This paper proposes a multiple‐input multiple‐output (MIMO) antenna design with 3‐port excitation. The antenna has a ground size of 260 × 200 mm2 and a portion size of 60 × 10 × 0.8 mm3. The design of the MIMO antenna is achieved using two inverted F‐type coupled‐fed monopole antennas and a loop antenna acting as an isolation element. The third antenna is designed as the isolation element, and acts not only as an isolation element to improve the mutual coupling between two antennas operating within the LTE 2300/2500/WLAN 2.4 GHz/5G C‐band, but also a radiator operating in the 5G C‐Band (3.4‐3.6 GHz). Such 3‐port MIMO antennas can be achieved by properly selecting the dimensions of the antennas and isolation element. The two coupled‐fed monopole antennas are operating in the LTE 2300/LTE 2500/WLAN 2.4/5G C‐Band bands, and the third antenna operates in the 5G C‐Band.