Design of compact planar ultrawideband antenna with dual-notched bands using slotted square patch and pi-shaped conductor-backed plane

A planar antenna with ultrawideband (UWB) performance and dual band-notched characteristics is proposed. The main features of the antenna are the compact dimensions and omnidirectional radiation across the whole band of operation. The radiator of the antenna is a slotted square patch. The ground plane is located at the bottom layer, which also includes a Π-shaped conductor-backed plane used to widen the impedance bandwidth. Dual band-notched characteristics are achieved by an inverted T-shaped strip inside the slotted radiator and a pair of mirror inverted L-shaped slots at the two sides of the radiator. The measured results of the manufactured (12 × 16 mm) antenna on 1.6 mm FR4 substrate show that the antenna operates with voltage standing wave ratio (VSWR) less than two over the frequency band from 2.5 to 10.8 GHz. That wideband is featured by the existence of two notched bands (3.23-4.3 and 5-6 GHz), where the VSWR is more than nine, aimed at suppressing any interference from IEEE802.16 WiMAX (3.3-3.6 GHz), C-band systems (3.7-4.2 GHz) and IEEE802.11a WLAN (5.15-5.825 GHz). The antenna has an omnidirectional radiation across the whole UWB as validated by the measured radiation pattern and gain.