Dual-Band Frequency-Reconfigurable Dual-Polarized Patch Antenna Based on Fundamental Modes

This letter proposes a dual-band, dual-polarized antenna design through the excitation of fundamental modes in both bands. The antenna employs a square patch integrated with four reactive stubs, which serve as capacitive loadings at low frequencies to lower the resonant frequency and make the antenna compact. Simultaneously, the stubs exhibit inductive properties exciting another fundamental mode of stable radiation at the high band. In addition, frequency tunability is extended to dual-band operation maintaining the high isolation between dual polarizations. The fabricated prototype covers the frequency ranges of 2.3 GHz to 2.49 GHz and 5.05 GHz to 5.95 GHz, with a compact size of 27.5 mm × 27.5 mm × 4.8 mm. The peak realized gain ranges from 4.8 dBi to 7 dBi, and the isolation between the dual polarizations exceeds 30 dB across the operating frequency bands.