Abstract: A Sonotrode for generating an ultrasonic field in industrial production processes such as chemical, food, petroleum, pharmaceutical, beverage or mining-related processes for reducing and eliminating foaming of liquid products has a compact one-piece form, wherein the sonotrode is provided with a main body part having a connector for connection with a high frequency generator and having a front face from which the ultrasonic field is directed to the desired spot or area of the product to be de-foamed, wherein the main body part has the shape of a compact block element and in that the front face is concave in shape in relation to a product surface such that the ultrasonic field is focused and directed to a specific area of a product foam to be treated in a concentrated form compared to a non-focused ultrasound.