Measuring sensor with at least one saw (surface acoustic wave ) element

• US 20090033175A1
• Filed: 04/20/2006
• Published: 02/05/2009
• Est. Priority Date: 04/21/2005
• Status: Active Grant

• Current Assignee: AVL List GmbH (List Privatstiftung)
• Original Assignee: AVL List GmbH (List Privatstiftung)
• Inventors: Friedl, Alexander, Hauser, Robert, Strmsek, Robert, Reindl, Leonhard M., Bruckner, Gudrun
• Granted Patent: US 7,755,250 B2
• Time in Patent Office: Days
• US Class Current: 310/313.R
• CPC Class Codes: G01D 5/485 using magnetostrictive devices
• CPC Class Codes: G06F 8/65 Updates security arrangements therefor G06F21/57

Abstract

A measuring sensor comprises at least one SAW (surface acoustic wave) element (20) serving as a sensor and identification unit, which is installed in a contactless manner inside a housing part (10) forming, in essence, a coaxial conductor. The housing part (10) is connected to the shield (13) of the connection cable whose signal conductor (12) extends in a contactless manner over a superficial coupling structure of the SAW element (20) without contact. In order to improve the near-field coupling, the coupling structure of the SAW element (20) comprises additively coupling partial structures, which are arranged on both sides of the signal conductor (12) and which, preferably with at least one strip conductor, encircle, at least for the most part, the SAW element (20) in the peripheral area, and which serve as an integrated discharge loop for pyroelectric charges.

Claims

1. A measuring sensor comprising at least one SAW element (20) serving as sensor and/or identification unit and having a housing part (10) forming essentially a coaxial conductor into which the SAW element (20) is installed in a contactless manner, and whereby said housing part is connected to the shield (13) of the connection cable whose signal conductor (12) extends in a contactless manner at least in the center across a superficial coupling structure (213, 214) of the SAW element (20), and whereby said signal conductor serves as near-field coupling of the electromagnetic field in the coaxial conductor with the SAW element (20), wherein the coupling structure (213, 214) of the SAW element (20) is provided with additively coupling partial structures, which are arranged at both sides of the signal conductor (12).

2. A measuring sensor according to claim 1, wherein the active components of the SAW element (20), such as interdigital transducers (22), the reflectors (23, 25, 26), and the delay line (24) etc. are to be arranged between two independent, loop-shaped and interconnected partial structures of the coupling structure (213), which mirror essentially the conductor track (12).

3. A measuring sensor according to claim 1, wherein a mainly inductive coupling antenna structure is attached on one side of the signal conductor (12) and a mainly capacitive coupling antenna structure serving as a partial structure of the coupling structure (214) is arranged on the other side of said signal conductor to combine the energy coming from the essentially circular magnetic field and the essentially radial electric field.

4. A measuring sensor according to claim 3, wherein the partial structures (213, 214) encircle, at least for the most part, the SAW element (20) with at least one of the conductor tracks in the peripheral area and serve as an integrated discharge loop for pyroelectric charges.

5. A measuring sensor according to claim 4, wherein the effective part of ohmic resistance can be changed through an adjustment of the diameter of the conductor tracks of the coupling structure (213, 214), preferably through a variation of the layer thickness applied on the conductor tracks, at least in specific areas, to adjust the operations frequency and/or the material characteristics and/or the radiation resistance.

6. A measuring sensor according to claim 5, wherein the coupling structure (213, 214) of the SAW element (20) is provided with additional contacts for the functionality test devices or the like.