An electromagnetic wave generator includes a 2DEG plate, a first resistor, a second resistor, a source and a floating plate and a dielectric body. The 2DEG plate is configured to form a 2DEG channel. The first resistor is connected to one side node of the 2DEG plate. The second resistor is connected to an opposite side node of the 2DEG plate. The source is disposed between the second resistor and a ground and configured to apply electric power to the 2DEG plate. The floating plate is configured to generate an electromagnetic wave using electric dipoles formed by the 2DEG channel. The dielectric body is formed between the 2DEG plate and the floating plate.