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 stop-bands 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 mm(2)) 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 ultra-wideband frequency band range.