Flexible and Self-compensating Reflectarray Antenna Enabled by the Sensor-antenna Integration

Flexible antenna, which is deformable and light-weighted, paves the way for the conformal integration in many applications such as airborne, cellular and vehicular. However, current paradigm of achieving conformal integration of flexible antenna mainly relies on antenna design based on a deterministic geometry, which prevent the realization of conformal antenna with universal design for arbitrary geometries. The performance of flexible antenna is also more vulnerable to the unexpected deformation with external loading when the size of the antenna increases, which makes it difficult to realize array antenna with large scale. In this work, we demonstrate a flexible reflectarray antenna with the ability to dynamically and self-adaptively compensate the wavefront distortion caused by the deformation of antenna. By introducing a topography-acquisition sensor array in a polyimide-based reflectarray antenna with a length of 480mm and a width of 240mm, the geometry of the antenna can be monitored in real-time. The deformation condition of the antenna is then employed to guide the reconfigurability of the antenna, which is enabled by varactor diodes and compensation algorithm based on artificial neural network, to achieve stable radiation characteristics of the antenna with various deformations. The experiment results show that the deviation of beam direction and gain are less than 2° and 1.6dB (3.2GHz ±200MHz) when applying time-varying loading below 50Hz. Wireless data transmission with the proposed antenna is also demonstration with dynamic deformations. This work is expected to provide a universal framework for achieving the robustness of flexible antenna to the deformation in conformal applications.