This study presents a high-gain, single-feed, wideband, and dual-band antenna covering the complete 2.4 GHz and 5.2 GHz Wireless Local Area Network (WLAN) frequency spectra. The proposed design features two nested radiators: an inner E-shaped patch operating at the higher (5.2 GHz) band and an outer rectangular patch for the lower (2.4 GHz) band. These radiators are tightly coupled to enhance the bandwidth at 5.2 GHz, while parasitic elements are integrated into the outer radiator to ensure full coverage of the 2.4 GHz band. A single-feed mechanism is employed to simplify the feeding structure and fabrication, thereby reducing overall costs. A grounded pin is utilized for band isolation, whereas the strong coupling between the inner and outer patches enables precise control and expansion of the operational bandwidths. The prototype was fabricated and measured, demonstrating -10 dB impedance bandwidths of 2.39–2.51 GHz and 4.95–5.82 GHz for the lower and higher bands, respectively. The antenna maintains a low profile with dimensions of 77 mm × 75 mm × 6.5 mm and achieves measured peak gain values of 7.8 dBi and 7.5 dBi for the lower and higher bands, respectively. Furthermore, the radiation patterns exhibit stable directional characteristics, indicating high isolation between the bands. The experimental results confirm that the proposed antenna fully spans 2.4 GHz and 5.2 GHz spectra, meeting key design objectives: wideband operation, compact size, high gain, and stable radiation performance. These distinct advantages make antenna a suitable candidate for next-generation WLAN routers, MIMO access points, and high-efficiency WLAN transceivers.