Novel Concepts for Conformal Load-Bearing Antenna Structure

Abstract : This report describes the activities undertaken by the author during his Defence Science Fellowship on the topic of Conformal Load-bearing Antenna Structure (CLAS) at the Air Force Research Laboratory, Air Vehicles Directorate, Structures Division, Advanced Structural Concepts Branch (AFRL/VASA), Multifunctional Structures Team at the Wright Patterson Air Force Base, Ohio, USA, from June 2006 to August 2007. The aim of CLAS is to enhance the performance and capability of air vehicles by integrating antennas into the load-bearing airframe structure. The author and AFRL/VASA team devised new CLAS concepts and selected one, Slotted Waveguide Antenna Stiffened Structure (SWASS), for further evaluation. In SWASS the top-hat cross-section stiffeners on thin skins or blade stiffeners in sandwich panels would serve the dual purpose of acting both as structural stiffeners and as slotted waveguide antennas. This concept was partially validated by modelling, design, manufacture and testing at the coupon level. Waveguides were manufactured from carbon fibre reinforced plastic and their insertion loss measured. Conventional AS4/3501-6 prepreg tape waveguides exhibited the lowest losses and, although these losses were well above those for metallic waveguides, they were expected to be acceptable for first generation SWASS antennas. Work is continuing to complete the validation.