CN1928536A - Microwave pottery materials fast detection device and method - Google Patents

Abstract

The fast detection device for microwave ceramics includes an opening parallel plate resonant cavity with step motor, a SCM, a driver for motor, a VNA, and a computer. This invention can detect target dielectric properties with no harm and high precision.

Description

Microwave ceramic material device for fast detecting and detection method thereof

Technical field

The present invention relates to a kind of detection of microwave ceramic material, the dielectric properties parameter that especially relates to a kind of microwave dielectric material is the device for fast detecting and the detection method thereof of relative dielectric constant, dielectric loss coefficient and temperature coefficient.

Background technology

In recent years, microwave dielectric ceramic materials has been widely used for making resonator, wave filter, dielectric substrate, diectric antenna, Medium Wave Guide loop etc., just bringing into play increasing effect in the modern communications field, is a kind of electronic information material that has a extensive future.The dielectric properties of this material mainly contain three parameters: relative dielectric constant (abbreviation specific inductive capacity), dielectric loss coefficient and temperature coefficient, quick and precisely measure this three parameters, and be an important step of exploitation microwave dielectric ceramic materials.

Wu Yi wait by force (Wu Yiqiang, Lu Jinping, etc., the straightforward procedure of microwave-medium ceramics dielectric constant measurement, electronic component and material, 2004,4) introduced the specific inductive capacity and the loss of equivalent air method test microwave dielectric ceramic materials sheet sample.Lv Wen medium (the parallel-plate resonance method is measured microwave-medium ceramics dielectric properties, electronic component and material, 2003,5 for Lv Wenzhong, Lai Xiwei) introduced the parallel-plate resonance method have measurement simply, advantage fast and accurately.Mediocre ancestor prosperous (Tang Zongxi, the measurement of dielectric resonator dielectric parameter Frequency Response and frequency-temperature coefficient, metering journal, 2002,23 (1)) has adopted short circuit type parallel-plate resonator cavity, carries out the test of frequency-temperature coefficient, has obtained gratifying effect.

Summary of the invention

The objective of the invention is to wait problem more slowly at existing microwave dielectric ceramic materials measuring speed, provide that a kind of measuring speed is very fast, applicability is wide, harmless, in batches, the degree of accuracy height, easy to operate, cost performance is high, particularly has more the device for fast detecting of the microwave dielectric ceramic materials of advantage on the fast detecting of microwave dielectric ceramic materials temperature coefficient.

Another object of the present invention is to provide a kind of method of fast detecting microwave dielectric ceramic materials.

Microwave ceramic material device for fast detecting of the present invention comprises:

1) the opening parallel-plate resonator cavity of band stepper motor: be provided with by two opening resonator cavitys that silver-plated red copper parallel-plate constitutes up and down, following parallel-plate bottom has ring gear, under step motor control, can rotate arbitrarily angled easily, plate is provided with at least 8 apertures, on aperture, insert sample pad, the parallel-plate center penetrates a cylindrical body up and down, cylindrical body is provided with two grooves, pass for coaxial wire, parallel-plate is positioned on bearing and the base up and down, and base is fixed on the chassis, and stepper motor is installed by chassis central authorities, the chassis another side is the holder of another coaxial cable, and cylindrical body can be made as cylinder.

2) Single-chip Controlling and stepper motor driver: be made up of power circuit, single chip machine controlling circuit and stepper motor driving circuit, power circuit provides required direct supply for stepper motor and single-chip microcomputer and other chip; Single chip machine controlling circuit is used for producing pulse signal and carry out signal allocation under the keyboard input instruction, the work of control motor-drive circuit; Stepper motor driving circuit is used to stepper motor to provide enough power with drive motor work, and the stepper motor driving circuit input end is connected with the single chip machine controlling circuit output terminal, and the stepper motor driving circuit output terminal is connected with the stepper motor input end.

3) vector network analyzer and computing machine: vector network analyzer is connected with computing machine by gpib interface, under computer control, the swept-frequency signal output terminal of vector network analyzer connects opening parallel-plate resonator cavity input end through concentric cable, and the resonance signal output terminal of opening parallel-plate resonator cavity connects vector network analyzer by another concentric cable.

Can adopt disclosed HP VEE when adopting microwave dielectric ceramic materials rapid measurement device of the present invention to detect is SDK (Software Development Kit), testing software under the establishment Windows system, this software is pointed out testing procedure, to measurement data gather in real time, K-theoretic operation K, error analysis, demonstration and storage.Realize fast, precision, harmless, microwave dielectric ceramic materials is carried out robotization detect in batches, good man-machine dialog interface, clearly form and curve reflect test result comprehensively.

Microwave dielectric ceramic materials method for quick of the present invention the steps include:

1) calibration vector network analyzer is measured the diameter and the height of cylindrical sample, input computing machine corresponding form.

2) will put into the constant-temperature temperature-control case with the opening parallel-plate resonator cavity of stepper motor, be placed in down one by one on the sample pad of parallel-plate with batch manufactured samples.

3) will import to strip out respectively and curve ringlet and outer conductor and weld with the output coaxial cable inner wire, make coupling ring, the parallel sample both sides that are adjusted to of two coupling rings are adjusted simultaneously and are gone up the parallel-plate height, parallel-plate is consistent with the distance of sample about making, and shuts the constant-temperature temperature-control chamber door.

4) start stepper motor, measure first sample under the room temperature, after stepper motor stops, this computer-chronograph will be preserved the viewed sample tuning curve of vector network analyzer, the resonance frequency that writes down this sample and quality factor, and the theoretical calculation formula of substitution specific inductive capacity and loss factor, calculate the specific inductive capacity and the loss factor of institute's test sample product rapidly, and insert automatically in the form of first sample; Start stepper motor once more, note the data of second sample in an identical manner, until having surveyed 8 samples, coupling ring is got back to the original place again.

