Sensor apparatus for transmitting electrical pulses from a signal line into and out of a vessel to measure a process variable—in order to be more informative

A sensor apparatus (1) for transmitting electrical pulses from a signal line (2) into and out of a vessel to measure a process variable, the sensor apparatus (1) comprising:

• a mounting section (3) for coupling the sensor apparatus to the vessel,
• at least two concentric at least partially overlapping dielectric inserts (6, 9, 10, 11, 17) stacked inside one another and located inside the mounting section (3),
• said dielectric inserts (6, 9, 10, 11, 17) comprising central apertures,
• a conductive probe element (4) mounted inside the mounting section (3) and extending through the apertures of the dielectric inserts (6, 9, 10, 11, 17) into the vessel,
• an electrical connector (5)
• configured for coupling the signal line (2) to the probe element (4),
• wherein an electric impedance inside the mounting section (3), is nearly constant and approximately equal to the electric impedance of the signal line (2), each dielectric insert (6, 9, 10, 11, 17) has one end facing towards the vessel and one end facing away from the vessel, all ends located inside the mounting section (3) have outer and inner surfaces, said surfaces being oriented such that the thickness of the insert decreases towards said ends, and the inner and outer diameters of each dielectric insert inside the mounting section (3) are at least one of constant and change gradually in a direction parallel to a longitudinal axis of the respective dielectric insert (6, 9, 10, 11, 17).