To meet United States Special Operations Commands (SOCOM) need for a small form factor antenna that enables Ultra High Frequency (UHF) satellite communications (SATCOM) for small handheld devices, Epirus proposes to investigate a planar two-arm spiral antenna with a hi-impedance (Hi-Z) ground plane that optimizes for size and meets SOCOMs stated performance objectives. The circular antenna possesses a 15 cm diameter and a depth of less than 5 cm. A conformal patch antenna on high dielectric constant substrate would be narrowband and not meet the 225 - 400 MHz requirement, but a spiral antenna on magnetic material substrate would enable wide bandwidth in a small volume. The spiral antenna proposed by Epirus can provide more than 3x reduction in the size and height over current commercially available UHF SATCOM antennas. For this effort, Epirus proposes to conduct a feasibility study for the proposed planar spiral antenna to support SOCOMs UHF SATCOM operations, prepare a bill of materials (BOM) and design for phase II prototype development, and deliver its results in a final report. Epirus, Inc. has reviewed the BAA and supporting documentation and has determined that there are no organizational conflicts of interest (OCI) concerns anticipated in the performance of this technical ef