5) set temperature on the constant-temperature temperature-control case, when temperature reaches, repeating step 4.

6) click computing machine, enter material temperature coefficient calculations program, program will read room temperature and the following resonant frequency value of surveying of design temperature automatically, obtain required the 3rd parameter (temperature coefficient) from the ratio of two difference on the frequencies and the temperature difference.

7) finish test, quit a program.

Vector network analyzer can adopt E8362B type vector network analyzer.

Microwave dielectric ceramic materials device for fast detecting of the present invention comprises opening parallel-plate resonator cavity, Single-chip Controlling and stepper motor driver, vector network analyzer and the computing machine etc. of being with stepper motor, and cooperate corresponding testing software, under the control that is programmed in computing machine and single-chip microcomputer, to real-time collection, K-theoretic operation K, error analysis, result's demonstration and the preservation of measurement data.Whole test process, automatically carry out, test condition unanimity under the different temperatures, data error is little, repeatability is high, back employing measure batch heats up, overcome short circuit type parallel-plate resonator cavity in the past, a sample heats up once, measures length consuming time, test duration of the present invention approximately is reduced to original 1/8th, the rotary batch mensuration changes short circuit type parallel-plate resonator cavity into open ended parallel-plate resonator cavity simultaneously, and sample does not contact with the metal parallel-plate, the loss that the contact of metal parallel-plate is caused greatly reduces, the tee T sample pad specific inductive capacity that adopts polystyrene material to make in addition is 2.0, and much smaller than the specific inductive capacity of specimen material, so sample pad can be ignored with error data cause, the temperature coefficient calculated value that adds material is relevant with two difference on the frequencies, and the existence of sample pad has no effect especially to two difference on the frequencies.Realize fast, accurately, harmless, convenient, in bulk microwave dielectric ceramic materials is tested, particularly in the quick test of microwave dielectric ceramic materials temperature coefficient, have more advantage, be applicable in research institutions and the factory and enterprise product test and application and development microwave dielectric ceramic materials.

Description of drawings

Fig. 1 is the composition block scheme of the device for fast detecting embodiment of microwave dielectric ceramic materials of the present invention.

Fig. 2 is the open ended parallel-plate cavity resonator structure synoptic diagram among Fig. 1.

Fig. 3 looks synoptic diagram for the open ended parallel-plate cavity resonator structure master among Fig. 1.

Fig. 4 is the open ended parallel-plate resonator cavity rotation synoptic diagram among Fig. 1.

Fig. 5 is the open ended parallel-plate cavity resonator structure decomposing schematic representation among Fig. 1.

Fig. 6 is the power circuit principle figure of the device for fast detecting embodiment of microwave dielectric ceramic materials of the present invention.

Fig. 7 is the Single-chip Controlling stepping motor system block diagram among Fig. 1.

Fig. 8 is single chip machine controlling circuit and the stepper motor driving circuit schematic diagram among Fig. 7.

Fig. 9 is the Single-chip Controlling FB(flow block) of the device for fast detecting embodiment of microwave dielectric ceramic materials of the present invention.

Embodiment

Following examples will the present invention is further illustrated in conjunction with the accompanying drawings.

Referring to Fig. 1, the device for fast detecting of microwave dielectric ceramic materials of the present invention is provided with opening parallel-plate resonator cavity 01, Single-chip Controlling and stepper motor driver 02, vector network analyzer 03, computing machine 04 and the constant-temperature temperature-control case 05 of band stepper motor.The input termination computing machine 04 of Single-chip Controlling and stepper motor driver 02, the opening parallel-plate resonator cavity 01 of the output terminal tape splicing stepper motor of Single-chip Controlling and stepper motor driver 02, the parallel-plate resonator cavity is connected with vector network analyzer 03 by concentric cable, vector network analyzer 03 is connected with computing machine 04 by gpib interface, under computing machine 04 control, the swept-frequency signal output terminal of vector network analyzer 03 connects the input end of opening parallel-plate resonator cavity 01 through concentric cable, and the pumping signal output terminal of opening parallel-plate resonator cavity 01 connects vector network analyzer 03 by another concentric cable.The opening parallel-plate resonator cavity 01 of band stepper motor is positioned in the constant-temperature temperature-control case 05.

Owing to utilize gpib interface that computing machine 04 is connected with vector network analyzer 03, therefore under computing machine 04 control, vector network analyzer 03 with swept-frequency signal through concentric cable, import opening parallel-plate resonator cavity 01, the excitation sample, when exciting signal frequency is consistent with the sample resonance frequency, harmonic peak will be by another concentric cable, export the signal coupling to vector network analyzer 03,04 pair in machine detects real time data acquisition, K-theoretic operation K, error analysis as calculated again, the result shows and preservation.In addition, with opening parallel-plate resonator cavity 01 whole putting in the constant-temperature temperature-control case 05, but the detected temperatures coefficient.

