CN1838476B - Suspended mictrostrip filter and duplexer and method for designing and debugging filter - Google Patents
Suspended mictrostrip filter and duplexer and method for designing and debugging filter Download PDFInfo
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- CN1838476B CN1838476B CN2005100338659A CN200510033865A CN1838476B CN 1838476 B CN1838476 B CN 1838476B CN 2005100338659 A CN2005100338659 A CN 2005100338659A CN 200510033865 A CN200510033865 A CN 200510033865A CN 1838476 B CN1838476 B CN 1838476B
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Abstract
This invention discloses a suspending strip line filter and duplexer and filter's design and adjusting method. The filter includes a cavity formed by metal hull, the inner of the cavity has a PCB double-faced board which fixed at the side wall of the metal hull, between the up and down inner wall there has a certain air height; one side of PCB double-faced board etches cross nodel line transmission line with destined type. The frequency deviation index of the filter and duplexer is decided by the PCB double-faced board etches cross nodel line transmission line graph's processing precision, so it is easy to control and it has high disposal quality.
Description
Technical field
The present invention relates to be used for the radio-frequency unit of communication technical field, relate in particular to a kind of filter that adopts the suspended mictrostrip structure, and the duplexer that constitutes by this filter; The invention still further relates to this Filter Design method and method for rapidly debugging.
Background technology
Along with the develop rapidly of wireless communication technique, the communication apparatus of various frequency ranges, various standards constantly occurs and comes into operation.For fear of the transmitting-receiving phase mutual interference that comprises between various communication system signals between self system, need to use radio-frequency filter carry out filtering.Particularly on the wireless base station,, need to use duplexer in order on same antenna, to realize receiving and sending signal.
Filter in wireless base system and duplexer can not adopt the filter of microstrip line construction commonly used, and main cause is that Insertion Loss is excessive.Industry all adopts cavity filter or cavity dielectric filter without any exception, and the principle of cavity filter is by the formation filter action that intercouples of electric field between the air resonance chamber and magnetic field, and the geometry in air resonance chamber has determined resonance frequency; Because machining has determined the precision of cavity, cause using have equivalent electric perhaps the screw of inductance effect adjust, could satisfy the index of filter duplexer, so cavity filter or cavity dielectric filter have following shortcoming:
● yields is low; The production lot consistency is poor, it is high to require on the machining accuracy;
● the cost height; Each cavity filter or cavity dielectric filter need have several, tens, tens screws to adjust repeatedly according to different index situations, because the processing and debugging complexity, the index frequency is adjusted complicated, causes the cost height.
● the manufacturing cycle is long; Because need debugging repeatedly, the input manpower time is many, causes the manufacturing cycle long;
● cavity filter is a precision metallic workpiece in addition, and index request is higher, and it is very difficult therefore significantly to reduce cost.
Summary of the invention
Technical problem to be solved by this invention is: a kind of filter that adopts the suspended mictrostrip structure is provided, the filter of this structure had both solved the problem that machining accuracy is required height, manufacturing cycle length, batch process consistency difference, had kept the low-loss characteristics of air transfer media simultaneously again.
Another object of the present invention is that a kind of duplexer that is made of the filter of this suspended mictrostrip structure is provided.
Another purpose of the present invention is that a kind of Fast design method and fast adjustment method of this filter also will be provided.
The present invention solves the problems of the technologies described above the technical scheme that is adopted to be:
A kind of suspended mictrostrip filter comprises a cavity that is formed by metal-back, and a PCB double sided board is set in the described cavity, and described PCB double sided board is fixed on the sidewall of described metal-back, and has certain air height with the inwall up and down of described metal-back; The one side of described PCB double sided board has the cross assistant warden as suspended mictrostrip to join transmission line by the reservation shape etching.
Described filter, wherein: described cross assistant warden connection transmission line saves unit cascaded the composition by the above cross of a joint; Each grade cross joint unit is made of cross joint, open-circuit line and the transmission line of predetermined structure size; Be covered with the PCB ground that communicates at the PCB double sided board tow sides that leave described cross assistant warden connection transmission line certain distance, and described PCB ground links to each other with described metal-back.
Described filter, wherein: described metal-back is made of last shielding box and following shielding box, about the described PCB double sided board that has cross assistant warden connection transmission line is fixedly mounted in the middle of the shielding box; The double-edged PCB of PCB double sided board ground is communicated with by some through holes, and closely contacts with described shielding box up and down.
Described filter, wherein: the barrier shield that adopts PCB ground to form between the described cross joint that links to each other is isolated.
Described filter, wherein: the air height between described shielding box up and down and the PCB double sided board is 1/2～4 times of described PCB double sided board thickness; Described PCB double sided board adopts the sheet material of low-loss dielectric constant.
Described filter, wherein: the open-circuit line of described cross joint unit is provided with bending in the precalculated position.
