CN101227018A - Method for inhibiting microwave filter parasitize pass band based on frequency change metallicity like material - Google Patents
Method for inhibiting microwave filter parasitize pass band based on frequency change metallicity like material Download PDFInfo
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- CN101227018A CN101227018A CNA2008100332961A CN200810033296A CN101227018A CN 101227018 A CN101227018 A CN 101227018A CN A2008100332961 A CNA2008100332961 A CN A2008100332961A CN 200810033296 A CN200810033296 A CN 200810033296A CN 101227018 A CN101227018 A CN 101227018A
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Abstract
The invention provides a method for basing on that frequency-dependent metallicity material inhibits microwave filter parasitic pass band belonging to the technology field of microwave communication, through a manner of an actuation probe in input and output coupling structure of the filter and increasing frequency-dependent metallicity material among short-circuiting pistons, in contrast to center frequency of the filter, the actuation probe is positioned on a potential antinodal point, and in contrast to center frequency of the parasitic pass band, the actuation probe is positioned on a potential nodal-point, thereby inhibiting the parasitic pass band. The invention not only can inhibit the parasitic pass band which is in even multiple frequencies of the center frequency, but also can inhibit the parasitic pass band which is in odd multiple frequencies of the center frequency, furthermore, and has the advantages of adjustability, wide applicability, simple structure and easy realization and the like.
Description
Technical field
What the present invention relates to is the method for the inhibition microwave filter parasitic passband of a kind of radar and technical field of micro communication, particularly a kind of based on frequently becoming the method that the metallike material suppresses the microwave filter parasitic passband.
Background technology
Microwave filter generally is made up of a plurality of resonators and coupled structure, has characteristics such as simple in structure, easy design, is used widely in the microwave communication field.But, because resonator has multiple resonance characteristic, make in the frequency response of microwave filter, remove centre frequency ω
0Outside the working passband of living in, also with ω
0Become the frequency place of integral multiple to have parasitic passband.The existence of these parasitic passbands can influence the operate as normal of system, brings serious electromagnetic compatibility (EMC) problem.In actual applications, often need to adopt certain methods that it is suppressed,, reduce the interference of parasitic passband system so that obtain the stopband of broad.
A kind of feasible method be at the resonator of microwave filter inner or and coupled structure between add waveguide segment, the cut-off frequency of waveguide is higher than the working passband of filter, but be lower than parasitic passband, and at its terminal microwave absorbing material of placing, make the electromagnetic wave that is in parasitic passband obtain, thereby realize inhibitory action than high attenuation.
Find through literature search prior art, in the 32 european microwave meeting in 1993, in " Waveguide bandpass filters withattenuation of higher-order passbands " literary composition that Wolfgang Menzel and Jan Machac are delivered, introduced exactly: between the resonator of this filter, placed that a kind of cut-off frequency is higher than the filter working passband but the little rectangular waveguide that is lower than parasitic passband.In this structure, the electromagnetic wave that has only frequency to be higher than little rectangular waveguide cut-off frequency can penetrate these little waveguides, and is in these small echos and leads terminal microwave absorbing material and absorb, thereby is suppressed.And for the frequency in the working passband, owing to be lower than the cut-off frequency of little rectangular waveguide, so can not penetrate these little waveguides, microwave absorbing material is transparent for them, basic not influence.The shortcoming of this structure is because the medium parameter of the fixed size of little waveguide and microwave absorbing material is immutable, make that this structure is non-adjustable, can't be applicable to the inhibition of tunable filter parasitic passband, and since the method electro-magnetic wave absorption of having adopted microwave absorbing material will be higher than little rectangular waveguide cut-off frequency fall, make the method be unsuitable for frequency division communication, can produce immeasurable destruction the useful information of adjacent channel.In addition, the method need be added little waveguide between adjacent resonators, can destroy the basic filter structure of filter.
In recent years, because cold plasma has good frequency selective characteristic (high pass characteristic) and adjustability, and for the electromagnetic wave that frequency is lower than plasma frequency, characteristics with metallike, add the development of plasma generation technique, make cold plasma become the metallike material, more and more being used of microwave communication field as a kind of good frequency.
