CN201285785Y - Low-pass filter - Google Patents
Low-pass filter Download PDFInfo
- Publication number
- CN201285785Y CN201285785Y CNU2008201235470U CN200820123547U CN201285785Y CN 201285785 Y CN201285785 Y CN 201285785Y CN U2008201235470 U CNU2008201235470 U CN U2008201235470U CN 200820123547 U CN200820123547 U CN 200820123547U CN 201285785 Y CN201285785 Y CN 201285785Y
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- coaxial
- diameter
- section
- pass filter
- low pass
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Abstract
The utility model relates to a coaxial low pass filter comprising an input port, an output port and a plurality of sections of cascaded coaxial transmission lines connected between the input port and the output port, wherein the diameter of the external conductor of each section of coaxial transmission line is different from that of the adjacent coaxial transmission line. The low pass filter can remove parasitic passbands out of the frequency band range which is needed to be inhibited, can effectively inhibit the influence of a higher harmonic mode to the performance of the low pass filter, and can also lower the weight of the filter, namely the manufacture cost.
Description
Technical field
The utility model relates to a kind of low pass filter, specifically, relates to a kind of internal and external conductor the on-axis low pass filter that stepped diameter changes all takes place.
Background technology
The circuit diagram of on-axis low pass filter has been shown among Fig. 1 a.Traditional coaxial reducing low pass filter, structure is shown in Fig. 1 b.The low pass filter of this structure is to form by the coaxial transmission line of 9 sections different resistance values is continuous.These coaxial transmission lines are divided into Low ESR coaxial transmission line (being made up of inner wire 101 and outer conductor 110) and high impedance coaxial transmission line (being made up of inner wire 102 and outer conductor 110).The equivalence of high impedance coaxial transmission line is a series inductance, and the equivalence of Low ESR coaxial transmission line is a shunt capacitance.
For the Low ESR coaxial transmission line, the diameter of outer conductor 110 (internal diameter) is b1, and the diameter of inner wire 101 (external diameter) is a1; For the high impedance coaxial line, the diameter of outer conductor 110 (internal diameter) is b2, and the diameter of inner wire 102 (external diameter) is a2.For the structure shown in Fig. 1 b, the outer conductor internal diameter of Low ESR and high impedance coaxial line is identical, i.e. b1=b2.And the inner conductor outer diameter of Low ESR and high impedance coaxial line is inequality, a1〉a2.Simultaneously, also filled dielectric between the Low ESR coaxial line internal and external conductor as support.
The basic mode that exists in the coaxial transmission line is the TEM mould, and this also is the mode of operation of on-axis low pass filter.First higher mode that exists in the coaxial line is the TE11 pattern, and what the resonance frequency of this pattern was approximate can be with following formulate.The existence of higher mode can influence the high frequency band suppression characteristic of low pass filter.
For the high impedance and the Low ESR coaxial transmission line of on-axis low pass filter, because b1=b2, and a1 a2, so the frequency of the higher mode that exists in Low ESR section transmission line is lower than the higher mode frequency in the high impedance section transmission line.Influencing the main cause of low pass filter high frequency band rejection, is exactly the higher mode in the Low ESR section transmission line.Therefore, improving the high frequency band rejection of low pass filter, need the higher mode in the inhibition Low ESR section transmission line, mainly is the TE11 pattern.
For powerful low pass filter,, just need to use the bigger coaxial line of diameter because higher power capacity will be arranged.Like this, the internal diameter external diameter of coaxial line is all bigger.From top formula as can be seen, the coaxial line inside/outside diameter size increases, and can reduce the frequency of TE11 pattern in the coaxial line, might have influence on the performance of low pass filter.
The utility model content
According to the utility model, a kind of on-axis low pass filter is provided, described on-axis low pass filter comprise input port, output port and be connected input port and output port between the multistage coaxial transmission line segment of cascade, wherein, the diameter of the outer conductor of each section coaxial transmission line segment is different from the diameter of the outer conductor of the coaxial transmission line segment that is adjacent.
According to the utility model, preferably, the coaxial transmission line segment that the inner wire of each section coaxial transmission line segment and the diameter of outer conductor all are adjacent is different.
According to the utility model, preferably, from with input or output the direct-connected coaxial section meter of port, the inner wire diameter of 2n-1 coaxial section is greater than the inner wire diameter of 2n coaxial section, and the outer conductor diameter of 2n-1 coaxial section is less than the outer conductor diameter of 2n coaxial section, and wherein n is a natural number.
