Lipka, D. Dohlus, M. Marx, M. Vilcins, S. Werner, M. JACoW Publishing Geneva, Switzerland 978-3-95450-201-1 10.18429/JACoW-IBIC2018-TUPB05 English 269-272 TUPB05 dipole resonance cavity FEL impedance Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-IBIC2018-TUPB05 http://jacow.org/ibic2018/papers/tupb05.pdf The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) is foreseen to host various experiments in the field of production of ultra-short electron bunches and novel high gradient acceleration techniques. The SINBAD linac, also called ARES (Accelerator Research Experiment at SINBAD), will be a conventional S-band linear RF accelerator allowing the production of low charge (within a range between 0.5 pC and 1000 pC) ultra-short electron bunches. To detect the low charge bunches a cavity beam position monitor is designed based on the experience from the EU-XFEL. It will consist of a stainless steel body with low Q factor of 70, a resonance frequency of 3.3 GHz and a relative wide gap of 15 mm to reach a high peak position sensitivity of 4.25 V/(nC mm). The design considerations and simulation results will be presented.