SU842524A1 - Device for measuring thickness of dielectric articles - Google Patents

Description

The invention relates to measuring technique and can be used in devices for controlling the thickness of dielectric media and products using radio wave methods.

A device for measuring the thickness of dielectric products is known, which contains serially connected *. Microwave generators, a directional coupler and a transceiver antenna, a signal processing unit, while the other output of the microwave generator is connected *, to whose indicator input [1]. fifteen

The operation of such a device is based on the application of the variable frequency method for reflections. The dependence of the resulting signal during the tuning of the microwave generator 20 will be oscillating, and the value of the desired thickness is found as, NG ·· * = ΫΓΊΗΞΕΓ ’s

where G · ’is the period of oscillations ·,

N is the number of periods (peaks); 30

- dielectric constant control. environment to be washed;

f2 and L, are the extreme frequencies during tuning;

C is the speed of light.

However, the known device does not provide sufficient measurement accuracy. The error is due to the fact that when calculating the thickness of the product, only an integer N of periods G is taken into account. The measurement error is especially large for small and medium thicknesses of products.

The purpose of the invention is to improve the accuracy of measurement.

To do this, in a known device for measuring the thickness of dielectric products containing a serially connected microwave generator, a directional coupler and a transmitting and receiving antenna, a signal processing unit, while the other output of the microwave generator is connected to the indicator input, two waveguide circulators are introduced, the middle outputs of which are connected by a segment transmission lines in

In this case, the phase difference between the reflected and reference signals will change by an amount to the other input, the device diagram is indipresented.

to measure the thickness of which a movable short-circuit is installed, while the inputs of the circulators' are connected respectively to the other shoulders of the directional coupler, and the outputs through the signal processing unit are connected to the cathode.

In the drawing of the proposed device, the dielectric product contains a microwave generator 1, a directional coupler 2, a transceiver antenna 3, a signal processing unit 4, an indicator 5, two waveguide circulators 6.7, a segment 8 of a transmission line, a movable short-circuit 9.

The device operates as follows.

. Microwave electromagnetic radiation from an electrically tunable microwave generator 1 ranging from L OT to L 02 with a selected modulation frequency F is directed through a symmetrical directional coupler 2 to the transmitting and receiving antenna 3 for interaction with the monitoring object. Part of the incident electromagnetic energy as a reference signal, is fed to the input of the circulator 7 through its middle output in the segment 8 of the transmission line, is reflected from the movable short circuit 9 and then goes to the second input of the signal processing unit 4; The reflected signal from the object of control, and where Zg Zg - wave length in the wave de ¹ at the extreme points · microwave oscillator tuning range.

When the thickness is changed by Δ h, the phase change is equal to »· j

where \ 1p ₄ and A-oz ^are the wavelengths of the microwave generator at the extreme points of the tuning range.

From (2) and (3) we find that ^ ₌ Δλ _Β · λθΗ .. · D _de . ₍₄₎

If the position of the movable short-circuit 9 changes to an integer value of the number of periods of the resulting signal in the upward direction, the correction d h calculated by formula (4) is subtracted from the value of And determined by formula (1), and vice versa.

Thus, in the proposed device significantly increases the accuracy and reliability of the thickness measurement.

Claims (1)

(54) A DEVICE FOR MEASURING THE DIELECTRIC PRODUCT THICKNESS which is equipped with a movable short circuit, while the inputs of the circulators are connected respectively to the other arms of the directional coupler, and the outputs through the signal processing unit are connected to another input of the indicator. The drawing shows a diagram of the proposed device. An apparatus for measuring the thickness of dielectric products contains. microwave generator 1, directional coupler 2, receiving and transmitting antenna 3, signal processing unit 4, indicator 5, two waveguide circulators 6.7, cut 8 transmission lines, moving short 9., The device operates as follows. . The electromagnetic radiation of the microwave range from the electrically tunable microwave generator 1 in the range from D, 01 to Z 02 with the selected modulation frequency F is directed through a symmetrical directional coupler 2 in,. receiving and transmitting antenna 3 to interact with the object of control. A part of the incident electromagnetic energy as a reference signal, arrives at the input of the circulator 7 through its average output into section 8 of the transmission line, reflects from the mobile port 9 and then goes to the second input of the signal processing unit 4; The signal rejected from the object to be monitored is fed through a receiving and transmitting antenna 3, a directional coupler 2 to the input of the circulator 6, and then its average output to section 8 of the transmission line is reflected from the moving short 9 and is fed to the first input of the signal processing unit 4. 4, the signal processing is a symmetrical bridge circuit, at the output of which a resultant beat signal is generated, which enters the input of indicator 5, the horizontal scan of oscillographic indicator 5 (axis X) is started from the modulator from the frequencies Oh F. The resolving signal of the beats is fed to the vertical input of the indicator 5 (Y-axis). When a non-integer number of periods (peaks) of the signal is obtained by shifting the position of the movable short circuit 9, an integer number is obtained, and then the thickness is determined using the formula (1 taking into account the correction due to the change of the position of the movable short circuit 9 by the value of a. the reference signals change by the value of jH el - d (, C) where io and Yar are the wavelengths in the wave at the extreme points of the tuning range of the microwave generator.When the thickness changes by D h, the phase change is equal to Xp-j -Ag-i - 1 og a-02 microwave wavelengths in the extreme points of the tuning range. And (2) and (3) we find that U 4 -D () - 1 When the position of the moving short circuit 9 is changed to an integer value of the number of periods of the resulting signal in magnification, the correction h h, calculated by the formula (4), subtracts from the value of h determined by the formula (1) and vice versa. Thus, in the proposed device the accuracy and reliability of thickness measurement is significantly increased. Formula of the invention The device for measuring the thickness of dielectric products containing series-connected, microwave generation torus, directional coupler and transceiver aktivnuy, signal processing unit, while the other output of the extra high voltage;; a frequency generator connected to the input of the indicator, characterized in that, two waveguide circulators are introduced, the average outputs which are connected by a segment of the transmission line in which the moving short is installed, while the inputs of the circulators are connected. to the other arms of the directional coupler, respectively, and the outputs are connected to another input through the signal processing unit Indicator. Sources of information taken into account in case of experience 1. Bogorodsky V.V., Rudakov V.N. Electromagnetic methods for determining the thickness of floating ice. , t. XXXil, vol. 7, 1962 (prototype).