A kind of duplexer that adopts suspended mictrostrip filter to form comprises a cavity that is formed by metal-back, is provided with emission filter and receiving filter in the described cavity; Emission filter is connected antenna with the ANT antenna end that receiving filter joins, and the TX transmitting terminal of emission filter connects transmitter circuitry, and the RX receiving terminal of receiving filter connects receiver circuit; One PCB double sided board is fixed on the sidewall of described metal-back, and etching has at least one group of cross assistant warden connection transmission line on the described PCB double sided board, as emission or receiving filter; The inwall up and down of described PCB double sided board and described metal-back has certain air height.
Described duplexer, wherein: described PCB double sided board same worn respectively two groups of cross assistant wardens connection transmission lines as emission filter and receiving filter; Adopt the T type to be connected between described emission filter and the receiving filter; Described ANT antenna end, TX transmitting terminal, RX receiving terminal are connected with antenna, transmitter circuitry, receiver circuit respectively by coaxial connector.
Described duplexer, wherein: the cross assistant warden of described emission filter and the receiving filter connection transmission line tow sides of described PCB double sided board that are placed in, and be in staggered distribution; Described emission filter is connected by through hole with the ANT antenna end of receiving filter.
A kind of method for designing of suspended mictrostrip filter, in the operating frequency of filter, adopt following steps:
A, according to the physical structure parameter of fixed suspended mictrostrip structure and the structure electric parameter of pcb board, find the solution at circuit and to draw the strip lines configuration of optimizing the back equivalence in the simulation software;
B, find the solution in the simulation software physical structure size that goes out the little band cross joint of suspending of Approximate Equivalent with strip line cross joint model solution at described circuit;
C, find the solution the physical structure size of the described little band cross joint that suspends of checking at the 3 D electromagnetic farm software.
Described method for designing is further comprising the steps of:
D, to each cross joint of suspended mictrostrip, carry out the 3 D electromagnetic farm software respectively and find the solution, draw the scattering parameter of each cross joint;
E, at each cross joint of suspended mictrostrip, find the solution in the simulation software at circuit, the scattering parameter of each cross joint of finding the solution with equivalent 3 D electromagnetic farm software is a goal prerequisite, finds the solution the length parameter L+ Δ L of little band cross joint open-circuit line model that suspends; Wherein, L is for finding the solution original open-circuit line length of the little band cross joint that suspends that solves in the simulation software at circuit; The serve as reasons open-circuit line length of open circuit equivalent capacity equivalence of Δ L;
F, draw each little band cross that suspends and save open-circuit line length L-Δ L accurately, and the open-circuit line of each little band cross joint that suspends is substituted original open-circuit line length L with open-circuit line length L-Δ L accurately.
Described method for designing, wherein: the physical structure parameter of the described suspended mictrostrip of steps A and the structure electric parameter of pcb board comprise: the air height up and down of suspended mictrostrip, transmission line thickness, the loss tangent angle and the dielectric constant of PCB medium.
A kind of method of adjustment of suspended mictrostrip filter may further comprise the steps:
A, choose the conducting strip that is used to adjust the filter frequency deviation; And the preset position of selecting described conducting strip, this preset position obviously changes the spacing between cross assistant warden connection transmission line and the ground;
B, according to the thickness and the conductive characteristic of described conducting strip, by actual emulation, draw exact position that the conducting strip number of plies or conducting strip be provided with concrete influence value to described filter frequencies skew;
C, need the suspended mictrostrip filter of correcting frequency shift after finishing for manufacturing, the described concrete influence value that draws according to actual frequency offset and step B is fixed on the conducting strip of the required number of plies on the described exact position.
Described method of adjustment, wherein: when the frequency of described filter offset downward, described method of adjustment comprised as follows:
Preset position described in the described steps A is: PCB ground and last shielding box contact position near the open-circuit line of described cross assistant warden connection transmission line;
The concrete processing of described step B is as follows: according to the thickness and the conductive characteristic of described conducting strip, by actual emulation, draw the conducting strip number of plies that the is arranged on preset position concrete influence value to described filter frequencies skew;
Exact position described in the described step C is equal to described preset position.
Described method of adjustment, wherein: when the frequency of described filter upwards was offset, described method of adjustment comprised as follows:
Preset position described in the described steps A is: under the open-circuit line end of described transmission line and with PCB reverse side ground wire and following shielding box contact position;
The concrete steps that described step B comprises are:
B1, according to the thickness and the conductive characteristic of described conducting strip, by actual emulation, when drawing conducting strip and being arranged on different exact position to the concrete influence value of described filter frequencies skew;
B2, on described PCB double sided board, identify described different exact position;
The conducting strip of the required number of plies described in the described step C is one deck conducting strip.
Described method of adjustment, wherein: described conducting strip adopts metallic gasket.
