EAGER: A Technology Demonstrator for a mmWave Rapid Scan Image Phased Array Radar for Cloud Research

Clouds play a crucial role in the Earth’s atmosphere by regulating the radiative balance, influencing precipitation patterns and intensity, and generating vertical air movements that redistribute heat, moisture, and momentum. Some aspects of cloud processes remain poorly understood, partly because the scientific community has lacked high spatial and temporal resolution measurements of clouds. Phased-array radar can help in this area, as these radars are able to rapidly scan using electronic beam steering. Phased-array radar has been used for decades in the defense sector and is expanding in use in the weather sector for precipitation observations. However, the technology has not yet been adopted for use as a ground-based cloud radar at millimeter wavelengths. This award will allow the research team to build a millimeter wavelength phased array demonstrator unit, which will examine the feasibility of a future ground-based, mobile phased array cloud radar. The downstream impact of this project will be to provide data for studies of cumulus evolution, cloud and precipitation processes, and tornado formation and wind structure. Students and early-career scientists will be involved in the design and testing of the unit, thereby providing hands-on training for the next generation of scientists and engineers. A community workshop will also be held to foster collaboration between scientists that are, or could be, using cloud radars for their research. This award is for the development of a technology demonstrator unit cell for a millimeter-wavelength rapid scan radar. Millimeter-wavelength radars are generally designed for the measurement of smaller particles, such as cloud droplets, versus traditional weather radars which measure precipitation-sized particles. While precipitation radars have employed phased-array technology with dual-polarization to rapidly scan and retrieve particle shapes, these enhancements have not been demonstrated for shorter wavelengths. This EAGER award will result in an 8x8 element array unit with a novel antenna architecture that would demonstrate the feasibility of a millimeter wavelength rapid scan imaging phased array radar. The proposed array unit-cell will be designed to have excellent co-polar match beam pattern (< 0.1 dB), high polarization isolation (< 40 dB), and large scanning performance. An over-the-air testing technique will be used to characterize and calibrate each active element in the phased array antenna in reception mode. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.