CN103592510A - Microwave frequency calibrator and calibration method thereof - Google Patents

Abstract

The invention discloses a microwave frequency calibrator and a calibration method thereof, and relates to measurement and debugging of microwave devices. The microwave frequency calibrator comprises an upper half cavity, a lower half cavity, an input-end waveguide coaxial converter and an output-end waveguide coaxial converter. After the upper half cavity and the lower half cavity are buckled, a square resonant cavity is formed internally. The two inner walls, which are parallel to each other in the longitudinal direction, of the resonant cavity are both square. The two inner wall, which are parallel to each other in the transverse direction, of the resonant cavity are both rectangular and provided with an input coupling window and an output coupling window respectively, wherein the input coupling window and the output coupling window are symmetrically distributed and used for being connected with the waveguide coaxial converters. The four longitudinal edges on the inner walls of the resonant cavity are provided with circular corners, so that the electromagnetic field of the resonant cavity is TE011 mode. According to the microwave frequency calibrator and the calibration method of the microwave frequency calibrator, influences, caused by a plurality variable measuring errors in a frequency offset calculation formula, on the calculation result are converted into changes of a resonant frequency comparison theoretical value of the high-resolution calibrator under the current environment, and therefore the calculation result of the frequency offset calculation formula is corrected. According to the microwave frequency calibrator and the calibration method of the microwave frequency calibrator, the structure is simple, use is convenient, the measurement accuracy is remarkably improved, and the performance is stable and reliable.

Description

A kind of microwave frequency calibrating device and calibration steps thereof

Technical field

The present invention relates to a kind of microwave measurement devices, particularly relate to a kind of microwave frequency calibrating device and calibration steps thereof.

Background technology

Along with the fast development of satellite communication system, the frequency resource of microwave frequency band is all the more nervous, and the number of channel is more and more, and channel spacing is more and more less, causes the microwave device in satellite communication system to propose more high-precision requirement.Microwave device in satellite communication system is generally operational under high vacuum environment.But the debugging of microwave device and test, except thermovacuum and micro discharge experiment, other are all under the non-vacuum environment of ground.The difference of environmental baseline, comprise the difference of air pressure, humidity, temperature, and the difference of working temperature all can make the frequency of operation of microwave device be offset.This just requires the frequency offset that consideration brings because of working environment difference in debugging and test process, and debugging and the pre-deviator of test frequency are set, thereby centre frequency and design when microwave device is used on star are consistent.

At present conventional transmitting frequency calibration method adopts frequency deviation experimental formula to calculate.Rule of thumb formula can calculate vacuum frequency deviation and temperature frequency deviation fast, thereby determines default amounts of frequency offset.But along with the raising to microwave device accuracy requirement, the precision of the result that utilization the method obtains is often unsatisfactory.Itself is experimental formula computing formula, and contain the numerous variablees of linear expansion coefficient that comprise air pressure, temperature, humidity, specific inductive capacity, magnetic permeability and material, and want to measure all variablees accurately, be unpractical, in work in the past, conventionally provide rough measured value or empirical value, this has just introduced larger error to the calculating of frequency deviation.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiencies in the prior art, a kind of microwave frequency calibrating device and calibration steps thereof are provided, the immeasurablel error of calculation is converted into by the detectable calibration factor of high resolving power calibrating device, thereby revise frequency offset calculation formula result of calculation, improve calibration.The present invention is simple in structure, easy to use, has significantly improved measuring accuracy, stable and reliable for performance, is especially applicable in present stage satellite-borne microwave device debugging and test process the high-precision requirement of vacuum frequency offset calculation.

