▎ 摘　　要

Electrical controllable charge density in graphene films has recently attracted considerable research interest for its potential applications in various active devices. In this letter, we demonstrate that graphene acts as an effective tunable loss resource to manipulate the electromagnetic response of a metallic resonant structure at microwave frequency. A transmission-tunable frequency selective surface (FSS) is realized by introducing a graphene sandwich into its near-field region. Remarkable transmission tuning from 81.7% to 25.2% at a resonant frequency of about 6.5 GHz is observed when applying bias voltage from 0 to 3.6 V. The graphene FSS prototype may open up a way for realizing electromagnetic active devices in the microwave range.