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Item type:Publication, Access status: without files , An inline fuel mixture monitoring system based on microwave permittivity measurements(IEEE, 2026-04-07); ; ; ; The maritime industry faces significant pressure to reduce CO2 emissions by up to 80% by 2050, as mandated by the “FuelEU Maritime” initiative of the European Union. Blending conventional fossil fuels with renewable drop-in fuels, such as hydrotreated vegetable oils (HVO), offers a viable medium-term solution. This letter presents a sensor system based on four cylindrical cavity resonators to monitor these mixing processes in real-time. By measuring the relative permittivity and applying an extended Clausius-Mossotti model, the system determines the mixing ratio within the fuel circulation loop of a marine engine. Experimental validation using a reduced-scale setup demonstrates a high accuracy with a maximum deviation of 4.5% compared to flow-rate sensors. The system effectively detects supply blockages, thereby providing a robust solution for ensuring compliance for possible regulations in maritime fuel systems.Publicationtype: Journal Article48 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Impact of prediction delay and machine learning model complexity on the performance of near-real-time CW radar heartbeat detectionContactless vital-sign measurement has gained increasing attention across a variety of sectors, including medical and automotive applications as well as sleep monitoring. Radar-based systems enable the detection of heartbeat-induced microvibrations on the skin surface. This work investigates two key aspects of machine-learning-based near-real-Time heartbeat detection in radar signals: The influence of a prediction delay relative to an electrocardiography (ECG) reference signal and the impact of model complexity. For a systematic analysis, 153 gated recurrent unit (GRU) models have been trained and evaluated. At a delay of 200 ms, F1 scores above 92.7% and interbeat interval (IBI) mean absolute errors (MAEs) of less than 40 ms can be achieved. With increasing delay, the error reduces further, reaching an F1 score of 95.9% and IBI MAE of 23.4 ms at 1300-ms delay. In model complexity analysis, the preferrable combination of model depth, width, and prediction delay strongly depends on the metric of interest.Publicationtype: Conference Paper44 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A compact four-way waveguide power divider optimized for additive manufacturingThis work presents a design scheme for a very compact in-phase elliptical waveguide divider specifically optimized for 3D printing. An E-And H-plane divider and a combination EH-plane divider based on this design scheme are presented with 64.1 %, 17.6 %, and 27.6 % simulated relative bandwidth in V-Band. The divider can be constructed using only CST Studio with no need for additional software. The EH-plane divider was manufactured and measured. The measurements show good agreement with the simulation results.Publicationtype: Conference Paper73 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Effective permittivity determination procedure for 3D-printed dielectric lensesThis work extends the usual design process of dielectric lenses by introducing a novel procedure for determining the effective permittivity of 3D-printed dielectric lenses. A determination lens with a significant side lobe characteristic is designed to determine the effective permittivity while accounting for the specific influences of the 3D-printing process. By using the obtained permittivity value, the lens design can be optimized to achieve a desired performance. A gain accuracy of 0.15 dBi and an SLL accuracy of less than 2.2 dBi is achieved. This procedure integrates seamlessly into the dielectric lens development process, enhancing its accuracy and reliability.Publicationtype: Conference Paper25 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Effective permittivity determination procedure for 3D-printed dielectric lensesThis work extends the usual design process of dielectric lenses by introducing a novel procedure for determining the effective permittivity of 3D-printed dielectric lenses. A determination lens with a significant side lobe characteristic is designed to determine the effective permittivity while accounting for the specific influences of the 3D-printing process. By using the obtained permittivity value, the lens design can be optimized to achieve a desired performance. A gain accuracy of 0.15 dBi and an SLL accuracy of less than 2.2 dBi is achieved. This procedure integrates seamlessly into the dielectric lens development process, enhancing its accuracy and reliability.Publicationtype: Conference Paper54 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Design of a microwave frontend for a trapped ion quantum computer(IEEE, 2025-03); ; ; ; Unlike classical computers, which represent information as binary '1' and '0', quantum computers use qubits that exist in a superposition of both, enabling parallel computation. This capability allows them to solve special kinds of problems faster than classical computers. To process information, qubits are manipulated by applying energy, such as via a microwave signal, which is provided by a microwave frontend that ensures an appropriate frequency spectrum and power level. This paper defines the key parameters and implements such a frontend for trapped ion quantum computers which follow the magnetic gradient induced coupling (MAGIC) principle. The frontend is manufactured on a printed circuit board and measurements prove its functionality. It achieves an idle gate fidelity of 99.9% (99.99%) at an output power of 6.32 dBm (2.4 dBm).Publicationtype: Conference Paper83 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Contactless transition for wideband double-ridge waveguides(IEEE, 2024); ; 82 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A novel method for determining the degree of hydrogen loading of LOHC using cavity based permittivity measurements(2023-01); ; ; Liquid organic hydrogen carriers are a promising candidate to reduce the risk of handling hydrogen. However, the determination of their hydrogenation is still the subject of research. In this paper, a novel method for measuring hydrogen loading based on the permittivity of the hydrogen carriers used is presented. The cavity resonator developed for this application is shown and the design decisions made as well as the processing required are explained. Finally, the results of the test measurements are presented and discussed.Publicationtype: Conference Paper67