A High‐Efficiency Shared‐Aperture Dual‐Polarized Microstrip Antenna for L‐Band Remote Sensing UAVs

Current unmanned aerial vehicle (UAV)‐based remote sensing systems for soil moisture detection face several challenges, including large antenna size, low efficiency, and measurement errors caused by non‐overlapping dual‐polarization coverage. To address these issues, this study proposes an efficient and compact L‐band shared‐aperture dual‐polarized microstrip antenna design. The key innovation lies in the integration of four techniques. First, an air gap between parasitic patches and the dielectric substrate broadens the operational bandwidth. Second, a high‐impedance surface (HIS) structure suppresses surface waves, significantly improving efficiency, gain, and radiation characteristics. Third, metallic patches combined with a Chebyshev impedance matcher provide precise frequency tuning and wideband impedance matching. Finally, a compact stacked structure with a multilayer symmetric feed network enables a shared‐aperture dual‐polarized layout, overcoming coverage misalignment and size limitations typical of non‐coaxial airborne antennas. The proposed antenna achieves excellent performance in the target frequency band. It demonstrates an average efficiency of 95%, a voltage standing wave ratio (VSWR) below 1.37, a peak gain of 13.42 dB, a 3‐dB beamwidth of 44.1°, and a sidelobe level below −12.79 dB. Comparative analysis shows that this shared‐aperture design offers substantial performance improvements and establishes a new benchmark for efficient, compact dual‐polarized microstrip antennas in low‐altitude L‐band remote sensing applications.