Technical solution of the present invention is: a kind of microwave frequency calibrating device, comprises first cavity, second cavity, input end waveguide coaxial converter, output terminal waveguide coaxial converter; First cavity and second cavity have square groove; After first cavity and second cavity fasten, in inside, form square resonator cavity, described resonator cavity is square at two inwalls that are longitudinally parallel to each other, and at two inwalls that are laterally parallel to each other, is rectangle and has symmetrical input coupling window and output coupling window; On the inwall of resonator cavity four longitudinally seamed edge have fillet, the electromagnetic field that makes resonator cavity is TE011 mould; Input coupling window connects input end waveguide coaxial converter, and output coupling window connects output terminal waveguide coaxial converter;

On the inwall of described resonator cavity, have bleeder vent.

A calibration steps for microwave frequency calibrating device, comprises the following steps:

Step 1: utilize character modules solver in simulation software, resonator cavity model, the inwall of resonator cavity is square, resonator cavity is square at two inwalls that are longitudinally parallel to each other, at two inwalls that are laterally parallel to each other, be rectangle, by adjusting the size of resonator cavity inwall, make resonator cavity resonance at design resonance frequency f ₀;

Step 2: in resonator cavity model, to four seamed edge roundings longitudinally on described inwall, by adjusting the size of described fillet, make the electromagnetic field of resonator cavity be distributed as TE011 mould;

Step 3: in resonator cavity model, open respectively symmetrical input coupling window and output coupling window on two inwalls that are laterally parallel to each other, by adjusting position and the size of input coupling window and output coupling window, make reflection parameters be less than 25dB;

Step 4: in resonator cavity model, according to the electromagnetic field of resonator cavity model, distribute, bleeder vent is added in the place on the inwall of resonator cavity a little less than electromagnetic field, by adjusting position and the size of bleeder vent, keep reflection parameters to be less than 25dB, obtain microwave frequency calibrating device rudimentary model;

Step 5: microwave frequency calibrating device rudimentary model is carried out to whole emulation, when transport property simulation curve have be less than 0.01MHz-three dB bandwidth and at design resonance frequency f ₀when peak value appears in place, obtain microwave frequency calibrating device model;

Step 6: carry out physical treatment according to microwave frequency calibrating device model, obtain microwave frequency calibrating device, and measure the actual resonance frequency f that microwave frequency calibrating device produces ₀', and calculate actual frequency deviation value Δ f',

Δf′=f ₀-f ₀′，

Step 7: calculate theoretical frequency deviation Δ f,

$\mathrm{\Δf}=f_0\{1-[1-(1.034\×\frac{{10}^{-4}}{T+273.15})\×(P+\frac{4810\×H\×{10}^{7.911-\frac{1653}{T+228}}}{T+273.15})\left]\right\}$

Wherein, T is temperature, unit ℃, and P is air pressure, the mmHg of unit, H is relative humidity, the span of H is 0～1;

Step 8: calculate calibration factor α,

α=Δf′/Δf

So far complete calibration;

Work as f ₀during change, according to new f ₀value, reenter step 1 to five, complete calibration;

Work as f ₀do not change, but when the environmental baseline of resonator changes, enter step 9;

Step 9: the value changing according to resonator environment condition, calculate new theoretical frequency deviation Δ f, actual frequency deviation Δ f'=α Δ f, completes calibration.

The present invention compared with prior art beneficial effect is:

(1) the present invention is converted on the impact of result of calculation the variation that the resonance frequency of calibrating device under current environment condition compared theoretical value by numerous variable measuring error in frequency offset calculation formula, and the conditions such as temperature, humidity, air pressure that can reduce change the impact that frequency offset calculation is caused.

(2) the present invention adopts square resonator cavity, the seamed edge of resonator cavity is carried out to rounding design, make resonator cavity shape between square chamber and cylindrical cavity, and make it be operated in pattern TE011 mould, obtain very high Q value, make calibrating device transmission curve occur sharp-pointed peak value at tuning-points place, thereby there is higher resolution, reach the calibration accuracy of 0.01-0.02MHz.

(3) the present invention is simple in structure, easy to use, and by bleeder vent is set on resonator cavity, guarantees that calibrating device Intranet air pressure is consistent, improves calibration accuracy.