Referring to Fig. 2～5, form opening resonator cavity by parallel-plate on the silver-plated red copper 11 and following parallel-plate 4; Following parallel-plate 4 bottoms have ring gear 3, under stepper motor 14 controls, can rotate arbitrarily angled easily, radius 2/3rds places on following parallel-plate 4 are drilled with 8 apertures 5 equably, insert the tee T sample pad 6 that polystyrene material is made, and can place 8 samples 7 simultaneously.When placing sample 7, directly mention parallel-plate 11 (not having any fixed screw), not only fast but also convenient, and the adjustable height of last parallel-plate 11 placements, put highly is by the determining positions of the nut under this plate 10.According to the size in the constant-temperature temperature-control case, and the radiation scope of electromagnetic field during sample resonance, the design diameter of two parallel-plates up and down is 180mm.Two parallel-plate centers penetrate the stainless steel cylinder 9 that diameter is 30mm, have two U type grooves 8 on the cylinder 9, pass for coaxial wire 12.Following parallel-plate 4 is positioned on stainless steel bearing 2 and the base 1, and base 1 is fixed on the chassis 26 that is of a size of 220mm * 260mm by screw.Stepper motor 13,14 and 15 is installed by 26 central authorities on the chassis.When adding a pulse signal for stepper motor 14, the driving gear of stepper motor 15 then turns over a step angle, the existence of this linear relationship has only periodic error and does not have cumulative error, makes and controls more simple with stepper motor in control fields such as speed and positions.For this reason, can adopt the less four phase eight beat motor of step angle, so that improve bearing accuracy.Chassis 26 another sides are provided with the holder 16 of another coaxial cable 25, have the triangular groove of 2 different sizes on the fixing clamper 21, to satisfy the fixing of different coaxial cable line footpaths.When set screw 22 screws out, the nut of rotary screw 18 tops, whole fixing clamper 20 and 21 can move up and down easily, and brace 23 is connected screw mandrel 18 with fixed bar 17, and by screw 24 brace 23 is locked in fixed bar 17 tops.

Single-chip Controlling and stepper motor driver are made up of power circuit, single chip machine controlling circuit and stepper motor driving circuit.

Referring to Fig. 6, power circuit is converted into the required 12V direct supply of stepper motor with alternating current AC220V by transformer T step-down, rectification, filtering, voltage stabilizing, and single-chip microcomputer and the required 5V direct supply of other chip.In Fig. 6, integrated regulator adopts LM7805 type and LM78 type integrated regulator respectively.

Referring to Fig. 7, in the Single-chip Controlling stepping motor system, under the input instruction of keyboard 81, single-chip microcomputer 82 produces pulse signal and carries out signal allocation, the photoisolator 83 of leading up to is controlled the work of motor-drive circuits 84, motor-drive circuit 84 drive stepping motor 85; Another road shows input instruction and running status by display driver circuit 86 backs by light-emitting diode display 87.The basic function of single chip machine controlling circuit is: the stepper motor speed adjustment of four gears, and the rotating control of stepper motor, the various requirement in the testing of materials process is satisfied in the single step adjustment in moving continuously and finely tuning.

Single chip machine controlling circuit and stepper motor driving circuit are referring to Fig. 8, and single chip machine controlling circuit adopts the low-power consumption of 98S51 type, 8 single-chip microcomputer IC of high-performance CMOS ₁, single-chip microcomputer IC ₁Include the Flash read-only program memory of the bilateral system programming of 4KB, device adopts high density, the nonvolatile storage technologies production of atmel corp, compatibility standard 8051 order set and pin.

Because single-chip microcomputer IC ₁The control signal of output directly drive stepping motor M is rotated, and a special motor-drive circuit must be arranged, and makes it that enough power drive machine operation be arranged.Control signal is delivered to Darlington amplifier tube Q through not gate at first through photocoupler in the circuit ₁, Q ₂, Q ₃And Q ₄Base stage, when the Darlington transistor conducting, the big electric current of output is enough to drive stepping motor M and rotates.In Fig. 8, integrated circuit (IC) ₂, IC ₃And IC ₄The driving circuit of combined display, resistance R ₁～R ₁₇, capacitor C ₁～C ₃, diode D ₁～D ₄And quartz crystal X etc. can adopt suitable model and parameter, parts S ₁～S ₅Be button.

Fig. 9 provides the Single-chip Controlling FB(flow block) of the device for fast detecting embodiment of microwave dielectric ceramic materials.

Aspect testing software, can adopt HP VEE is SDK (Software Development Kit), the testing software under the establishment Windows system, this software is pointed out testing procedure, to measurement data gather in real time, K-theoretic operation K, error analysis, demonstration and storage.Realize fast, precision, harmless, in bulk microwave dielectric ceramic materials is carried out robotization and detects, good man-machine dialog interface, clearly form and curve reflect test result comprehensively.Measure microwave dielectric ceramic materials fast and can adopt following steps:

1) calibration microwave network analyzer (as the E8362B type) starts in the computing machine and develops voluntarily with the microwave-medium ceramics testing software, measures the diameter D and the height L of cylindrical sample, in the corresponding form of input computing machine.

2) will put into the constant-temperature temperature-control case with the opening parallel-plate resonator cavity of stepper motor, be placed in down one by one on the tee T sample pad of parallel-plate (rotating disc) with batch manufactured samples (being less than 8 usually).

3) with the parallel sample both sides that are adjusted to of coupling ring, adjust simultaneously and go up the parallel-plate height, make the distance of upper and lower plates and sample unanimous on the whole, and shut the constant-temperature temperature-control chamber door.

4) connect lower keyboard, start stepper motor, measure first sample under the room temperature, after stepper motor stops, this computer-chronograph will be preserved the viewed sample tuning curve of vector network analyzer, the resonance frequency that writes down this sample and quality factor, and the theoretical calculation formula of substitution specific inductive capacity and loss factor, calculate the specific inductive capacity and the loss factor of institute's test sample product rapidly, and insert automatically in the form of first sample.Start stepper motor once more, identical mode is noted the data of second sample, and until having surveyed 8 samples, coupling ring is got back to the original place again.

5) set temperature on the constant-temperature temperature-control case, place 80 degree usually, when temperature reaches, repeating step 4).

