One of the two identical exposure units viewed from top. From an antenna in the middle (under the central plate; not visible in this picture) electromagnetic fields were fed into the radial waveguide and absorbed by either the animals in the cages or by absorbers at the boundaries of the waveguides. Each of the upper segments had a trapezoidal opening to allow for removing and inserting the cages. The openings were closed with wire mesh lids in order to guarantee penetration of light and gases and to prevented high-frequency electromagnetic radiation to leave or enter the exposure unit. Water bottles were placed outside the waveguides to prevent unwanted absorption.