(4) calibration steps of the present invention, by the calibrating device of design different frequency range, to meet debugging and the detection calibration demand of different frequency range microwave device, the scope of application is wide.

Accompanying drawing explanation

Fig. 1 is the one-piece construction schematic diagram of High-precision Microwave frequency calibrator of the present invention;

Fig. 2 is the blast structural representation of High-precision Microwave frequency calibrator of the present invention;

Fig. 3 is the simulation architecture schematic diagram of High-precision Microwave frequency calibrator of the present invention;

Fig. 4 is the transport property simulation curve of High-precision Microwave frequency calibrator of the present invention.

Embodiment

As shown in Figure 1, the present invention includes first cavity 1, second cavity 2, input end waveguide coaxial converter 3, output terminal waveguide coaxial converter 4;

As shown in Figure 2, first cavity 1 and second cavity 2 have square groove, and first cavity 1 and second cavity 2 fasten, and by trip bolt 5, strengthen being fixedly connected with, and the square groove of first cavity 1 and second cavity 2 forms square resonator cavity in inside; Resonator cavity is square at two inwalls that are longitudinally parallel to each other, the resonator cavity of square sectional is conducive to obtain higher Q value, resonator cavity is rectangle and has symmetrical input coupling window 7 and output coupling window 8 at two inwalls that are laterally parallel to each other, and convenient test is used.The shape of coupling window can have any shape, be preferably square because be more convenient for processing and manufacturing.Input coupling window 7 connects input end waveguide coaxial converter 3, and output coupling window 8 connects output terminal waveguide coaxial converter 4.On the inwall of resonator cavity four longitudinally seamed edge have fillet, the existence of fillet makes the shape of resonator cavity between square chamber and cylindrical cavity, it is TE011 mould that such shape can make the electromagnetic field of resonator cavity, this pattern has very high Q value, TE101 pattern far above rectangle resonator, also TE113 and the TE114 pattern higher than at present conventional cylindrical cavity dual mode filter, used, it is more sharp-pointed that calibrating device transmission curve is compared other patterns at tuning-points place, there is narrower three dB bandwidth, thereby there is higher resolution, thereby reach the calibration accuracy of 0.01～0.02MHz.

$Q_u={\mathrm{\ω}}_0\frac{W_T}{P_{\mathrm{loss}}}$

Q _ufor the nonloaded Q of resonator, embodied the precipitous degree of tuning curve.W _tfor average storage power, P _lossfor resonator consumed power.Because distinctive shape structure of TE011 mould makes the magnetic-field component on the wall of chamber very little, so consumed power P _lossalso very little, at W _tin the situation that on average storage power is certain, there is relatively high Q value.

As shown in Figure 3, on the inwall of resonator cavity, have bleeder vent, the object that bleeder vent is set is to guarantee that calibrating device Intranet air pressure is consistent, improves calibration accuracy.The quantity of the bleeder vent shown in Fig. 3 is 3, in practice, the concrete condition during according to modeling is determined, as long as the reflection parameters under design resonance frequency is less than 25dB, in general, the weak position of electromagnetic field during the electromagnetic field that the position of bleeder vent is resonator cavity distributes.Make the existence of bleeder vent not only can meet that physical property requires but on device electrical performance substantially without affecting.

A calibration steps for microwave frequency calibrating device, comprises the following steps:

Step 1: in simulation software, as CST, HFSS etc., utilize the character modules solver in software, build cuboidal resonator cavity model, by designing the length of square resonator cavity, make resonator cavity resonance at design resonance frequency f ₀,

$f_0=\frac{c}{2\mathrm{\π}}\sqrt{{\left(\frac{{\mathrm{\ρ}}_{01}}{a}\right)}^2+\left(\frac{\mathrm{q\π}}{d}\right)},$

Wherein c is the light velocity, ρ ₀₁for Bessel's function J ₁(x) the m time root, the Cross section Design of resonator cavity is for square is to reach maximum Q value, and a is this foursquare length of side, the height that d is resonator cavity.

