A wide slot antenna fed by a microstrip line ended with a hexagonal tuning stub and its variation with dual band-notched function for ultrawideband operations are presented. The fundamental configuration is a rectangular slot on a printed circuit board with a low relative dielectric constant of 2.65. Three tuning stubs are employed at the edges of the slot to ensure the impedance matching. This original antenna achieves an operation bandwidth from 3.1 to 11.5 GHz with a stable gain performance and a very compact size of 22 mm×22 mm×0.5 mm. By etching a C-shaped slit and a Hilbert fractal curve slit on the original antenna without retuning, band-notched characteristics in the 3.40-3.69 GHz WiMAX band and the 5.15-5.825 GHz WLAN band can be realized, respectively. A rectangular patch is added to eliminate the spurious notched band around 10.5 GHz.
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