The Experiment consisted of joint work of three detectors, called Twin-Horn Microwave Receivers, or Radiometers.

Each receiver carried out observations in the same region of the sky, but in a different frequency range. The three receivers were tuned respectively at 10, 15 and 33 Giga Hertz.

The three radiometers working at different frequencies were scaled in size, so as to reproduce the same instrument response on the sky.