A recently developed 220GHz incoherent radar has potential for remote sensing of low reflectivity atmosphere targets in
Cloud Chamber. Stepped frequency system is used and bandwidth 10GHz. Preliminary reflectivity measurements of
clouds for ranges between 0.2m~4m in narrow Cloud Chamber. The instrument is briefly described. Highlighting
uncertainties due to highly variable attenuation and signal interference. Then the results of investigations of the
transmitter, receiver, Antennas, as well as the atmospheric Propagation Effects are presented. The results of this effort
demonstrate that the radar is a stable, sensitive, system capable of providing accurate power for clouds.
Stepped frequency pulses can be applied in Terahertz radar system, which has been proven by simulation.
The stepped frequency THz radar can provide centimeter accuracy. The theory of stepped frequency pulse
imaging is introduced, and the model is set up. According to the range-doppler algorithm, some results can
be got. At last, The THz imaging system is designed.