Abstract: A simulator chamber has interior walls which have been made reflective by lining them with a very low emissivity material, such as aluminum foil. A portion of the chamber's ceiling is open to the sky and a 45.degree. sloping surface is provided beneath the ceiling opening. A relatively quiet, i.e. cold, environment at radiometric frequencies, i.e. 18 gigahertz-300 gigahertz, within the chamber results. Arranged within the chamber is an array of dynamically controlled noise sources which, when energized, emit energy at radiometric frequencies. The array is capable of simulating the radiometric appearance of particular terrestial scenes, including terrain and selected monuments or objects.