Optimized Multiband Circularly Polarized Patch Antenna With Coupled Sub‐Patches for Wireless Applications

In this paper, a high gain multiband patch antenna is designed and analyzed for use in wireless applications. Coupled sub‐patches are integrated around a central hexagonal patch to extend the operating frequency and improve gain across multiple frequency bands. These sub‐patches modify the current distribution within the antenna and allow the excitation of multiple TM modes at different frequencies. An analytical study is conducted and validated through an equivalent circuit model to accurately determine the resonant frequencies of the proposed antenna. The results indicate that the proposed antenna achieves a gain of 4 dB at 3.6 GHz and a high gain of 9 dB at 5.2, 5.8, and 6.4 GHz, confirming its suitability for multiband applications. It supports multiple resonant modes, including TM₁₁, TM₁₂ and TM₃₁. The maximum gain of the antenna is improved by 3 dB due to the integration of sub‐ surfaces without an additional layer. Efficiency has also improved, from 81% with the conventional design to 95% with the coupled sub‐patches. The antenna exhibits circular polarization across all its resonant frequency bands. The proposed antenna was first designed in CST, then its performance was evaluated with HFSS to verify its design, and the equivalent circuit was validated with ADS. Finally, the antenna was fabricated and measured.