The Department of Defense, specifically the U.S. Air Force, is seeking proposals for the SBIR topic titled "APPEAR - Aperture Projects for Passive Engineering and Advanced Research." The objective of this initiative is to explore and develop innovative antenna aperture techniques and technologies that enhance passive sensing capabilities for detecting various signals of interest, particularly in contested environments. This effort is critical for advancing the Air Force's operational effectiveness by leveraging commercial-off-the-shelf (COTS) solutions and minimizing active transmissions to maintain strategic advantages. Proposals are due by May 21, 2025, with the opportunity to directly transition to Phase II for those who demonstrate prior relevant experience. Interested parties can find more information and submit proposals through the provided source link: SBIR Topic.