| 摘要 |
A circuit for a radar level gauge for measuring the level of the surface of a product stored in a container, wherein the gauge includes a radar for transmitting microwave signals from a multiband antenna unit towards the surface for receiving microwave signals reflected by the surface and for determining the level based on an evaluation of the time lapsed between the received and the transmitted signals and said radar operating on at least two different frequency bands. The circuit includes: a first microwave provision means for providing a microwave signal of a first frequency band having a first center frequency, a second microwave provision means for providing a microwave signal of a second frequency band having a second center frequency. The ratio between the second and the first center frequency is quantified as at least greater than 1.5:1 and preferably greater than 2:1. Switches are operated by means of a control signal for switching the circuit to operate on said first frequency band or said second frequency band.
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