Material level sensor having a wire-horn launcher

• US 6,452,467 B1
• Filed: 04/01/1999
• Issued: 09/17/2002
• Est. Priority Date: 04/01/1999
• Status: Expired due to Term

• Current Assignee: Mcewan Technologies LLC
• Original Assignee: Mcewan Technologies LLC
• Inventors: McEwan, Thomas E.
• Primary Examiner(s): LEE, BENNY T
• Application Number:
  US09/282,962
• Time in Patent Office: 1,265 Days
• Field of Search: 333/240, 333/236, 333/34, 732/90.R
• US Class Current: 333/240
• CPC Class Codes: G01S 7/02 of systems according to group G01S13/00
• CPC Class Codes: H01Q 1/225 used in level-measurement devices, e.g. for level gauge measurement
• CPC Class Codes: H01Q 13/08 Radiating ends of two-conductor microwave transmission lines, e.g. of coaxial lines, of microstrip lines

Abstract

A single-wire time-domain reflectometer (TDR) combines the best performance features of prior art “electronic dipsticks” in a high accuracy implementation that allows tank penetration though a small opening. A wire-horn structure is employed to launch TDR pulses onto a single wire transmission line, wherein the horn wires can be flexed inwards so the dipstick structure can be inserted through a small tank opening. Once inside the tank, the horn wires flex to their normal state to provide a controlled reference reflection while simultaneously providing high coupling efficiency to the dipstick. The TDR system determines the fill-level of a tank by measuring the time difference between a reflection created at the wire-horn, which all is at the top of a tank, and a reflection from a material in the tank. The TDR employs automatic time-of-peak (TOP) detectors and incorporates a 2-diode sampler, a low-aberration pulse generator, and a 0.001% accurate timebase.

Claims

1. A method for coupling a pulse onto a guide wire and producing a controlled marker reflection, comprising:

producing a step impedance discontinuity at a mounting location of the guide wire to produce a marker reflection,

smoothly tapering the impedance from the step discontinuity to the impedance of the guide wire to efficiently couple a pulse onto the guide wire.

2. A guide wire launcher for launching electromagnetic pulses onto a guide wire, comprising a horn formed of a plurality of wires or open leaves mounted about the guide wire and having an abrupt impedance discontinuity at the mounting location to generate a controlled marker reflection.

3. The guide wire launcher of claim 2 wherein the wires or open leaves are flexible.

4. The guide wire launcher of claim 2 wherein the wires or open leaves are flared.

5. The guide wire launcher of claim 2 wherein the horn is formed of said plurality of wires or open leaves having a smooth impedance taper to a Goubau line impedance.