CN1371534A - High-frequency band pass filter assembly comprising attenuation poles - Google Patents
High-frequency band pass filter assembly comprising attenuation poles Download PDFInfo
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- CN1371534A CN1371534A CN00812268A CN00812268A CN1371534A CN 1371534 A CN1371534 A CN 1371534A CN 00812268 A CN00812268 A CN 00812268A CN 00812268 A CN00812268 A CN 00812268A CN 1371534 A CN1371534 A CN 1371534A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/203—Strip line filters
- H01P1/20327—Electromagnetic interstage coupling
- H01P1/20354—Non-comb or non-interdigital filters
- H01P1/20381—Special shape resonators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/202—Coaxial filters
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/203—Strip line filters
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/201—Filters for transverse electromagnetic waves
- H01P1/203—Strip line filters
- H01P1/20327—Electromagnetic interstage coupling
- H01P1/20354—Non-comb or non-interdigital filters
- H01P1/20363—Linear resonators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
- H01P1/207—Hollow waveguide filters
- H01P1/209—Hollow waveguide filters comprising one or more branching arms or cavities wholly outside the main waveguide
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Abstract
The invention relates to a high-frequency band pass filter assembly, comprising a master resonator and at least one stop-band resonator which is coupled thereto, wherein each resonator has one of the prior art designs, such as an axis resonator, a hollow conductor resonator, a dielectric resonator or a planar resonator in the art of micro-band line. The aim of the invention is to construct a filter structure in such a way, that with a given number of poles, the highest possible number of transmission zero positions occur in the stop bands, whereby in relation to known resonator configurations, no overcoupling is used between non-adjoining resonators. To this end, the stop-band resonator(s) is/are coupled to the master resonator in such a way that the stop-band resonator generates both transmission zero positions and transmission pole positions in tandem with the master resonator. In a prefered embodiment, a master resonator of a limited section of line, m pairs of stop-band resonator and a filter realizing symmetric impedance have 2m+1 pole positions and 2m transmission zero positions. In another embodiment, a filter of un-symmetric impedance realizes that each filter has two pole positions and two transmission zero positions.
Description
The present invention relates to the high freguency bandpass filter device, it constitutes by a main resonator with at least one band resistance resonator of described main resonator coupling, wherein said main resonator is limited by a conductor segment, described conductor segment disconnecting or the breakpoint of the form of metallic walls is the border, and has the electromagnetism natural oscillation on centre frequency on both sides.Particularly, the present invention relates to the foundation of band pass filter, described band pass filter is made up of the resonator of the coupling of the high selectivity filtering that is used for high-frequency electromagnetic signal in about 0.5-100 gigahertz operating frequency.
In for example ground and satellite auxiliary radio broadcasting, radio link and mobile telephone system, and in the communication system of radar and navigation system etc., high freguency bandpass filter is important assembly.At this moment, single filter is as the filter in radio receiver, takes on the function of selecting in advance,, suppress not wish the interference signal wanted, and bank of filters taken on the frequency channel function that is.In transmitting set, except other, use each band pass filter to be suppressed at out of band spectrum part (off-band spectralshares) in the output signal of amplifier, and use the filter combination of output multiplexer form that each carrier is convergeed to shared antenna.
In high freguency bandpass filter, at first can between active and passive design, make differentiation.Suppose on linear and low noise level, to be strict with, only may be to use at this passive filter than labor.The function of passive electromagnetic filter is based on the energy in store electricity and magnetic field.In the filter that is made of the separate structure element, electricity and magnetic field energy (that is, in electric capacity and inductance) in a limited number of discrete component that the space separates are stored apart from each other.Because the physical dimension of these separate structure elements must be than little many of guide wavelength 1/10th, the unloaded Q of this structure falls suddenly when size reduces simultaneously, so, each structure that is made of the resonator that is coupled is preferably used in steep limit (steep-edge) filter that surpasses about 1 gigahertz, rather than the discrete electric capacity and the inductance of interconnection.
The design of resonator has various, and they show the cordwood filter type of analyzing here.Conductor segment with TEM coaxial conductor segment and hollow forms coaxial resonator or cavity resonator, and wherein electromagnetic field is by the conductive surface complete closed.These resonators can partially or even wholly be filled with the low-loss dielectric substance, propagate to reduce volume and to change spatial field.In dielectric resonator, main produce an inclusion enclave (field inclusion), and if necessary, from shielding of this interface space attenuation laterally by metallic sheath by the interface between dielectric substance and surrounding air.The planar resonator that comprises microstrip line, stripline runs and coplanar resonator is to be made of the planographic conductor on dielectric substrates.
The selection of the design of resonator is the influence that is subjected to the unloaded Q of the resonator of wave filter technology standard (stating as follows) requirement.In the prior art, high unloaded Q means the bigger physical dimension of resonator.Whole the utilized volume of all resonators is restricted in lower gigahertz scope median filter in addition.The demand that obtains volume through the multiplexing resonator of vertical mode (double mode resonator) reduces about 50%.Contain the planar resonator of the cooling of high-temperature superconductor by use, the rule for the unloaded Q of height means big physical dimension can obtain an exception.Occurred towards another technological development direction of the high Q resonator of miniaturization the development progress of the ultralow consume dielectric substance of the high-k of using from dielectric resonator.(heating, multipacting) also design has influence to the compatibility of desired power supply to the selective resonance device.
