It should be appreciated that the embodiments of multi-spectral interrogators and target devices shown in FIGS. 11A and 11B are illustrative and that there are variations. For example, in some embodiments, there may be zero, one, two, three, or any other suitable number of amplifiers of any suitable type between any pair of circuits shown in FIGS. 11A and 11B. As another example, there may be zero, one, two, three, or any other suitable number of filters of any suitable type between any pair of circuits shown in FIGS. 11A and 11B. As yet another example, the target device 1185 may be implemented without frequency multiplier 1190, in some embodiments. It should also be appreciated that any of the amplifiers, frequency mixers, frequency multipliers, and filters shown in FIGS. 11A and 11b may be of any suitable type and may be implemented in any suitable way, as aspects of the technology described herein are not limited in this respect. Additionally, it should be appreciated that each of waveform generators 1102 and 1171 may be configured to generate RF signals of any suitable type including any of the types described herein with reference to waveform generator 110.
