CN102435863A - Variable temperature measurement device for dielectric performance of dielectric material based on quasi-optical resonant cavity - Google Patents

Abstract

The invention discloses a variable temperature measurement device for the dielectric performance of a dielectric material based on a quasi-optical resonant cavity and belongs to the field of test of the dielectric performance of microwave and millimeter wave dielectric materials. The variable temperature measurement device comprises the quasi-optical resonant cavity, an induction heating control device, an induction heating ring, a vacuum furnace chamber, a circulating water-cooling system and a vector network analyzer, wherein the quasi-optical resonant cavity is a plano-concave cavity which consists of a spherical mirror and a plane mirror; and the quasi-optical resonant cavity is connected with the vector network analyzer through two coupling holes by using waveguide and coaxial cables to form a test loop. By comprehensively employing an induction heating technology, a circulating water-cooling technology and a vacuum technology, during variable temperature measurement of the dielectric performance of the dielectric material by using a quasi-optical resonant cavity test method, the variable temperature measurement device has the advantages of high heating efficiency and wide variable temperature range, wherein a measurement temperature can be above 2,000 DEG C; the variable temperature measurement device can stably operate for a long time under the condition of guaranteeing measurement accuracy; and oxidation or other damages of an optical resonant cavity can be avoided.

Description

A kind of dielectric material dielectric properties alternating temperature measurement mechanism based on quasi-optical resonator

Technical field

The invention belongs to microwave, millimeter wave dielectric material dielectric properties field tests, relate to quasi-optics chamber measuring method and device.

Background technology

Along with the development and the application of communication system, weapon precise guidance and ECM, the dielectric properties of accurately understanding circuit dielectric substrate material, radome material are more and more important.When the working temperature of these materials changed, corresponding variation also can take place in their dielectric properties.Therefore, understand the dielectric properties of material under the different operating temperature, the application and the design of material be significant!

To the dielectric properties test of dielectric material in microwave, millimere-wave band, using more widely, measuring method is the quasi-optical resonator method of testing.The version of the quasi-optical resonator that generally uses at present is hemihedry sphere quasi-optical resonator, and this cavity is made up of a spherical mirror and a level crossing, is commonly called as flat-concave cavity.The quasi-optical resonator of this kind version generally only is used for the measurement of the dielectric properties of dielectric material under the normal temperature environment, if be applied to the measurement of the dielectric properties under the varying temperature environment, then need improve the structure of cavity.

Document " Feng Liping, Wei is high, the Ku wave band dielectric high temperature automatic measurement system of beginning to speak, the light laser and the particle beams, 2006, vol.18, No.8, pp1323～1326. " adopts the heating furnace mode, utilizes the silit heating bar to heat, and temperature can reach 1300 ℃.There are two shortcomings in structure in the document; The one, cavity body structure is exposed in the air, under the hot operation condition, impels the level crossing metal oxidized rapidly; Long-term use will influence the quality factor (Q value) of quasi-optical resonator, thereby influence the measuring accuracy of dielectric properties; The 2nd, the efficiency of heating surface of this kind structure is not high, the variable temperature scope is wide inadequately.

Summary of the invention

The purpose of this invention is to provide a kind of dielectric material dielectric properties alternating temperature measurement mechanism, to realize the temperature variation testing of microwave, millimeter wave dielectric dielectric material performance based on quasi-optical resonator.This device can be realized the alternating temperature measurement of dielectric material dielectric properties under many ℃ of environment of normal temperature to 2000, has efficiency of heating surface height, variable temperature wide ranges, and can long-term stable operation under assurance measuring accuracy condition.

