Numerical analysis of a ITO based circularly polarized optically transparent THz antenna employing characteristic mode analysis

Abstract

An optically transparent circularly polarized indium tin oxide (ITO) based antenna having operability in THz region is proposed in this paper. An E-shaped slot and an I-shaped slot are embedded into an E-shaped radiating patch modeled by ITO and conductive carbon nanotube (CNT) on a polyimide substrate to obtain circular polarization. The unequal parallel slits of the E-shaped patch with an E-shaped slot lead to introduce two orthogonal modes, and hence circular polarization is achieved. Besides, integration of an I-shaped slot also helps to create the difference in magnitude of current distribution between the two working modes to get better axial ratio. The patch of the antenna is covered with highly CNT film which improves the overall performance of the antenna. To overcome the limitations of the traditional design process, characteristic mode analysis is carried out which helps to realize and analyze circular polarization generation mechanism effectively. The proposed antenna shows a wide 3-dB axial ratio bandwidth of 9.66%. A reasonable gain of 2.61 dBic is obtained at 1.11 THz with excellent radiation performance. Wide 3-dB axial ratio bandwidth with reasonable gain makes this light weight transparent small-antenna competent for wireless and satellites applications.