Abstract: In order to solve the problem that impedance bandwidth of tightly coupled array(TCA)was greatly affected by ground plane，a multilayer TCA was designed with a resistive frequency selective surface(RFSS)，the influence of sheet resistivity and mutual coupling to impedance bandwidth was analyzed，the performance of TCA with and without scaning was simulated.Results indicate that impedance bandwidth of this TCA is greatly improved by inserting a split ring resonator RFSS between array and ground plane，which minishes ground plane reflection and suppresses short circuited frequency.The radiation performance is stable during whole impedance bandwidth and the gain of this TCA is decreased due to the loss of RFSS.This multilayer TCA has characteristic of broad bandwidth，low profile and easily conformal installation，which can be applied to small ultra-wideband phased antenna array system.