A Comparative Analysis between Circuit Analog and Capacitive Circuit based Broadband Absorbers

Abstract

This paper presents two broadband absorber structures based on circuit analog (CA) and capacitive circuit (CC) concepts. Each of the proposed designs is made of multiple resistive layers separated by an air spacer and terminated by a ground plane. The CA structure employs square resistive loops printed on dielectric substrates, whereas square resistive patches are being used in the CC geometry. The proposed CA absorber exhibits 142.08% absorption bandwidth (for absorptivity> 90%) at the expense of a large thickness (0.296Ao, λo being the wavelength which corresponds to the central absorption frequency). On the other hand, the CC absorber provides 76.41% absorption bandwidth corresponding to a thinner substrate (0.135λo). Both the designs are polarization-independent and angularly stable, despite having small profile, low resistance, and simple design. A comparison has also been made between the CA and CC concepts, thereby highlighting their performances over one another.