Ultrawideband terahertz antenna for multiband circularly polarized applications

A coplanar waveguide fed slot-loaded octagonal monopole antenna for ultrawideband terahertz applications is investigated in this paper. The antenna geometry consists of an octagonal radiator loaded with a circular slot, asymmetric feedline, and defected pentadecagon stub-loaded coplanar ground plane. This antenna is operating from 3.62 to 32.06 THz. It has three circularly polarized operating bands with 3-dB axial ratio bandwidth of 66.76% (4.53–9.07 THz), 3.52% (20.64–21.38 THz) and 0.72% (30.26–30.48 THz). The overall footprint of this antenna is 20 × 22 µm2. Stable radiation patterns at low frequencies while distorted radiation patterns at higher frequencies are observed. The peak realized gain of the proposed antenna structure is 8.44 dB. The proposed antenna structure has wide circularly polarized bandwidth, wide impedance bandwidth, and very compact dimensions compared to previously reported structures.