A multiple subcarriers modulator (200) for a backscatter device comprised in a backscatter communication system is disclosed. The multiple subcarriers modulator comprises an antenna switch (210) and an impedance matrix (220) comprising a number of impedances. The multiple subcarriers modulator further comprises a first modulator (230) configured to generate a first modulated signal by modulating a first data stream with a first subcarrier having a first frequency and a second modulator (240) configured to generate a second modulated signal by modulating a second data stream with a second subcarrier having a second frequency. The multiple subcarriers modulator further comprises a summing circuit (250) configured to generate a control signal by combining the first and second modulated signals and a switch controller (270) configured to control the antenna switch such that one of the impedance in the impedance matrix is connected to an antenna based on the control signal.