Terahertz (THz) wave frequency region is part of the electromagnetic spectrum. This spectrum is located between 0.3 THz to 10 THz or between radio waves and optics. The THz frequency region has potentials in many different applications, such as imaging, spectroscopy, and wireless communication. However, some problems are still remaining and should be solved to develop THz technology system for an actual use, such as expensive fabrication facilities, lack of recent device performances, and low speed measurement process. This research proposes a bow-tie antenna in the THz region to provide wideband bandwidth for THz broadband applications. This antenna uses high resistivity Silicon material a substrate and Gold metal layer in a specified pattern as a radiating element. The initial bow-tie antenna design is elaborated by combining a capacitive bar technique placed near the antenna feed gap to improve return loss and wide bandwidth. This research is conducted by using the calculation method to analyze the initial antenna model and simulation by using commercial simulator software of CST Microwave studio to perform design optimization. The initial antenna before combined with the capacitive bar has a resonant frequency of 1 THz with return loss (RL) at -11.758 dB, and bandwidth 114.6 GHz from VSWR equal 2. The results from the THz bow-tie antenna combined with the capacitive bar show resonant frequency at 1 THz with RL at -40 dB, and bandwidth 457.47 GHz from VSWR equal 2. The capacitive bar technique has been successfully improved more bandwidth and better resonant frequency at 1 THz.