Step 2: in resonator cavity model, to four seamed edge roundings longitudinally on described inwall, by adjusting the size of fillet, make the electromagnetic field of resonator cavity be distributed as TE011 mould.

Step 3: open symmetrical input coupling window (7) and output coupling window (8) on resonator cavity model, by adjusting position and the size of input coupling window (7) and output coupling window (8), make reflection parameters be less than 25dB.In general, on resonator cavity, offer the structures such as window or air hole, all can affect the transport property at resonant frequency place.For making resonator cavity guarantee that to the full extent transmission is maximum, reflection is minimum, and when setting up resonator cavity model, position, size or the quantity of coupling window or air hole class formation all needs repeatedly to adjust to reach best transmission state.The present invention requires reflection parameters to be less than 25dB, guarantees calibration accuracy.

Step 4: distribute according to the electromagnetic field of resonator cavity model, bleeder vent is added in the weak place of electromagnetic field on the inwall of resonator cavity.The object of bleeder vent is consistent in order to guarantee the air pressure inside and outside resonator cavity, guarantees calibration accuracy.But bleeder vent offer itself can affect the transmission of resonance frequency, so when building model, by adjusting position and the size of bleeder vent, keep reflection parameters to be less than 25dB, make it not only can meet that physical property requires but on device electrical performance substantially without affecting.According to different operating frequency range, select suitable bleeder vent size.Design resonance frequency is larger, and bleeder vent is less, according to Electromagnetic Simulation, calculates, the general above bleeder vent diameter of 20GHz 1mm, 15～20GHz bleeder vent diameter 1.5mm, 10～15GHz bleeder vent diameter 1.8mm, the following 2mm of 10GHZ.So far, obtain microwave frequency calibrating device rudimentary model.

Step 5: microwave frequency calibrating device rudimentary model is carried out to whole emulation, obtains transport property simulation curve as shown in Figure 4, when transport property simulation curve have be less than 0.01MHz-three dB bandwidth and at design resonance frequency f ₀when peak value appears in place, obtain microwave frequency calibrating device model; Design resonance frequency shown in figure is 12.545988GHz, and-three dB bandwidth is less than 0.01MHz, can obtain very high frequency calibration precision, and calibration accuracy can reach 0.01MHz.

Step 6: carry out physical treatment according to the whole simulation result of microwave frequency calibrating device, obtain microwave frequency calibrating device, and measure the actual resonance frequency f that microwave frequency calibrating device produces ₀', and calculate actual frequency deviation value Δ f',

Δf′=f ₀-f ₀′，

Step 7: calculate theoretical frequency deviation Δ f,

$\mathrm{\Δf}=f_0\{1-[1-(1.034\×\frac{{10}^{-4}}{T+273.15})\×(P+\frac{4810\×H\×{10}^{7.911-\frac{1653}{T+228}}}{T+273.15})\left]\right\}$

Wherein, T is temperature, unit ℃, and P is air pressure, the mmHg of unit, H is relative humidity, span is 0～1;

Step 8: calculate calibration factor α,

α=Δf′/Δf

So far complete calibration;

Work as f ₀during change, according to new f ₀value, reenter step 1 to five, complete calibration;

Work as f ₀do not change, but when the environmental baseline of resonator changes, when the temperature of resonator environment of living in, air pressure or relative humidity change, enter step 9;

Step 9: the value changing according to resonator environment condition, bring new T, P or H, the new theoretical frequency deviation Δ f of calculating into, obtain new actual frequency deviation Δ f'=α Δ f, complete calibration.

