OPUS4-52772 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hajian, A. A1 - Konegger, T. A1 - Bielecki, K. A1 - Mieller, Björn A1 - Rabe, Torsten A1 - Schwarz, S. A1 - Zellner, C. A1 - Schmid, U. T1 - Wet chemical porosification with phosphate buffer solutions for permittivity reduction of LTCC substrates N2 - The wireless high-frequency technology requires a robust, cost-effective, and highly integrated substrate technology offering the capability for areas of tailored permittivity. The wet-chemical porosification of low temperature co-fired ceramics (LTCC) substrates offers such an approach by locally embedding air. Porosification of LTCC in both extremely acidic and alkaline media has been investigated in previous works. However, for improving the available knowledge on the porosification of LTCC with H3PO4 as a standard and a widely used etching solution, the impact of solution concentration was systematically investigated and a substantial improvement in the etching performance was achieved. Moreover, in the present study, for the first time, the intermediate pH values, and the impact of pH as a key parameter on the etching process have been investigated. For this purpose, the applicability of phosphate buffer solution (PBS) as a prospective novel etchant mixture for the porosification of a commercially available LTCC tape (Ceramtape GC) was explored. Valuable information about surface morphology, crystalline composition, and the pore structure of the etched LTCCs was gathered employing scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and mercury porosimetry measurements. Based on these findings, the performance of PBS-based etchant systems towards the generation of porous LTCCs combining high depths of porosification with acceptable surface characteristics for subsequent metallization is demonstrated. Based on the obtained results, by application of a 0.2 mol L−1 solution of PBS, the effective relative permittivity of test samples with a thickness of approximately 600 µm and a porosification depth of 186 µm from each side, could be reduced up to 10% of its initial “as fired” value. Also, based on the measurement results and by measuring the depth of porosification, the permittivity of the etched layer was estimated to show a reduction of up to 22% compared to the initial “as fired” value. KW - LTCC KW - Porosification KW - Wet chemical etching KW - Permittivity reduction PY - 2020 DO - https://doi.org/10.1016/j.jallcom.2020.158059 SN - 0925-8388 VL - 863 SP - 158059 PB - Elsevier B.V. AN - OPUS4-51800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -