Patent ID: 8397566

Claim:
A measuring device, wherein an apparatus is integrated in said measuring device, which, via a sending and/or receiving unit, radiates broadband high-frequency signals having a center wavelength into an open or closed, spatial system, and/or receives the high-frequency signals from the open or closed, spatial system, and ascertains, via a travel-time measurement of the emitted high frequency signals, a fill level of a fill substance, the high-frequency signals are microwave signals, said apparatus comprising: at least one dielectric substrate layer of a predetermined thickness; and a conductor structure, which includes at least one signal path and two reference paths arranged symmetrically to the signal path, which together form a coplanar line, wherein: said conductor structure is separated into segments and said segments are arranged on two oppositely lying sides of said at least one dielectric substrate layer, in such a manner that, said segments of said conductor structure overlap, in predetermined coupling regions, with a predetermined breadth and predetermined length being spatially separated by said at least one dielectric substrate layer of a predetermined thickness; a galvanic isolation of the coplanar line is realized in such a manner that the coupling regions of said segments of the conductor structure transfer the high-frequency signals by electromagnetic coupling; said thickness of said at least one dielectric substrate layer being smaller than a quarter of the center wavelength λc/4; said breadth of the coupling regions of the conductor structures and/or said thickness of said at least one dielectric substrate layer is/are embodied such that the electromagnetic coupling of the high-frequency signals is maximum through the coupling regions, and a wave resistance of the conductor structure is matched; said predetermined length of the overlaps in the coupling regions is approximately a quarter of the center wavelength; and at least three coupling regions of said predetermined coupling regions of electromagnetic couplings are arranged serially one after the other in each signal path and in each reference path as a multiple galvanic isolation, which separates an intrinsically safe region from a non-intrinsically-safe region in the measuring device.