Terahertz dielectric characterization of low-loss materials for 6G and ADAS application

Terahertz wave becomes key technology for 6G next generation communication and advanced driver assistance (ADAS) applications. US Federal Communications Commission opens experimental spectrum licenses for 6G. The spectrum falls in the 95 GHz to 3 THz range. The automotive ADAS employs sub-THz radar to plan routes and avoid obstacles. The sub-THz radars usually select the spectrum of 24GHz, 77GHz and 79GHz. Composite communication materials, such as quartz glass, bakelite and polycarbonate are the basic ingredients for 6G communication and ADAS application. In communication channel modeling, the microelectronics device packaging and environment materials' dielectric parameters should be known in advance. In detail, the transmission characteristics (transmittance, reflectance) and complex permittivity of various materials need to be characterized. Vector Network Analyzer (VNA) is usually employed to measure specific band dielectric parameters. To get broadband characteristics, the VNA needs to be calibrated at each frequency band. To get materials broadband dielectric property, the VNA method is expensive and time-consuming. Terahertz time domain spectroscopy (THz-TDS) emitted a pulse THz signal. The frequency domain spectroscopic waveform was gotten by Fourier Transform, and dielectric parameters were calculated. The frequency range is broadband from 30 GHz to 2 THz. The frequency resolution is as high as 380MHz. The permittivity is consistent with the VNA measured result, but THz-TDS do not need band switching and calibration. It is a promising candidate for evaluating the dielectric characteristics of 6G communication and ADAS materials.