FIG. 11B is a block diagram illustrating components multi-spectral interrogator 1170 and multi-spectral target device 1185, in accordance with some embodiments of the technology described herein. In the embodiment illustrated in FIG. 11B, the interrogator 1170 transmits two different RF signals to target device: (1) a first RF signal generated at least in part by using waveform generator 1171 (this signal is analogous to the signal transmitted by interrogator 1100 described with reference to FIG. 11A); and (2) a second RF signal generated by local oscillator 1174 (this has no counterpart in the embodiment of FIG. 11A). After being received by the target device, this second RF signal (after any suitable amplification and/or frequency multiplication) may be mixed with the first RF signal to shift the first RF signal by a desired amount to obtain a frequency-shifted RF signal. In turn, the frequency-shifted RF signal may be frequency multiplied by any suitable factors to generate RF signals to transmit back to interrogator device 1170. This configuration is described in greater detail below.
