Reduction of mutual coupling between millimeter-wave cylindrical DRA using a soft surface for mimo applications

This paper presents studies on the effects on the mutual coupling of a soft surface constituted by a plate formed by alternating PEC/PMC strips. The mutual coupling is evaluated between two cylindrical DRAs separated by 0.5 λ operating at millimeter-waves. The soft proposed surface is basically a microstrip implementation of the corrugated surface where the depth of the corrugation is λ/4 leading to PMC boundary condition on the top of the corrugation. A 15.5 dB minimum mutual coupling reduction is observed at 64 GHz. A superstrate is also used to increase the gain to compensate the losses and oxygen absorption at 60 GHz. Simulations of S parameters and gain are obtained using HFSS and confirmed the principle of mutual coupling reduction by the current soft surface. This DRA array is suitable for millimeter -wave MIMO applications.