6) click computing machine, enter material temperature coefficient calculations program, program will read room temperature and the following resonant frequency value of surveying of 80 degree automatically, obtain required the 3rd parameter (temperature coefficient) from the ratio of two difference on the frequencies and the temperature difference.

7) finish test, quit a program.

Test result is referring to table 1 and table 2, whole test process, automatically carry out, test condition unanimity under the different temperatures, data error is little, repeatability is high, and measure batch is adopted in the back of heating up, and overcomes short circuit type parallel-plate resonator cavity in the past, a sample heats up once, measure length consuming time, the test duration of the present invention approximately be reduced to original eight/, rotary batch mensuration simultaneously, change short circuit type parallel-plate resonator cavity into open ended parallel-plate resonator cavity, sample does not contact with the metal parallel-plate, and the loss that the contact of metal parallel-plate is caused reduces, the tee T sample pad specific inductive capacity 2 that adopt polystyrene material to make this moment, specific inductive capacity much smaller than specimen material, therefore sample pad can be ignored with error data cause, and the temperature coefficient calculated value of material is relevant with two difference on the frequencies in addition, and the existence of sample pad is to have no effect to two difference on the frequencies.

Table 1 test result

Sample	The open ended mode is measured				The short circuit type mode is measured
									f 0 (GHz)	ε r′	tanδ (×10 -5)	f 0·Q (GHz)	f 0 (GHz)	ε r′	tanδ (×10 -5)	f 0·Q (GHz)
	BCZN	4.956	36.94	9.74	50967	6.164*	36.89*	13.80*									44667*
THK915									3.926	89.60	53.40	7343	4.769*	89.44*	70.00*	6813*
	3-1340	5.066	36.24	8.81	57038	6.317*	36.01*	11.60*									54457*
THK84									4.413	83.10	51.72	8531	5.229*	82.86*	61.20*	8541*
	3-1440	5.402	32.34	16.73	32289	6.920	32.24	23.06									30009
1-1440									5.634	30.30	22.22	25355	7.284	30.22	30.34	24008
	3-1400	5.376	32.56	18.23	29474	6.959	32.56	25.04									27796
3-1360									5.284	34.29	14.75	35823	6.752	34.23	19.73	34222

Band * data are electronics University of Science and Technology measurement result.

Table 2 monocyte sample is measurement result repeatedly

Δε _r′/ε _r′≤0.08％。Δtanδ/tanδ≤0.2％

Below provide open ended parallel-plate dielectric resonator method relative dielectric constant calculated examples.

For Gao Jie, the low microwave ceramic material that decreases, in order to improve the precision of test, the method of open ended is proposed, this moment, parallel metal sheet did not directly contact with the medium post, but draw back certain distance, can reduce the metal conduction loss in the test, with respect to the TE of short circuit type parallel-plate dielectric resonator ₀₁₁Mould, main moding this moment is TE _{01 δ}Mould.Process to simplify the analysis, the relational expression of derivation resonance frequency and relative dielectric constant, under not impact analysis result's prerequisite, make following 3 hypothesis:

1. dielectric sample is that isotropy is harmless; 2. sheet metal is intact conduction; 3. distance does not have radiation loss this moment less than the free space half-wavelength of resonance frequency correspondence between two sheet metals.

Rotational symmetry mould TE _{01 δ}Be most important a kind of mode of operation in the real medium resonator applications, have only E _φ, H _ρ, H _zThree components, this pattern has a plurality of advantages:

1. electric field and magnetic field all are the circle symmetries, and coupling is convenient; 2. the intensity height of energy in dielectric resonator, the loss that metal is on every side introduced is little; 3. pattern is recognized easily, and its electrical property is easy to be measured more accurately; 4.Q be worth higher.

Utilize the variation theory of computing eigenvalue, it is I:r＜a and II:r＞a two parts that the space that two sheet metals are comprised is divided into, and considers continuously at r=a place, finds the solution the Helmholtz equation.Analysis axis symmetric pattern TE _{01 δ}, can obtain the matrix equation that resonance frequency and relative dielectric constant concern.According to Theory of Electromagnetic Field, the electric field of surface current excitation is represented:

$E_{\mathrm{\φ}}^I(r,z)=-{\mathrm{ik}}_0{Z}_f{\∫}_0^{L^{\′}}{G}^I(r,a,z,z^{\′})H_z(a,z^{\′}){\mathrm{dz}}^{\′}---\left(1\right)$

$E_{\mathrm{\φ}}^{\mathrm{II}}(r,z)={\mathrm{ik}}_0{Z}_f{\∫}_0^{L^{\′}}{G}^{\mathrm{II}}(r,a,z,z^{\′})H_z(a,z^{\′}){\mathrm{dz}}^{\′}---\left(2\right)$

In formula (1) and (2): L '=L+L ₁+ L ₂, G (r, r ', z, z ') is the Green function of Helmholtz operator; H _z(a, z ') is at the lip-deep magnetic field of r=a z component, Z _fBe the space wave impedance, I, II are respectively r＜a and two zones of r＞a.

At the r=a place continuously, E equates, has $E_{\mathrm{\φ}}^I-E_{\mathrm{\φ}}^{\mathrm{II}}=0.$

Use R ^I, R ^IIThe expression integral operator, {  _jBe the complete collection of functions of (0, L '),

<R ^IH _z(a，z) _j>+<R ^IIH _z(a，z) _j>＝0 j＝1，2，3… (3)

In the formula (3),＜the expression inner product.

If $H_z=\underset{i=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}{c}_i{\mathrm{\&phi;}}_i\left(z\right),$ c _iBe undetermined coefficient, { φ _iIt is the complete collection of functions of (0, L ').

