Abstract: An implantable medical device has a conductive housing, electronic circuitry for the operation of the implantable medical device, and radio frequency circuitry for transmitting and/or receiving radio frequency signals, the electronic circuitry and the radio frequency circuitry being interconnected and arranged within in the housing. The housing has at least one slot therein, and a slot feed operatively interconnected between the radio frequency circuitry and the slot. The electrically conductive housing provided with the at least one slot is operable as an antenna for the radio frequency signals. The electric circuitry, the radio frequency circuitry, and the interconnection can be enclosed by the housing so that they are shielded from external radiation in any direction.

Abstract: The present invention relates to a radar level gauge (1) comprising an antenna (2), a tank sealing (3), an electronics unit (4) and a waveguide feed (5) between the electronics unit (4) and the antenna (2). The waveguide (5) is essentially straight and has a 90°-symmetric cross section and is further arranged to accommodate two essentially orthogonal waveguide modes. The waveguide (5) further has a length (I) below two times the range resolution of said radar level gauge (1). The present invention further relates to a method for improved radar level gauging using a radar level gauge (1) as above.

Abstract: There is provided a radar level gauge using microwaves for measuring a level of a surface of a product in a tank, comprising an antenna for transmitting microwaves to the surface and receiving microwaves reflected by the surface, a measurement circuitry feeding said antenna through a hollow wave guide and said wave guide including at least an antenna wave guide member, at one end couplable to the antenna and at its other end having an opening in an intersection across the wave guide, wherein the radar level gauge further comprises: a dielectric barrier extending along said intersection across the opening of said antenna wave guide member for non-conductively separating said antenna wave guide member from the measurement circuitry, said dielectric barrier having a first side facing the wave guide in a direction towards the antenna wave guide member and said dielectric barrier having a second side facing a direction substantially away from said antenna wave guide member.

Abstract: An antenna device in a radar-based level gauge mounted at an opening in a roof of a tank, the antenna device comprising at least one elongated radiating structure, which has a length that is substantially larger, preferably more than 3-5 times longer, than a maximum cross-sectional length dimension of the opening; is oriented in a non-vertical position; and is configured and fed to produce an essentially vertical radiation beam directed downwards in the tank. Preferably, the antenna device is foldable and is inserted into the tank through the opening and oriented in the non-vertical position by means of folding the radiating structure.

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: 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.

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: 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.

Abstract: A method for radar-based gauging of the level of a substance in a tank (13) having at least one interfering structure, e.g. a beam (16a); an agitator (16b) or a tank side wall (16c), comprises transmitting a microwave signal in a predetermined polarization state (LHCP) towards the surface (14) of the substance and the at least one interfering structure; detecting, separately in two different polarization states (LHCP, RHCP), microwave signals (32, 33, 34) as reflected against the surface of the substance and against the at least one interfering structure; distinguishing based on signal strengths of the microwave signals detected separately in the two different polarization states, the detected microwave signal (32), which has been reflected against the surface of the substance; and calculating based on a propagation time of the distinguished microwave signal the level of the substance in the tank.

Abstract: A method for radar-based gauging of the level of a substance in a tank (13) having at least one interfering structure (16a-c), comprises the steps of: (i) transmitting a microwave signal in a plurality of radiation lobes (15a-b; 15a-d), each of which being individually directed towards the substance and at least one of which being directed towards the interfering structure; (ii) for each of the radiation lobes detecting temporally resolved the microwave signal as reflected against the substance, and for at least one of the lobes detecting the microwave signal as reflected against the interfering structure; (iii) based on signal strengths of the detected microwave signals, distinguishing the detected microwave signals, which have been reflected against the substance; and (iv) based on a propagation time of at least one of the microwave signals distinguished as those, which have been reflected against the substance, calculating the level of the substance.

Abstract: A method for radar-based gauging of the level of a substance in a tank (13) having at least one interfering structure (16a-c), comprises the steps of: (i) transmitting a microwave signal in a plurality of radiation lobes (15a-b; 15a-d), each of which being individually directed towards the substance and at least one of which being directed towards the interfering structure; (ii) for each of the radiation lobes detecting temporally resolved the microwave signal as reflected against the substance, and for at least one of the lobes detecting the microwave signal as reflected against the interfering structure; (iii) based on signal strengths of the detected microwave signals, distinguishing the detected microwave signals, which have been reflected against the substance; and (iv) based on a propagation time of at least one of the microwave signals distinguished as those, which have been reflected against the substance, calculating the level of the substance.

Abstract: A method for radar-based gauging of the level of a substance in a tank (13) having at least one interfering structure, e.g. a beam (16a); an agitator (16b) or a tank side wall (16c), comprises transmitting a microwave signal in a predetermined polarization state (LHCP) towards the surface (14) of the substance and the at least one interfering structure; detecting, separately in two different polarization states (LHCP, RHCP), microwave signals (32, 33, 34) as reflected against the surf ace of the substance and against the at least one interfering structure; distinguishing based on signal strengths of the microwave signals detected separately in the two different polarization states, the detected microwave signal (32), which has been reflected against the surface of the substance; and calculating based on a propagation time of the distinguished microwave signal the level of the substance in the tank.

Abstract: An antenna device in a radar-based level gauge mounted at an opening in a roof of a tank, the antenna device comprising at least one elongated radiating structure, which has a length that is substantially larger, preferably more than 3-5 times longer, than a maximum cross-sectional length dimension of the opening; is oriented in a non-vertical position; and is configured and fed to produce an essentially vertical radiation beam directed downwards in the tank. Preferably, the antenna device is foldable and is inserted into the tank through the opening and oriented in the non-vertical position by means of folding the radiating structure.

Abstract: A microwave signal that varies linearly in frequency through a sweep period is radiated to and reflected back from a target body. In one mixer the directly generated signal is mixed with the reflected signal to produce a difference frequency corresponding to distance; another mixer mixes the directly generated signal with the same signal delayed for a constant time, to produce a reference difference frequency. Each difference frequency is digitized as a pulse train. The sweep period is divided into successive short time intervals, each of which can begin with a pulse of the lower frequency train and to each of which is assigned a numerical weighting factor, said factors for successive intervals differing stepwise in value. Pulses of each train occurring during each such interval are multiplied by the factor for the interval. All such multiplied pulses are counted through the sweep period to obtain a pair of pulse totals, and a quotient relationship between those totals gives an accurate measure of distance.