In this communication, a four port MIMO antenna is proposed for multiband applications. The antenna structure is comprised with stepped-fed radiating elements. The multiple resonances are achieved with ground plane loaded with Complementary Split Ring Resonator (CSRR) and meandered line slots. The proposed antenna has hepta-band resonating behavior. The proposed antenna is resonated at the 3.5GHz, 6.5GHz, 10.9 GHz, 18GHz, 11GHz, 14GHz and 28GHz which are useful for WLAN, WiMAX, 5G Network and Radar System. The antenna is implemented on the roger substrate with overall size of 36×36 mm2. The improved isolation of up to-30 dB among the element is accomplished by orthogonal placement of the radiating element. The design of the antenna is simulated and analyzed using CST-Microwave Studio Tool. The average peak gain of the antenna is 7 dBi over the interested bands. The gain, efficiency, and operating bandwidth and isolation of the proposed antenna are also compared with the existing literature. ECC of the proposed MIMO antenna is less than 0.1 and other satisfactory MIMO performance criteria are to be considered as proposed antenna is good candidate for several wireless applications.