Beneficial effect of the present invention is: because the filter and the duplexer of the technical program, the frequency shift (FS) index of actual finished product is mainly determined by the machining accuracy of cross assistant warden connection transmission line figure on the pcb board, promptly be equivalent to the machining accuracy of control metallic cavity has been transformed into the accuracy of manufacture of control PCB figure, and the machining accuracy of PCB is far above the machining accuracy of mechanical structure, and the precision of control PCB figure is easier to realize; Therefore, filter of the present invention and duplexer are to shielding box machining and the no special required precision of PCB double sided board processing, and the making yields is high, need not debugging substantially, can guarantee to produce in batches good characteristic consistency simultaneously; Therefore can greatly reduce cost, and be easy to produce in batches, delivery cycle can be shortened greatly.
This Filter Design method provided by the invention, owing to adopted and utilized circuit to find the solution in the simulation software the local Approximate Equivalent suspended mictrostrip of strip line cross joint model cross joint model optimization to go out a suspended mictrostrip cross assistant warden connection filter, and the technical scheme of finding the solution the little band cross joint of suspending of simulation software optimization again with 3 D electromagnetic farm software correcting circuit, therefore solve circuit and found the solution suspend in the simulation software little band cross joint model and the inaccurate technical barrier of little band open-circuit line model that suspends, realized designing rapidly and accurately the suspended mictrostrip cross joint type filter that satisfies design objective.
The fast adjustment method of this filter provided by the invention.Because after this Design of Filter is finished before the PCB double sided board processing and fabricating, just draw the concrete influence value of the position of the number of plies of the conducting strip that is used for adjusting the filter frequencies skew and effect, and on pcb board, make sign this filter frequencies skew by actual emulation; Therefore need the filter of correcting frequency shift for machining the back minority, can proofread and correct adjustment rapidly and accurately with conducting strip is disposable; Has the simple time saving advantage of debugging.
Description of drawings
Fig. 1 is the profile of suspended mictrostrip filter of the present invention;
Fig. 2 is cross joint cell schematics;
Fig. 3 removes the vertical view of shielding box for suspended mictrostrip filter;
Fig. 4 is suspended mictrostrip filter test result figure;
Fig. 5 is the schematic diagram of the open-circuit line bending of cross joint;
Fig. 6 is the block diagram of duplexer;
Fig. 7 a Fig. 7 b be the suspended mictrostrip duplexer pcb board just/anti-two sides schematic diagram;
Fig. 8 a Fig. 8 b is the schematic diagram of the strip lines configuration of suspended mictrostrip structure and equivalence;
Fig. 9 finds the solution the solving result comparison curves of strip line cross joint in the simulation software for the circuit of suspended mictrostrip cross joint and Approximate Equivalent in the 3 D electromagnetic farm software;
Figure 10 is the equivalent circuit diagram of little band open-circuit line cross section of suspending;
Figure 11 a, b, c, d, e, f, g, h are the cross joint comparison curves that L finds the solution the S parameter at the 3 D electromagnetic farm software before circuit is found the solution simulation software and optimized behind the optimization L+ Δ L;
Figure 12 is asymmetric strip lines configuration figure;
Figure 13 is the pcb board front elevation during for the filter that uses the conducting strip emending frequency and offset downward;
During filter that Figure 14 offsets downward for emending frequency, the position signal that conducting strip is laid;
Pcb board front elevation and reverse side figure when Figure 15 a Figure 15 b makes progress the filter that is offset for using the conducting strip emending frequency;
When Figure 16 makes progress the filter that is offset for emending frequency, the position signal that conducting strip is laid;
Figure 17 is the signal of sign frequency correction value correspondence position on pcb board.
Embodiment
With embodiment the present invention is described in further detail with reference to the accompanying drawings below:
Referring to Fig. 1 Fig. 2 Fig. 3, suspended mictrostrip filter of the present invention, its basic structure comprises: a cavity that is formed by metal-back 1, one PCB double sided board 20 is set in the described cavity, the PCB double sided board is fixed on the sidewall of metal-back, and PCB double sided board and metal-back has certain air height h up and down between the inwall; The front-side etch of described PCB double sided board has the cross assistant warden connection transmission line 30 of reservation shape, cross assistant warden connection transmission line 30 saves unit cascaded the composition by as shown in Figure 2 cross more than the joint, and each grade cross joint unit all is made of cross joint 33, open-circuit line 32 and the transmission line 31 of predetermined structure size, a resonator or impedance transducer are formed in each cross joint unit, form filter by the cross joint of cascade simultaneously; On the pcb board that leaves cross assistant warden connection transmission line certain distance, just the PCB double sided board tow sides around cross assistant warden connection transmission line all be covered with the PCB ground 21 that communicates, and PCB ground 21 link to each other with described metal-back.Adopt the filter of structure as mentioned above, the index of its actual finished product is mainly decided by the machining accuracy of cross assistant warden connection transmission line figure on the pcb board, and compare by the machining accuracy decision with the cavity filter frequency shift (FS), obviously, the machining accuracy of control PCB figure is easy to many than the control machining accuracy, be easier to realize that therefore the yields of filter of the present invention is high.
