X-band Circularly Polarized Microstrip Array Antenna for Full Polarization UAV-SAR

In the realm of regional emergency observation and real-time, high-resolution data acquisition, there is a burgeoning interest in the development of UAV equipped with Synthetic Aperture Radar systems (UAV-SAR). However, a critical challenge lies in achieving a UAV-SAR system that meets criteria such as high resolution, lightweight design, minimized payload, power efficiency, operational viability at high altitudes, robustness in extreme environments, extended flight durations, and full polarimetric functionality.To address this challenge, our research group envisages the creation of an X-band circularly polarized UAV-SAR system, designed specifically for disaster management and environmental monitoring, leveraging the 25 kg payload capacity of the UAV platform. The effective functioning of the SAR system necessitates a broadband antenna with complete circular polarization capabilities to ensure precise observations. The antenna must also be compact, lightweight, possess high gain, accommodate broadband chirp pulse signals, and exhibit excellent antenna isolation and axial ratio (AR).To this end, we put forth a novel design featuring a 4×4 array antenna outfitted with axe-shaped radiating elements. The proposed antenna underwent rigorous simulation, fabrication, and assessment within an anechoic chamber. Additionally, an indoor polarimetric scattering SAR experiment was conducted employing canonical targets to assess the polarimetric SAR proficiency of the system equipped with the proposed antenna.