Design of Filtering RIS with Out-of-Band Electromagnetic Transparency

In this paper, a filtering reconfigurable intelligent surface (RIS) with out-of-band electromagnetic transparency is proposed. The filtering RIS element consists of two dielectric substrate layers in a vertical arrangement. Two metallic square rings, a PIN diode, and lumped inductances are placed on the substrates. The tunable reflection phase shift is achieved by switching the PIN diode. In addition, the filtering response in magnitude is realized. A RIS array is designed and simulated, and the simulated results show that the adjustable beams are realized. Furthermore, the favorable gain filtering response and the characteristic of out-of-band transparency are achieved.