The feature that the electrical property of band pass filter has is, frequency bandwidth (transmission frequency bandwidth) and transmission band position, the insertion loss of the maximum in transmission band and minimum return loss, the width of the transport zone between transmission band and stopband district, and the minimum reverse attenuation in the stopband district.
For the performance of filter construction further is described quantitatively, use in transmission band decay zero point (reflection zero) number N and in the stopband district peak atenuation (transmission zero) number M on the limited frequency of appointment.In the characteristic of using zero reflection and transmission zero, with the performance in (imagination) lossless situation as the basis, and according to their order repeated calculation zero-bit.
In order to realize a band pass filter, can be with N
RIndividual resonator is coupled to together, and the whole system of the resonator of feasible coupling has the total number N=N of zero attenuation in the logical zone of band
R(N=2N when multiplexing resonator
R).In addition, suitable coupling measure (face as follows) makes the sum M＜N of peak atenuation can appear in the stopband district on the limited frequency.
Produce essential zero attenuation than (" the relative steepness at filter edge ") and count N from shifting width and transmission band, and thereby produce the minimum number of essential resonator.
The following explanation of the advantage that obtains with the present invention is very important, that is, the essential zero attenuation in transmission band is counted N, reduces along with the increase of the M/N on the relative steepness at the filter edge of setting is dull.On the transmission band of setting, if use the accurate elliptic filter of M＞0, rather than the Chebyshev filter of M=0, for the edge steepness that requires, lower several N, therefore less resonator is counted N
R, be enough.When the real elliptic filter that uses M=N-1 replaced the accurate elliptic filter of M＜N-1, essential several N further reduced.
Because ohm and dielectric loss in the resonator of filter, the filter freguency response variation makes the steepness at available filter edge that rounded off effect limits, and the insertion loss of the dissipation in transmission band increases.Because this variation substantially only depends on N, do not depend on that transmission zero counts M, by increasing M/N, on the unloaded Q of the resonator of setting, can realize that higher edge steepness and low the dissipation insert the filter of loss.
In the filter that coupled resonators is formed, the square substantially method that produces the present use of transmission zero relates to, and except the direct coupling of adjacent resonator, introduces coupling (surmounting coupling) between the resonator of direct neighbor not.The logical cascade by each resonator of the band of prior art constitutes, and wherein the interior resonance device is coupled with their two adjacent resonators at least, two external resonators and the coupling of their filter port.If transmission zero does not appear in the additional coupling between non-adjacent resonator on finite frequency, promptly be suitable for M=0.The coupling that surmounts with suitable intensity and symbol, i.e. coupling between non-adjacent resonator causes the transmission zero in the stopband district, wherein depends on the position of coupling path, and each surmounts coupling and produces one to two transmission range.If the purpose of above-mentioned reason is the M/N ratio that reaches big as far as possible, with the maximum degree of freedom in the frequency location of selecting each transmission zero, this causes a kind of coupling scheme so, promptly, so-called " typical coupled structure ", and when using N-2 different surmounting to be coupled, and supposing that N is an even number, causing N-2 the transmission zero that can freely be provided with.With respect to the M=N-2 zero-bit of transmission band symmetry, need at least (N-2)/2 to surmount coupling.Like this have an actual realization that big figure surmounts the filter of coupling, generally cause the topological problem in the spatial arrangements of selecting each resonator and coupling element.Because in described typical coupled structure, first and last resonator must be coupled, therefore be in each other directly near in, so, in the filter of high order N, realize encountering problems in the sufficiently high reverse attenuation.
According to prior art, the configuration of so-called " the structure (extracted-pole-structure) that the limit of extraction arranged " of use in the Anglo-Saxon document, realize transmission zero, as substituting of the resonator configuration that surmount coupling of use between non-adjacent resonator, wherein Fu Jia resonator is coupled to power line, to the input and/or the output port of the band pass filter that on limited frequency, does not have transmission zero (M=0), make them realize transmission zero in the stopband district.Can recognize a kind of such configuration from DE 42 32 054 A1.Wherein the band stop filter that is made of a coaxial resonator at least is connected in series one does not have (M=0) Microwave Ceramic Filter of transmission zero on limited frequency (cascade of being made up of band pass filter and the band stop filter of M=0).With the interfering frequency of this band stop filter elimination outside transmission band.At United States Patent (USP) 3,747, among the 030A, the inputing or outputing of filter that the lumped elements of about quarter-wave straight line resonator and M=0 constitutes is connected in parallel.Its result, a band stop filter is connected with two port nets of this filter.The shortcoming of the band pass filter cascade of a band stop filter and M=0 is band stop filter uses additional resonator hereto, that is, must uses for the filter of the zero attenuation of N in transmission band to add up to N
RThe resonator of＞N.