The concrete structure that suspended mictrostrip filter of the present invention adopts as shown in Figure 1, described metal-back is made of with following shielding box 11 last shielding box 10, the PCB double sided board 20 that has a cross assistant warden connection transmission line 30 is fixedly mounted on up and down in the middle of the shielding box, PCB double sided board 20 keeps certain air height with shielding box inwall up and down, during specific design, the PCB double sided board adopts the sheet material of low-loss dielectric constant, air height h is 1/2～4 times of PCB double sided board sheet metal thickness d, make all transmission from air 4 of most of energy like this, reduced filter insertion loss effectively.According to the conventional design of microwave, on the pcb board back side under the cross assistant warden connection transmission line, do not walk any line, exert an influence to avoid that the cross assistant warden is joined transmission line; And in the present invention, the barrier shield that adopts PCB copper sheet ground 21 to form between the described cross joint that links to each other is isolated, and as shown in Figure 3, is used for reducing influencing each other between the cross joint.PCB double sided board tow sides around cross assistant warden connection transmission line are all spread copper sheet in addition, form large stretch of PCB ground, simultaneously about the copper sheet place beat a large amount of via hole 22 PCB be interconnected double-edgedly; When described PCB double sided board was installed in up and down in the middle of the shielding box, positive and negative PCB ground closely contacted with shielding box up and down, and by metal fastenings (screw) PCB ground was tightly linked to each other with shielding box up and down; This mode had both made filter possess good heat sinking function, also had good shield effectiveness simultaneously.The filter of above-mentioned concrete structure, kept the advantage that loss is low, filtering performance is good, its characteristic test the results are shown in Figure 4, make simultaneously and assembly technology is simple and convenient, machining accuracy is controlled easily, disposable yields is high, as long as the pcb board that handle processes is placed on down in the shielding box, burn-on and add shielding box behind the coaxial connector, shielding box is fastening with screw up and down, need not any debugging, all satisfies design objective more than 90%.Therefore can reduce cost significantly, shorten the manufacturing cycle.
The cross joint graphics shape of the cross assistant warden connection transmission line among the present invention, size and cross assistant warden connection number are decided according to the specific design demand, and be unrestricted.And in actual design is made, can also be according to concrete needs, suspended mictrostrip filter of the present invention is carried out deformation process, for example in order to dwindle filter size, as shown in Figure 5, to processings of bending of the cross joint open-circuit line of cross assistant warden connection transmission line, promptly be provided with bending 321 in the precalculated position that cross saves the open-circuit line of unit, have same effect, but reduced the cross assistant warden and joined the area that transmission line takies pcb board.
Utilize suspended mictrostrip filter of the present invention can form duplexer.Duplexer as shown in Figure 6, form by emission filter and receiving filter, emission filter is connected antenna with the ANT antenna end that receiving filter joins, and the TX transmitting terminal of emission filter connects transmitter circuitry, and the RX receiving terminal of receiving filter connects receiver circuit.Duplexer allows transmitter signal from transmitter circuitry only by transmitter band guiding antenna, allows simultaneously only by frequency acceptance band it to be fed to receiver from the received signal of antenna, realizes carrying out receiving and transmitting signal simultaneously with the same antenna; Adopt duplexer can prevent to transmit interference, and received signal is to the interference of transmitter circuitry to receiver circuit.Duplexer of the present invention comprises a cavity that is formed by metal-back equally, is provided with emission filter and receiving filter in the described cavity; One PCB double sided board is fixed on the sidewall of described metal-back, and etching has at least one group of cross assistant warden connection transmission line on the described PCB double sided board, as emission or receiving filter; The inwall up and down of PCB double sided board and described metal-back has certain air height.Instantiation is shown in Fig. 7 a Fig. 7 a b, and described PCB double sided board same worn respectively two groups of cross assistant wardens connection transmission lines as emission filter and receiving filter, and employing T type is connected between the end of described emission filter and receiving filter; Pcb board is fixed on up and down in the middle of the shielding box, and the ground of PCB directly contacts with shielding box up and down; Described ANT antenna end, TX transmitting terminal, RX receiving port are connected with antenna, transmitter circuitry, receiver circuit respectively by coaxial connector.Duplexer of the present invention in force, the tow sides of PCB double sided board can also be placed in the cross assistant warden of emission filter and receiving filter connection transmission line, and be in staggered distribution as the cross assistant warden of emission filter connection transmission line and cross assistant warden connection transmission line as receiving filter, emission filter is connected by through hole with the ANT antenna end of receiving filter.The above-mentioned duplexer of forming with suspended mictrostrip filter has all advantages of aforementioned suspended mictrostrip filter.
