Method and a device for measuring dielectric characteristics of material bodies

• US 7,868,627 B2
• Filed: 08/07/2009
• Issued: 01/11/2011
• Est. Priority Date: 02/14/2007
• Status: Expired due to Fees

• Current Assignee: Joint-Stock Company "High Tech"
• Original Assignee: Joint-Stock Company "High Tech"
• Inventors: Turkovskyi, Ivan I.
• Primary Examiner(s): Dole; Timothy J
• Assistant Examiner(s): Zhu; John
• Application Number:
  US12/537,771
• Publication Number:
  US 20100001747A1
• Time in Patent Office: 522 Days
• Field of Search: 324/702, 324/637, 324/638
• US Class Current: 324/642
• CPC Class Codes: G01N 22/00 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 Class Codes: G01R 27/06 Measuring reflection coefficients; Measuring standing-wave ratio

Abstract

A method and a device for measuring dielectric characteristics by generating a microwave signal, dividing the signal into reference and sounding signals, irradiating a body with the microwave signal, receiving the reflected, reference and total signals and in detecting said signals. The irradiation is carried out by a waveguide wave, the wave number of which in the free space filled with dielectric, is selected within a range from 1.0 to 1.07 the propagation number of the waveguide wave.

Claims

1. A method for measuring dielectric characteristics of materials, comprising:

generating an extremely high frequency (EHF) signal,

dividing the EHF signal into a reference signal and a probe signal,

contacting the material with a rectangular waveguide comprising a prism-shaped dielectric insert, wherein the insert is in contact with the material,

irradiating the material with the EHF signal through the waveguide,

receiving a reflected signal, a reference signal, and a combined signal, and

detecting the reflected signal, the reference signal, and the combined signal,

wherein the ratio of the wave number of the EHF signal in dielectric-filled free space to the longitudinal wave number of the EHF signal in the waveguide is (∈

·

k²)^0.5/(∈

·

k²−

(π

/a)²)^0.5 and is between 1 and 1.07,

where ∈

is a relative dielectric permittivity of the insert;

where a is the smaller dimension of the rectangular cross-section of the waveguide; and

where k is a wave number of the EHF signal for empty free space equal to k=2π

v/c, where v is the radiation frequency, and c is the speed of light in vacuum.

2. The method according, to claim 1, further comprising tuning of phase difference between the reflected and the reference signals using a short-circuit waveguide.

3. The method according to claim 2, wherein the tuning of the phase difference between the reflected and the reference signals comprises contacting an end-face of the waveguide with a polished metal mirror.

4. A device for measuring dielectric characteristics of materials, comprising:

an extremely high frequency (EHF) generator comprising a first output,

a power splitter comprising an input, a first output, and a second output,

a first breaker comprising an output, a first input, and a second input,

a second breaker comprising an output, a first input, and a second input,

a circulator comprising an input, a first output, and a second output,

a rectangular waveguide probe,

a dielectric prism mounted within a cavity of a terminal section of the waveguide probe;

a summator comprising an output, a first input, and a second input,

a quadratic detector comprising an input and an output,

an amplifier for signals at a modulation frequency,

a synchronous detector comprising a first output,

an analog-to-digital converter (ADC), and

a visualization device,

wherein the first output of the EHF generator is connected with the input of the power splitter,

wherein the first output of the power splitter is connected with the first input of the first breaker,

wherein the second output of the power splitter is connected with the first input of the second breaker,

wherein the second input of the first breaker is connected with the first output of the synchronous detector,

wherein the second input of the second breaker is connected with the first output of the synchronous detector,

wherein the output of the first breaker is connected with the input of the circulator,

wherein the first output of the circulator is connected with the waveguide probe,

wherein the second output of the circulator is connected with the first input of the summator,

wherein the second input of the summator is connected with the output of the second breaker,

wherein the output of the summator is connected with the input of the quadratic detector,

wherein the output of the summator is serially connected with the amplifier, the synchronous detector, the ADC, and the visualization device,

wherein, for at least one positive integer g, the following conditions linking the relative dielectric permittivity of the material of the prism, an inclination angle of a face of the prism to an axis of the waveguide probe, a cross-section of the waveguide probe, and the wave number hold;

0<

arc sin([∈

·

k²−

(mπ

/b)²−

(nπ

/a)²]^0.5/[∈

·

k²]^0.5)−

(2g+1)·

β

<

arc sin(1/√

∈

),

where ∈

is the relative dielectric permittivity of the material of the prism,

where a and b are a length and a width of the cross-section of the waveguide probe,

where β

is the inclination angle of the face of the dielectric prism to the axis of the waveguide probe,

where m and n are integers and are orders of propagating modes of the dielectric-filled waveguide,

where g is an integer greater than zero,

where k is a wave number of EHF radiation generated for empty free space equal to k=2π

v/c, where v is the radiation frequency, and c is the speed of light in vacuum.