For allow signal the coincidence frequency scope by and in the function of adjacent frequency range stopband signal, also can use two separately band stop filters in stopband district, replace a band pass filter.At this moment, the transmission band of use is between two stopband districts of this band stop filter.From United States Patent (USP) 5,291,161A recognizes the filter of this class, and it is made of the salient line that continuous main straight line and electric current are coupled to it, and wherein each salient line produces a transmission zero.From IEEE journal about microwave theory and technology, volume MTT-30, the 9th phase, September nineteen eighty-two, page or leaf 1361-1367, I.C.Hunger and J.R.Rhodes showed, and " but " literary composition also can be used capacitively coupled salient line to the microwave band-elimination filter of electronic tuning (Electronically tunable microwave Banstop Filter) as can be known, the relief straight lines that replaces the electric current coupling is to produce transmission zero.Also can recognize a kind of continuous transmission line (branch line) that is coupled with salient line from DE 24 42 618 C2.By using N
RThe salient line of individual coupling as a shortcoming of such filter construction band resistance resonator, that form from the inlet of filter to the continuous main line of outlet is, the height reverse attenuation still is limited to the frequency range of finite width, therefore, permission this filter outside these scopes passes through again.Second shortcoming is, zero attenuation is counted N and be lower than resonator number in the transmission band of using between two stopband districts, therefore, can not reach between transmission band and stopband district for the resonator of setting and count N
RThe maximum gradient at the filter edge that can obtain.
Therefore, the purpose of this invention is to provide a kind of method that realizes band pass filter, described band pass filter comprises the resonator of each coupling, it has as desirable, orientable nearly M=N-1 the peak atenuation in band stop filter, wherein do not use any resonator that surmounts coupling, " limit that extraction is arranged " and, make it possible to avoid the shortcoming of above-mentioned each method with the band stop filter structure of continuous main line.
According to the present invention, reached above-mentioned purpose by the clause that illustrates in the claims.The present invention proposes bandpass filter structures, wherein band resistance resonator is incorporated in the described structure, make each band resistance resonator both be implemented among the transmission zero of the hope in the stopband district, realize a zero attenuation in transmission band with remaining filter construction again.The feature of these bandpass filter structures is according to the preferred embodiment of the invention:
(a) each band pass filter is made up of the filtering device of the impedance symmetry that describes in detail below with N=2m+1 (m=natural number) individual limit and N-1 transmission zero; Or form by the cascade that the filtering device of the impedance symmetry that further specifies below with N=2 limit and M=2 transmission zero constitutes.
(b) has the filtering device of the impedance symmetry of N=3 limit and M=2 transmission zero, the straightway that is the border by two breakpoints that are called main resonator constitutes, a pair of band resistance resonator is coupled to its centre, wherein the longitudinal field on main resonator distributes and makes the resonance frequency that is coupling in main resonator (centre frequency) of band resistance resonator go up disappearance, but, get limited value on its frequency departing from.Select the length of main resonator, make half of its wavelength that equals the described line on the centre frequency of described band pass filter.Obstruction frequency for the selection of a band resistance resonator, littler than described centre frequency, the described centre frequency of obstruction frequency ratio of another band resistance resonator is big, make each of these two band resistance resonators produce transmission zero and by with the interactional additional port of described main resonator.If the filtering device of single impedance symmetry is used as described band pass filter, an end of described main resonator and described filter input electricity, electric current or magnetic couplings, the output coupling of the other end and described filter.If described band pass filter is to constitute from the cascade of the filtering device of several impedance symmetries, be not coupled to end electricity, electric current or the magnetic couplings of the adjacent main resonator that inputs or outputs port.
(c) has an impedance balanced-filter spare of N=2m+1 limit (m=greater than 1 natural number) and M=N-1=2m transmission zero, the line segment that is the border by two breakpoints that are called as main resonator constitutes, with respect to the right band resistance resonator of its coupling m, they are separated from each other out half the distance of wavelength of about centre frequency, thereby the longitudinal field on described main resonator distributes and the resonance frequency that is coupling in the main resonator device (centre frequency) that plays band resistance resonator to be gone up disappear, but gets limited value on the frequency of said frequencies departing from.Select the length of main resonator, make its substantially with centre frequency on half the m of wavelength of line doubly consistent, and hinder the right distance of resonator from the tyre that the end of main resonator begins, be about line wavelength 1/4th.Select described m every pair right two bands of band resistance resonator to hinder the obstruction frequency of resonators, make, compare centre frequency, one less, another is bigger, so that each of described two band resistance resonators all produces transmission zero, and produces an additional pole by interacting with described main resonator.If single impedance balanced-filter spare plays band pass filter, an end of described main resonator and input electricity, electric current or the magnetic couplings of described filter, and output electricity, electric current or the magnetic couplings of the other end and described filter.If band pass filter is to be set up by the filtering device cascade of several impedance symmetries, so, be not coupled to described end electricity, electric current or the magnetic couplings that inputs or outputs the adjacent main resonator of port.
