An antenna device according to an example embodiment includes a silicon substrate of first type doping, at least two first doped regions formed by second type doping different from the first type doping, a second doped region formed by the second type doping outside a channel region surrounding the at least two first doped regions, and at least two gates disposed on a dielectric layer. In the antenna device, a resonant frequency is adjusted according to an external voltage individually applied to the at least two gates, and polarization information of a terahertz (THz) light source is obtained based on a pattern and an amount of an electric field measured at the at least two gates.