Radio-frequency localization techniques and associated systems, devices, and methods

A method for determining a distance between a target device and an interrogator device, the method comprising:

• generating a first electric signal using the interrogator device and converting, using a transmit antenna on a substrate of the interrogator device, the first electric signal to a first radio-frequency (RF) signal having a first center frequency between 50 GHz and 70 GHz for transmission to the target device;
• in response to converting the first electric signal to a first RF signal, converting, using a receive antenna on the substrate of the interrogator device, a second RF signal transmitted from the target device to a second electric signal having a second center frequency between 100 GHz and 140 GHz;
• generating, from the first and second electric signals and using signal transformation circuitry integrated with a semiconductor die mounted on the substrate of the interrogator device, a third electric signal;
• and
• determining the distance between the target device and the interrogator device using the third electric signal.