Achieving a compact-size, high-performance antenna covering the K-Ka bands is not an easy task. A Multi-Input Multi-Ooutput (MIMO) funnel-shaped wideband antenna for RADAR applications is introduced in this paper. One of the flaws of the MIMO antenna is its size. In modern communications, the space given for an antenna is minimal due to the compact size of the communication devices. In the present work, by keeping space occupancy in mind, two element compact antennas, with 76×34×1.6 mm3 size, operating bandwidth of 24.7 GHz, isolation greater than 18.9 dB, and gain of 9.26 dB, were designed. The designed funnel shape patches and defective ground structure provide better gain and isolation, therefore allowing for larger bandwidth. Furthermore, the simulated and measured results are in good agreement.