Dual band-notched small monopole antenna with bandwidth enhancement by means of defected ground structure (DGS) for UWB application

In this study, a small and compact dual band-notched microstrip-fed printed monopole antenna for ultra-wideband applications has been presented. This antenna consists of a square patch as radiator and a defected ground structure (DGS). In order to generate dual band-notched function, we use four slots in the ground plane. A parametric study of the proposed antenna is provided to achieve the dual band-notched by adjusting the lengths of the rectangular-shaped slots. The proposed antenna can easily adjust its stop-band functions by half-wavelength. Mainly, desired stopbands are obtained without any variation on the patch. Using of this structure on the ground plane, the impedance bandwidth is effectively improved at the higher band, which results in a wide usable fractional bandwidth of more than 134% (2.7-13.7 GHz), defined by VSWR<2, with two notched bands, covering all the 5.2/5.8-GHz WLAN, 3.5/5.5-GHz WiMAX, and 4-GHz C-bands. The constructed antenna is small (15x15 mm2) when compared with previously proposed single- and double-filtering monopole antennas with DGS in terms of slots on the ground only. The antenna has a desirable voltage standing wave ratio (VSWR) level and acceptable antenna gain for ultrawideband frequency band range.