The CHILL radar is an advanced, transportable dual-polarized dual-wavelength (S- and X-band) weather radar system. The radar utilizes a custom-designed, 8.5-meter (28 feet) diameter parabolic dual-offset Gregorian reflector antenna. This unique design outperforms traditional radar antennas as it mitigates the effects of side lobes in the received signal. When measured, the side lobes were found to be less than -50 dB in S-band and less than -70 dB in X-band. The radar signal is transmitted in coaxial beams with a 1.1° beam width for S-band and a 0.3° beam width for X-band. Two dual Klystron transmitters generate the signal for the S-band frequency (one for each polarization orientations) while a single Magnetron transmitter is used for the X-band frequency (which drives both polarization channels). The frequencies are transmitted through separate feed horns. The co-polar and cross-polar components of the received signal are processed into multiple data outputs. These outputs include conventional meteorological moments (Reflectivity, Differential Reflectivity, Specific Differential Phase, Cross-Polar Correlation, etc.), covariances, and in-phase and quadrature voltage time series; all of which are generated by a state-of-the-art digital signal processor.

The air-inflated radome surrounding the CHILL Radar was designed by engineers from the CSU RF, 5G, and Radar Labs. The reinforced nylon shell protects all of the CHILL radar’s sensitive electro-mechanical devices from the elements. It has an equatorial diameter of 22.3 meters and a maximum height of 16.2 meters. Multiple air vents surround the inside of the radome. These act as the pneumatics keeping the radome consistently inflated throughout each day.

The CHILL radar is operated through an interactive radar control system. It communicates to the radar via a TCP/IP connection so that both local and remote users can access and control the radar in real-time. The CSU RF, 5G, and Radar team maintains an archive of each data collection as well for post-case study and analysis.

The goal of CHILL research is to advance developments in radar meteorology, RF engineering and remote sensing by serving as an advanced research instrument and giving graduate students the unique opportunity to gain hands-on experience with applied signal processing, full-scale system design, and atmospheric analytics.