Technical scheme of the present invention is following:

A kind of dielectric material dielectric properties alternating temperature measurement mechanism based on quasi-optical resonator, as shown in Figure 1, comprise quasi-optical resonator 1, induction heating control device 2, induction heating circle 3, vacuum furnace chamber 4, circulating water cooling system 5 and vector network analyzer 6.Said quasi-optical resonator 1 adopts the flat-concave cavity structure of being made up of spherical mirror 11 and level crossing 12, and wherein spherical mirror 11 is fixed in the upper space of vacuum furnace chamber 4, and level crossing 12 is fixed in the lower space of vacuum furnace chamber 4.As shown in Figure 2, have on the said spherical mirror 11 to have two coupling apertures 111,112, quasi-optical resonator 1 is connected through waveguide, concentric cable and vector network analyzer 6 through two coupling apertures 111,112, forms test loop.The top has metal sleeve 13 around the said level crossing 12, and the height of sleeve 13 is as the criterion with the quality factor (Q value) that does not influence quasi-optical resonator.Said induction heating circle 3 adopts copper tube to make, and is fixed in the lower space of vacuum furnace chamber 4, makes level crossing 12 be positioned at the inside of induction heating circle 3.The two ends of induction heating circle 3 are passed the sidewall of vacuum drying oven 4 and are realized that with said heating control apparatus 2 electricity links to each other, is connected to realize a recirculated water cooling loop with said circulating water cooling system 5 simultaneously.

The concrete course of work of the present invention is: vector network analyzer 6 is connected with quasi-optical resonator 1 through concentric cable, the waveguide coupling aperture 111,112 on spherical mirror 11, and the measured medium sample is placed on the center of level crossing 12; Earlier vacuum furnace chamber 4 is vacuumized, charge into protection nitrogen again, then open induction heating control device 2, utilize induction heating control device 2 to heat, open water-cooling system 5 simultaneously and carry out water-cooled through 3 pairs of dielectric sample of induction coil.When reaching the requirement temperature, promptly stop heating.Utilize vector network analyzer 6 and corresponding software that material is carried out test analysis then.

The present invention is in the high temperature measurement process; Though the high-temperature region concentrates on the inside of induction heating circle 3; If but it is too high to measure temperature, vacuum furnace chamber 4 inner other positions (mainly comprising spherical mirror 11 and vacuum furnace chamber 4 chamber walls) temperature also can raise, for fear of the damage of high temperature to spherical mirror 11 and vacuum furnace chamber 4; Also be in order to improve the alternating temperature efficiency of measurement simultaneously; Can: 1) as shown in Figure 3, at the annular water-cooling groove 113 of said spherical mirror 11 inner increases, the two ends 114,115 of said annular water-cooling groove 113 are connected with water-cooling system 5 to realize another recirculated water cooling loop through water pipe; 2) pars intramuralis increases equally distributed pipeline configuration in the chamber of said vacuum furnace chamber 4, and the two ends of said pipeline configuration are connected with water-cooling system 5 to realize another recirculated water cooling loop.

The invention has the beneficial effects as follows:

Dielectric material dielectric properties alternating temperature measurement mechanism based on quasi-optical resonator provided by the invention; Owing to adopt induction heating technique and circulating water cooling system; Be equipped with the vacuum furnace chamber simultaneously; Make the present invention when adopting the quasi-optical resonator method of testing that the dielectric material dielectric properties are carried out the alternating temperature measurement; Have efficiency of heating surface height, variable temperature wide ranges (measuring temperature can reach more than 2000 ℃), and in that guarantee under the measuring accuracy condition can long-term stable operation and can not cause oxidation or other damages of optical resonator.

Description of drawings

Fig. 1 is the structural representation of the dielectric material dielectric properties alternating temperature measurement mechanism based on quasi-optical resonator provided by the invention.

Wherein, the 1st, quasi-optical resonator, the 2nd, induction heating control device, the 3rd, induction heating circle, the 4th, vacuum furnace chamber, the 5th, water-cooling system, the 6th, vector network analyzer.

Fig. 2 is the quasi-optical resonator synoptic diagram.

Fig. 3 is a quasi-optical resonator spherical mirror synoptic diagram.

Among Fig. 2 to Fig. 3, the 11st, spherical mirror, the 12nd, level crossing, the 13rd, metal sleeve, 111 and 112 are coupling aperture, 113 annular water-cooling grooves.

