A Simple Compact Cross-Band Reconfigurable Microstrip Patch Antenna Array

This letter presents a low-profile, multilayer planar microstrip patch antenna (MPA) array with cross-band frequency reconfigurability. The compact single-port MPA element, sized 7.8 mm × 7.8 mm × 3 mm, operates in the C and K_u bands and comprises a driven patch surrounded by five parasitic patches interconnected via four PIN diodes for frequency switching. A compact interelement spacing combined with a novel Γ-shaped coupled-feed structure is utilized to harness mutual coupling, thereby extending the attainable frequency reconfiguration range. An 8 × 8 antenna array was fabricated and experimentally characterized, demonstrating central operating frequencies of 4.9 GHz and 17.8 GHz in two distinct reconfigurable states. The design achieves a frequency reconfiguration ratio of 4.06:1, covering a total frequency reconfigurability span of 14 GHz across noncontiguous bands. Measured results show strong agreement with simulations, validating the proposed concept.