A band-pass frequency selective surface (FSS) structure using capacitance layers is proposed to improve the performance of angular stability. It consists of band-pass FSSs, supporting dielectrics, and capacitance layers out of band-pass FSS. The supporting dielectrics and capacitance layers work as a transmission line and capacitance impedance matcher. Through the impedance matcher, the bandwidth is stabilized, and insertion loss at passband is reduced from -0.76 dB to -0.39 dB for incident angles up to 60°. The equivalent circuit of the proposed structure is presented, and the Smith chart is given to explain the mechanism of the capacitance layers. Finally, a prototype is manufactured and measured. A relatively good agreement is obtained between simulations and measurements. Therefore, the proposed structure can be an effective solution to improve the angular stability performance of band-pass FSS design.
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