A novel approach on design of a fractal inspired logarithmic spiral antenna-based absorber for polarization and incident angle insensitive broadband electromagnetic energy harvesting

Abstract

Design analysis employing numerical analysis has become one of the most significant components in realizing broadband spiral absorbers in the infrared (IR) region. To date, there have been very few research studies on broadband electromagnetic (EM) wave absorptions by such absorbers in that frequency band. Therefore, in this research, we have proposed a new type of absorber based on gradient log-spiral to enhance the absorption bandwidth in the IR region. The absorbers are designed by considering arrangements of different log-spiral arms in a fractal-like pattern. Investigation was carried out in both unit cell and array configuration. Strong average absorption reaching 88.5% in the unit cell and 83.6% in the array configuration was observed over the bandwidth from 4.5 to 100 THz for a wide range of incident angles. The absorption of the unit cell absorber remains almost stable up to 45° for transverse electric and 75° for transverse magnetic mode polarizations. This unique approach opens a new direction of imaging, EM stealth, camouflaging, and wireless EM energy harvesting applications.