We present a 2-port terahertz vector network analyzer (VNA) based on four continuous-wave (CW) photomixers and a pair of telecom-wavelength CW lasers. The presented optoelectronic VNA is free-space coupled and can operate continuously from 0.1 THz to 1 THz with a resolution of 2 MHz. We demonstrate two different applications with it: the determination of the material properties of a quartz wafer and the characterization of a terahertz distributed Bragg reflector (DBR).
