  We report on the measurement of terahertz electric-field vector waveforms by
using a system that contains no mechanical moving parts. It is known that two
phase-locked femtosecond lasers with different repetition rates can be used to
perform time-domain spectroscopy without using a mechanical delay stage.
Furthermore, an electro-optic modulator can be used to perform polarization
measurements without rotating any polarizers or waveplates. We experimentally
demonstrate the combination of these two methods and explain the analysis of
data obtained by such a system. Such a system provides a robust platform that
can promote the usage of polarization-sensitive terahertz time-domain
spectroscopy in basic science and practical applications. For the experimental
demonstration, we alter the polarization of a terahertz wave by a polarizer.