The present invention is calculating on the basis of theoretical frequency deviation, by the higher high resolving power calibrating device of design Q value, actual frequency deviation under current environment condition and theoretical frequency deviation are compared, the conditions such as temperature, humidity, air pressure that can reduce change the impact that frequency offset calculation is caused, greatly improved calibration accuracy, can adapt to the debugging of the microwave device of any frequency range, effectively improve adjustment accuracy, be particularly suitable for satellite-borne microwave device.

The content not being described in detail in instructions of the present invention belongs to those skilled in the art's known technology.

Claims (3)

1. a microwave frequency calibrating device, is characterized in that: comprise first cavity (1), second cavity (2), input end waveguide coaxial converter (3), output terminal waveguide coaxial converter (4); First cavity (1) and second cavity (2) have square groove; After first cavity (1) and second cavity (2) fasten, in inside, form square resonator cavity, described resonator cavity is square at two inwalls that are longitudinally parallel to each other, and at two inwalls that are laterally parallel to each other, is rectangle and has symmetrical input coupling window (7) and output coupling window (8); On the inwall of resonator cavity four longitudinally seamed edge have fillet, the electromagnetic field that makes resonator cavity is TE011 mould; Input coupling window (7) connects input end waveguide coaxial converter (3), and output coupling window (8) connects output terminal waveguide coaxial converter (4).

2. a kind of microwave frequency calibrating device according to claim 1, is characterized in that: on the inwall of described resonator cavity, have bleeder vent.

3. the calibration steps of a kind of microwave frequency calibrating device according to claim 1, is characterized in that: comprise the following steps:

Step 1: utilize character modules solver in simulation software, resonator cavity model, the inwall of resonator cavity is square, resonator cavity is square at two inwalls that are longitudinally parallel to each other, at two inwalls that are laterally parallel to each other, be rectangle, by adjusting the size of resonator cavity inwall, make resonator cavity resonance at design resonance frequency f ₀;

Step 2: in resonator cavity model, to four seamed edge roundings longitudinally on described inwall, by adjusting the size of described fillet, make the electromagnetic field of resonator cavity be distributed as TE011 mould;

Step 3: in resonator cavity model, on two inwalls that are laterally parallel to each other, open respectively symmetrical input coupling window (7) and output coupling window (8), by adjusting position and the size of input coupling window (7) and output coupling window (8), make reflection parameters be less than 25dB;

Step 4: in resonator cavity model, according to the electromagnetic field of resonator cavity model, distribute, bleeder vent is added in the place on the inwall of resonator cavity a little less than electromagnetic field, by adjusting position and the size of bleeder vent, keep reflection parameters to be less than 25dB, obtain microwave frequency calibrating device rudimentary model;

Step 5: microwave frequency calibrating device rudimentary model is carried out to whole emulation, when transport property simulation curve have be less than 0.01MHz-three dB bandwidth and at design resonance frequency f ₀when peak value appears in place, obtain microwave frequency calibrating device model;

Step 6: carry out physical treatment according to microwave frequency calibrating device model, obtain microwave frequency calibrating device, and measure the actual resonance frequency f that microwave frequency calibrating device produces ₀', and calculate actual frequency deviation value Δ f',

Δf′=f ₀-f ₀′，

Step 7: calculate theoretical frequency deviation Δ f,

$\mathrm{\Δf}=f_0\{1-[1-(1.034\×\frac{{10}^{-4}}{T+273.15})\×(P+\frac{4810\×H\×{10}^{7.911-\frac{1653}{T+228}}}{T+273.15})\left]\right\}$

Wherein, T is temperature, unit ℃, and P is air pressure, the mmHg of unit, H is relative humidity, the span of H is 0～1;

Step 8: calculate calibration factor α,

α=Δf′/Δf

So far complete calibration;

Work as f ₀during change, according to new f ₀value, reenter step 1 to five, complete calibration;

Work as f ₀do not change, but when the environmental baseline of resonator changes, enter step 9;

Step 9: the value changing according to resonator environment condition, calculate new theoretical frequency deviation Δ f, actual frequency deviation Δ f'=α Δ f, completes calibration.

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