A Near-Millimeter Wave interferometric radar

Due to the paucity of high-power sources along with strong electromagnetic absorption by water vapor at frequencies between ~100 GHz and ~10 THz, there are very few radar systems operating in the terahertz range of the spectrum. Source technology, however, is improving, thus facilitating radar systems operating in this gap. The Near-Millimeter Wave (NMMW) range typically refers to frequencies from 100 to 1000 GHz, or, wavelengths straddling the transition from millimeter to sub-millimeter (3 mm to 300 μm). At the lower end of this range where components are more readily available and atmospheric attenuation is moderate an interferometric radar system for imaging surfaces up to several hundred meters has been designed and is being built. By scanning a fan beam and receiving at two displaced locations, three dimensional images of the surface topography (in range, azimuth and height) can be generated. This paper describes the design considerations for this radar and the prototype system.