A high-speed THz permittivity measurement system featuring a simple 2-tone generation method using LO leakage

A fast and simple permittivity measurement system at the terahertz wave band is proposed. A 2-tone method is used to measure permittivity. To generate the 2-tone signal simply, a method using just a single frequency oscillator and LO leakage at the transmitter is proposed. For fast measurement of the two-tone phase difference, a self-heterodyne technique with a simple diode is applied in the receiver. The proposed system achieved a measurement time of 0.03 ms at one point, which is 1/200 compared to a conventional system, with an error of less than 6%.