Design, development, and calibration of a high-power UHF radar with a large multichannel antenna array

The Center for Oldest Ice Exploration (COLDEX) is an NSF-funded multi-institution collaboration to explore Antarctica for the oldest possible continuous ice record. It comprises of exploration and modelling teams that are using instruments like radars, lidars, gravimeters, and magnetometers to select candidate locations to collect a continuous 1.5-million-year ice core. To assist in this search for old ice, the Center for Remote Sensing and Integrated Systems (CReSIS) at the University of Kansas developed a new airborne higher-power version of the 600-900 MHz Accumulation Radar with a much larger multichannel cross-track antenna array. The fuselage portion of the antenna array is a 64-element 0.9 m by 3.8 m array with 4 elements in along-track and 16 elements in cross-track. Each element is a dual-polarized microstrip antenna and each column of 4 elements is power combined into a single channel resulting in 16 cross-track channels. Power is transmitted across 4 cross-track channels on either side of the fuselage array alternatingly to produce a total peak power of 6.4 kW (before losses). Three additional antennas are integrated on each wing to lengthen the antenna aperture. A novel receiver concept is developed using limiters to compress the dynamic range to simultaneously capture the strong ice surface and weak ice bottom returns. This system was flown on a Basler aircraft at the South Pole during the 2022-2023 Austral Summer season and will be flown again during the upcoming 2023-2024 season for repeat interferometry. This work describes the current radar system design and proposes to develop improvements to the compact, high-power divider and large multichannel polarimetric array used by the radar. It then proposes to develop and implement a system engineering perspective on the calibration of this multi-pass imaging radar.