According to the utility model, preferably, the diameter of the inner wire of the coaxial transmission line segment that the diameter of the inner wire of each section coaxial transmission line segment is adjacent is identical.
According to the utility model, preferably, from with input or output the direct-connected coaxial section meter of port, the outer conductor diameter of 2n-1 coaxial section is less than the outer conductor diameter of 2n coaxial section, and the inner wire diameter of all coaxial sections equates that all wherein n is a natural number.
According to low pass filter of the present utility model, its advantage is, parasitic passband can be shifted out the frequency band range that filter need suppress, and suppresses higher mode effectively to the low pass filter Effect on Performance, and the weight that can reduce filter simultaneously is cost of manufacture.
Description of drawings
Fig. 1 a represents the circuit diagram of on-axis low pass filter;
Fig. 1 b represents traditional coaxial reducing low pass filter;
Fig. 2 is the schematic diagram according to the coaxial low-pass filter of first kind of execution mode of the present utility model; With
Fig. 3 is the schematic diagram according to the coaxial low-pass filter of second kind of execution mode of the present utility model.
Embodiment
Introduce execution mode below with reference to accompanying drawings in detail according to low pass filter of the present utility model.
Fig. 2 is the schematic diagram according to the coaxial low-pass filter of first kind of execution mode of the present utility model.As shown in Figure 2, this low pass filter 200 comprises the coaxial section of multistage cascade, and the inner wire of two neighboring sections coaxial cable is connected to each other and outer conductor also is connected to each other in these coaxial sections.As shown in Figure 2, outside input port and output port (port outer conductor 210, port inner wire 20 and 21), low pass filter 200 also comprises for example nine sections coaxial cables, in these coaxial sections, the inner wire of two adjacent coaxial sections is all different with the outer conductor diameter.As shown in Figure 2, see that first section coaxial cable is made of inner wire 201 and outer conductor 211 from the left side, second section coaxial cable is made of inner wire 202 and outer conductor 212, the 3rd section coaxial cable is identical with first section, and the 4th section coaxial cable is identical with second section coaxial cable, and the rest may be inferred.Wherein the diameter of the inner wire 201 of first section coaxial cable is greater than the diameter of the inner wire 202 of second section coaxial cable, and the diameter of the outer conductor 211 of first section coaxial cable is less than the diameter of the outer conductor 212 of second section coaxial cable.The 3rd section coaxial cable is identical with first section, and the 4th section identical with second section, and the rest may be inferred.Generally speaking, from with input or output the direct-connected coaxial section meter of port, sequence number is that the inner wire diameter of the coaxial section of odd number is the inner wire diameter of the coaxial section of even number greater than sequence number, and sequence number is that the outer conductor diameter of the coaxial section of odd number is the outer conductor diameter of the coaxial section of even number less than sequence number, promptly, the inner wire diameter of 2n-1 coaxial section is greater than the inner wire diameter of 2n coaxial section, and the outer conductor diameter of 2n-1 coaxial section is less than the outer conductor diameter of 2n coaxial section, and wherein n is a natural number.
According to first kind of execution mode of the present utility model, reduce the outer conductor diameter of Low ESR section transmission line, like this, guaranteeing under the constant situation of coaxial line impedance the frequency of coaxial line TE11 pattern to be moved to height.Can not fundamentally eliminate the higher mode parasitic passband of low pass filter according to the filter of first kind of execution mode, but parasitic passband can be shifted out the frequency band range that filter need suppress.
