Shape optimization method for curved-groove DGS of MIMO antenna-array based on the trigonometric function expansion

Abstract

In this paper, a shape optimization method for Multiple-Input Multiple-Output (MIMO) antenna-array with curved-groove defect ground structure (DGS) is proposed to improve the decoupling performances and maintain the radiation performances of array. The curved-groove DGS is depicted by the irregular shaped neutral-line and the neutral-line displacement shifted along the positive and negative y-axis directions. The curve shape function of the neutral-line is constructed and expressed as a trigonometric series. Thus, the factors corresponding to the trigonometric function expansion are used as the shape description parameters. The proposed method is to achieve the desired array performances by optimizing the shape description parameters of the curved-groove DGS. The parametric modelling is established based on the relationships between the performances and the shape description parameters, and the optimization problem is effectively solved by GA. A typical numerical example, i.e., a 2 × 1 MIMO array (36.9 × 24 × 1.6 mm3), verifies the effectiveness of the proposed method. The results show that, compared with non-DGS and the linear-groove DGS, the optimized curved-groove DGS can effectively suppress the mutual coupling of 37.92 dB and 21.73 dB, respectively, while ensuring that the array has the excellent performances and covers the predetermined WLAN frequency range (5.725 GHz ~ 5.825 GHz).