(d) except the filtering device of impedance symmetry, can use each to have the filtering device of the non-impedance symmetry of N=2 limit and M=2 transmission zero, set up band pass filter from the cascade of several filtering devices.The filtering device of described non-impedance symmetry is made of main resonator, the wavelength of the line on the centre frequency of its length and described band pass filter about 1/4th corresponding, wherein an end is coupled on the adjacent filtering device, make that this line end is high resistance end (an electric field strength maximum), the other end is coupled to the port that inputs or outputs of adjacent filtering device or described band pass filter, make that described line end is low resistance terminal (in a line end electric current maximum), and wherein, the low resistance end electricity of a pair of band resistance resonator and main resonator or electric current coupling.
The differentiation of making above between impedance symmetry and non-impedance balanced-filter spare, be interpreted as, in the filtering device of impedance symmetry, when input and output port connects with identical terminal resistance, the maximum of the electric power transfer factor reaches the value of a given insignificant loss, in the situation of non-transmission balanced-filter spare, only can reach electric power transfer completely simultaneously for extremely asymmetric port resistance.
Embodiment shown in basic principle shown in the 1-4 and the accompanying drawing 5-12 further describes the present invention with reference to the accompanying drawings below.
Fig. 1 e provides the basic structure schematic diagram of impedance balanced-filter spare of the present invention, described filtering device has N=3 limit and M=2 transmission zero, Fig. 1 a-1d provides the structural representation of reflection present technique state simultaneously, therefore only plays the progressively effect of the basic principle of the structure of the present invention shown in the key-drawing 1e.
Fig. 1 a schematically illustrates the high-frequency line 1 of homogeneous, and wherein this line can be designed to metal TEM line, as a coaxial line, and planar line, as microstrip line, or stripline runs or complanar line, or the conductor of hollow or dielectric wire.Do not consider to scatter and disappear, the frequency response 2 of electric power transfer factor, that is, and the electric power P that on reflexless terminal port 2, exists
2With the electric power P that reaches port one
InThe frequency dependence of ratio, with frequency-independent, in the operating frequency range that is verified of described line, equal 1.
Fig. 1 b provides the schematic diagram with respect to the structure of Fig. 1 a remodeling, and wherein two breakpoints 3 are introduced in the length of line symmetrically.These breakpoints define the line segment of finite length a, thereon, on half consistent those frequencies of locating of integral multiple of the wavelength of described length and line, the electromagnetism natural oscillation appears, and the feature of these natural oscillations is, have electricity and the node of magnetic field intensity and the standing wave of antinode along described line, wherein the node of electric or magnetic field intensity exists in the symmetrical plane 4 on the resonance frequency.The structure representative that produces like this, 1 known in the prior art pole bandpass filter, its feature are that the frequency response 5 of electric power transfer factor is in frequency f
0Maximum P is arranged
2/ P
In=1 (zero attenuation).Limit the breakpoint of line segment, for example, the form that line taking technically disconnects, or be designed to metal coating, by at described line with play the intensity of the coupling between the end of line segment of described resonator effect, can change the frequency bandwidth Δ f of transmission curve, this is known in the prior art.
Fig. 1 c illustrates the structure with respect to the remodeling of Fig. 1 a, and wherein resonant circuit 6 (" band resistance resonator ") is coupled to described line, so that the frequency response 7 of electric power transfer factor is in frequency f
5On have transmission zero.This structure representative is from the structure (" notch filter ") of the known limit band stop filter of prior art.
Fig. 1 d illustrates the modified structure with respect to Fig. 1 c, and wherein coupling has two band resistance resonators 8 that change resonance frequency, rather than a band resistance resonator, causes at f
S1And f
S2On two transmission zeros.
Relate to respect to an important square face of the present invention, hinder the structure of the right combination formation of resonator according to Fig. 1 e from the structure of Fig. 1 b and the band of Fig. 1 d.The line segment of finite length forms a resonator, is called main resonator at this, and it has at the electric or magnetic field of centre node.An important square face of the present invention is to be chosen in the coupling between each band resistance resonator and the main resonator, in frequency f
0Go up this coupling disappearance on main resonator, wherein for example, suppose to exist the electric field node, this realizes by the coupling of selection magnetic field when having the magnetic field node by selecting an electric coupling to realize between main resonator and band resistance resonator.Its result, on the one hand, in frequency f
0Last band resistance resonator be to can not disturbing the resonance of main resonator, and on the other hand, for f
0Different frequencies, band resistance resonator to and main resonator between coupling produce two additional natural oscillations.Therefore, in this structure of the present invention, described two band resistance resonators play dual-use function, that is, they realize two transmission zeros on the one hand, shown in Fig. 1 d structure, and on the other hand, produce with described line segment and add up to 3 natural oscillation (3 limits).Therefore, suppose accurate selective resonance frequency and stiffness of coupling, the feature of the frequency response 10 of the structure of Fig. 1 e is, at f
1, f
2And f
3On three transmission maximums (zero attenuation) are arranged, and at f
S1And f
S2On two transmission zeros are arranged.In this filtering device of realizing 3 limits and two transmission zeros, the frequency location of transmission zero is determined that by the resonance frequency of band resistance resonator the middle peaked frequency location of transmission is determined by the length of main resonator.Two peaked positions of outer transmission, the intensity by the coupling between main resonator and band resistance resonator can change, and wherein hypothesis increases coupling, and these frequencies move to centre frequency.
