Researchers at Purdue University have developed an instrument/software that allows remote sensing of surface soil moisture from an airborne instrument using reflective electromagnetic radiation. This can provide the most efficient method to collect measurements and survey an entire field with high spatial density in a short period of time. It makes use of lower-frequency signals which are required to penetrate the soil. Resolution is determined only by the frequency of the signal, under the assumption of a near-specular reflection, not the antenna size.