Mutual coupling reduction using defected ground structure (DGS) for array applications

In this paper, a compact dumbbell shaped defected ground structure (DGS) is applied to reduce the mutual coupling between array elements with 0.47 λ₀ elements spacing. The dumbbell DGS is inserted in the E-plane between the adjacent array coupled elements to suppress the pronounced surface waves. A four-element array with dumbbell shaped DGS is designed, fabricated on a substrate with dielectric constant of 10.2 and thickness of 1.27mm and measured. The results show that a reduction in mutual coupling of 35.6 dB is obtained between elements at the operation frequency of the array. The microstrip arrays with and without DGS are studied by the waveguide simulator method and fabricated by photolithographic technique. The analysis indicates that increasing number of dumbbells reduces the mutual coupling between elements. However, the gain and bandwidth are reduced. The results agree with those obtained by the waveguide simulator method.