28GHz-43GHz Nadir/Near-Nadir (~70-90 degrees wrt horizontal) Low Probability of Intercept Radio Frequency Direction Finding/GeoLocation Capability

In this NAVY SBIR Phase I program, we propose a radio frequency (RF) direction finding sensor for low probability of intercept (LPI) RF radar system. This sensor consists of a dielectric fisheye lenses and an innovative focus plane detector array (FPDA). The fisheye lenses, as a RF antenna, have been broadly used in camera and electronic-optical systems (from visible to infrared wavelength). In this program, using dielectric materials such as teflon or sapphire, we will fabricate fisheye lenses operable in RF/millimeter wave regions. The lenses can project the RF signal over a semi-sphere onto its focus plane. A novel FPDA based on emerging spintronic devices, with each element being much smaller than 0.1 mm, will accurately detect the diffracted field distribution produced by the lenses. The center of the distribution is related to the direction of the incident waves. The direction can thus be extracted from the position of the distribution in the focus plane and parameters of the fisheye lenses.