We present a newly developed high-resolution frequency-modulated continuous-wave (FMCW) radar system for sounding the sub-ice topography. The system, working in the frequency range from 200 to 400 MHz, was developed to measure thickness and internal layers in cold ice with a resolution better than 1m. This system has the potential to measure accumulation rates, an important input for improved knowledge of the mass balance of polar ice sheets. First measurements for the test, calibration and optimization of the new ice sounder were made in December 2005 near the Ellsworth Mountains, specifically in Patriot Hills, West Antarctica, at 80°18'S, 81°22'W. The complete radar system was installed on a ski-mounted support frame, and towed by hand across the ice surface. The measurement results show the capability of this system to measure ice thickness up to 1000m and to define internal layers within the ice body.