Testing scheme of granite dielectric constant by network

Every industry needs to have a very clear understanding of the materials they use , In order to shorten the time spent on design inspection and quality assurance . Each material has some unique electrical characteristics , Related to dielectric properties .

Dielectric constant is the main parameter that reflects the dielectric properties or polarization properties of piezoelectric smart materials under the action of electrostatic field , Usually use ε To express . Piezoelectric components for different purposes have different requirements for the dielectric constant of piezoelectric smart materials . When the shape of piezoelectric smart materials 、 When the size is certain , Dielectric constant ε By measuring the inherent capacitance of piezoelectric smart materials CP To make sure .

According to the dielectric constant of the material, the polarity of the polymer material can be judged . Usually , The relative dielectric constant is greater than 3.6 The substance of is polar substance ; The relative dielectric constant is 2.8~3.6 The substances in the range are weakly polar substances ; The relative dielectric constant is less than 2.8 It is a nonpolar substance .

There are coaxial probe methods for measuring dielectric constant by network 、 Transmission line method 、 Free space law 、 Resonant cavity method 、 Parallel plate method and inductance measurement method , Several important factors must be considered when selecting the most appropriate measurement method

1、 frequency range ;

2、εr and μr Expected value ;

3、 Required measurement accuracy ;

4、 Material properties ( For example, homogeneous 、 Isotropy );

5、 Material form ( Such as liquid 、 Powder 、 solid 、 thin slice );

6、 Sample size limit ;

7、 Destructive and non-destructive to materials ;

8、 Contact or non-contact ;

9、 temperature ;

10、 cost ;

This article introduces the method of measuring the dielectric constant of building materials by network , We choose coaxial probe method for this test , The advantage of this method is convenience , No need to destroy , Suitable for loss MUT; Liquid and semi-solid , solid , The requirements for the tested materials are not high , The test surface needs to be polished smooth before the test , The thickness of the measured object should preferably be greater than two centimeters , There is no requirement for diameter and shape

The test method in this article requires devices ： Vector network analyzer 、 Coaxial probe 、 Short circuit piece 、 Deionized water 、 Tested object 、 Testing software

Prepare for the test ： Polish the tested object smooth , The test sample is granite , Ensure smooth surface

The test uses Rhode's supporting software , First set the frequency range of the test , The scope of this test is 100MHz-3GHz, test 200 A little bit , Calibration is required before each test , Calibration is divided into three steps ：

1、 Use a short circuit piece for calibration （ Total reflection ）

2、 Air calibration （ The signal has no reflection ）

3, Deionized water calibration

After the calibration is completed, you can start the direct test , Aim the high-performance probe at the tested object , You can start the test without shaking , The software can directly convert the test results into dielectric constants , Direct reading