Another important square face of the present invention is, shown in Fig. 2 a-2c, for realizing having the filter of M=2m transmission zero and N=M+1=2m+1 limit, according to the principle of the popularization of Fig. 1 e.Fig. 2 a also illustrates the situation according to the m=1 of Fig. 1 e.Line segment is half of wavelength (" centre frequency line wavelength ") on centre frequency as described, so, the coupling type between band resistance resonator and main resonator, whether the maximum that depends on electric field or magnetic field is positioned at the end of described line segment.The situation that electric field maximum is arranged in the end, described electric field is in frequency f
0On have in the symmetrical plane node, therefore described two band resistance resonators must have maximum value of magnetic field to require simultaneously on the end according to above-mentioned design principle electric coupling: because the cause of magnetic field node should have the magnetic field coupling to exist.When on the end, maximum value of magnetic field being arranged, in order to use the magnetic coupling between band resistance resonator and main resonator, the length of described line segment must with whole consistent wavelength, a rather than semi-uniform of the wavelength of reaching the standard grade with centre frequency.
Fig. 2 b illustrates m=2, that is, half the band resistance resonator of wavelength of two pairs of about lines that are separated from each other is wherein used in the popularization of the present invention of N=5 limit and M=4 transmission zero.
Fig. 2 c illustrates the extension of the present invention to the filtering device with N=7 limit and M=N-1=6 transmission zero.
Illustrate at Fig. 2 a-2c and to count N according to the limit of filtering device of the present invention and increase and to be limited, wherein count the prolongation of main resonator and more and more make the natural resonance of main resonator converge to described frequency range in order to increase limit by the undesirable higher natural mode shape position of main resonator.Although can realize with filter than big limit number for this restriction is arranged, an alternative embodiment of the invention proposes two alternative methods, be cascade according to the filtering device of the impedance symmetry of Fig. 2 a-2c and introduce the filtering device of the asymmetric impedance of two limits of each filtering device tool and two transmission zeros.
Fig. 3 illustrates, band N=N
gThe filter of * Q limit and M=N-Q transmission zero is how to have N from each
gIndividual limit and M
gThe Q of=N-1 transmission zero filtering device cascade formation.Shown example is, by 3 N
g9 limits that=3 filtering device is formed (9 ring) filter and by 3 N with 6 transmission zeros
g10 pole filters that 8 transmission zeros are arranged that=5 filtering device is formed.
By the filtering device of remodeling according to the right impedance symmetry of the band band resistance resonator of Fig. 1 e, according to the present invention, realize the filtering device of non-impedance symmetry, one of wherein said two breakpoints are placed near the position of band resistance resonator to being coupled.This produces the structure of the T shape shown in Fig. 4 a, it has breakpoint 2 (high resistance end), it approximately separates 1/4th centre frequency line wavelength from the coupling of band resistance resonator, and has second breakpoint 3 (" low resistance end "), and it is positioned near right coupling place of band resistance resonator.
For non-impedance symmetry is compensated, in the cascade of forming by non-impedance balanced-filter spare, add at least one impedance symmetry part.Shown in Fig. 4 b, on an end of cascade, can be provided with or center insertion (seeing Fig. 4 c) impedance symmetry part 5.
For at Fig. 1 e, 2a-2c, a lot of possible technical configuration have appearred in the filter construction of the present invention that schematically illustrates on 3 and 4, and what wherein they differed from one another is:
A) be used to set up the line type of described main resonator;
B) design of described band resistance resonator;
C) coupling type between described band resistance resonator and main resonator;
D) configuration of the breakpoint between the main resonator in cascade and described main resonator and the port.
Fig. 5 illustrates an example, and how expression with the form of single filter spare, can realize 7 pole filters of 6 transmission zeros according to the principle shown in Fig. 2 c of coaxial line technology.Main resonator 1 has square interior lines, and length equals 1.5 times of wavelength on the centre frequency.The form of coupler is held in the breakpoint power taking of restriction line segment.To form the coaxial line segments that shortens in the end with resistance resonator 2, and capacitively be coupled to described main resonator with about line wavelength 1/4th length.
Fig. 6 illustrates the remodeling according to 5 structure, and wherein band resistance resonator 2 is with the interior line current coupling of main resonator, but is positioned on the end under the condensive load.
Fig. 7 illustrates by two non-impedance balanced-filter spares and the structure that impedance symmetry part is formed, and wherein obtains 9 limits and 8 transmission zeros.
