Abstract: The bandgap characteristic of single-negative metamaterial can be utilized to reduce electromagnetic coupling between elements of an antenna array. In this paper, a novel epsilon-negative anti-parallel-spiral-shaped (ENG-APSL) resonator is designed and investigated. The circuit model technique and wave-guide transmission method are used to analyze the electromagnetic characteristics of the resonator, and the effective parameters are also extracted. Several well engineered ENG-APSL resonators are arranged between two closely spaced (0.37λ₀) rectangular patch antennas for coupling reduction. By loading the insulators, the E-plane coupling of the array is reduced by 21dB. For the operation frequencies that close to 5.1 GHz, the 25 dB isolation band-width of 5.1% is obtained. The proposed insulator also has the advantages of electrically small dimensions and simple structure.