Apparatus for determining or monitoring the fill level of a substance in a container

Patent metadata

Field	Value
Publication number	US-9243948-B2
Application number	US-201214126561-A
Country	US
Kind code	B2
Filing date	May 21, 2012
Priority date	Jun 24, 2011
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

An apparatus for determining or monitoring the fill level of a substance in a container, including a high frequency oscillator, an in/out coupling unit, an antenna, which transmits measuring signals, which are coupled in via the in/out coupling unit, in the direction of the surface of the fill substance, respectively receives the measuring signals reflected on the surface of the fill substance, and an evaluating circuit, to which the measuring signals reflected on the surface of the fill substance are supplied and which ascertains the fill level in the container via a travel-time difference method. The high frequency oscillator includes a transistor with a source branch, a drain branch and a gate branch, at least one frequency tuning component and at least one frequency determining component. The frequency determining component of the high frequency oscillator is arranged in the source branch of the transistor.

First claim

The invention claimed is:

1. An apparatus for determining or monitoring the fill level of a substance in a container, comprising:
a high frequency oscillator producing high-frequency measuring signals;
an in/out coupling unit, an antenna, which transmits the high-frequency measuring signals in the direction of the surface of the fill substance and receives the measuring signals reflected on the surface of the fill substance; and
an evaluation unit, which, based on the travel-time difference of the transmitted measuring signals and the reflected measuring signals, ascertains the fill level in the container, wherein:
said high frequency oscillator has a transistor with a source branch, a drain branch and a gate branch, at least one frequency tuning component and at least one frequency determining component; and
said frequency determining component of said high frequency oscillator is arranged in the source branch of said transistor.

2. The apparatus as claimed in claim 1 , wherein:
said high frequency module is so designed that it produces broadband high frequency pulses.

3. The apparatus as claimed in claim 1 , wherein:
said high frequency module is so designed that it produces FMCW signals, respectively frequency modulated, continuous wave signals.

4. The apparatus as claimed in claim 1 , wherein:
said transistor is a field effect transistor or a bipolar transistor.

5. The apparatus as claimed in claim 1 , wherein:
said frequency tuning component is arranged in said gate branch.

6. The apparatus as claimed in claim 5 , wherein:
said frequency tuning component is an inductor, which interacts with a parasitic capacitance of said transistor.

7. The apparatus as claimed in claim 1 , wherein:
said frequency determining component is a capacitive voltage divider, which is preferably composed of a parasitic capacitance present in said transistor and/or of a first capacitor arranged outside of said transistor and a series circuit composed of a second capacitor and a third capacitor.

8. The apparatus as claimed in claim 7 , wherein:
said third capacitor is a varactor diode.

9. The apparatus as claimed in claim 7 , wherein:
parallel to the series circuit of said second capacitor and said third capacitor, especially parallel to said varactor diode, a resistor is connected, via which the working point of said transistor is adjustable.

10. The apparatus as claimed in claim 1 , wherein:
the high frequency oscillator is embodied with microstrip line technology.

Assignees

• Blodt Thomas
• Endress & Hauser Gmbh & Co Kg

Inventors

• Blodt Thomas

Classifications

• G01F23/2962

  Measuring transit time of reflected waves · CPC title

• H03B2200/0006

  Clapp oscillator · CPC title

• G01F23/284 Primary

  Electromagnetic waves · CPC title

• H03B5/1203

  the amplifier being a single transistor · CPC title

• H03B5/1228

  the amplifier comprising one or more field effect transistors · CPC title