@inproceedings{HoernerBochtlerCervellinoetal.2013, author = {H{\"o}rner, Eugen and Bochtler, Ulrich and Cervellino, Roman and Zentgraf, Ralf and Trunzer, Dominic and W{\"o}lfel, Maximilian and B{\"o}ttcher, Arthur and Schneider, Johannes}, title = {Drahtlose Hochtemperaturmessung mit Oberfl{\"a}chenwellensensoren (OW-Sensor)}, series = {Energy Harvesting Congress, M{\"u}nchen}, booktitle = {Energy Harvesting Congress, M{\"u}nchen}, year = {2013}, subject = {Oberfl{\"a}chenwellenelement}, language = {de} } @phdthesis{Woelfel2018, author = {W{\"o}lfel, Maximilian}, title = {Hochintegriertes hardwaregest{\"u}tztes Messverfahren zur Untersuchung von fehlerbehafteten {\"U}bertragungskan{\"a}len in TETRA-Objektfunkversorgungen}, school = {Technische Hochschule Aschaffenburg}, year = {2018}, subject = {TETRA, Telekommunikation}, language = {de} } @inproceedings{ProbstHitzingerBochtleretal.2021, author = {Probst, Anne-Catherine and Hitzinger, Hans and Bochtler, Ulrich and W{\"o}lfel, Maximilian and Schmitt, Christoph}, title = {High Frequency Power Amplifier for Wideband Wireless Communication Systems}, series = {Proceedings of the 2021 Kleinheubach Conference}, volume = {2021}, booktitle = {Proceedings of the 2021 Kleinheubach Conference}, editor = {U.R.S.I. Landesausschuss in Deutschland e.V. 2021,}, doi = {10.23919/IEEECONF54431.2021.9598443}, pages = {4}, year = {2021}, abstract = {Increasing data transmission rates and bandwidth both belong to the challenges of the development of high-performance wireless communication systems. Multi-channel communication systems commonly use several narrowband power amplifiers each one for a single communication channel. Lossy couplers are needed both to separate the different channels from each other at the amplifiers input and to combine the amplified signals on each channel at the output. This approach depicts a poor efficiency and is limited to a few number of channels since each channel duplication involves 3 dB losses due to couplers. Alternatively, broadband radio frequency power amplifiers ensuring the simultaneous transmission of several carriers on a wide frequency range contribute to increase the cost and resource efficiency of transceivers in wireless communication systems. Gain flatness, a high output power, and low power levels of second and third order harmonics are required on the whole operating frequency range of the power amplifier in multi-carrier communication systems since overtones will degrade the quality of the communication. The present work investigates the performances of a broadband push-pull power amplifier based on LDMOS transistors, the input matching network using a 8:1 transmission line transformer. For the first time investigations on harmonic distortions of the amplified signal when using a transformer with 8:1 impedance transformation ratio are presented. Characterisation of the power amplifiers performances is focused on gain flatness, output power, harmonic distortions and efficiency at 110 W.}, subject = {Hochfrequenzverst{\"a}rker}, language = {en} } @article{KoehlerWoelfelCibaetal.2018, author = {K{\"o}hler, Tim and W{\"o}lfel, Maximilian and Ciba, Manuel and Bochtler, Ulrich and Thielemann, Christiane}, title = {Terrestrial Trunked Radio (TETRA) exposure of neuronal in vitro networks}, series = {Environmental Research}, volume = {2018}, journal = {Environmental Research}, number = {162}, doi = {10.1016/j.envres.2017.12.007}, pages = {1 -- 7}, year = {2018}, abstract = {Terrestrial Trunked Radio (TETRA) is a worldwide common mobile communication standard, used by authorities and organizations with security tasks. Previous studies reported on health effects of TETRA, with focus on the specific pulse frequency of 17.64 Hz, which affects calcium efflux in neuronal cells. Likewise among others, it was reported that TETRA affects heart rate variability, neurophysiology and leads to headaches. In contrast, other studies conclude that TETRA does not affect calcium efflux of cells and has no effect on people's health. In the present study we examine whether TETRA short- and long-term exposure could affect the electrophysiology of neuronal in vitro networks. Experiments were performed with a carrier frequency of 395 MHz, a pulse frequency of 17.64 Hz and a differential quaternary phase-shift keying (π/4 DQPSK) modulation. Specific absorption rates (SAR) of 1.17 W/kg and 2.21 W/kg were applied. In conclusion, the present results do not indicate any effect of TETRA exposure on electrophysiology of neuronal in vitro networks, neither for short-term nor long-term exposure. This applies to the examined parameters spike rate, burst rate, burst duration and network synchrony.}, subject = {Neuronales Netz}, language = {en} } @inproceedings{KoehlerWoelfelBochtleretal.2016, author = {K{\"o}hler, Tim and W{\"o}lfel, Maximilian and Bochtler, Ulrich and Thielemann, Christiane}, title = {TETRA specific long-term exposure of neuronal in vitro networks}, series = {BioEM2016}, booktitle = {BioEM2016}, year = {2016}, subject = {Neuronales Netz}, language = {en} } @inproceedings{NeumaierProbstWoelfeletal.2025, author = {Neumaier, Marcel and Probst, Anne-Catherine and W{\"o}lfel, Maximilian and Bochtler, Ulrich}, title = {Performance Analysis in a Digital TETRA-Simulcast System}, series = {2025 16th German Microwave Conference (GeMiC)}, booktitle = {2025 16th German Microwave Conference (GeMiC)}, year = {2025}, abstract = {In radio communication of mission-critical services, resilient solutions are strongly required to account for public safety. Additionally to the cellular network based on the professional mobile radio European standard TETRA, a digital TETRA-simulcast system is proposed as a redundant network to ensure area coverage in case of base station failure caused e.g. by disasters. This paper presents a preliminary study about network planning of a frequency-efficient digital TETRA-simulcast system to be physically deployed in a hilly region of Germany. Coverage as well as ray tracing analysis and channel modeling were performed by simulations and prove to be helpful tools for the systematic optimization of system performances, especially with regard to the control of intersymbol interference in overlapping zones.}, subject = {TETRA, Telekommunikation}, language = {en} } @inproceedings{ProbstNeumaierHufgardetal.2025, author = {Probst, Anne-Catherine and Neumaier, Marcel and Hufgard, Christopher and W{\"o}lfel, Maximilian and Schmitt, Christoph and Bochtler, Ulrich}, title = {Network Planning a Digital TETRA-Simulcast-System}, series = {Kleinheubacher Tagung, Miltenberg, 23.09.2025 - 25.09.2025}, booktitle = {Kleinheubacher Tagung, Miltenberg, 23.09.2025 - 25.09.2025}, year = {2025}, subject = {TETRA, Telekommunikation}, language = {en} }