Extreme Offset-Fed Reflectarray Antenna for Compact Deployable Platforms

摘要

A design of a 5.8 GHz reflectarray antenna for operational conditions driven by a compact deployable unmanned aerial vehicle needy for RF systems but lacking space is discussed. Reflectarray surface is mounted on the underside of an unmanned aerial vehicle (UAV) wing allowing compressed fit in the deployment launcher. A series-fed patch array, mounted on the fuselage, is used as a feed source. The platform and its deploymentmechanism limit the reflectarray size to 11.6 lambda x 1.9 lambda. Moreover, the offset feed illuminates reflectarray at angles ranging from 14 degrees to 83 degrees contributing to the operation seldom discussed in the literature. A single-layer subwavelength unit cell composed of concentric metallic loops is adopted due to its wider bandwidth, lower sensitivity to incidence angles, and enhanced phase distribution for efficient beam control. The impact of in-flight mechanical forces and high offset angles on performance and bandwidth is also studied. A scaled prototype is fabricated and tested at 15 GHz. The measurements show an antenna gain of 17.1 dBi with distinct directive beam pointing downwards.