Fig. 8 illustrates the filter of the impedance symmetry resonating device composition with 5 limits and 4 transmission zeros, and it is to realize according to the square hollow line of H10 wave mode.Described main resonator 1 is to be made of the square hollow line that shorten at two ends, and it has and the corresponding to length of hollow line wavelength on centre frequency.Realize 4 band resistance resonators 2 with the form that shortens 1/4 hollow conductor section.For example can be coupled to each port via coaxial fitting 3.
Fig. 9 is illustrated under the situation of the filter of being made up of the filtering device of two impedance symmetries, example with the dielectric resonator realization, wherein said two filtering devices produce three limits and two transmission zeros, so band pass filter has and adds up to limit and 4 transmission zeros of 6.By suitable dielectric substance, the material that promptly has high as far as possible dielectric constant, low loss angle and low temperature coefficient (as barium titanate zirconate), the position of main resonator of making 1 and band resistance resonator 2, be positioned at bottom surface with pad 3 with a certain distance from metal shell 5, be enough to the ohmic loss of avoiding too high, described pad is for example made by quartz material.The size of described main resonator is such, makes it at f
0Natural resonance with the field distribution shown in Fig. 9 b, and respectively the size of band resistance resonator is like this, makes them block frequency f at 4
1-f
4Last resonance, wherein they have the field distribution according to Fig. 9 c.Because the spatial field of main resonator distributes, at f
0, it is not coupled to the resonance field of band resistance resonator.But, for except f
0Outer other frequencies obtain the coupling in the middle of main resonator and band resistance resonator, and the result is 4 additional natural resonances to occur.For example, use conductor loops 4 can produce the coupling to port.
Figure 10 illustrates the example by the possible design of the another one of the filtering device of dielectric substance manufacturing.Main resonator 5 comprises that the dielectric with length a is square, described length substantially with the consistent wavelength of surface wave on dielectric is square.This produces the field distribution with the corresponding main resonator of Figure 10 b.4 band resistance resonator 1-4 comprise that also dielectric is square, and their each length b1-b4 influence the frequency location of these 4 transmission zeros.The whole structure that is made of described dielectric main resonator and 4 dielectric tapes resistance resonator has realized 5 natural oscillations.The frequency location of each limit can be by changing at the stiffness of coupling of advocating peace between the band resistance resonator.With inserting air or being h than the width of the dielectric substance of low-k
1-h
4Resonator between " gap ", change this stiffness of coupling.
Also can be applied to the planar resonator structure according to principle of the present invention, as microstrip line construction, wherein the microstrip line construction by the high-temperature superconductor manufacturing also is valuable, because although be that microminiaturized level is very high, these structures still have high unloaded Q.
Figure 11 has illustrated in stripline technique and to have realized non-impedance symmetry resonating device according to the present invention.Figure 11 a at first looks back the of the prior art known principle of mini strip line resonator.In this structure, suitable dielectric substrates 1 carries continuous conductor layer 2 in a side, carries structurized conductor layer at opposite side.Figure 11 a illustrates the well-known structures of mini strip line resonator 3, and its end is capacitively to be coupled with power supply lead wire 4 and 5.The frequency response 6 of electric power transfer factor is in frequency f
0On have maximum, the intensity of the coupling that this peaked width can be by on described thread end (breakpoint) changes.How Figure 11 b can realize non-impedance balanced-filter spare if being illustrated in the stripline technique.To this, use the conductor structure of T shape, 1/4th of the line wavelength of the length of each arm and centre frequency is unanimous on the whole in described structure, and wherein the asymmetry of correct qualification is necessary for its function in the length of side arm 3 or width.The simple forming process of side arm representative band resistance resonator is wherein blocked the effect length that frequency is subjected to arm.Side arm forms a structure with the 3rd arm, and it is at two different frequency upper resonances, so that the T structure is represented the special shape of double mode resonator.Output port can capacitively be coupled to T shape structure in the mode of Figure 11 b.The characteristic of the frequency response 6 of the dual-port that such mode forms is two transmission maximums and two transmission zeros, and wherein because asymmetric, the peaked absolute value of transmission can be away from another.For this reason, opposite with the filtering device of an impedance symmetry single asymmetric filters part is not still represented spendable band pass filter.As illustrated in the example of all above-mentioned enforcements, also can for example use heterogeneous line segment of various width in every way with this microstrip line construction remodeling.
Figure 12 illustrates the example of 9 pole filters that how can form 8 transmission zeros by the filtering device 1 and the conventional half-wave resonator 2 of 4 non-impedance symmetries.Except additional limit is provided, the resonator 2 in cascade in coupling place with respect to the contact of T shape resonator, will be transformed into lower impedance level at the impedance on the port 2 (as 50 ohm).For example, can determine the parameter of each filtering device, so that obtain the Cauer characteristic of frequency response.