Summary of the invention
The objective of the invention is to overcome the some shortcomings and the defective that exist in the prior art, provide a kind of, it is utilized become metallike material (cold plasma) frequently based on frequently becoming the method that the metallike material suppresses the microwave filter parasitic passband.The present invention has advantages such as applicability is wide, adjustable, simple in structure, easy realization, can be under the prerequisite that does not change the basic filter structure of conventional microwave filters, only by transforming the height inhibition effect that its input and output coupled structure can realize its parasitic passband.And the present invention not only can suppress the residing parasitic passband of even-multiple frequency of centre frequency, can also suppress the residing parasitic passband of odd multiple number of frequency of centre frequency.What is more important the present invention can be used to the parasitic passband of tunable filter is suppressed.
The present invention is achieved by the following technical solutions, the present invention is by transforming the input and output coupled structure of microwave filter, realization is to the inhibition of its parasitic passband, be specially: increase between excitation probe in the input and output coupled structure of filter and the short circuit face and become metallike material (cold plasma) frequently, make excitation probe for the filter center frequency, be in the voltage wave antinode, and for the centre frequency of parasitic passband, be in the voltage wave node, thereby its parasitic passband is inhibited.
The inventive method may further comprise the steps:
The first step adopts the input and output coupled structure of probe coupled modes as microwave filter, and the mode by the input and output impedance matching, determines probe insertion depth and the probe distance apart from short circuit face.
In second step, select frequently to become the metallike material.Frequently become the metallike material and be meant in whole frequency range, to have and frequently select characteristic, can realize total reflection, present metallike, and the parameter of its material own is adjustable at band segment, relatively more commonly used as cold plasma etc.Cold plasma has high pass characteristic, for being higher than the ripple of its plasma frequency, can transmission, but for being lower than the ripple of its plasma frequency, total reflection takes place, present metallike.Cold plasma can be made up of any material that is suitable for ionization, as inert gas and other mist etc.Inert gas commonly used such as argon gas, neon, helium, krypton gas, xenon etc.When adopting different gas ionizations to generate plasma, needed ionization potential is different.General adopting quartz glass chamber is as plasma container, and it is grown and wide waveguide broadside and narrow limit that is approximately equal to filter.
The 3rd step is according to the working passband centre frequency ω of filter
0With the centre frequency i ω that will suppress parasitic passband
0 ', i=2,3 ... determine plasma frequency ω
p, make plasma frequency ω
pThe centre frequency i ω that is higher than the filter working passband
0 ', but be lower than the centre frequency i ω that will suppress parasitic passband
0 'And then, by plasma frequency, can calculate the electron density in the corresponding plasma.
Communication theory is as can be known in plasma according to electromagnetic wave, for the electromagnetic wave that frequency is lower than plasma frequency, plasma has metallike, full emission takes place at the plasma interface in the incident wave that promptly is lower than plasma frequency, the ripple that is transmitted in the plasma medium is the ripple that withers and falls, and amplitude is pressed the very fast decay of index.At this moment, the path after the plasma medium is transparent for the electromagnetic wave that frequency is lower than plasma frequency.On the other hand, because plasma has good frequency selective characteristic (high pass characteristic), make for the electromagnetic wave that frequency is higher than plasma frequency, will pass the plasma interface, enter in the plasma medium, after running into the short circuit metal face, total reflection takes place.This shows, because the existence of plasma makes the working passband of filter and the transmission path of the interior frequency of parasitic passband make a distinction, thereby makes the transmission that can accomplish not influence working passband when suppressing parasitic passband.
The 4th step, on selected plasma frequency basis, adjust the distance of probe apart from the plasma interface, make that the incident frequency is ω
0The time, probe is in the voltage wave antinode, and energy reaches maximum coupling, and this moment, the plasma interface can replace by an equivalent short circuit face, and the distance of its equivalent short circuit face square probe is n λ
G0/ 4 (n=1,3 ...).
The 5th step, the thickness of adjustment plasmasphere, making the incident frequency is i ω
0 'The time, the position of probe is in the voltage node point, and the energy coupling is minimum, and the caused discontinuous available distance probes of plasmasphere this moment is (1/2+m) λ
GiShort circuit face replace, i=2,3 ... m=1,2 ... thereby make the centre frequency i ω of filter working passband
0 'The parasitic passband at place is inhibited.
