A Sapphire Substrate-Based Frequency Reconfigurable Microstrip Antenna

As a planar antenna structure, microstrip antennas leverage their low-profile geometry, conformal adaptability, and mass-production capabilities to achieve flexible multi-band, multi-polarization, or beamforming functionalities through adjustments in patch geometry, feeding methods, and substrate material parameters. These antennas are widely used in mobile terminals, radar systems, and wearable devices. This paper proposes a frequency reconfigurable microstrip antenna design based on a sapphire substrate. By optimizing radiation patch topology and switch loading positions in conjunction with the high-frequency response characteristics of the sapphire substrate, wide-range, low-loss frequency switching is achieved. Resonant frequency reconfiguration is enabled through controlled diode activation and deactivation. The designed reconfigurable microstrip antenna achieves resonant frequencies at 5.26 GHz and 8.64 GHz, demonstrating excellent radiation performance.