Claims (17)
1. high freguency bandpass filter device, at least one band that comprises main resonator (1) and be coupled on the described main resonator (1) hinders resonator (4,6,8), main resonator (1) wherein, by in both sides with disconnecting or the breakpoint of metallic walls form (Fig. 2 a 2 and 3) limits as the line segment on border, and at centre frequency (f
0) on have the electromagnetism natural oscillation, it is characterized in that: the described band resistance resonator (4) that is coupled to main resonator, for the ripple on main resonator (1) line segment, at its obstruction frequency (f
s) the last reflectivity that realizes main resonator; And at least one band resistance resonator is coupled with described main resonator on the certain position on the section along the line, described position is, thereon because along the electricity of described line and the spatial variations in magnetic field, on the centre frequency of described band pass filter, the coupling with frequency dependence between band resistance resonator and the main resonator disappears.
2. according to the high freguency bandpass filter device of claim 1, it is characterized in that: described at least one band resistance resonator comprises a pair of band resistance resonator that is mutually symmetrical and arranges.
3. according to the high freguency bandpass filter of claim 1, it is characterized in that: described at least one band resistance resonator is electrically coupled to described main resonator.
4. according to the high freguency bandpass filter of claim 1, it is characterized in that: at least one band resistance resonator magnetic couplings is to main resonator.
5. according to the high freguency bandpass filter of claim 1, it is characterized in that: at least one band resistance resonator electric current is coupled to main resonator.
6. according to the high freguency bandpass filter of claim 1, it has three natural frequencys and two transmission zeros, it is characterized in that: main resonator comprises a line segment, its length is roughly half of wavelength on the centre frequency with described band pass filter, and two band resistance resonators are coupled to main resonator in the centre of described line segment, make the coupling at centre frequency the above and frequency dependence disappear, the obstruction frequency of one of described two band resistance resonators is less than the centre frequency of described band pass filter, the obstruction frequency of another band resistance resonator is greater than the centre frequency of described band pass filter, the obstruction frequency of two band resistance resonators is chosen in the stopband district of the transmission zero of wishing to have band pass filter, and three transmission maximums in transmission band, along with the intensity of the coupling between band resistance resonator and main resonator and move, make trip loss in transmission band in predefined minimum value.
7. according to the high freguency bandpass filter of claim 1, it has five natural frequencys and four transmission zeros, it is characterized in that: main resonator is to be formed by line segment, the length cardinal principle of described line segment and the consistent wavelength on centre frequency, two pairs of band resistance resonators are coupled to main resonator, wherein said two pairs of band resistance resonators are along be separated from each other half of wavelength on about centre frequency of the line segment of described main resonator, and hinder in addition resonator to described line segment end in the middle of separate described wavelength approximately 1/4th distances, make that on the centre frequency of band pass filter the coupling with frequency dependence disappears.
8. according to the bandpass filter device of claim 1, it has 2m+1 natural frequency and 2m transmission zero, m is a natural number, it is characterized in that: described main resonator is to be formed by line segment, the length of described line segment be about on centre frequency wavelength half m doubly, m is coupled to main resonator to band resistance resonator, described m to band resistance resonator along be separated from each other wavelength one half-distance on the centre frequency of described line segment, and other band resistance resonator to and the end of described line segment between distance be about 1/4th of described wavelength, make to disappear on the centre frequency that is coupling in band pass filter with frequency dependence.
9. according to the band pass filter of claim 1, it has 2m+1 natural frequency and 2m transmission zero, m is a natural number, it is characterized in that: main resonator is to be formed by line segment, the length of described line segment is in the pact of half of the wavelength of centre frequency (m+1) doubly, m hinders resonator to being coupled on the main resonator to band, described m to band resistance resonator along be separated from each other half distance of wavelength on the centre frequency of described line segment, and band externally resistance resonator to and the end of described line segment between half of wavelength of described approximately line separately, make on the centre frequency of band pass filter coupling disappearance with frequency dependence.
10. according to the band pass filter of claim 1, it has Q filtering device of cascade, wherein these filtering devices are that band pass filter by one of claim 2-5 forms, it is characterized in that: play the adjacent end portion coupling of the line segment of the end electric or magnetic of line segment of filtering device of main resonator effect or electric current ground and next filtering device, and wherein, two of the line segment of Wai Bu filtering device outer ends with input or output the port coupling.
11. band pass filter according to claim 1, it has two transmission poles and two transmission zeros, and (Fig. 4 a), main resonator by line segment (Fig. 4 a 1) form constitutes, its length be on the centre frequency of band pass filter wavelength 1/4th, it is characterized in that: input port (port one) electricity of an end (2) and band pass filter, magnetic or electric current coupling make that the maximum in the electric field strength on the centre frequency appears on the described end; Its other end (3) is coupled with output port electricity, magnetic or the electric current of band pass filter, makes to appear on this end in the electric field strength minimum value on the centre frequency; Be coupling near second port (Fig. 4 a 3) a pair of band resistance resonator electricity, magnetic or electric current; The obstruction frequency of the selection of described two band resistance resonators equates with the preset frequency of the transmission zero in the stopband district; By changing, can change two peaked frequency locations of transmission in transmission band at band resistance resonator with along the stiffness of coupling between the about quarter-wave of described line segment.