Need to prove that in waveguide, multiple resonance characteristic is mainly reflected on the guide wavelength, as second and third passband center at λ
G0/ 2, λ
G0On/3 the frequency, because λ
gBecome with frequency, so λ
G0/ 2 and λ
G0The frequency of/3 correspondences is slightly less than 2 ω
0, 3 ω
0, the parasitic passband centre frequency of practical application is with λ
G0/ 2 and λ
G0/ 3 respective frequencies are as the criterion.
But when the filter timing, its parasitic passband can change with working passband.At this moment, can be by adjusting plasma frequency, plasma container makes probe overstate for the parasitic passband centre frequency after changing and newly is in its voltage wave node, thereby parasitic passband is inhibited apart from the distance of probe and the mode of depth of probe.
The present invention suppresses the parasitic passband method with other and compares, and is characterized in significant and outstanding.At first, the present invention passes through to transform the inhibition of the input and output coupled structure realization of microwave filter to parasitic passband, thereby avoided destruction to basic filter structure, make the present invention wider than some other inhibition method applicability, the manufacturing process that not only can be used for new microwave filter, but also can be used for the conventional microwave filters that multiple structure had been used is already undergone technological transformation, mention its parasitic passband rejection.Secondly, because in the present invention, the medium parameter of plasma is adjustable, so the present invention can be applicable to suppress the parasitic passband of adjustable microwave filter.When the parasitic passband of adjustable microwave filter changes along with the variation of center passband, only need to adjust plasma frequency, just can adjust the medium parameter of plasma, be aided with the distance of adjustment short circuit identity distance probe and the insertion depth of probe again, the parasitic passband after can suppressing again to change.Once more, because repressed parasitic passband only is reflected among the present invention, and be not absorbed, so, can not produce and destroy the useful information of adjacent channel applicable to frequency division communication.In addition, characteristics such as that the present invention also has is simple in structure, easy realization can improve the design efficiency of microwave filter.
Embodiment
Below embodiments of the invention are elaborated: present embodiment is being to implement under the prerequisite with the technical solution of the present invention, provided detailed execution mode and concrete operating process, but protection scope of the present invention is not limited to following embodiment.
Embodiment 1
To suppress 3 ω of shunt inductance coupling rectangular waveguide filter
0Place's parasitic passband is an example.The type microwave filter adopts the rectangular waveguide section of half-wave guide wavelength as series resonator, uses shunt inductance metal matrix as the coupled structure between resonator.Its rectangular waveguide model is the mark model BJ-32 of country, and its broadside is that 72.14mm and narrow limit are 34.04mm, and main passband central frequency is 3.1GHz, 2 ω
0Place's parasitic passband centre frequency is 5.0467GHz, 3 ω
0Place's parasitic passband centre frequency is 7.2043GHz.2 ω
0With 3 ω
0Place's parasitic passband centre frequency is utilized λ respectively
G0/ 2 and λ
G0/ 3 calculate.Below be the detailed description of present embodiment:
The first step, adopt the input and output coupled structure of antisymmetric probe coupled modes as microwave filter, by input and output being impedance-matched to 50 Ω coaxial lines, and be optimized on this basis, obtaining the probe insertion depth is 21.632mm, probe is 31.976mm apart from the distance of short circuit face, and the distance that probe departs from waveguide broadside center is 9.0175mm.Because conventional probe coupled structure itself can suppress 2 ω
0Place's parasitic passband so only transform in single-ended employing this method of filter input and output coupled structure in the present embodiment, is used to suppress 3 ω
0Place's parasitic passband, and the other end adopts the conventional probe coupled structure, is used to suppress 2 ω
0Place's parasitic passband.
In second step, the cold plasma of selecting the ionization argon gas to generate becomes the metallike material as frequency, and the ionization potential of this moment is 15.8eV.The quartz glass chamber of adopting rectangle is as plasma container, and its long and wide waveguide broadside and narrow limit that is approximately equal to filter is about 72.14mm and 34.04mm respectively, and its cavity wall thickness is 1mm, and material is a quartz glass, and its relative dielectric constant is 3.57.
