We proposed a flexible electron density measurement system based on the interferometer for confinement study. An INRD guide antenna for spatial scan capability of a probe beam has been analytically designed. As a result of fabricating and evaluating the antenna, it was confirmed that the antenna has a predicted performance. We also evaluated the analysis method of a sampled data with numerical simulation in order to calculate phase shift due to the plasma density. A 3000 order FIR filter could successfully separate a sample signal with various frequencies into a signal with a single frequency when S/N is not critical.