Self-Isolated Multiple-Input-Multiple-Output Antenna for mm-Wave Applications

A low-cost innovative MIMO antenna configuration with minimal separation between the radiating elements and high isolation over a wide frequency band is presented. Several precisely designed slots with various forms, locations, and sizes are etched on the radiating patches to improve inter-element isolation throughout the mm-wave band of 30–41 GHz impedance bandwidth. This achieved elements isolation better than 70 dB with an inter-element spacing of 0.2 mm (0.02A at 30 GHz). The suggested self-isolation method is validated by designing a 1x2 MIMO array configuration. The innovative mm-wave antenna has the following characteristics over the desired bandwidth: high impedance bandwidth (30%) and low mutual coupling (70 dB). To the authors' knowledge, the present design is the first to demonstrate such broadband isolation enhancement in the mm-wave frequency range without any sophisticated decoupling structure such as metamaterial or frequency-selective surface.