Terahertz (THz) frequency band offers several advantages over microwave band such as larger bandwidth and radiation capability for various imaging applications. One of the important components is the THz detector applicable for room temperature use. For the lower THz frequency band, an antenna-coupled microbolometer is considered as the THz wave detector due to its compact structure and easy to fabricate. In this paper, we design and simulate the antenna-coupled microbolometer for 1 THz frequency band. Simulation is conducted by using CST Microwave Studio. A surface current analysis is performed to understand the effect of the increasing resistance of the microbolometer to the power efficiency performance. From the simulation results, the proposed design and analysis method reveals that power efficiency of the microbolometer can be increased by increasing the resistance of the microbolometer.