Sensor with tail or transmission line for vehicle leak testing
A method begins by detecting a variance of one or more RF characteristics of a wireless sensor from a desired value of the one or more RF characteristics, due to exposure to an environmental condition. The tuning circuit is operably coupled to an antenna that includes a tail section that is located in a radio frequency (RF) limited area, and a head section that is located in a non-RF limited area. The method continues by adjusting the tuning circuit in response to the detecting of the variance. The method continues by generating a message regarding the adjusting of the tuning circuit, wherein a level of the adjusting of the tuning circuit is representative of the variance of the one or more RF characteristics sensed by the tail section. The method continues by transmitting the message to one or more of an RF reader and a computing device.
1. A wireless sensor comprises:
an antenna having a tail section and a head section, wherein the tail section is for placement in a radio frequency (RF) limited area for sensing an environmental condition, and wherein the head section is for placement in a non-RF limited area;
a tuning circuit operably coupled to the antenna, wherein the head section, the tail section, and the tuning circuit collectively have one or more RF characteristics, and wherein, when the tail section is exposed to the environmental condition, the exposure causes the one or more RF characteristics to vary;
a processing module operable to:
detect a variance of the one or more RF characteristics from a first value of the one or more RF characteristics to a second value of the one or more RF characteristics;
in response to the detecting of the variance, adjust the tuning circuit to substantially re-establish the first value of the one or more RF characteristics; and
generate a message regarding the adjusting of the tuning circuit, wherein the message includes a level of the adjusting of the tuning circuit which is representative of the variance of the one or more RF characteristics sensed by the tail section; and
a transmitter operably coupled to transmit the message.
2. The wireless sensor of claim 1 , wherein the tuning circuit comprises one or more of:
a tank circuit;
a reference circuit; and
a detector circuit.
3. The wireless sensor of claim 1 , wherein the tail section comprises:
a transmission line pole; and
a transmission line anti-pole, wherein the transmission line pole and the transmission line anti-pole are substantially in parallel and substantially a same length.
4. The wireless sensor of claim 1 , wherein the head section is operably coupled to the tuning circuit.
5. The wireless sensor of claim 1 , wherein an RF characteristic of the one or more RF characteristics comprises:
an impedance at a frequency;
a resonant frequency;
a quality factor; and
a gain.
6. The wireless sensor of claim 1 , wherein the antenna includes one or more ground planes.
7. The wireless sensor of claim 1 , wherein the head section comprises:
a topmask layer, a top layer, a kapton layer, a transfer tape layer, and a backside metal layer.
8. The wireless sensor of claim 1 , wherein the tail section comprises:
a topmask layer, a top layer, a kapton layer, a bottom layer and a bottommask layer.
9. The wireless sensor of claim 1 , wherein the antenna comprises:
a patch antenna portion, wherein the patch antenna portion includes a pole and an anti-pole, and wherein the patch antenna portion is operable to receive RF signals from a computing device and transmit responses to the computing device;
an antenna ground plane, wherein the antenna ground plane is operable to provide a ground plane for the tail section; and
a die attach area, wherein the die attach area is operable to be coupled to the processing module and the tuning circuit.
10. A method comprises:
detecting, by a processing module of a wireless sensor, a variance of one or more RF characteristics of the wireless sensor from a first value of the one or more RF characteristics to a second value of the one or more RF characteristics, wherein the wireless sensor includes an antenna, a tuning circuit and a transmitter, wherein the antenna includes a head section and a tail section, wherein the tuning circuit is operably coupled to the antenna, wherein the tail section is located in a radio frequency (RF) limited area, wherein the head section is located in a non-RF limited area, wherein the head section, the tail section and the tuning circuit collectively have the one or more RF characteristics, and wherein an exposure of the tail section to an environmental condition causes the one or more RF characteristics to vary;
adjusting, by the processing module of the wireless sensor, the tuning circuit in response to the detecting of the variance to re-establish the first value of the one or more RF characteristics;
generating, by the processing module of the wireless sensor, a message regarding the adjusting of the tuning circuit, wherein the message includes a level of the adjusting of the tuning circuit which is representative of the variance of the one or more RF characteristics sensed by the tail section; and
transmitting, by the transmitter of the wireless sensor, the message to one or more of an RF reader and a computing device.
11. The method of claim 10 , wherein the adjusting the tuning circuit comprises one or more of:
adjusting a tank circuit of the tuning circuit;
adjusting a reference circuit of the tuning circuit; and
adjusting a detector circuit of the tuning circuit.
12. The method of claim 10 , wherein the detecting the variance of an RF characteristic of the one or more RF characteristics comprises:
detecting a variance of the RF characteristic of a transmission line pole of the tail section; and
detecting a variance of the RF characteristic of a transmission line anti-pole of the tail section.
13. The method of claim 10 , wherein the detecting the variance of an RF characteristic of the one or more RF characteristics comprises:
detecting a variance of an impedance at a frequency;
detecting a variance of a resonant frequency;
detecting a variance of a quality factor; and
detecting a variance of a gain.
14. The method of claim 10 further comprises:
receiving, by a patch antenna portion of the antenna, RF signals from the RF reader or the computing device, wherein the patch antenna portion includes a pole and an anti-pole, wherein the antenna includes an antenna ground plane and die attach area, wherein the antenna ground plane provides a ground plane for the tail section, and wherein the die attach area is operably coupled to the processing module and the tuning circuit; and
transmitting, by the transmitter of the wireless sensor, responses to the RF reader or the computing device.