I. Introduction
Very high frequency band, which includes the ranges of teraherz, provides advantages such as wide, continuous bandwidth, increased inherent directivity, and the ability to support minimized antenna. Although the terahertz band is especially attractive in that it can provide a far wider bandwidth than the communication bandwidth provided by the millimeter wave, technologies related to the parts and devices needed to fully utilize this type of wide bandwidth are undeveloped or currently under development[1] [2]. In addition, the terahertz band has the radio wave characteristics of becoming strongly absorbed to atmospheric moisture such as vapor, penetrating non-ionized substances such as plastic and wood, and reflecting on metal, which are the features that cause signal attenuation and path loss, resulting in short radio wave reach and vulnerability to interference or blockage by obstacles[3].