Make w _Ij=＜R ^Iφ _i,  _jThe R of 〉+＜ ^IIφ _i,  _j, det[W then]=0 (5)

(according to Weinstein variation theory, constantly the dimension that enlarges will make and the value monotone increasing of determinant that is to say approximate value trend actual value W battle array dimension n for i, j≤n) be tending towards infinitely great at this moment.That is: ε _r ⁽¹⁾≤ ε _r ⁽²⁾≤ Λ≤ε _r ⁽ⁿ⁾Λ≤ε _r

Make L ₁=L ₂, according to boundary condition, get normalized testing function:

Further conversion obtains matrix element and is respectively:

$w_{i1}=\left\{\begin{array}{c}\frac{L}{L^{\&prime;}}\frac{J_1\left(x_i\right)}{x_i{J}_0\left(x_i\right)}[1+\frac{\sin \left({\mathrm{\&gamma;}}_{i}L\right)}{{\mathrm{\&gamma;}}_{i}L}+(1-\frac{L}{L^{\&prime;}})\frac{I_1\left(y_i\right)}{y_i{I}_0\left(y_i\right)}[1-\frac{\sin \left({\mathrm{\&gamma;}}_{i}L\right)}{{\mathrm{\&gamma;}}_i(L^{\&prime;}-L)}]\\ +\frac{K_1\left(y_i\right)}{y_i{K}_0\left(y_i\right)}-\frac{8{({\mathrm{\&epsiv;}}_r-1)}^2{k_0}^4}{a^2{L}^{\&prime;}}\underset{m=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{(P_m{A}_i+B_i)(Q_m{A}_i-B_i)}{{({u_m}^2+{{\mathrm{\&gamma;}}_i}^2)}^2{({{\mathrm{<figure-callout\; id="2"\; label="v\; m"\; filenames="A20061014175600192.png"\; state="\{\{state\}\}">v</figure-callout>}}_m}^2+{{\mathrm{\&gamma;}}_i}^2)}^2(P_m+Q_m)}\end{array}\right\}---\left(7\right)$

$w_{\mathrm{ij}}=\left\{\begin{array}{c}\frac{4}{L^{\&prime;}}\frac{B_i{A}_j-B_j{A}_i}{{{\mathrm{\&gamma;}}_i}^2-{{\mathrm{\&gamma;}}_j}^2}[\frac{J_1\left(x_i\right)}{x_i{J}_0\left(x_i\right)}-\frac{I_1\left(y_i\right)}{y_i{I}_0\left(y_i\right)}\\ -\frac{8({\mathrm{\&epsiv;}}_r-1){k_0}^2}{a^2{L}^{\&prime;}}\&CenterDot;\underset{m=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{1}{({u_m}^2+{{\mathrm{\&gamma;}}_i}^2)({{\mathrm{<figure-callout\; id="2"\; label="v\; m"\; filenames="A20061014175600192.png"\; state="\{\{state\}\}">v</figure-callout>}}_m}^2+{{\mathrm{\&gamma;}}_i}^2)(P_m+Q_m)}\\ \&CenterDot;[\frac{(P_m{A}_j+B_j)(Q_m{A}_i-B_i)}{({u_m}^2+{{\mathrm{\&gamma;}}_j}^2)}-\frac{(P_m{A}_i+B_i)(Q_m{A}_j-B_j)}{({{\mathrm{<figure-callout\; id="2"\; label="v\; m"\; filenames="A20061014175600192.png"\; state="\{\{state\}\}">v</figure-callout>}}_m}^2+{{\mathrm{\&gamma;}}_j}^2)}]\end{array}\right\}---\left(8\right)$

Wherein:

${\mathrm{\&gamma;}}_k=(2k-1)\frac{\mathrm{\&pi;}}{L^{\&prime;}},A_k=\cos \left({\mathrm{\&gamma;}}_k\frac{L}{2}\right),B_k={\mathrm{\&gamma;}}_k\sin \left({\mathrm{\&gamma;}}_k\frac{L}{2}\right),$

$x_k=a\sqrt{{\mathrm{\&epsiv;}}_r{k_0}^2-{{\mathrm{\&gamma;}}_{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="A20061014175600192.png"\; state="\{\{state\}\}">k</figure-callout>}}}^2},y_k=a\sqrt{{{\mathrm{\&gamma;}}_k}^2-{k_0}^2},P_m=u_m\tanh \left(u_m\frac{L}{2}\right),$ Q _m＝v _mcoth(v _mL ₁)，

$u_m=\sqrt{{h_m}^2-{\mathrm{\&epsiv;}}_r{k_0}^2},v_m=\sqrt{{h_m}^2-{k_0}^2},$

k＝i，j，k ₀＝2π/λ ₀，L′＝L+2L ₁，i、j＝1，2，3，…

h _mBe equation J ₀(h _mA)=0 a m root, ε _rIt is the relative dielectric constant of sample; J _nBe Bessel function of the first kind, I _n, K _nBe respectively the first and second class modified Bessel functions.By the resonant frequency value of measuring, calculate the relative dielectric constant of sample.

