As discussed herein including with reference to FIG. 9C, in some embodiments, a target device may include a local oscillator configured to generate a signal having a fixed frequency used to offset the frequencies in RF signals received from an interrogator device as part of generating RF signals to transmit back to the interrogator device. For example, in some embodiments, a target device may include: (1) an oscillator configured to generate a first RF signal having a first center frequency f1 (the first RF signal may be a continuous wave signal having a fixed frequency to be used as an offset frequency); (2) a receive antenna configured to receive, from an interrogator, a second RF signal having a second center frequency f2 (the second RF signal may be a chirp, for example); and (3) a frequency mixer configured to mix the first RF signal with the second RF signal to obtain a third RF signal having a third center frequency f3 (e.g., where f3=f2±f1). The target device may further include a transmit antenna configured to transmit the third RF signal to the interrogator device.
