A novel compact four element Multiple Input Multiple Output (MIMO) antenna is proposed. The antenna is composed of four E-shaped patch elements and operates at 5.8GHz. The single E-shaped patch antenna, operate at this frequency is designed using the invasive weed optimization algorithm. This algorithm is then applied to design the selected orthogonal polarization arrangement for two and four element MIMO antenna for high degree of isolation. In order to measure the array performance under MIMO signaling conditions a multi-port metric is used to characterize the compact array rather than the scattering matrix characterization.