Embodiment

A kind of dielectric material dielectric properties alternating temperature measurement mechanism based on quasi-optical resonator, as shown in Figure 1, comprise quasi-optical resonator 1, induction heating control device 2, induction heating circle 3, vacuum furnace chamber 4, circulating water cooling system 5 and vector network analyzer 6.Said quasi-optical resonator 1 adopts the flat-concave cavity structure of being made up of spherical mirror 11 and level crossing 12, and wherein spherical mirror 11 is fixed in the upper space of vacuum furnace chamber 4, and level crossing 12 is fixed in the lower space of vacuum furnace chamber 4.As shown in Figure 2, have on the said spherical mirror 11 to have two coupling apertures 111,112, quasi-optical resonator 1 is connected through waveguide, concentric cable and vector network analyzer 6 through two coupling apertures 111,112, forms test loop.The top has metal sleeve 13 around the said level crossing 12, and the height of sleeve 13 is as the criterion with the quality factor (Q value) that does not influence quasi-optical resonator.Said induction heating circle 3 adopts copper tube to make, and is fixed in the lower space of vacuum furnace chamber 4, makes level crossing 12 be positioned at the inside of induction heating circle 3.The two ends of induction heating circle 3 are passed the sidewall of vacuum drying oven 4 and are realized that with said heating control apparatus 2 electricity links to each other, is connected to realize a recirculated water cooling loop with said circulating water cooling system 5 simultaneously.

The present invention is in the high temperature measurement process; Though the high-temperature region concentrates on the inside of induction heating circle 3; If but it is too high to measure temperature, vacuum furnace chamber 4 inner other positions (mainly comprising spherical mirror 11 and vacuum furnace chamber 4 chamber walls) temperature also can raise, for fear of the damage of high temperature to spherical mirror 11 and vacuum furnace chamber 4; Also be in order to improve the alternating temperature efficiency of measurement simultaneously; Can: 1) as shown in Figure 3, at the annular water-cooling groove 113 of said spherical mirror 11 inner increases, the two ends 114,115 of said annular water-cooling groove 113 are connected with water-cooling system 5 to realize another recirculated water cooling loop through water pipe; 2) pars intramuralis increases equally distributed pipeline configuration in the chamber of said vacuum furnace chamber 4, and the two ends of said pipeline configuration are connected with water-cooling system 5 to realize another recirculated water cooling loop.

The detailed process of utilizing the present invention that the dielectric properties of dielectric material are carried out temperature variation testing is:

Step 1: vacuum drying oven 4 is vacuumized earlier, charge into nitrogen protection after finishing.Open induction heating control device 2.Meanwhile, water-cooling system 5 is opened running, for vacuum drying oven 4, induction heating circle 3 and quasi-optical resonator spherical mirror 11 provide circulating cooling liquid.

Step 2: be heated to cavity (not putting into the measured medium material sample) temperature required.

Step 3: utilize network analyzer 6 to measure the resonance frequency f of cavity under this temperature environment ₀With the cavity quality factor q ₀, and record.

Step 4: after treating whole device cooling, load the measured medium material sample, place it in the center of level crossing 12.Repeating step 2, the resonance frequency f of record loaded cavity (after putting into sample) _0sWith the loaded cavity quality factor q _s

Step 5:, can calculate the relative dielectric constant and the loss tangent of dielectric material according to the resonance frequency before and after the measured cavity load sample and the variation of Q-unloaded.Its computing formula is following:

According to quasi-optical resonator basic mode resonant frequency equation:

$f_{00q}=\frac{c}{2D}[q+1+\frac{1}{\mathrm{\π}}\arctan \sqrt{D/(R_0-D)}].........\left(1\right)$

In the formula, c is the light velocity, and D is the chamber of quasi-optical resonator long (distance of upper end from the coupling aperture lower end to level crossing), R ₀Be the radius-of-curvature of spherical mirror, q is the longitudinal modulus of quasi-optical resonator.

Cavity resonance frequency f by precedence record ₀With the long D in chamber (measuring), get final product the mode of resonance that inverse goes out basic mode.After mode of resonance is confirmed, according to the cavity resonance frequency f ₀With the q value, can go out the accurate more long D in chamber by inverse.