About suspended mictrostrip cross joint Filter Design, because suspended mictrostrip is a kind of very complicated version, there are not calculating formula and general approximate calculation formula accurately, only the approximate calculation formula is arranged just under some special case, so suspended mictrostrip is found the solution to find the solution in simulation software and the 3 D electromagnetic field simulation software to design and is finished usually at circuit.3 D electromagnetic field simulation software can carry out the field finds the solution the figure of arbitrary shape, have emulation solving result very accurately, but simulation time is long, is not suitable for being used to have the emulation under a plurality of parameters optimization situations to find the solution; And circuit is found the solution the method that simulation software adopts circuit to find the solution, have faster and find the solution the time, but can't consider the figure of irregular figure and model-free, and the model that the little band open-circuit line that suspends in the cross joint unit, little band cross joint that suspends are found the solution in the simulation software at circuit is inaccurate; If find the solution the filter that a concrete size figure is tried to achieve by simulation software at circuit earlier according to common method for designing, in the 3 D electromagnetic farm software, find the solution the confirmation result then, with regard to needing the above-mentioned optimization solution procedure of carrying out again and again, obtain a filter that meets the design objective requirement until finding the solution at the 3 D electromagnetic farm software.This design process can be very very long, and have uncertainty.Find the solution suspend in the simulation software little band cross joint model and the inaccurate technical barrier of little band open-circuit line model that suspends in order to solve circuit, realize the quick design of suspended mictrostrip cross joint type filter, the invention provides a kind of Fast design method of suspended mictrostrip cross joint filter.
Referring to Fig. 8 a and Fig. 8 b, the basic principle of method for designing of the present invention is: because transmission line is in certain operating frequency and electrical length scope, the impedance of the suspended mictrostrip 30 of same widths and length and strip line 60 transmission lines and electrical length equate, therefore for concrete suspended mictrostrip structure, can obtain the strip lines configuration of an Approximate Equivalent; And find the solution in the simulation software at circuit, strip line cross joint model has higher accuracy, therefore utilizes circuit to find the solution the optimization result that strip line cross joint model solution in the simulation software goes out the suspended mictrostrip cross joint of Approximate Equivalent.Its method comprises the steps: in the operating frequency of filter,
A, according to the physical structure parameter of fixed suspended mictrostrip and the structure electric parameter of pcb board, as: the pcb board distance is 5 air height, transmission line 30 thickness up and down, the loss tangent angle and the dielectric constant of PCB medium 70 are found the solution the strip lines configuration that draws the equivalence of optimization back in the simulation software at circuit: the loss tangent angle of the effective dielectric constant of promptly equivalent PCB medium 71 and strip line medium height and equivalence;
B, find the solution in the simulation software optimization result who goes out the little band cross joint of suspending of Approximate Equivalent with strip line cross joint model solution at described circuit, physical structure sizes such as the length of little band cross joint that promptly suspends, width;
C, find the solution the optimization result of the described little band cross joint that suspends of checking at the 3 D electromagnetic farm software.
Adopt said method, find the solution simulation software strip line cross joint model equivalence at circuit and suspend under little band cross joint model case,, just can save cascaded filter by suspended mictrostrip cross of optimization according to concrete Design of Filter index.From solving result shown in Figure 9 relatively, find the solution in the simulation software with strip line cross joint model approximation at circuit as can be seen and substitute little band cross joint Model Design emulation solving result (curve b) that suspends, (curve is basically identical a) with the solving result of suspended mictrostrip cross joint in the 3 D electromagnetic farm software; That is to say circuit find the solution strip line cross joint model in the simulation software can local Approximate Equivalent 3 D electromagnetic farm software in suspended mictrostrip cross joint result, the test result basically identical after just finishing with design.Solved the inaccurate difficult problem of little band cross joint model that suspends.
According to the concrete suspended mictrostrip cross joint cascaded filter that said method obtains, owing to do not consider to suspend the inaccurate influence of little band open-circuit line model, both solving results have deviation slightly.In order to eliminate the inaccurate influence of little band open-circuit line model that suspends, need the optimization result that said method is obtained to carry out treatment for correcting.Little band open-circuit line model that causes suspending is incorrect, mainly is not consider to open a way the influence of equivalent capacity.As shown in figure 10, the open circuit equivalent capacity also is equivalent to a bit of desirable open-circuit line, that is to say the equivalence open circuit section ratio actual cross-section end segment distance Δ L that stretched out.To this, can come treatment for correcting by following method.Therefore, suspended mictrostrip cross joint Filter Design method also comprises the steps:
D, to each cross joint of suspended mictrostrip, carry out the 3 D electromagnetic farm software respectively and find the solution, draw the scattering parameter (S parameter) of each cross joint;
E, at each cross joint of suspended mictrostrip, find the solution in the simulation software at circuit, the S parameter of each cross joint of finding the solution with equivalent 3 D electromagnetic farm software is a goal prerequisite, finds the solution the length parameter L+ Δ L of little band cross joint open-circuit line model that suspends; Wherein, L finds the solution original open-circuit line length that little band cross that suspends that (optimizations) go out saves for finding the solution in the simulation software at circuit; The serve as reasons open-circuit line length of open circuit equivalent capacity equivalence of Δ L;
F, draw each little band cross that suspends and save open-circuit line length L-Δ L accurately, the value of L-Δ L is exactly to offset the open-circuit line length actual value of suspended mictrostrip open-circuit line model after inaccurate; And with the open-circuit line of each little band cross joint that the suspends alternative original open-circuit line length L of open-circuit line length L-Δ L accurately; Again according to former concatenated in order cross joint, design the suspended mictrostrip cross joint type filter after finishing exactly afterwards.
