A MIMO antenna with ACS- asymmetric coplanar strip feeding technique with compact size for UWB applications of band-notched features is presented. The proposed MIMO antenna contains two orthogonally placed rectangular-shaped radiating elements. The orthogonal mechanism of placement of radiating elements provides a good amount of isolation from 3.09 GHz to 11.13 GHz. The size of the antenna is 27 × 27 mm2. The isolation is more than 17 dB for most of the UWB range. The proposed MIMO antenna represents nearly omnidirectional radiation pattern and low value of envelope correlation coefficient. Because of the usage of ACS feeding techniques, the antenna size is reduced, and it is a uniplanar structure. The diversity performance of the MIMO antenna is explained in terms of ECC-Envelope Correlation Coefficient, DG-Diversity Gain, and TARC-Total Active Reflection coefficient.