Research on a 2.5D Frequency Selective Absorber with two Absorption Bands and Steep-Drop Characteristics

This paper proposes a 2.5-dimensional (2.5D) frequency-selective absorber (FSA) with two absorption bands on either side of the transmission window, which is realized using a bandpass FSS with two transmitting poles and two transmitting zeros. A wider transmission passband with good frequency steep- drop characteristic is achieved by printing two layers of metal rings and circular combined plates to form two LC resonance circuits and a loaded metal via in the middle. The results indicate that the FSA possesses frequency-selective characteristics and has the potential to integrate radiation properties.