An experimental double-layer active frequency-selective surface (AFSS) for stealth radome is proposed.The AFSS is a planar structure which is composed of a fixed frequency-selective surface (FSS),a PIN diodes array,and a DC bias network.The AFSS elements incorporating switchable PIN diodes are discussed.By means of controlling the DC bias network,it is possible to switch the frequency response for reflecting and transmitting.Measured and simulated data validate that when the incidence angle varies from 0° to 30° the AFSS produces more than-11.5 dB isolation across 6-18 GHz when forward biased.The insertion loss (IL) is less than 0.5 dB across 10-11 GHz when reverse biased.