Mitigation of Mutual Coupling in Bent Monopole Arrays

Abstract

Sufficient electromagnetic isolation between antenna array elements is necessary in low-profile arrays, where elements are closely spaced. This study examines techniques to reduce mutual coupling in a flexible monopole antenna array, which may need to be bent depending on the application. Mutual coupling is more significant in arrays when they are bent. Three parasitic geometric shapes are introduced and combined to reduce mutual coupling in arrays of various aperture sizes. The flexible array is optimized using a combination of the three parasitic structures, yielding an average mutual coupling of $-21$ dB in a planar configuration. To validate the effectiveness of the proposed structure, an $8\times 1$ array has been manufactured using cotton as a substrate. The bent array has demonstrated a bandwidth of 23% with mutual coupling reduced from $-14$ to $-22$ dB by adding the proposed structures. The flexible design with low coupling between adjacent elements makes the proposed antenna array a promising candidate for wearable multiantenna wireless communication applications.