Device and method for variably attenuating an electromagnetic signal radiated by a microwave source

An attenuation device for variably attenuating an electromagnetic signal radiated by a microwave source, the attenuation device comprising:

• a cylinder formed by a cylinder wall comprising a first flange, and a second flange, wherein the cylinder wall is closed at a first end thereof by the first flange and at a second end thereof by the second flange, further wherein the cylinder wall is pierced at the first end by a liquid inlet/outlet port and at the second end by an air inlet/outlet port;
• a piston being arranged in the cylinder and being displaceable in the cylinder, wherein the piston bounds with the first flange a variable volume filled with an electromagnetic energy absorbing liquid;
• a displacement sensor for sensing a position of the piston the cylinder;
• and
• a control member for remotely controlling the displacement of the piston.