Design of a Broadband Microwave Power Detector Based on Metasurfaces With Linear Response and Thermal Sensing

In this study, a broadband microwave power detector based on an energy-harvesting metasurface is proposed, enabling efficient detection of incident microwave power density via electromagnetic-to-thermal energy conversion. The device comprises a resonant ring, a dielectric substrate, a metallic reflective layer, and four 50 Ω load resistors. By leveraging a multi-mode resonant structure, the detector achieves broadband absorption exceeding 80% over the frequency range of 2.284–5.945 GHz, with absorption rates exceeding 90% within the 2.482–5.893 GHz range. Notably, high absorption efficiencies of 88.59% and 97.21% are achieved at the key frequencies of 2.45 GHz and 5.8 GHz, respectively, with an average energy harvesting efficiency reaching 98%. Simulation results confirm a strong linear correlation between the temperature of the load resistors and the incident power density, with response rates of 1.12 and 1.33 K/(mW/cm²) at 2.45 GHz and 5.8 GHz, respectively—substantially outperforming traditional single-frequency detectors. Moreover, the device maintains high robustness under polarization angles ranging from 0° to 60° and varying low-frequency incidence angles. Compared to conventional detection schemes, the proposed design offers distinct advantages, including structural simplicity, low cost, and high scalability. When combined with thermal imaging technology, the system enables contactless and visualized monitoring of microwave power distribution, providing a practical and efficient power detection solution for large-scale wireless energy transmission systems such as space-based solar power stations.