Transmissive type dual band polarization converter integrated microstrip patch antenna in THz regime

This article proposes the generation of both LHCP and RHCP waves simultaneously –at two distinct frequencies by using a single-layered compact polarization converter (PC). The proposed PC has been designed with a gold pattern inscribed on a polyimide substrate. A modified I-shaped structure with semi-circular curved ends provides a quadrature phase shift between the orthogonal components of the incident electric field with a high transmission coefficient and low insertion loss across the two THz frequency bands. Two equivalent circuit models have been proposed for TE and TM modes separately. As a proof of concept of the proper functioning of the proposed PC, one dual-band linearly polarized antenna is designed and integrated with the PC. The linearly polarized radiated waves from the dual-band antenna across 1.55 THz and 4.05 THz have been successfully converted into both the RHCP and LHCP waves simultaneously. The integration of a simple profile PC with a dual-band THz antenna to produce dual CP radiated waves simultaneously are the key achievements of this proposed work. Moreover, the results of equivalent circuit models for both TE and TM modes are justified after proper validation with the full-wave EM simulation results. The proposed dual-band PC, dual-band THz antenna, and the integrated structures are systematically investigated using FEM-based CST Microwave studio.