Compact 4 element Sierpinski Knopp fractal UWB MIMO antenna with dual band notch

In this communication, a 4 element ultra-wide band (UWB) multiple-input multiple-output (MIMO) antenna is presented. The total size of the proposed antenna is 40 x 40mm(2). A novel Sierpinski Knopp fractal geometry is used in the antenna radiator design to accomplish miniaturization. The antenna elements are placed orthogonal to each other. The spacing between any pair of elements is 0.11 ( being the free space wavelength at 7.15GHz). A CSRR shape like slot is etched on the radiating element to achieve dual band notch characteristics at WiMax 3.5 GHz and WLAN 5.4 GHz regions. The proposed antenna operates from 2.6 to 10.6GHz, exhibiting a reflection coefficient S-11<-10dB and an isolation better than 20dB. The MIMO antenna does not require any additional structure to improve isolation. Envelope correlation coefficient (ECC) and capacity loss (CL) are calculated to evaluate the diversity performance of the proposed antenna. The measured values exhibit better match with the simulated results.