  It is expected that a radio signal in the microwave range is produced in the
atmosphere due to molecular bremsstrahlung initiated by extensive air showers.
The CROME (Cosmic-Ray Observation via Microwave Emission) experiment was built
to search for this microwave signal. Radiation from the atmosphere is monitored
in the extended C band (3.4--4.2 GHz) in coincidence with showers detected by
the KASCADE-Grande experiment. The detector setup consists of several parabolic
antennas and fast read-out electronics. The sensitivity of the detector has
been measured with different methods. First results after half a year of data
taking are presented.