In the 3rd step, because in the present embodiment, adopt the probe coupled modes, 2 ω
0Place's parasitic passband can be inhibited naturally, so utilize plasma to suppress 3 ω at these need
0Place's parasitic passband.According to main passband central frequency is 3.1GHz, 3 ω
0Place's parasitic passband centre frequency is 7.2043GHz, determines that plasma frequency need satisfy 3.1GHz＜ω
p＜7.2043GHz obtains through optimization, when plasma frequency is 2.6 * 10
10During rad/s (this is an angular frequency, and respective frequencies is 4.1401GHz),
Suppress effect
Better, the electron density in corresponding plasma this moment is 3.9106 * 10
20m
-3
In the 4th step, the adjustment probe is 9.396mm apart from the distance of plasma interface, makes that the incident frequency is main passband central frequency ω
0In the time of (3.1GHz), probe is in the voltage wave antinode, and energy reaches maximum coupling, and the plasma interface can be n λ apart from probe with one
G0/ 4 (n=1,3 ...) and equivalent short circuit face come equivalence.
In the 5th step, the thickness (being the housing depth of plasma container) of adjusting plasmasphere is 19.955mm, and making the incident frequency is 3 ω
0In the time of (7.2043GHz), the position of probe is in the voltage node point, and the energy coupling is minimum, and the caused discontinuous available distance probes of plasmasphere this moment is m λ
G3/ 2 (m=1,2 ...) and short circuit face replace, thereby make 3 ω
0Place's parasitic passband is inhibited.
Show according to calculating: 3 ω
0Locate parasitic passband can be suppressed in-below the 23dB.Simultaneously, can also find that other parasitic passbands and clutter are also further suppressed, as 2 ω
0Place's parasitic passband has not reduced about 4.81dB when not adding plasma, and generally speaking, in 3.25GHz～8.81GHz, the stopband of this filter can be suppressed in-below the 20dB.
Embodiment 2
In the present embodiment, the basic filter structure of microwave filter is with embodiment 1.Similarly, present embodiment is with 3 ω of rejects trap
0Place's parasitic passband is a purpose.Different is to become the metallike material frequently to use the cold plasma that the ionization neon generates instead with embodiment 1, and some other parameter changes, as probe apart from the distance of plasma interface and the thickness of plasmasphere.In the present embodiment, because the variation of these parameters has slightly winner's passband central frequency and changes, become 3.125GHz, 2 corresponding ω
0Place's parasitic passband centre frequency is 5.1080GHz, 3 ω
0Place's parasitic passband centre frequency is 7.3009GHz.Below be the detailed description of present embodiment:
The first step, adopt the input and output coupled structure of antisymmetric probe coupled modes as microwave filter, by input and output being impedance-matched to 50 Ω coaxial lines, and be optimized on this basis, obtaining the probe insertion depth is 21.632mm, probe is 31.976mm apart from the distance of short circuit face, and the distance that probe departs from waveguide broadside center is 9.0175mm.Because conventional probe coupled structure itself can suppress 2 ω
0Place's parasitic passband so only transform in single-ended employing this method of filter input and output coupled structure in the present embodiment, is used to suppress 3 ω
0Place's parasitic passband, and the other end adopts the conventional probe coupled structure, is used to suppress 2 ω
0Place's parasitic passband.
In second step, the cold plasma of selecting the ionization neon to generate becomes the metallike material as frequency, and the ionization potential of this moment is higher, is 21.6eV.The quartz glass chamber of adopting rectangle is as plasma container, and its long and wide waveguide broadside and narrow limit that is approximately equal to filter is about 72.14mm and 34.04mm respectively, and its cavity wall thickness is 1mm, and material is a quartz glass, and its relative dielectric constant is 3.57.
In the 3rd step, because in the present embodiment, adopt the probe coupled modes, 2 ω
0Place's parasitic passband can be inhibited naturally, so utilize plasma to suppress 3 ω at these need
0Place's parasitic passband.According to main passband central frequency is 3.125GHz, 3 ω
0Place's parasitic passband centre frequency is 7.3009GHz, determines that plasma frequency need satisfy 3.125GHz＜ω
p＜7.3009GHz, selecting plasma frequency is 2.4 * 10
10During rad/s (this is an angular frequency, and respective frequencies is 3.8217GHz), obtain certain inhibition effect, the electron density in the corresponding plasma is 3.3321 * 10 at this moment
20m
-3
In the 4th step, the adjustment probe is 14.3959mm apart from the distance of plasma interface, makes that the incident frequency is main passband central frequency ω
0In the time of (3.125GHz), probe is in the voltage wave antinode, and energy reaches maximum coupling, and the plasma interface can be n λ apart from probe with one
G0/ 4 (n=1,3 ...) and equivalent short circuit face come equivalence.
