Abstract
To date, there have been very few research on electromagnetic (EM) wave absorption by such antennas in the infrared (IR) region. Therefore, in this article we have proposed a new type of gradient log-spiral antenna to enhance the absorption bandwidth. The unit cell antenna is designed by considering the special arrangements of different log-spiral arms. The unit cell antenna can achieve an average absorption ≥88.5% from 4.5 to 100 THz under normally incident plane waves. The absorption of the antenna is incident angle insensitive up to 45° and polarization independent up to 75°for both the transverse electric (TE) and transverse magnetic (TM) modes. The antenna shows high directivity of 6.68 dBi and high gain of 3.55 dB with 3dB beamwidth 59.2°. Moreover, omnidirectional directivity is observed in both low, mid and high frequencies. This innovative design approach opens a new path for thermal detection, bolometer, and energy harvesting research.