The fabrication and modeling of bow-tie antenna integrated uni-traveling carrier photodiodes (UTC-PD) are presented. The experimental results show that a −10.68  dBm RF power can be obtained from the 4  ×  50  μm² area UTC-PD at 100 GHz. The device is modeled by high frequency simulation software. The trend of variation of the measured terahertz (THz) power with frequency matches well with the simulation results. Based on the model, the effects of the shape and the contact pads of the antenna on the THz power emission properties of the device are studied numerically, which helps to further optimize the device design.