A Novel Multiband Fractal Antenna for Wireless Application

This paper proposes a novel multiband antenna using circle and triangle fractals for wireless application. By cutting a triangle slot in the circular monopole, a novel fractal method of the circular nested triangle structure is presented. The above structure is iterated four times, which forms the proposed fractal antenna. The antenna adopts the microstrip feeding method. In order to improve out band rejection and expand bandwidth, a ring resonator is designed on the back of the dielectric plate. The designed antenna covers 1.8 GHz–2.9 GHz applied to Bluetooth, TD-SCDMA, WCDMA, CDMA2000, and LTE33-41, 3.4 GHz–4.6 GHz applied to LTE 42/43 and WiMAX, and 5 GHz–5.6 GHz applied to WLAN. The substrate is FR4 with a dielectric constant of 4.4 and a loss tangent of 0.02. The size of the fabricated antenna is 87.5 × 61 × 1.6 mm. The measured pick gain achieves 2.98 dBi, 2.58 dBi, and 3.34 dBi at 2.6 GHz, 3.8 GHz, and 5.3 GHz, respectively. The measurement and simulation results are in good agreement, which verifies the rationality of the design.