Reducing coupling of RF interrogated SAWs to external bodies

• US 20050269902A1
• Filed: 06/04/2004
• Published: 12/08/2005
• Est. Priority Date: 06/04/2004
• Status: Active Grant

• Current Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Original Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Inventors: Thiesen, Jack
• Granted Patent: US 7,224,100 B2
• Time in Patent Office: Days
• US Class Current: 310/313.R
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: G01L 19/14 Housings G01L19/0007, G01L19/0084, G01L19/0092, G01L19/04, G01L19/06 take precedence
• CPC Class Codes: G01L 9/0025 with acoustic surface waves

Abstract

Disclosed is an apparatus and methodology for providing reduced coupling of radio frequency (RF) interrogated surface acoustic wave (SAW) based sensors to external bodies. Coupling, and therefore electrical loading of the sensor element, is reduced by providing an electrically conductive housing surrounding the SAW sensor element and by electrically coupling one terminal of the SAW sensor element to the electrically conductive housing. Electrical connection to an additional terminal of the SAW sensor element is provided by way of an electrically isolated connection through the electrically conductive housing.

Claims

1. A method of making a surface acoustic wave (SAW) based sensor, comprising the steps of:

providing a surface acoustic wave sensor element, said surface acoustic wave sensor element having first and second electrical terminals;

providing an electrically conductive housing;

providing a first feed through electrical connection pin having first and second end portions, the second end portion passing through a portion of the electrically conductive housing;

providing electrical isolation between the first feed through electrical connection pin and the electrically conductive housing;

connecting the second end portion of the first feed through electrical connection pin to the first electrical terminal of said surface acoustic wave sensor; and

connecting the second electrical terminal of the surface acoustic wave sensor to the electrically conductive housing for shielding.

2. The method of claim 1, wherein the step of connecting the second electrical terminal of the surface acoustic wave sensor to the electrically conductive housing comprises the steps of:

providing a second feed through electrical connection pin having first and second end portions, the second end portion passing through a portion of the electrically conductive housing;

providing electrical coupling between a portion of the second feed through electrical connection pin and the electrically conductive housing; and

connecting the second end portion of the second feed through electrical connection pin to the second electrical terminal of said surface acoustic wave sensor.

3. The method of claim 1, wherein the step of providing electrical isolation comprises providing a dielectric glass seal surrounding a portion of the first feed through electrically conductive pin.

4. The method of claim 2, wherein the step of providing electrical coupling comprises providing a metal-to-metal seal surrounding a portion of the second electrically conductive pin.

5. The method of claim 2, wherein the step of providing electrical coupling comprises bonding the second end portion of the second feed through electrical connection pin to an internal surface of the electrically conductive housing.

6. A method of reducing coupling of radio frequency (RF) interrogated surface acoustic wave (SAW) based sensors to external bodies, comprising the steps of:

providing a surface acoustic wave sensor element, said surface acoustic wave sensor element having first and second electrical terminals;

providing an electrically conductive housing;

providing a feed through electrical connection pin having first and second end portions, the second end portion passing through a portion of the electrically conductive housing;

providing electrical isolation between the feed through electrical connection pin and the electrically conductive housing;

connecting the second end portion of the feed through electrical connection pin to the first electrical terminal of the surface acoustic wave sensor element;

connecting the second electrical terminal of the surface acoustic wave sensor element to the electrically conductive housing;

providing an antenna element having first and second end portions; and

connecting the first end portion of the antenna element to the first end portion of the feed through electrical connection pin.

7. The method of claim 6, wherein the step of providing electrical isolation comprises providing a dielectric glass seal surrounding a portion of the feed through electrically conductive pin.

8. The method of claim 6, wherein the step of connecting the second electrical terminal of the surface acoustic wave sensor to the electrically conductive housing comprises the steps of:

providing a second feed through electrical connection pin having first and second end portions, the second end portion passing through a portion of the electrically conductive housing;

providing electrical coupling between a portion of the second feed through electrical connection pin and the electrically conductive housing; and

connecting the second end portion of the second feed through electrical connection pin to the second electrical terminal of said surface acoustic wave sensor.

9. The method of claim 6, wherein the step of providing electrical coupling comprises providing a metal-to-metal seal surrounding a portion of the second electrically conductive pin.

10. The method of claim 6, wherein the step of providing electrical coupling comprises bonding the second end portion of the second feed through electrical connection pin to an internal surface of the electrically conductive housing

11. A surface acoustic wave (SAW) sensor, comprising:

a surface acoustic wave (SAW) sensor element having first and second electrical termination points;

a conductive metallic housing surrounding and enclosing said SAW sensor element;

a feed through electrically conductive pin piercing said conductive metallic housing, said feed through electrically conductive pin having a first end portion and a second end portion;

a dielectric seal surrounding a portion of said feed through electrically conductive pin;

a first electrical connector connecting the first end portion of the feed through electrically conductive pin to the first electrical termination point of the surface acoustic wave sensor element; and

an electrical connection connecting the second electrical termination point of the surface acoustic wave sensor element to said conductive metallic housing.

12. The surface acoustic wave sensor of claim 11, wherein said electrical connection comprises:

a second feed through electrically conductive pin piercing said conductive metallic housing, said second feed through electrically conductive pin having a first end portion and a second end portion;

a metal-to-metal seal surrounding a portion of said second feed through electrically conductive pin electrically connecting said second feed through electrically conductive pin to said electrically conductive housing; and

an electrical conductor connecting said second electrical termination point of the surface acoustic wave sensor element to the second end portion of said second feed through electrically conductive pin.

13. The surface acoustic wave sensor of claim 11, wherein said electrical connection comprises:

a second feed through electrically conductive pin piercing said conductive metallic housing, said second feed through electrically conductive pin having a first end portion and a second portion electrically bonded to an internal surface of the housing; and

an electrical conductor connecting said second electrical termination point of the surface acoustic wave sensor element to the second end portion of said second feed through electrically conductive pin.