12. band pass filter according to claim 11, it have band resistance resonator to and the coupling of the electric current between the quarter-wave approximately length along described line segment, it is characterized in that: this line segment hinders the resonators (Figure 11 b) that resonators formation has the T shape of two different natural frequencies with described two bands; The lower end electric coupling of the vertical part of the input of described filter and " T "; The upper end electric coupling of the vertical part of the output of filter and " T ".
13. the band pass filter that the filtering device cascade constitutes, it is made of the logical structure of band one of among the logical structure of band of claim 11 or 12 and the claim 1-9.
14. according to the band pass filter one of among the claim 1-13, it is characterized in that: each resonator design is a coaxial resonator.
15. according to the band pass filter one of among the claim 1-13, it is characterized in that: each resonator design is the resonator of hollow space.
16. according to the band pass filter one of among the claim 1-13, it is characterized in that: each resonator design is a dielectric resonator.
17. according to the band pass filter one of among the claim 1-13, it has planar microstrip line resonator or the coplanar resonator that comprises the planar resonator of being made up of high-temperature superconductor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19941311A DE19941311C1 (en) | 1999-08-31 | 1999-08-31 | Band filter |
| DE19941311.8 | 1999-08-31 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1371534A true CN1371534A (en) | 2002-09-25 |
| CN1241289C CN1241289C (en) | 2006-02-08 |
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ID=7920218
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB008122687A Expired - Fee Related CN1241289C (en) | 1999-08-31 | 2000-08-26 | High-frequency band pass filter assembly comprising attenuation poles |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP1212806B1 (en) |
| JP (1) | JP2003508948A (en) |
| KR (1) | KR20020047141A (en) |
| CN (1) | CN1241289C (en) |
| AT (1) | ATE233956T1 (en) |
| AU (1) | AU7280000A (en) |
| CA (1) | CA2383777A1 (en) |
| DE (2) | DE19941311C1 (en) |
| ES (1) | ES2191642T3 (en) |
| IL (1) | IL148267A0 (en) |
| WO (1) | WO2001017057A1 (en) |
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| US3747030A (en) * | 1971-06-07 | 1973-07-17 | Oak Electro Netics Corp | Band pass filter with transmission line section |
| AU470870B2 (en) * | 1973-10-29 | 1976-04-01 | Matsushita Electric Industrial Co., Ltd. | Filters employing elements with distributed constants |
| FR2546340B1 (en) * | 1983-05-20 | 1985-12-06 | Thomson Csf | TUNABLE COAXIAL BAND CUTTER MICROPHONE FILTER WITH DIELECTRIC RESONATORS |
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| US5291161A (en) * | 1991-07-22 | 1994-03-01 | Matsushita Electric Industrial Co., Ltd. | Microwave band-pass filter having frequency characteristic of insertion loss steeply increasing on one outside of pass-band |
| DE4232054A1 (en) * | 1992-09-24 | 1994-03-31 | Siemens Matsushita Components | Microwave ceramic filter - incorporates throughput frequency band-defining filter and series-connected coaxial resonator as band stop |
-
1999
- 1999-08-31 DE DE19941311A patent/DE19941311C1/en not_active Expired - Fee Related
-
2000
- 2000-08-26 CA CA002383777A patent/CA2383777A1/en not_active Abandoned
- 2000-08-26 KR KR1020027002811A patent/KR20020047141A/en not_active Application Discontinuation
- 2000-08-26 AT AT00960529T patent/ATE233956T1/en not_active IP Right Cessation
- 2000-08-26 JP JP2001520502A patent/JP2003508948A/en active Pending
- 2000-08-26 IL IL14826700A patent/IL148267A0/en unknown
- 2000-08-26 WO PCT/EP2000/008333 patent/WO2001017057A1/en active IP Right Grant
- 2000-08-26 DE DE50001421T patent/DE50001421D1/en not_active Expired - Fee Related
- 2000-08-26 ES ES00960529T patent/ES2191642T3/en not_active Expired - Lifetime
- 2000-08-26 AU AU72800/00A patent/AU7280000A/en not_active Abandoned
- 2000-08-26 EP EP00960529A patent/EP1212806B1/en not_active Expired - Lifetime
- 2000-08-26 CN CNB008122687A patent/CN1241289C/en not_active Expired - Fee Related
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Also Published As
| Publication number | Publication date |
|---|---|
| CN1241289C (en) | 2006-02-08 |
| JP2003508948A (en) | 2003-03-04 |
| IL148267A0 (en) | 2002-09-12 |
| ES2191642T3 (en) | 2003-09-16 |
| DE19941311C1 (en) | 2001-06-07 |
| DE50001421D1 (en) | 2003-04-10 |
| AU7280000A (en) | 2001-03-26 |
| CA2383777A1 (en) | 2001-03-08 |
| EP1212806B1 (en) | 2003-03-05 |
| ATE233956T1 (en) | 2003-03-15 |
| WO2001017057A1 (en) | 2001-03-08 |
| EP1212806A1 (en) | 2002-06-12 |
| KR20020047141A (en) | 2002-06-21 |
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