The Green function of finding the solution the Helmholtz operator of open ended parallel-plate symmetrical structure is:

$G^I(r,r^{\&prime;},z,z^{\&prime;})=\frac{2}{a^2}\underset{m=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{J_1\left(h_{m}r\right)J_1\left(h_m{r}^{\&prime;}\right)}{{J_1}^2\left(h_{m}a\right)}{G}_m(z,z^{\&prime;})$

In the formula, G _m(z, z ') is the Green function of one dimension;

$G_m(z,z^{\&prime;})=\left\{\begin{array}{cc}\frac{g_{1m}\left(z\right)g_{2m}\left(z^{\&prime;}\right)}{S_m}& z{<z}^{\&prime;}\\ \frac{g_{1m}\left(z^{\&prime;}\right)g_{2m}\left(z\right)}{S_m}& z{>z}^{\&prime;}\end{array}\right.$

In the formula, $S_m=u_m{v}_m[u_m\sinh \left(\frac{u_{m}L}{2}\right)\sinh \left(v_m{L}_1\right)+v_m\cosh \left(\frac{u_{m}L}{2}\right)\cosh \left(v_m{L}_1\right)]$

$g_{1m}=\left\{\begin{array}{cc}{v}_m\cosh \left(u_{m}z\right)& 0<z<\frac{L}{2}\\ v_m\cosh \left(\frac{u_{m}L}{2}\right)\cosh \left[v_m(z-\frac{L}{2})\right]+u_m\sinh \left(\frac{u_{m}L}{2}\right)\sinh \left[v_m(z-\frac{L}{2})\right]& \frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20061014175600192.png"\; state="\{\{state\}\}">L</figure-callout>}}{2}<z{<L}_1+\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20061014175600192.png"\; state="\{\{state\}\}">L</figure-callout>}}{2}\end{array}\right.$

$g_{2m}=\left\{\begin{array}{cc}{u}_m\sinh \left(v_m{L}_1\right)\cosh \left[u_m(\frac{L}{2}-z)\right]+v_m\cosh \left(v_m{L}_1\right)\sinh \left[u_m(\frac{L}{2}-Z)\right]& 0<z<\frac{L}{2}\\ u_m\sinh \left[v_m(L_1+\frac{L}{2}-z)\right],& \frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20061014175600192.png"\; state="\{\{state\}\}">L</figure-callout>}}{2}<z<L_1+\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20061014175600192.png"\; state="\{\{state\}\}">L</figure-callout>}}{2}\end{array}\right.$

G ^II(r，r′，z，z′)＝X·Y

$X=\frac{2}{L^{\&prime;}}\underset{i=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\frac{\cos \left({\mathrm{\&gamma;}}_{i}z\right)\cos \left({\mathrm{\&gamma;}}_i{z}^{\&prime;}\right)}{K_0\left(y_i\right)}$

$Y=\left\{\begin{array}{cc}[I_0\left(y_i\right)K_1\left(\frac{y_i}{a}r\right)+K_0\left(y_i\right)I_1\left(\frac{y_i}{a}r\right)]K_1\left(\frac{y_i}{a}{r}^{\&prime;}\right)& r{<r}^{\&prime;}\\ [I_0\left(y_i\right)K_1\left(\frac{y_i}{a}{r}^{\&prime;}\right)+K_0\left(y_i\right)I_1\left(\frac{y_i}{a}{r}^{\&prime;}\right)]K_1\left(\frac{y_i}{a}r\right)& r>r^{\&prime;}\end{array}\right.$

The quality factor that below provide microwave-medium ceramics are calculated.

Mainly introducing the theory of testing of microwave ceramics dielectric loss angle tangent derives, quality factor from resonator, introduced the Q value relation of open circuit parallel-plate dielectric resonator, when testing with network analyzer, obtain to have the process of related parameter by parallel-plate dielectric resonator transmission coefficient, and use perturbation method to obtain the measuring method of dielectric sample loss tangent.Consider the influence of conduction loss, can more accurately know the loss value of dielectric sample.

1) quality factor of dielectric resonator

The quality factor of dielectric resonator are called for short the Q value, are the important indicator of dielectric resonator in circuit application, are defined as:

In the formula (9), ω is a resonance angular frequency, and W is total electromagnetic energy of resonator storage, and P is a power attenuation, and it comprises various possible power attenuations.

Be positioned over the enclosed medium resonator of free space, its loss is the dielectric loss and the radiation loss of resonator itself, for the dielectric resonator in circuit structure and actual the use, except top two kinds of losses, also to consider resonator other dielectric loss and conductor losses on every side.Therefore, the power attenuation of dielectric resonator can be written as:

P＝P _d+P _c+P _r (10)

P wherein _dBe all dielectric losses, P _cBe conductor losses, P _rIt is radiation loss.Can get the dielectric resonator nonloaded Q is:

$Q_u=\frac{\mathrm{\&omega;W}}{P_d+P_c+P_r}---\left(11\right)$

Or be expressed as:

$\frac{1}{Q_u}=\frac{1}{Q_d}+\frac{1}{Q_c}+\frac{1}{Q_r}---\left(12\right)$

In the formula (12), $Q_d=\mathrm{\&omega;}\frac{W}{P_d},$ Be Q value, owing to a little less than the air loss extremely, can ignore by All Media loss decision.So during other dielectric loss around not considering resonator, Q _dEqual the inverse of the loss tangent of resonator material, i.e. Q _d=1/tan δ; $Q_c=\mathrm{\&omega;}\frac{W}{P_c},$ It is Q value by the decision of the conductor losses around the resonator; $Q_r=\mathrm{\&omega;}\frac{W}{P_r},$ It is the Q value that determines by radiation loss.

When L/a≤1, b/a 〉=3 (b is the radius of two sheet metals), radiation loss has been reduced to below 0.1% of sheet metal loss, can ignore, for the parallel-plate dielectric resonator of open ended, distance is less than the free space half-wavelength of resonance frequency correspondence, i.e. L '≤λ when between two sheet metals ₀, there is not radiation loss at/2 o'clock.