In the 5th step, the thickness (being the housing depth of plasma container) of adjusting plasmasphere is 17.5mm, and making the incident frequency is 3 ω
0In the time of (7.3009GHz), the position of probe is in the voltage node point, and the energy coupling is minimum, and the caused discontinuous available distance probes of plasmasphere this moment is m λ
G3/ 2 (m=1,2 ...) and short circuit face replace, thereby make 3 ω
0Place's parasitic passband is inhibited.
Show according to calculating: 3 ω
0Locate parasitic passband can be suppressed in-below the 13dB, have certain inhibitory action.
Claims (4)
1. one kind based on frequently becoming the method that the metallike material suppresses the microwave filter parasitic passband, it is characterized in that, increase between excitation probe in the input and output coupled structure of filter and the short circuit face and become the metallike material frequently, make excitation probe for the filter center frequency, be in the voltage wave antinode, and for the centre frequency of parasitic passband, be in the voltage wave node, thereby its parasitic passband is inhibited.
2. according to claim 1ly it is characterized in that, may further comprise the steps based on frequently becoming the method that the metallike material suppresses the microwave filter parasitic passband:
The first step adopts the input and output coupled structure of probe coupled modes as microwave filter, and the mode by the input and output impedance matching, determines probe insertion depth and the probe distance apart from short circuit face;
In second step, select cold plasma as frequently becoming the metallike material;
The 3rd step is according to the working passband centre frequency ω of filter
0With the centre frequency i ω that will suppress parasitic passband
0 ', i=2,3 ... determine plasma frequency ω
p, make plasma frequency ω
pThe centre frequency i ω that is higher than the filter working passband
0 ', but be lower than the centre frequency i ω that will suppress parasitic passband
0 ', and then, obtain electron density in the corresponding plasma by plasma frequency;
The 4th step, on selected plasma frequency basis, adjust the distance of probe apart from the plasma interface, making the incident frequency is ω
0The time, probe is in the voltage wave antinode, and energy reaches maximum coupling, and this moment, the plasma interface replaced with an equivalent short circuit face, and the distance of its equivalent short circuit face square probe is n λ
G0/ 4, n=1,3 ...
The 5th step, the thickness of adjustment plasmasphere, making the incident frequency is i ω
0 'The time, the position of probe is in the voltage node point, and the energy coupling is minimum, and distance probes of the caused discontinuous usefulness of plasmasphere this moment is (1/2+m) λ
GiShort circuit face replace, i=2,3 ... m=1,2 ... thereby make the centre frequency i ω of filter working passband
0 'The parasitic passband at place is inhibited.
3. according to claim 1ly it is characterized in that described cold plasma is by the ionization inert gas, perhaps their mist generation based on frequently becoming the method that the metallike material suppresses the microwave filter parasitic passband.
4. according to claim 2 or the 3 described methods that become metallike material inhibition microwave filter parasitic passband based on frequency, it is characterized in that, described cold plasma, its container adopting quartz glass chamber, long and wide waveguide broadside and the narrow limit that equals filter respectively, quartz glass chamber.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101409378B (en) * | 2008-10-23 | 2012-07-04 | 上海交通大学 | Apparatus for restraining waveguide filter parasitic passband |
| CN106301245A (en) * | 2016-08-25 | 2017-01-04 | 合肥中科离子医学技术装备有限公司 | A kind of apparatus and method suppressing discharge-tube amplifier harmonic wave |
| CN109742551A (en) * | 2019-01-04 | 2019-05-10 | 北京环境特性研究所 | A kind of adjustable slit gap type period frequency screening device for filling plasma |
-
2008
- 2008-01-31 CN CNA2008100332961A patent/CN101227018A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101409378B (en) * | 2008-10-23 | 2012-07-04 | 上海交通大学 | Apparatus for restraining waveguide filter parasitic passband |
| CN106301245A (en) * | 2016-08-25 | 2017-01-04 | 合肥中科离子医学技术装备有限公司 | A kind of apparatus and method suppressing discharge-tube amplifier harmonic wave |
| CN106301245B (en) * | 2016-08-25 | 2018-03-09 | 合肥中科离子医学技术装备有限公司 | A kind of apparatus and method for suppressing discharge-tube amplifier harmonic wave |
| CN109742551A (en) * | 2019-01-04 | 2019-05-10 | 北京环境特性研究所 | A kind of adjustable slit gap type period frequency screening device for filling plasma |
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