This Small Business Innovation Research (SBIR) Phase II research project will consist of the design, development, and manufacturing of a novel low-multipath GPS antenna for high accuracy applications. This antenna prototype utilizes two key technologies: (1) a new design of GPS antennas using high-technology materials and manufacturing methodologies, that enables low-multipath, gain control, multi-frequency, tunability, and size reduction; and ( 2) a novel geometry of the metal ground plane to further rejects multipath interference. At the end of Phase II the anticipated results include, multipath error mitigation uniformly at L-Band, gain improvement at low elevation angles up to 10 dB with respect to choke ring antennas, multi-frequency operation at GPS and GALILEO frequencies, and at least 33% smaller size than other commercial low multipath antennas.<br/><br/>Because multipath interference reduction significantly improves GPS accuracy, the proposed multi-frequency GPS antenna will benefit the international scientific community that relies on high precision GPS for new advances in Earth and atmospheric sciences. In particular, the novel substrate antenna will allow accurate real-time GPS measurements, otherwise impossible, in support of the NSF funded EarthScope program, that is intended for the study of the structure and evolution of the North America continent using a network of GPS receivers.