Uniplanar dual-band printed compound loop antenna for WLAN/WiMAX applications

A novel uniplanar dual-band printed compound loop antenna for WLAN/WiMAX applications is proposed. The proposed antenna consists of a small inner rectangular ring, an outer rectangular loop with three slits and a parasitic strip on one side of the substrate. Fed by the inner ring and collaborated with double rings and the parasitic strip, three resonant frequencies can be achieved, where the parasitic metallic strip between the rings can not only induce a new middle resonant frequency but also improve the impedance matching at the low-frequency band greatly. By magnetic-electrical coupling, dual-band performance with the lower-wide band covering 2.37-3.78 GHz and the upper-frequency band covering 5.15-5.85 GHz can be obtained. It is experimentally demonstrated that the proposed antenna with the performance of broadband (covering 2.4/5 GHz WLAN including 2.4-2.484 GHz, 5.15-5.825 GHz and 3.5/5 GHz WiMAX including 3.4-3.69 GHz, 5.25-5.85 GHz, respectively), good dipole-like radiation characteristics, stable gain and high-radiation efficiency, is an excellent candidate for WLAN/WiMAX applications.