Figure 11 shows that the cross joint L before circuit is found the solution simulation software and optimized behind the optimization L+ Δ L finds the solution S parameter comparative example at the 3 D electromagnetic farm software, the curve of the two is overlapping substantially as can be seen, and the inaccurate problem of little band open-circuit line model that suspends of having eliminated is described.Adopt this method, just need not in the 3 D electromagnetic farm software, to optimize the parameter of filter, only need each cross joint of concrete filter is found the solution the S parameter one time, a large amount of design works is all found the solution in the simulation software at circuit and is finished, significantly reduced the finding the solution the time of 3 D electromagnetic farm software, improved suspended mictrostrip cross joint type Filter Design efficient.
In the method for designing of the present invention, the Approximate Equivalent strip line cross joint structural model of mentioning is not limited only to symmetrical strip lines configuration Approximate Equivalent, also comprises the Approximate Equivalent of asymmetric strip lines configuration.As shown in figure 12, the strip lines configuration when height h1 equals height h2 among the figure is called symmetrical strip line equivalence strip lines configuration; Strip lines configuration when height h1 is not equal to height h2 among the figure is called asymmetric strip line equivalence strip lines configuration.
In the fabrication and processing process of suspended mictrostrip cross joint type filter, because the air height about the shielding box mismachining tolerance causes between shielding box and PCB double sided board changes, perhaps pcb board thickness of slab tolerance, and PCB producer is to the mismachining tolerance of cross assistant warden connection transmission line, may cause the frequency of filter that the deviation of maximum 5MHz to 10MHz takes place, cause filter can't satisfy design objective, therefore, need debug the suspended mictrostrip cross joint type filter that does not satisfy design objective, to reduce scrapping of processing back finished product, further improve yields.For this reason, the present invention also provides the method for a kind of rapid adjustment suspended mictrostrip cross joint type filter frequencies skew, and only need adjust once just can be not satisfying the filter that being adjusted to of design objective satisfied design objective.
Owing to change the spacing between transmission line and the ground, can cause transmission line to arrive the change of the equivalent capacity size on ground, thereby cause the filter frequencies skew; The filter that the present invention utilizes these characteristics can't satisfy index to the established frequence skew is proofreaied and correct.Method of adjustment of the present invention, its basic step is:
A, choose and be used to adjust the conducting strip of filter frequency deviation and measure its thickness in advance, and the preset position of selecting conducting strip; This preset position can obviously change the spacing between cross assistant warden connection transmission line and the ground;
B, according to the thickness and the conductive characteristic of conducting strip, by actual emulation, draw exact position that the conducting strip number of plies or conducting strip be provided with concrete influence value to described filter frequencies skew;
C, need the suspended mictrostrip filter of correcting frequency shift after finishing for manufacturing, the described concrete influence value that draws according to actual frequency offset and step B, the conducting strip of the required number of plies is fixed on the described exact position, just can finishes adjustment once the frequency shift (FS) of suspended mictrostrip cross joint type filter.
Suspended mictrostrip cross joint type filter for structure shown in Figure 1, the open-circuit line place of 1/4 wavelength and the air height between the shielding box is the most responsive to frequency shift (FS) up and down, as long as near the copper sheet open-circuit line increases certain thickness thin conducting strip on the ground, just can realize the frequency correction of filter.Therefore adopt following concrete method of adjustment respectively for the filter that frequency upwards is offset and frequency offsets downward.
The bearing calibration of the filter that offsets downward for frequency:
A, as Figure 13, shown in Figure 14, choose and have certain thickness conducting strip 8, conducting strip is preset at PCB ground 21 and last shielding box 10 contact positions near the open-circuit line of cross assistant warden connection transmission line;
B, according to the thickness and the conductive characteristic of conducting strip 8, by actual emulation, draw the conducting strip number of plies that is arranged on this position concrete influence value to described filter frequencies skew;
C, need the suspended mictrostrip filter of correcting frequency shift after finishing for manufacturing, according to actual frequency offset and the conducting strip number of plies to the filter frequencies concrete influence value of skew upwards, select for use 1～3 conducting strip to be placed near the ground that contacts with last shielding box the PCB double sided board open-circuit line, the filter that frequency offsets downward just can correct at once.The exact position of this moment is exactly a preset position.
