Design process of a miniaturized reconfigurable antenna for 5G sub-6 GHz and diverse applications

This article presents a compact crab-shaped gain-reconfigurable antenna (CSRA) designed for 5G sub-6 GHz wireless applications. The antenna achieves enhanced gain in a miniaturized form factor by incorporating a hexagonal split-ring structure controlled via two radio frequency (RF) positive-intrinsic-negative (PIN) diodes (BAR64-02V). While the antenna is primarily designed to operate at 3.50 ​GHz for sub-6 GHz 5G applications, RF switching enables the CSRA to cover a broader frequency spectrum, including the S-band, X-band, and portions of the Ku-band. The proposed antenna offers several advantages: It is low-cost (fabricated on an FR-4 substrate), compact (achieving 64.07 ​% size reduction compared to conventional designs), and features both frequency and gain reconfigurability through digitally controlled PIN diode switching. The reflection coefficients of the antenna, both without diodes and across all four switching states, were experimentally validated in the laboratory using a Keysight FieldFox microwave analyzer (N9916A, 14 ​GHz). The simulated radiation patterns and gain characteristics closely matched the measured values, demonstrating an excellent agreement. This study bridges the gap between traditional and next-generation antenna designs by offering a compact, cost-effective, and high-performance solution for multiband, reconfigurable wireless communication systems. The integration of double-split-ring resonators and dynamic reconfigurability makes the proposed antenna a strong candidate for various applications, including S-band and X-band systems, as well as the emerging lower 6G band (7.125–8.400 ​GHz).