US Patent 11201775 Technique for backscattering transmission

A technique for transmitting data from a passive radio device (100) is described. As to a method aspect of the technique, an antenna (102) of the passive radio device (100) is exposed to an incident radio signal (502). A frequency domain representation of the incident radio signal (502) comprised at least one muted gap between active subcarriers within a bandwidth of the incident radio signal (502). The incident radio signal (502) is backscattered from the antenna by modulating an impedance of the antenna according to the data using at least two different modulation frequencies that differ by less than the bandwidth.