This analysis represents a circular shape based cladding with two elliptical shape cores in photonic crystal fiber (PCF) for the terahertz (THz) range. Here, we present a single-mode photonic crystal fiber (SM-PCF) with five layers of circular shape of air holes (CAH) structure along with two layers of elliptical shape of air holes (EAH) core configuration in the center to decrease the different types of losses. For broad-band communications, our proposed SM-PCF is highly useful due to the obtaining of ultra-low effective material loss (UML) in the terahertz regime. Perfectly matched layers (PMLs) and finite element method (FEM) established on COMSOL Multiphysics software has been used to design this PCF fiber. Simulated outcomes show a particularly an UML deficit of 0.014 cm −1 , power fraction in the core area (CA) and large effective area (EA) of 72%, and 5.90 × 10 −8 m 2 respectively at 1 terahertz (THz) frequency. Also, other aspects of optical fiber for THz signal banquet with confinement loss (CL), scattering loss (SL) and V-parameter have been calculated here. Moreover, our proposed SM-PCF shows single-mode propagation by V-parameter pointer over 0.80-3 THz frequency. So, we can say that our designed PCF fiber will be suitable for various effective communication areas at the terahertz (THz) spectrum.