The study on terahertz radiators will not only boost the development of theoretical research, but also raise severe challenges to solid-state electronics and circuit technology. In the present paper, the transmission characteristics of microstrip-slot coupling structures are primarily studied in 1-3THz band.Based on the single-layer dielectric structure, a double-layer dielectric microstrip-slot coupling structure with air as one layer is presented. It is reported that adding air layer based on the single-layer structure helps reduce the loss. Besides, given the factors of Engineering processing, the structure of three-layer media is also proposed; it is found that the structure of three-layer media still has exhibits transmission loss when the engineering realization is satisfied. However, this study suggests that the loss of the three-layer structure is higher than that of the two-layer structure, whereas the effect is better than that of the single-layer structure.INDEX TERMS Terahertz, multilayer structure, transmission characteristics, odd mode, even mode.