For the upwards bearing calibration of the filter of skew of frequency:
A, choose and have certain thickness conducting strip 8, with conducting strip be preset at as under open-circuit line 32 ends of Figure 15 transmission line shown in Figure 16 and with PCB reverse side ground wire 21 and shielding box 11 contact positions down; Place conducting strip herein, being equivalent to reduce can increase the equivalent capacity between open-circuit line and ground effectively over against conducting strip open-circuit line spacing over the ground partly; Therefore, the part that conducting strip covers open-circuit line is big more, and it is many more that equivalent capacity increases;
B1, according to the thickness and the conductive characteristic of described conducting strip, by actual emulation, when drawing conducting strip and being arranged on different exact position about preset position, to the described filter frequencies concrete influence value of skew upwards;
B2, as shown in figure 17 identifies the different exact position of frequency correction value correspondence with the silk-screen method on the manuscript of pcb board and the PCB double sided board after the processing; The precise local fix that conducting strip should be placed when for example filter frequencies upwards was offset 5MHz, and the precise local fix that should place when upwards being offset 10MHz of filter frequencies;
C, need the suspended mictrostrip filter of correcting frequency shift after finishing for manufacturing, the exact position that is provided with according to actual frequency offset and conducting strip is to the filter frequencies concrete influence value of skew upwards, one conducting strip is placed on the relevant position shown in the PCB silk-screen sign 23, with PCB double sided board and following shielding box conducting strip is tightly clamped, combine closely, the frequency upwards filter of skew just can correct at once.
The above conducting strip employing that is offset that is used for adjusting frequency has certain thickness metallic gasket, as scale copper, also can adopt the pad of high dielectric constant, low-loss other material.
Be understandable that, for those of ordinary skills, can be equal to replacement or change according to technical scheme of the present invention and inventive concept thereof, and all these changes or replacement all should belong to the protection range of the appended claim of the present invention.
Claims (16)
1. suspended mictrostrip filter, comprise a cavity that forms by metal-back, it is characterized in that: a PCB double sided board is set in the described cavity, and described PCB double sided board is fixed on the sidewall of described metal-back, and has certain air height with the inwall up and down of described metal-back; The one side of described PCB double sided board has the cross assistant warden as suspended mictrostrip to join transmission line by the reservation shape etching.
2. filter according to claim 1 is characterized in that: described cross assistant warden connection transmission line saves unit cascaded the composition by the above cross of a joint; Each grade cross joint unit is made of cross joint, open-circuit line and the transmission line of predetermined structure size; Be covered with the PCB ground that communicates at the PCB double sided board tow sides that leave described cross assistant warden connection transmission line certain distance, and described PCB ground links to each other with described metal-back.
3. filter according to claim 2 is characterized in that: described metal-back is made of last shielding box and following shielding box, about the described PCB double sided board that has cross assistant warden connection transmission line is fixedly mounted in the middle of the shielding box; The double-edged PCB of PCB double sided board ground is communicated with by some through holes, and closely contacts with described shielding box up and down.
4. filter according to claim 3 is characterized in that: the barrier shield that adopts PCB ground to form between the described cross joint that links to each other is isolated.
5. filter according to claim 4 is characterized in that: the air height between described shielding box up and down and the PCB double sided board is 1/2～4 times of described PCB double sided board thickness; Described PCB double sided board adopts the sheet material of low-loss dielectric constant.
6. according to the described filter of the arbitrary claim of claim 1 to 5, it is characterized in that: the open-circuit line of described cross joint unit is provided with bending in the precalculated position.
7. a duplexer that adopts suspended mictrostrip filter to form comprises a cavity that is formed by metal-back, is provided with emission filter and receiving filter in the described cavity; Emission filter is connected antenna with the ANT antenna end that receiving filter joins, and the TX transmitting terminal of emission filter connects transmitter circuitry, and the RX receiving terminal of receiving filter connects receiver circuit; It is characterized in that: a PCB double sided board is fixed on the sidewall of described metal-back, and etching has at least one group of cross assistant warden connection transmission line on the described PCB double sided board, as emission or receiving filter; The inwall up and down of described PCB double sided board and described metal-back has certain air height.
8. duplexer according to claim 7 is characterized in that: described PCB double sided board same worn respectively two groups of cross assistant wardens connection transmission lines as emission filter and receiving filter; Adopt the T type to be connected between described emission filter and the receiving filter; Described ANT antenna end, TX transmitting terminal, RX receiving terminal are connected with antenna, transmitter circuitry, receiver circuit respectively by coaxial connector.
9. duplexer according to claim 7 is characterized in that: the cross assistant warden of described emission filter and the receiving filter connection transmission line tow sides of described PCB double sided board that are placed in, and be in staggered distribution; Described emission filter is connected by through hole with the ANT antenna end of receiving filter.
