OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials;Integrated Sensing and Cyber;Microelectronics The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. OBJECTIVE: Originate an additive manufacturing-based technology suitable for use in creating conformal antennas that also function as structural skins/air flow surfaces for airborne pods and wing-based Unmanned Aerial Vehicles (UAV). Also desired is the development of related techniques, which can be used for ground vehicles and drones. DESCRIPTION: Conformal antennas became popular during the conflict in Afghanistan when their lack of visual signatures provided an operational stealth advantage. Since then, the increased maturity of electromagnetic simulation codes has allowed the impact of multiple feed points on nonplanar surfaces on the frequency dependence of antenna patterns to be controlled in the design process. The same codes now allow the frequency span of periodically spaced resonant element arrays to increase from 4:1 to as much as 50:1 by implementing electrical interconnections between actual phase centers for radiation. Conformal antennas lack the need to modify the design of antenna fins. Such changes impact air flow and hence flight performance and require expensive design verification costs for both pods and UAV. Ultra-wideband antennas are also inherently more attractive than narrow band ones since many techniques exist to reconfigure wideband systems into multiple narrow band ones for cases where frequency scanning or limited operation adaptation are acceptable. Moreover, functional specific antenna fins limit the maximum production volume of a given transceiver's realization, raising per unit acquisition and logistics costs and increasing the likelihood of manufacturing delay. Thus, it is desired for wideband, conformal antennas to develop as generic packaging commodities. It is notable that additive manufacturing techniques have been used to construct complex periodic arrays, though the range may still be limited by structural and electrical properties of the inks . It is known that the addition of carbon nanotubes to various polymers change their electrical properties from insulating to conductive, though how close to high purity copper in electrical properties can be achieved is unclear, especially in a material strong enough to be used as thin shells with good structural properties. Thus, it is unknown if conformal antennas for unmanned platforms, such as pods and UAV, should be constructed as single layers with local control of the electrical conductivity or multilayered prints and using standard additive conductor structures at each feed point or slot antenna concepts. Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. owned and operated with no foreign influence as defined by 32 U.S.C. 2004.20 et seq., National Industrial Security Program Executive Agent and Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Counterintelligence and Security Agency (DCSA) formerly Defense Security Service (DSS). The selected contractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances. This will allow contractor personnel to perform on advanced phases of this project as set forth by DCSA and NAVAIR in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material during the advanced phases of this contract IAW the National Industrial Security Program Operating Manual (NISPOM), which can be found at Title 32, Part 2004.20 of the Code of Federal Regulations. PHASE I: Develop a design for a 4:1, > 90 field of view (FOV) antenna for 6 to 24 GHz on a cylindrical volume 10 in. (25.4 cm) in outer diameter and having minimal internal stiffening structure, 5 ft (1.52 m) long and with two pairs of wings that can be realized using the simulation code and manufacturing process identified in the Description. During the base, both complete the design in simulation and produce prototype planar array coupons having more than four elements. Experimentally document the electrical and structural properties of the printed materials and the functionality of these coupons as directional emitters. Identify all the roadblocks to realizing the performance objective defined in the original proposal. The Phase I effort will include prototype plans to be developed under Phase II. PHASE II: Work with the naval sponsors to refine the design into a target platform of specific operational class and functional requirements. Deliver a scaled first prototype in the Base period. An iteration thereof that addresses sponsor concerns should be completed in the Option period. This iteration is then to be flight tested during the Phase II Option with the internal volume occupied only by onboard signal emitters and any required batteries. This work is expected to be export controlled and could become classified secret. Work in Phase II may become classified. Please see note in the Description section. PHASE III DUAL USE APPLICATIONS: Focus on integration of the design concept into a particular functional system. Work with program office staff to produce further improvements to shells loaded with more realistic internal transceivers and document their functionality under fielded conditions. These shells become a generic part wherein the RF antenna characteristics are determined by connections and hardware inside the volume. Commercial applications could include hour to day-long deployments as reconfigurable extra/temporary replacement relay stations for wireless systems. Also, car collision avoidance systems use sparsely arrayed antennas on increasingly nonmetallic surfaces as active radars, while driver entertainment and assistance systems require multiple communications network capacity. REFERENCES: 1. Gojny, F. H.; Wichmann, M. H. G.; K pke, U.; Fiedler, B. and Schulte, K. Carbon nanotube-reinforced epoxy-composites: enhanced stiffness and fracture toughness at low nanotube content. Composites science and technology, 64(15), 2004, pp. 2363-2371. https://doi.org/10.1016/j.compscitech.2004.04.002 2. Jiang, Q.; Zhang, H.; Rusakov, D.; Yousefi, N. and Bismarck, A. Additive manufactured carbon nanotube/epoxy nanocomposites for heavy-duty applications. ACS Applied Polymer Materials, 3(1), 2020, pp. 93-97. https://doi.org/10.1021/acsapm.0c01011 3. Thostenson, E. T.; Ren, Z. and Chou, T. W. Advances in the science and technology of carbon nanotubes and their composites: a review. Composites science and technology, 61(13), 2001, pp. 1899-1912. https://doi.org/10.1016/S0266-3538(01)00094-X 4. National Industrial Security Program Executive Agent and Operating Manual (NISP), 32 U.S.C. 2004.20 et seq. (1993). https://www.ecfr.gov/current/title-32/subtitle-B/chapter-XX/part-2004 KEYWORDS: Distributed Antenna Arrays; Slot Antennas; Carbon Nanotubes; Additive Manufacturing; Wideband Antennas; Reconfigurable Antennas
