A multiband fractal ring antenna fed by capacitive coupling

In this paper, a multiband fractal ring antenna fed by capacitive coupling is presented. The antenna is designed by generating the Minkowski fractal model on around the radiating ring antenna. Especially, the antenna is fed by using a technique of capacitive coupling to achieve the impedance bandwidth for supporting the operating frequency band of wireless communication systems, including 2.45 GHz, 3.50 GHz, and 5.20 GHz, respectively. The antenna covers the operating frequency band applications of the wireless communication standard, including IEEE 802.11 a/b/g (WLAN), IEEE 802.15.1a (Bluetooth), IEEE 802.16a (WiMAX), and IMT advanced system (4G mobile communication system), respectively. Moreover, the radiation pattern is improved to propagate the omnidirectional pattern at all of operating frequency bands, due to the fractal ring. The experimental and simulated results are presented and discussed.