High-Gain Single-Layer Circularly Polarized Antenna With Integrated L-Shaped for Multiband Wireless Applications

Abstract

In this paper, a high-gain multiband antenna with circular polarization in a single-layer design is developed for the 5G, WiMAX, and WLAN bands. The proposed antenna incorporates novel L-shaped elements strategically placed to improve its performance. These elements change the current distribution within the proposed design and allow operation in multiple TM modes over different frequencies. A theoretical analysis is also presented to calculate the TM modes at each resonant frequency to gain a better understanding of the antenna's performance. An equivalent circuit of the proposed antenna is developed to accurately verify the operating bands. The results show that the antenna supports multiple resonant modes, including TM₁₁, TM₀₂, TM₃₁, and TM₂₁, enabling high gains of 8.5, 7, 11.5, and 7.5 dBi at 3.5, 4.6, 5.2, and 5.8 GHz, respectively, while maintaining circular polarization across all frequency bands. Compared to a conventional patch antenna, the proposed design shows an improvement in maximum gain of 4.5 dBi, an increase in radiation efficiency of up to 6%, and improvements in both multiband capabilities and circular polarization. The current distributions and E-field within the proposed antenna confirm the expected TM modes and agree well with the theoretical calculations. The proposed antenna was designed with CST software, verified with HFSS, analyzed with an equivalent circuit in ADS, and then fabricated and measured to confirm its reliability. Unlike multilayer designs, the proposed antenna provides higher gain with more than 50% reduction in printed layers and no air gaps, resulting in a significant reduction in fabrication complexity and cost. Its multiband capability, high efficiency, and low-cost fabrication make it a strong candidate for modern wireless systems.