A measurement setup for measuring attenuation through an irregular surface of a device under test, comprising: - a reference reflector; - a three dimensional imaging system having a field of view, the three dimensional imaging system being configured to use electromagnetic signals in the frequency range of a radar system; the measurement setup having a reference state and a measurement state; the imaging system, in the reference state, being configured to take a reference image of the reference reflector; the imaging system, in the measurement state, being configured to take a measurement image of the reference reflector while the device under test is arranged between the imaging system and the reference reflector; the imaging system being further configured to compare the images taken in the reference state and the measurement state to determine the attenuation of the device under test; characterized in that the reference reflector has a collection of diffuse scattering members; and in that the measurement setup comprises a positioning system; wherein the positioning system, in the reference state, is configured to position the reference reflector without the device under test in the field of view of the imaging system; and wherein the positioning system, in the measurement state, is further configured to position the reference reflector and the device under test in the field of view of the imaging system, the device under test being located between the imaging system and the reference reflector. - a reference reflector; - a three dimensional imaging system having a field of view, the three dimensional imaging system being configured to use electromagnetic signals in the frequency range of a radar system; the measurement setup having a reference state and a measurement state; the imaging system, in the reference state, being configured to take a reference image of the reference reflector; the imaging system, in the measurement state, being configured to take a measurement image of the reference reflector while the device under test is arranged between the imaging system and the reference reflector; the imaging system being further configured to compare the images taken in the reference state and the measurement state to determine the attenuation of the device under test; characterized in that the reference reflector has a collection of diffuse scattering members; and in that the measurement setup comprises a positioning system; wherein the positioning system, in the reference state, is configured to position the reference reflector without the device under test in the field of view of the imaging system; and wherein the positioning system, in the measurement state, is further configured to position the reference reflector and the device under test in the field of view of the imaging system, the device under test being located between the imaging system and the reference reflector. the measurement setup having a reference state and a measurement state; the imaging system, in the reference state, being configured to take a reference image of the reference reflector; the imaging system, in the measurement state, being configured to take a measurement image of the reference reflector while the device under test is arranged between the imaging system and the reference reflector; the imaging system being further configured to compare the images taken in the reference state and the measurement state to determine the attenuation of the device under test; characterized in that the reference reflector has a collection of diffuse scattering members; and in that the measurement setup comprises a positioning system; wherein the positioning system, in the reference state, is configured to position the reference reflector without the device under test in the field of view of the imaging system; and wherein the positioning system, in the measurement state, is further configured to position the reference reflector and the device under test in the field of view of the imaging system, the device under test being located between the imaging system and the reference reflector.