In this paper, a modified square slot antenna with modified radiating patch, for UWB applications is proposed. The proposed antenna consists of a square radiating patch with a double fed structure and a ground plane with a pair of L-shaped slots which provides a wide usable fractional bandwidth of more than 140% (3--18 GHz). By optimizing the L-shaped slots dimensions and rectangular slot width, the total bandwidth of the antenna is greatly improved. The designed antenna has a small size of 35×35 mm2.
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