The HIAPER cloud radar (HCR) is an airborne, polarimetric, millimeter-wavelength radar that serves the atmospheric science community by providing cloud remote sensing capabilities to the NSF/NCAR HIAPER aircraft.
HCR provides unique observations of the formation and evolution of clouds. Its high sensitivity allows for the precise detection of liquid and ice clouds, aiding our understanding of the effects of clouds on the regional and global weather and climate. Derived scientific products, such as melting layer altitude, convective and stratiform echo type, or hydrometerorparticle identification, provide additional information on the ovserved cloud and precipitation processes.

In a pod-based design a single lens antenna is used for both transmit and reception. The transceiver uses a two-stage up and down conversion super-heterodyne design. The transmit waveform, from a waveform generator, passes through the two-stage up-conversion to the transmit frequency 94.40625 GHz. It is then amplified by an extended interaction klystron amplifier (EIKA) to 1.6 kW peak power. System performance on transmit and receive paths is closely monitored using a coupler and a noise source. Both computed moments (reflectivity, velocity, spectral width, etc.) and raw in-phase and quadrature time series data are archived in HCR.