Compact CPW-fed UWB MIMO antenna with a novel modified Minkowski fractal defected ground structure (DGS) for high isolation and triple band-notch characteristic

A compact printed ultra-wideband (UWB) multiple input multiple output (MIMO) antenna with coplanar waveguide feed for portable UWB applications is presented. The radiator and ground plane of the antenna are etched with an overall size of 26.75mmx41.5mm. The UWB MIMO antenna consists of two planar identical monopole antenna elements and a novel modified Minkowski fractal defect is introduced in the ground plane for enhancing the isolation of the MIMO system. The proposed antenna has an impedance bandwidth (for |S-11|<-10dB) ranging from 3.1 to 11.5GHz (VSWR2) and an isolation of more than 15dB is achieved between the adjacent planar monopoles. The band rejection phenomenon in wireless local area network band is achieved by etching rotated C-shaped slots from the respective patches. Also, two identical rectangular slots are etched on the respective ground planes which enhances the lower UWB bandwidth and cause interference suppression at Wi-Max and C-band (3.3-3.7 and 3.7-4.2GHz), respectively. A further improvement in isolation from 14.71 to 21.81dB is achieved by the addition of parallel rectangular strips at the back side of the antenna. Acceptable agreement is obtained between the simulated and measured antenna performance parameters.