Hybrid RF antenna-solar cell for ground-based space solar power systems

A transparent antenna integrated with a solar cell is proposed for use in hybrid RF energy harvesting and photovoltaic (PV) systems. The antenna is designed by incorporating a mesh grid into a proximity-coupled patch antenna, allowing light to pass through while maintaining the ability to receive RF power in the 5 GHz band. Simulations show that the antenna resonates at approximately 5.6 GHz, with a-10 dB bandwidth of 12.7 % and a gain of 7 dBi. An RF energy harvesting circuit, also operating at 5 GHz, is evaluated for integration with the antenna and solar cell. This circuit, based on Schottky diode rectification, achieves a maximum power conversion efficiency of 50 %. Experimentally, the antenna's impedance matching and bandwidth are significantly reduced when tested without the solar cell but improve when positioned 5 mm above it. The measured RF harvesting efficiency using the integrated system is just below 30 %. Additionally, the solar cell retains about 80 % of its standalone efficiency when combined with the transparent antenna. This reduction in photovoltaic performance may limit the system's applicability depending on energy collection priorities. However, the proposed hybrid RF-solar system shows promise, particularly for array configurations, and could benefit from further improvements using more transparent conductive materials in the antenna design.