Measuring device for dielectric constant determination

Patent metadata

Field	Value
Publication number	US-10983069-B2
Application number	US-201816223628-A
Country	US
Kind code	B2
Filing date	Dec 18, 2018
Priority date	Dec 20, 2017
Publication date	Apr 20, 2021
Grant date	Apr 20, 2021

Abstract

The present disclosure relates to a measuring device for measuring a dielectric constant of fill substances in containers. The measuring device includes: a transmitting circuit for transmitting a first electromagnetic high-frequency signal and a second electromagnetic high-frequency signal; a receiving circuit for receiving the two high-frequency signals; and an evaluation circuit to ascertain a first phase shift between the transmitting and the receiving of the first high-frequency signal, to ascertain a second phase shift between the transmitting and the receiving of the second high-frequency signal, and to ascertain an amplitude of one of the received high-frequency signals. Based on these three values, the dielectric constant is determined. By determining phase shift at different frequencies, it is possible according to the present disclosure, especially in the case of solid-type fill substances, to determine their dielectric constant uncorrupted, thus without influence of air inclusions or moisture.

First claim

The invention claimed is:

1. A measuring device for measuring a dielectric constant of a fill substance in a container, comprising:
a transmitting circuit designed to transmit in the direction of the fill substance a first electromagnetic high-frequency signal having a first frequency and a second electromagnetic high-frequency signal having a second frequency;
a receiving circuit arranged and embodied to receive the first high-frequency signal and the second high-frequency signal; and
an evaluation circuit configured:
to ascertain a first phase shift between the transmitted first high-frequency signal and the received first high-frequency signal;
to ascertain a second phase shift between the transmitted second high-frequency signal and the received second high-frequency signal;
to ascertain an amplitude of the received first high-frequency signal; and
based on the amplitude, the first phase shift, and the second phase shift, to determine the dielectric constant,
wherein the evaluation circuit is configured to determine the dielectric constant of the fill substance according to the following formula:

(

c
0

*

Δφ
1

2
⁢
π
⁢

f

H
⁢
F
⁢
1

)

2

-
1

D
⁢
K

-
1

=

(

1
-
r

)

=

(

c
0

*

Δφ
2

2
⁢
π
⁢

f

H
⁢
F
⁢
2

)

2

-
1

D
⁢
K

-
1

wherein c 0 is a propagation velocity of electromagnetic waves in a vacuum, Δφ 1 is the first phase shift, f HF1 is the first frequency, DK is the dielectric constant, r is a fraction of air/moisture in the fill substance, Δφ 2 is the second phase shift, and f HF2 is the second frequency.

2. The measuring device as claimed in claim 1 , wherein the transmitting circuit is so designed that the first frequency and the second frequency lie between 10 MHz and 10 GHz.

3. The measuring device as claimed in claim 1 , wherein the evaluation circuit is further configured to ascertain an amplitude of the first high-frequency signal and the second high-frequency signal.

4. The measuring device as claimed in claim 1 , wherein the transmitting circuit includes a first oscillatory circuit designed to produce the first high-frequency signal and/or the second high-frequency signal.

5. The measuring device as claimed in claim 4 , wherein the first oscillatory circuit is designed to simultaneously produce the first high-frequency signal and the second high-frequency signal.

6. The measuring device as claimed in claim 4 , wherein the first oscillatory circuit is designed to produce the second high-frequency signal with a first harmonic of the first high-frequency signal.

7. The measuring device as claimed in claim 4 , wherein the transmitting circuit further includes a second oscillatory circuit for producing the second high-frequency signal.

8. The measuring device as claimed in claim 1 , wherein the transmitting circuit includes a first transmitting antenna for transmitting the first high-frequency signal and the second high-frequency signal.

9. The measuring device as claimed in claim 1 , wherein the transmitting circuit includes a first transmitting antenna for transmitting the first high-frequency signal and further includes a second transmitting antenna for transmitting the second high-frequency signal.

10. The measuring device as claimed in claim 1 , wherein the receiving circuit includes a first receiving antenna for receiving the first high-frequency signal and the second high-frequency signal.

11. The measuring device as claimed in claim 1 , wherein the receiving circuit includes a first receiving antenna for receiving the first high-frequency signal and further includes a second receiving antenna for receiving the second high-frequency signal.

12. The measuring device as claimed in claim 8 , wherein the first transmitting antenna is designed as a rod antenna, a horn antenna, or a planar antenna.

13. The measuring device as claimed in claim 9 , wherein the first transmitting antenna and the second transmitting antenna are designed as rod antennas, horn antennas, or planar antennas.

14. The measuring device as claimed in claim 10 , wherein the first receiving antenna is designed as a rod antenna, a horn antenna, or a planar antenna.

15. The measuring device as claimed in claim 11 , wherein the first receiving antenna and the second receiving antenna are designed as rod antennas, horn antennas, or planar antennas.

16. The measuring device as claimed in claim 1 , wherein the transmitting circuit is designed to transmit the first high-frequency signal and/or the second high-frequency signal with amplitude modulation, and wherein the receiving circuit is embodied to detect the amplitude modulation and to associate the detected amplitude modulation w

Assignees

• Endress Hauser Se Co Kg

Inventors

• Blödt Thomas
• Brengartner Tobias

Classifications

• G01N22/00 Primary

  Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more (G01N3/00 - G01N17/00, G01N24/00 take precedence) · CPC title