If W _d, W _aBe respectively the electric field energy that stores in medium and the air, P _dBe the average power consumption in the medium, according to Theory of Electromagnetic Field, as can be known:

Wherein: σ _dIt is medium conductivity.So: P _d=2 ω W _dTan δ.Because total electromagnetic energy in the system: W=2 (W _d+ W _a), according to definition then:

$Q_d=\mathrm{\&omega;}\frac{W}{P_d}=\frac{1}{\tan \mathrm{\&delta;}}\frac{W_d+W_a}{W_d}---\left(15\right)$

Applicating medium perturbation method theory as can be known,

Then have: $\frac{{\mathrm{\&Delta;f}}_0}{f_0}=-\frac{{{\mathrm{\&Delta;\&epsiv;}}_r}^{\&prime;}}{2{{\mathrm{\&epsiv;}}_r}^{\&prime;}}\frac{W_d}{W_d+W_a}---\left(17\right)$

That is: $Q_d=\frac{1}{\tan \mathrm{\&delta;}}\frac{f_0}{2(-\mathrm{\&Delta;}{f}_0/{{\mathrm{\&Delta;\&epsiv;}}_r}^{\&prime;}){{\mathrm{\&epsiv;}}_r}^{\&prime;}}---\left(18\right)$

In the formula, tan δ is the loss tangent of resonator material.With regard to the Q value of sample, during owing to resonance, most store energy is in sample, sometimes directly Q _dThe Q that is used as sample.

In order accurately to measure the Q value (Q of sample ^-1=tan δ), conduction loss is also taken into account, adopt the method for propositions such as Kajfez, for TE _{01 δ}Symmetric mode has only the tangential magnetic field component on metallic conductor plate surface, when conductor plate when improving conductor, the total magnetic energy in the system is W _mUtilize tangential magnetic field and magnetic energy increment relation, the power consumption on metallic conductor plate surface is:

$P_c=2\mathrm{\&omega;\&Delta;}{W}_m\left(\frac{{\mathrm{\&delta;}}_c}{2}\right)=\mathrm{\&epsiv;\&Delta;}{W}_m\left({\mathrm{\&delta;}}_c\right)$

$Q_{\mathrm{cu}}=\frac{\mathrm{\&omega;}{W}_m}{P_c}=\frac{W_m}{\mathrm{\&Delta;}{W}_m\left({\mathrm{\&delta;}}_c\right)}$

In the formula, Q _CuBe the conduction loss that goes up metallic conductor, δ _cBe the skin depth of conductor, Δ W _mBe the outside mobile δ of conductor plate _cThe time the magnetic energy increment, according to the shape perturbation theory, exist:

$\frac{{\mathrm{\&Delta;f}}_0\left({\mathrm{\&delta;}}_c\right)}{f_0}=\frac{\mathrm{\&Delta;}{W}_m-\mathrm{\&Delta;}{W}_e}{W_m},$ This moment Δ W _e=0, so,

$Q_{\mathrm{cu}}=\frac{f_0}{{\mathrm{\&Delta;f}}_0\left({\mathrm{\&delta;}}_c\right)}$

For the open ended parallel plate resonator, $\mathrm{\&Delta;L}=\frac{\&PartialD;L}{{\&PartialD;L}_1}\mathrm{\&Delta;}{L}_1+\frac{\&PartialD;L}{{\&PartialD;f}_0}{\mathrm{\&Delta;f}}_0=0,$ As can be known:

$Q_{\mathrm{cu}}=\frac{f_0}{(-\mathrm{\&Delta;}{f}_0/\mathrm{\&Delta;}{L}_1){\mathrm{\&delta;}}_c}---\left(19\right)$

1/Q _c＝2/Q _cu (20)

Wherein: Q _cBe to characterize total conduction loss Q factor, the system architecture symmetry, the sheet metal loss equates up and down.

2) relation of IL and S21

At the Q of carrying that has that handles from the network analyzer measurement _LConvert no-load Q to _uBefore, must have a look the transmission coefficient S that inserts loss (IL) and test from network analyzer ₂₁Relation between the two.Can insert the circuit discussion IL of loss and the relation of S21 from definition.

According to the repeatedly incident of signal wave on inserting surface and the stack of reflection, can obtain the incident power of signal source to incoordination load.

3) Q of carrying and no-load Q relation is arranged

Test macro can motivate many modes of resonance with coupling ring, surveys transmission coefficient with network analyzer, can determine the resonance frequency of each pattern, also can obtain the loaded Q of each pattern simultaneously.The two-port network resonator of test macro can be represented with mode transmission resonator equivalent electrical circuit.

4) the metal surface conductivity determines

In order to improve measuring accuracy, consider the influence of conduction loss, relate to the value of skin depth, promptly the value of bottom crown conductivity on the test macro is done coating because of bottom crown on the design system adopts silver, and belonging to good conductor has: $\frac{\mathrm{\&sigma;}}{\mathrm{\&omega;\&epsiv;}}>>1,$ So

${\mathrm{\&delta;}}_c=\frac{1}{\mathrm{\&omega;}\sqrt{\frac{\mathrm{\&epsiv;\&mu;}}{2}[\sqrt{1+{\left(\frac{\mathrm{\&sigma;}}{\mathrm{\&omega;\&epsiv;}}\right)}^2-1]}}},$ Promptly ${\mathrm{\&delta;}}_c=\sqrt{\frac{2}{\mathrm{\&omega;\&mu;\&sigma;}}}=\frac{1}{\sqrt{\mathrm{\&pi;f\&mu;\&sigma;}}}---\left(21\right)$

The ideal conducting rate σ of silver is 6.17 * 10 ⁷S/m.But because conductance is relevant with the situations such as material, thermal treatment, processing and silver-plated thickness of parallel-plate, different processing conditionss can make actual conductance depart from its ideal value.This just need accurately measure the conductance of parallel-plate.

