Novel Compact UWB Planar Monopole Antenna Using a Ribbon-Shaped Slot

Ultra-Wideband (UWB) is a wireless communication technology that can be utilized for precise indoor positioning system. UWB is low power-consuming and resistant to complex multipath environments, thanks to a short pulse signal. Since the main desired characteristics of the UWB antennas for radio-frequency localization systems are wide bandwidth, omnidirectional radiation pattern, and low profile for simple integration with printed circuit boards, various planar monopole antennas for UWB applications were proposed to meet the requirements. In order to satisfy these conditions, in this paper, a novel compact UWB planar monopole antenna operating in 3.1 GHz–10.8 GHz is designed on FR-4 substrate. The overall size of the antenna is
$12.5\times 12.5\times $
1 mm
³
, which is
$0.129\,\,\lambda _{0} \times 0.258\,\,\lambda _{0} \times 0.01\,\,\lambda _{0}$
in free space at the lowest frequency. The transmission line is designed based on a coplanar waveguide with ground (CPWG) and vias in the CPWG are employed to eliminate non-radiating phenomenon at some specific frequencies. The shape of the radiator is modified from the hexagonal shape and a ribbon-shaped slot inside the radiator is adapted to improve the operating frequency range. The proposed UWB planar monopole antenna is fabricated and measured. The proposed antenna provides good antenna performance from 3.1 to 10.8 GHz and also the radiation patterns at various frequencies are omnidirectional pattern.