Abstract: Subharmonic tags for passive far-field sensing are provided having at least one antenna configured to receive an interrogation signal having a plurality of interrogation frequencies, a passive LTI network in electrical communication with the at least one antenna, and two or more resonators, each resonator having a different resonant frequency and a corresponding trigger frequency different than the resonant frequency, wherein the passive LTI network is configured such that the tag only produces a response signal for trigger frequencies that are different from any of the resonant frequencies of the resonators, each resonator of the subharmonic tag configured to produce a response signal having a different frequency than the trigger frequency, the subharmonic tag configured to produce an output signal responding to the interrogation signal, the output signal including one or more of the response signals.

Abstract: Provided herein are methods and systems for quasi-harmonic tags (qHT) including an electromagnetic resonator, an input mesh including an input notch filter having a resonant frequency of ?input, an output mesh including an output notch filter having a resonant frequency of ?output; and an antenna, wherein the qHT is configured to emit a comb output signal responsive to an input signal having an input frequency (op twice a resonance frequency of at least one of the electromagnetic resonators.

Abstract: A sensing device is provided having sensing circuitry, connected to an input port and the output port, with a sensor having an impedance sensitive to a parameter of interest, one or more passive electrical components, and a variable capacitor. The sensing circuitry is triggered to generate an output signal for transmission from the output port, the output signal dependent on the parameter of interest sensed by the sensor and on an input power value, Pin, of an input signal received at the input port being greater than a parametric threshold power value, Pth. A sensing system includes the sensing device and a transmitting device to transmit the input signal to the sensing device at a frequency representative of the parameter of interest. A receiving device, which can be incorporated with or located remotely from the transmitting device, receives the output signal of the sensing device, which has a frequency that is half of the frequency of the input signal transmitted by the transmitting device.

Abstract: A sensing device is provided having sensing circuitry, connected to an input port and the output port, with a sensor having an impedance sensitive to a parameter of interest, one or more passive electrical components, and a variable capacitor. The sensing circuitry is triggered to generate an output signal for transmission from the output port, the output signal dependent on the parameter of interest sensed by the sensor and on an input power value, Pin, of an input signal received at the input port being greater than a parametric threshold power value, Pth. A sensing system includes the sensing device and a transmitting device to transmit the input signal to the sensing device at a frequency representative of the parameter of interest. A receiving device, which can be incorporated with or located remotely from the transmitting device, receives the output signal of the sensing device, which has a frequency that is half of the frequency of the input signal transmitted by the transmitting device.