Assay method is to adopt same dielectric resonator sample, and the ratio of pre-set sample diameter and thickness makes two mode of resonance TE of sample _OmnAnd TE _{Om ' n '}The resonance frequency of (m ≠ m ', n ≠ n ') is close, approximately thinks that the loss tangent of their correspondences equates, thus the surface resistance R of this Frequency point correspondence _sCan determine by formula (21), can obtain actual conductivity value at last.

$R_s=\frac{A_{0\mathrm{mn}}/Q_{0\mathrm{mn}}{-A}_{0m\&prime;n\&prime;}/Q_{0m\&prime;n\&prime;}}{B_{0\mathrm{mn}}{-B}_{0m\&prime;n\&prime;}}---\left(22\right)$

In the formula: A _Omn=1+F (u) G (v)/ε _r'

$B_{\mathrm{omn}}={\left(\frac{\mathrm{nc}}{2f_{0}L}\right)}^3\frac{1+F\left(u\right)G\left(v\right)}{30{\mathrm{\&pi;}}^{2}n{{\mathrm{\&epsiv;}}^{\&prime;}}_r}$

$F\left(u\right)=\frac{J_1^2\left(u\right)}{J_1^2\left(u\right)-J_0\left(u\right)J_2\left(u\right)}$

$G\left(v\right)=\frac{K_0\left(v\right)K_2\left(v\right)-K_1^2\left(v\right)}{K_1^2\left(v\right)}$

$R_s=\sqrt{\frac{{\mathrm{\&pi;f}}_0{\mathrm{\&mu;}}_0}{\mathrm{\&sigma;}}}---\left(23\right)$

The conductivity of sheet metal is calculated by respective formula.Table 3 is that four measurement data of a sample are tried to achieve the σ measured value.(f ₀＝9.30GHz，D/L≈2.0)

Table 3 parallel-plate conductivity measurement data

Number of times	Q u(TE 012)	Q u(TE 021)	σ(×10 7S/m)
				1	1490	2002	2.73
2	1280	1640	2.75
				3	1337	1742	2.69
4	1436	1906	2.72

Its assembly average is 2.72 * 10 ⁷S/m, standard deviation is: 0.03 * 10 ⁷S/m.

By the σ value of measuring, according to formula (23), under different resonator test frequencies, skin depth just has different values, for the accurate Calculation dielectric loss provides condition.

Claims (2)

1. the device for fast detecting of microwave ceramic material is characterized in that comprising:

1) the opening parallel-plate resonator cavity of band stepper motor: be provided with by two opening resonator cavitys that silver-plated red copper parallel-plate constitutes up and down, following parallel-plate bottom has ring gear, under step motor control, can rotate arbitrarily angled easily, plate is provided with at least 8 apertures, on aperture, insert sample pad, the parallel-plate center penetrates a cylindrical body up and down, cylindrical body is provided with two grooves, pass for coaxial wire, parallel-plate is positioned on bearing and the base up and down, and base is fixed on the chassis, and stepper motor is installed by chassis central authorities, the chassis another side is the holder of another coaxial cable, and cylindrical body can be made as cylinder;

2) Single-chip Controlling and stepper motor driver: be made up of power circuit, single chip machine controlling circuit and stepper motor driving circuit, power circuit provides required direct supply for stepper motor and single-chip microcomputer and other chip; Single chip machine controlling circuit is used for producing pulse signal and carry out signal allocation under the keyboard input instruction, the work of control motor-drive circuit, stepper motor driving circuit is used to stepper motor to provide enough power with drive motor work, the stepper motor driving circuit input end connects the single chip machine controlling circuit output terminal, stepper motor driving circuit output termination stepper motor;

3) vector network analyzer and computing machine: vector network analyzer is connected with computing machine by gpib interface, under computer control, the swept-frequency signal output terminal of vector network analyzer connects opening parallel-plate resonator cavity input end through concentric cable, and the resonance signal output terminal of opening parallel-plate resonator cavity connects vector network analyzer by another concentric cable.

2. the quick measuring method of microwave ceramic material is characterized in that the steps include:

1) calibration vector network analyzer is measured the diameter D and the height L of cylindrical sample, in the input computing machine corresponding form;

2) will put into the constant-temperature temperature-control case with the opening parallel-plate resonator cavity of stepper motor, be placed in down one by one on the sample pad of parallel-plate with batch manufactured samples;

3) will import to strip out respectively and curve ringlet and outer conductor and weld with the output coaxial cable inner wire, make coupling ring, the parallel sample both sides that are adjusted to of two coupling rings are adjusted simultaneously and are gone up the parallel-plate height, the distance of parallel-plate and sample is unanimous on the whole about making, and shuts the constant-temperature temperature-control chamber door;

4) start stepper motor, measure first sample under the room temperature, after stepper motor stops, computing machine is preserved the viewed sample tuning curve of vector network analyzer, the resonance frequency that writes down this sample and quality factor, and the theoretical calculation formula of substitution specific inductive capacity and loss factor, calculate the specific inductive capacity and the loss factor of institute's test sample product, and insert automatically in the form of first sample; Start stepper motor once more, note the data of second sample in an identical manner, until having surveyed 8 samples, coupling ring is got back to the original place again;

5) set temperature on the constant-temperature temperature-control case, when temperature reaches, repeating step 4;

6) click computing machine, enter material temperature coefficient calculations program, program will read room temperature and the following resonant frequency value of surveying of design temperature automatically, obtain required temperature coefficient from the ratio of two difference on the frequencies and the temperature difference;

7) finish test, quit a program.

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