10. the method for a design suspended mictrostrip filter as claimed in claim 1, in the operating frequency of filter, adopt following steps:
A, according to the physical structure parameter of fixed suspended mictrostrip structure and the structure electric parameter of pcb board, find the solution at circuit and to draw the strip lines configuration of optimizing the back equivalence in the simulation software;
B, find the solution in the simulation software physical structure size that goes out the little band cross joint of suspending of Approximate Equivalent with strip line cross joint model solution at described circuit;
C, find the solution the physical structure size of the described little band cross joint that suspends of checking at the 3 D electromagnetic farm software.
11. method for designing according to claim 10 is characterized in that: described method for designing is further comprising the steps of:
D, to each cross joint of suspended mictrostrip, carry out the 3 D electromagnetic farm software respectively and find the solution, draw the scattering parameter of each cross joint;
E, at each cross joint of suspended mictrostrip, find the solution in the simulation software at circuit, the scattering parameter of each cross joint of finding the solution with equivalent 3 D electromagnetic farm software is a goal prerequisite; Find the solution the length parameter L+ Δ L of little band cross joint open-circuit line model that suspends; Wherein, L is for finding the solution original open-circuit line length of the little band cross joint that suspends that solves in the simulation software at circuit; The serve as reasons open-circuit line length of open circuit equivalent capacity equivalence of Δ L;
F, draw each little band cross that suspends and save open-circuit line length L-Δ L accurately, and the open-circuit line of each little band cross joint that suspends is substituted original open-circuit line length L with open-circuit line length L-Δ L accurately.
12. according to claim 10 or 11 described methods for designing, it is characterized in that: the physical structure parameter of the described suspended mictrostrip of steps A and the structure electric parameter of pcb board comprise: the air height up and down of suspended mictrostrip, transmission line thickness, the loss tangent angle and the dielectric constant of PCB medium.
13. a method of adjusting suspended mictrostrip filter as claimed in claim 1 may further comprise the steps:
A, choose the conducting strip that is used to adjust the filter frequency deviation; And the preset position of selecting described conducting strip, this preset position obviously changes the spacing between cross assistant warden connection transmission line and the ground;
B, according to the thickness and the conductive characteristic of described conducting strip, by actual emulation, draw exact position that the conducting strip number of plies or conducting strip be provided with concrete influence value to described filter frequencies skew;
C, need the suspended mictrostrip filter of correcting frequency shift after finishing for manufacturing, the described concrete influence value that draws according to actual frequency offset and step B is fixed on the conducting strip of the required number of plies on the described exact position.
14. method of adjustment according to claim 13 is characterized in that: when the frequency of described filter offset downward, described method of adjustment comprised as follows:
Preset position described in the described steps A is: PCB ground and last shielding box contact position near the open-circuit line of described cross assistant warden connection transmission line;
The concrete processing of described step B is as follows: according to the thickness and the conductive characteristic of described conducting strip, by actual emulation, draw the conducting strip number of plies that the is arranged on preset position concrete influence value to described filter frequencies skew;
Exact position described in the described step C is equal to described preset position.
15. method of adjustment according to claim 13 is characterized in that: when the frequency of described filter upwards was offset, described method of adjustment comprised as follows:
Preset position described in the described steps A is: under the open-circuit line end of described transmission line and with PCB reverse side ground wire and following shielding box contact position;
The concrete steps that described step B comprises are:
B1, according to the thickness and the conductive characteristic of described conducting strip, by actual emulation, when drawing conducting strip and being arranged on different exact position to the concrete influence value of described filter frequencies skew;
B2, on described PCB double sided board, identify described different exact position;
The conducting strip of the required number of plies described in the described step C is one deck conducting strip.
16. according to the described method of adjustment of the arbitrary claim of claim 13 to 15, it is characterized in that: described conducting strip adopts metallic gasket.
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| CN2005100338659A CN1838476B (en) | 2005-03-24 | 2005-03-24 | Suspended mictrostrip filter and duplexer and method for designing and debugging filter |
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| CN2005100338659A CN1838476B (en) | 2005-03-24 | 2005-03-24 | Suspended mictrostrip filter and duplexer and method for designing and debugging filter |
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| CN1838476A CN1838476A (en) | 2006-09-27 |
| CN1838476B true CN1838476B (en) | 2010-04-28 |
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Cited By (1)
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| CN103579721A (en) * | 2012-07-30 | 2014-02-12 | 苏州络湾电子科技有限公司 | Radio frequency filter, device comprising radio frequency filter and design method of device comprising radio frequency filters |
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| CN108598638B (en) * | 2018-04-13 | 2019-10-11 | 电子科技大学 | The multiplexer structure of suspended substrate stripline is integrated based on medium |
| CN109378560B (en) * | 2018-10-10 | 2020-06-05 | 北京航天微电科技有限公司 | Silicon-based cavity shielding filter |
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| CN1838476A (en) | 2006-09-27 |
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