3-D Woven Conformal Antenna Structures

New missions require that airborne radars operate at increasing ranges with higher target resolution. This combination necessitates the cost-effective deployment of large apertures while maintaining aerodynamic performance. Externally mounted antenna arrays are not a satisfactory solution due to the large size at low frequencies, for example with UHF foliage penetration radar. Another approach employs copper-on-Kapton® (or RF-on-flex) circuits adhered to composite airframe wings and fuselages. However, Kapton® does not bond well to composites and requires delicate surface treatments that disrupt the manufacturing process while introducing delamination risks. We propose an alternate structurally-integrated conformal antenna approach employing 3D woven sheets of conductive fibers incorporating microwave array structures and through-layer structural reinforcements in a single co-cured structure. Impact resistance, fatigue tolerance and shear load carrying capability are improved with manufacturing compatible processes while overall airframe loads are reduced. The proposed work will demonstrate advanced structurally-integrated conductive fiber antenna technology and transition this technology to an airframe with the cooperation of our transition partner. During Phase I, we constructed a canonical microwave antenna using conductive fiber stitched preforms and epoxy resin transfer molding (RTM). We are currently weaving 3D antenna preforms and constructing a ten square foot radiator section for manufacturability studies. In Phase II, we will extend these results by constructing several larger radiator panels and extensively testing the RF and structural performance. With our transition partner, we will transition this technology to the LOBSTAR array on the Air Force’s Sensorcraft, and investigate other structurally-integrated antenna applications on fighter and transport aircraft as well as UAVs.