Uniplanar polarisation diversity antenna for ultrawideband systems

A new compact, uniplanar, polarisation-diversity, monopole-like slot antenna for ultra-wideband (UWB) systems is presented. The proposed design effectively integrates orthogonally fed slot antennas, utilising the uniplanar nature of coplanar waveguide without degrading the time-domain characteristics and diversity performance. To achieve high isolation between the ports, a strip is integrated diagonally in the ground plane. Furthermore, by loading arc shaped slot resonators on the feeding structures, the proposed antenna successfully rejects the undesired subband, assigned for IEEE 802.11a and HIPERLAN/2. The measured results demonstrate that the antenna provides a 2:1 voltage standing wave ratio (VSWR) band from 2.76 to 10.75 GHz whereas showing rejection in the frequency band 4.75-6.12 GHz, along with an inter-port isolation better than 15 dB. The proposed radiator displays a nearly omnidirectional radiation pattern, along with a moderate gain and efficiency. The envelope correlation coefficient discloses a good diversity performance across the UWB spectrum. Furthermore, the time-domain analysis shows minimum dispersion to the radiated pulse. In addition, the experimental analysis indicates that the proposed design is less disposed to the housing effects when mounted in metallic casing. All these features make the proposed antenna a viable candidate for UWB dual-polarised multiple-input-multiple-output applications.