The computing formula of the relative dielectric constant of sample is:

$\frac{1}{n}\tan (\mathrm{nkt}-{\mathrm{\φ}}_t)=-\tan (\mathrm{kd}-{\mathrm{\φ}}_d).........\left(2\right)$

In the formula: φ _t=arctan (t/nz ₀) ... (3)

φ _d＝arctan(d″/z ₀)-arctan(t/n ²z ₀) …………(4)

$w_0^2=\frac{2}{k}[(d+t/n^2)(R_0-d-t/n^2){]}^{1/2}.........\left(5\right)$

d＝D-t …………(6)

$z_0=\sqrt{d^{\′\′}(R_0-d^{\′\′})}.........\left(7\right)$

d″＝d+t/n ² …………(8)

$n=\sqrt{{\mathrm{\ϵ}}_r}.........\left(9\right)$

k＝2π·f _0s/c …………(10)

Wherein: c is the light velocity, and D is that the chamber of quasi-optical resonator is long, R ₀Be the radius-of-curvature of spherical mirror, t is the thickness of dielectric sample.

Resonance frequency f by previous measurement loaded cavity _0s, sample thickness t and according to the cavity resonance frequency f ₀The long D in quasi-optical resonator chamber that inverse goes out can separate transcendental equation, thereby obtains the relative dielectric constant of sample.

The calculating of loss tangent:

$\tan \mathrm{\δ}=\frac{1}{Q_e}\·\frac{\mathrm{t\Δ}+d}{\mathrm{t\Δ}+\frac{1}{2k}\left[\sin 2(\mathrm{kd}-{\mathrm{\φ}}_d)\right]}.........\left(11\right)$

Wherein: $\frac{1}{Q_e}=\frac{1}{Q_s}-\frac{1}{Q_1}.........\left(12\right)$

$Q_1=Q_0\·\frac{2(\mathrm{t\Δ}+d)}{D(\mathrm{\Δ}+1)}.........\left(13\right)$

$\mathrm{\Δ}=\frac{n^2}{n^2{\cos }^2(\mathrm{nkt}-{\mathrm{\φ}}_t)+{\sin }^2(\mathrm{nkt}-{\mathrm{\φ}}_t)}.........\left(14\right)$

Q in formula _sBe the quality factor of loaded cavity, Q ₁Be the quality factor of putting into perfect medium sample (lossless), Q ₀Be the quality factor of cavity.

Step through the front is calculated relative dielectric constant, and the loaded cavity quality factor q that had before recorded _sWith the cavity quality factor q ₀Can calculate the loss tangent of sample.

Claims (3)

1. the dielectric material dielectric properties alternating temperature measurement mechanism based on quasi-optical resonator comprises quasi-optical resonator (1), induction heating control device (2), induction heating circle (3), vacuum furnace chamber (4), circulating water cooling system (5) and vector network analyzer (6); It is characterized in that:

Said quasi-optical resonator (1) adopts the flat-concave cavity structure of being made up of spherical mirror (11) and level crossing (12), and wherein spherical mirror (11) is fixed in the upper space of vacuum furnace chamber (4), and level crossing (12) is fixed in the lower space of vacuum furnace chamber (4); Have on the said spherical mirror (11) and have two coupling apertures (111,112), quasi-optical resonator (1) is connected through waveguide, concentric cable and vector network analyzer (6) through two coupling apertures (111,112), forms test loop; Said level crossing (12) top on every side has metal sleeve (13), and the height of sleeve (13) is as the criterion with the quality factor that does not influence quasi-optical resonator; Said induction heating circle (3) adopts copper tube to make, and is fixed in the lower space of vacuum furnace chamber (4), makes level crossing (12) be positioned at the inside of induction heating circle (3); The two ends of induction heating circle (3) are passed the sidewall of vacuum drying oven (4) and are realized that with said heating control apparatus (2) electricity links to each other, is connected to realize a recirculated water cooling loop with said circulating water cooling system (5) simultaneously.

2. the dielectric material dielectric properties alternating temperature measurement mechanism based on quasi-optical resonator according to claim 1; It is characterized in that; Said spherical mirror (11) inside has annular water-cooling groove (113), and the two ends of said annular water-cooling groove (113) (114,115) are connected to realize another recirculated water cooling loop with water-cooling system (5) through water pipe.

3. the dielectric material dielectric properties alternating temperature measurement mechanism based on quasi-optical resonator according to claim 1 and 2; It is characterized in that; The chamber pars intramuralis of said vacuum furnace chamber (4) has equally distributed pipeline configuration, and the two ends of said pipeline configuration are connected to realize another recirculated water cooling loop with water-cooling system (5).

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