A Ku-band Tunable Absorptive Frequency Selective Reflector

In this paper, a Ku-band tunable absorptive frequency selective reflector (TAFSR) is proposed. The TAFSR has a sandwich structure: an active resistive sheet at the top layer, and PEC at the bottom layer, divided by F4B substrate. The resistive sheet layer is composed of a simple straight strip between two metallic strips with PIN diodes loaded to get the tunable reflective coefficient. PIN diodes can be equivalent to serial RL circuit. Two metallic strips and the gap between units is equivalent to serial LC circuit to control the resonant center frequency. The biased strip can be equivalent to the parallel inductance circuit as the electric structure and the biased lines simultaneously. The influence of the PIN diodes' tunable resistance is analyzed through equivalent circuit model. The measurement results show that the -10dB tunable absorptive band of the proposed TAFSR can be achieved in Ku-band from 10.3 GHz to 19.2 GHz.