| 摘要 |
A radar level gauge system (1), for determining a filling level of a product (6) contained in a tank (5), comprising a transceiver (10) arranged outside the tank for generating, transmitting and receiving electromagnetic signals; a single conductor probe (3) arranged inside the tank and electrically connected to the transceiver via a feed-through (15; 19) arranged at the top of a nozzle (16) of the tank. The single conductor probe (3) extends through the nozzle (16) towards and into the product contained in the tank, for guiding a transmitted signal (S T ) from the transceiver towards a surface of the product, and for returning a surface echo signal (S R ) resulting from reflection of the transmitted signal at the surface back towards the transceiver. An impedance matching arrangement (35; 40; 44; 48) is provided to the probe (3) and extends along a portion of the probe. An extension of the impedance matching arrangement (35; 40; 44; 48), in a direction perpendicular to the probe (3), is constant or changes with increasing distance from the feed-through (15; 19) with a first rate of change inside the nozzle (16), and changes with increasing distance from the feed-through (15; 19) with a second, negative rate of change below the nozzle (16) over a distance corresponding to at least a quarter of a wavelength of the transmitted signal (S T ). The second rate of change is more negative than the first rate of change. |