Fig. 3 shows the schematic diagram according to the coaxial low-pass filter of second kind of execution mode of the present utility model.As shown in Figure 3, this low pass filter 300 comprises the coaxial section of multistage cascade, and the inner wire of two neighboring sections coaxial cable is connected to each other and outer conductor also is connected to each other in these coaxial sections.As shown in Figure 3, input port and output port (port outer conductor 310 except filter, port inner wire 30 and 31) outside, low pass filter 300 also comprises for example nine sections coaxial cables, in these coaxial sections, the inner wire equal diameters of two adjacent coaxial sections, and the outer conductor diameter is unequal.As shown in Figure 3, see that first section coaxial cable is made of inner wire 301 and outer conductor 311 from the left side, second section coaxial cable is made of inner wire 302 and outer conductor 312, the 3rd section coaxial cable is identical with first section, and the 4th section coaxial cable is identical with second section coaxial cable, and the rest may be inferred.Wherein the diameter of the inner wire 301 of first section coaxial cable equals the diameter of the inner wire 302 of second section coaxial cable, and the diameter of the outer conductor 311 of first section coaxial cable is less than the diameter of the outer conductor 312 of second section coaxial cable.The 3rd section coaxial cable is identical with first section, and the 4th section identical with second section, and the rest may be inferred.Generally speaking, from with input or output the direct-connected coaxial section meter of port, sequence number is that the outer conductor diameter of the coaxial section of odd number is the outer conductor diameter of the coaxial section of even number less than sequence number, and the inner wire diameter of all coaxial sections all equates, promptly, the outer conductor diameter of 2n-1 coaxial section is less than the outer conductor diameter of 2n coaxial section, and the inner wire diameter of all coaxial sections equates that all wherein n is a natural number.
According to second kind of execution mode of the present utility model, the internal diameter of Low ESR and high-impedance transmission line is identical, i.e. a1=a2, and external diameter is inequality, b1＜b2.Filter according to second kind of execution mode is identical with the filter operation principle of first kind of execution mode, but because the diameter of Low ESR section coaxial line internal and external conductor is littler, the frequency of higher mode parasitic passband is just higher, and is just littler to the performance impact of low pass filter.In addition, owing to unified the diameter of all coaxial inner conductors, in fact the inner wire of the filter of second kind of execution mode can be made an integral body, has reduced processing cost and assembly cost.
Two kinds of above-mentioned execution modes, the size of filter input/output port there is no specific (special) requirements, can select according to actual conditions, be 50 ohm as long as guarantee port Impedance.
The utility model should be appreciated that by the explanation of above embodiment the utility model is not limited to described embodiment and scheme; Here these that are comprised are implemented and the purpose of scheme is, help those skilled in the art to put into practice the utility model; Those skilled in the art is easy under the situation that does not break away from the utility model design, further improvement and perfect.Therefore, the utility model only is subjected to the qualification of the application's claims, and the various technical schemes that the design of all and the utility model is identical are all within this claim protection range.
Claims (5)
1, a kind of on-axis low pass filter, it is characterized in that, described on-axis low pass filter comprise input port, output port and be connected input port and output port between the multistage coaxial transmission line segment of cascade, wherein, the diameter of the outer conductor of each section coaxial transmission line segment is different from the diameter of the outer conductor of the coaxial transmission line segment that is adjacent.
According to the described on-axis low pass filter of claim 1, it is characterized in that 2, the coaxial transmission line segment that the inner wire of each section coaxial transmission line segment and the diameter of outer conductor all are adjacent is different.
3, according to the described on-axis low pass filter of claim 2, it is characterized in that, from with input or output the direct-connected coaxial section meter of port, the inner wire diameter of 2n-1 coaxial section is greater than the inner wire diameter of 2n coaxial section, and the outer conductor diameter of 2n-1 coaxial section is less than the outer conductor diameter of 2n coaxial section, and wherein n is a natural number.
According to the described on-axis low pass filter of claim 1, it is characterized in that 4, the diameter of the inner wire of the coaxial transmission line segment that the diameter of the inner wire of each section coaxial transmission line segment is adjacent is identical.
5, according to the described on-axis low pass filter of claim 4, it is characterized in that, from with input or output the direct-connected coaxial section meter of port, the outer conductor diameter of 2n-1 coaxial section is less than the outer conductor diameter of 2n coaxial section, and the inner wire diameter of all coaxial sections equates that all wherein n is a natural number.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008201235470U CN201285785Y (en) | 2008-11-04 | 2008-11-04 | Low-pass filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008201235470U CN201285785Y (en) | 2008-11-04 | 2008-11-04 | Low-pass filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201285785Y true CN201285785Y (en) | 2009-08-05 |
Family
ID=40950765
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNU2008201235470U Expired - Fee Related CN201285785Y (en) | 2008-11-04 | 2008-11-04 | Low-pass filter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201285785Y (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107681239A (en) * | 2017-09-15 | 2018-02-09 | 广东通宇通讯股份有限公司 | Cable |
-
2008
- 2008-11-04 CN CNU2008201235470U patent/CN201285785Y/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107681239A (en) * | 2017-09-15 | 2018-02-09 | 广东通宇通讯股份有限公司 | Cable |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20090805 Termination date: 20091204 |