Abstract: A separation frequency detector circuit and a method for detection of a separation frequency in a radar level gauge. A first circuit element (1) is arranged to receive a first clock frequency, and a second clock frequency. An instantaneous value of the first clock frequency will be transferred to and held at an output Q of the first circuit element (1) once each period of the second clock frequency. A predetermined value will be transferred to and held at an output Q of a second circuit element (3) triggered by the output Q of the first circuit element (1), and the predetermined value will be cleared from the output Q of the second circuit element (3) a predetermined time period after being triggered. An output is obtainable as a short pulse with a leading edge which will be synchronized with the first change of the leading signal edge of the first circuit element (1).

Abstract: The invention relates to a pressure sealing device and a method for decreasing the cut-off frequency in such a pressure sealing device used in a radar level gauging system for gauging a filling level of a product kept in a container, the sealing device comprises a waveguide for feeding microwaves in at least one of the following mode types: transverse electric mode, transverse magnetic mode or hybrid mode. Said waveguide is sealed by a dielectric material. A center conductor is arranged at least partially within said dielectric material.

Abstract: The present invention relates to the field of radar level gauging systems, in which a level of a surface of a product stored in a container is measured. The gauging system comprises: a radar level gauge arranged above the surface of the product which is arranged to transmit a microwave signal towards the product surface and receive a reflected microwave signal from the product surface; a calculation unit arranged to determine a measured value of the product level based upon the received signal; means for comparing the measured value of the product level with a predetermined value; and a second level gauge arranged closed to the bottom of the container and arranged to determine the product level when the measured value is below the predetermined value.

Abstract: A bottom reflector for a radar-based level gauge, which measures a level of a liquid stored in a tank by means of transmitting a microwave signal towards the surface of the liquid from the top of the tank, receiving the microwave signal as reflected against the surface of the liquid, and calculating the level of the liquid from the propagation time of the transmitted and reflected microwave signal, wherein the bottom reflector is adapted to be mounted close to the bottom of the tank and comprises a reflecting structure having a first reflection coefficient for the microwave signal when the level of the liquid is above the reflecting structure and a second reflection coefficient for the microwave signal when the level of the liquid is below the reflecting structure, wherein the first reflection coefficient is substantially lower than the second reflection coefficient.