Disclosed is a measurement system (1) for analysing RF signals. The measurement system (1) comprises an optically transparent enclosure (11) comprising an optically pumpable gas, and a printed circuit board, PCB (12A, 12B) comprising an electrical transmission line (121-123) for guiding the RF signal to be analyzed through the enclosure (11) and a reflective planar face. The measurement system (1) further comprises an optical pump (13) for emitting preferably coherent light onto the reflective planar face, and a detector (14) for detecting an optical property of the emitted light being reflected by the reflective planar face. This provides a better laser/microwave overlap in atomic vapor quantum sensing setups, where it is crucial to overlap the regions with highest laser intensity and microwave field strength.