Radio frequency identification (RFID) moisture tag(s) and sensors with extended sensing via capillaries
A radio frequency identification (RFID) tag includes a power harvesting circuit that operates generate power for the RFID tag from a continuous wave of a radio frequency (RF) signal. The RFID tag further includes a tuning circuit that is tuned based on a capacitance setting, where the capacitance setting is indicative of a power level of the power. The RFID tag further includes a processing module operably coupled to the tuning circuit, where the processing module operates to generate the capacitance setting to obtain a desired power level for the power.
1. A method comprises:
determining, by a self-tuning engine of a radio frequency identification (RFID) tag, a power level of a supply signal produced by converting a radio frequency (RF) signal into the supply signal;
when the power level of the supply signal compares unfavorably to a desired power level, generating, by the self-tuning engine, a tuning adjust signal based on the comparison of the power level;
determining, by the self-tuning engine, a second power level of the supply signal produced subsequently to a resonant frequency of the RFID tag being changed based on the tuning adjust signal; and
when the second power level of the supply signal compares favorably to the desired power level, generating, by the self-tuning engine, an enable signal to enable RFID tag communication.
2. The method of claim 1 , wherein the desired power level comprises:
a minimum power to facilitate communication with the RFID tag.
3. The method of claim 2 further comprises:
comparing, by the self-tuning engine, the second power level with an optimal power level;
when the second power level of the supply signal compares unfavorably to the optimal power level, generating, by the self-tuning engine, a second tuning adjust signal based on the comparison of the second power level;
determining, by the self-tuning engine, a third power level of the supply signal produced subsequently to the resonant frequency of the RFID tag being changed based on the second tuning adjust signal; and
when the third power level of the supply signal compares unfavorably to the optimal power level, generating, by the self-tuning engine, a third tuning adjust signal based on the comparison of the third power level.
4. The method of claim 1 further comprises:
writing, by the self-tuning engine, a digital representation of the tuning adjust signal into a memory of the RFID tag.
5. The method of claim 4 further comprises:
transmitting, by the RFID tag, an RF signal that includes the digital representation of the tuning adjust signal.
6. The method of claim 1 further comprises:
when the power level of the supply signal compares favorably to the desired power level, generating, by the self-tuning engine, the enable signal to enable RFID tag communication.
7. A non-transitory computer-readable medium of a radio frequency identification (RFID) tag, wherein the non-transitory computer-readable medium comprises:
a first memory section that stores operational instructions that, when executed by the RFID tag, causes the RFID tag to:
determine a power level of a supply signal produced by converting a radio frequency (RF) signal into the supply signal;
a second memory section that stores operational instructions that, when executed by the RFID tag, causes the RFID tag to:
when the power level of the supply signal compares unfavorably to a desired power level,
generate a tuning adjust signal based on the comparison of the power level;
the first memory section further stores operational instructions that, when executed by the RFID tag, causes the RFID tag to:
determine a second power level of the supply signal produced subsequently to a resonant frequency of the RFID tag being changed based on the tuning adjust signal; and
the second memory section further stores operational instructions that, when executed by the RFID tag, causes the RFID tag to:
when the second power level of the supply signal compares favorably to the desired power level, generate an enable signal to enable RFID tag communication.
8. The non-transitory computer-readable medium of claim 7 , wherein the desired power level comprises:
a minimum power to facilitate communication with the RFID tag.
9. The non-transitory computer-readable medium of claim 8 further comprises:
the first memory section further stores operational instructions that, when executed by the RFID tag, causes the RFID tag to:
compare the second power level with an optimal power level;
when the second power level of the supply signal compares unfavorably to the optimal power level, generate a second tuning adjust signal based on the comparison of the second power level;
determine a third power level of the supply signal produced subsequently to the resonant frequency of the RFID tag being changed based on the second tuning adjust signal; and
when the third power level of the supply signal compares unfavorably to the optimal power level, generate a third tuning adjust signal based on the comparison of the third power level.
10. The non-transitory computer-readable medium of claim 7 further comprises:
a third memory section that stores operational instructions that, when executed by the RFID tag, causes the RFID tag to:
write a digital representation of the tuning adjust signal into a memory of the RFID tag.
11. The non-transitory computer-readable medium of claim 10 further comprises:
the third memory section further stores operational instructions that, when executed by the RFID tag, causes the RFID tag to:
transmit an RF signal that includes the digital representation of the tuning adjust signal.
12. The non-transitory computer-readable medium of claim 7 further comprises:
the second memory section further stores operational instructions that, when executed by the RFID tag, causes the RFID tag to:
when the power level of the supply signal compares favorably to the desired power level, generate the enable signal to enable RFID tag communication.