EP0350256A2 - Band elimination filter - Google Patents
Band elimination filter Download PDFInfo
- Publication number
- EP0350256A2 EP0350256A2 EP89306771A EP89306771A EP0350256A2 EP 0350256 A2 EP0350256 A2 EP 0350256A2 EP 89306771 A EP89306771 A EP 89306771A EP 89306771 A EP89306771 A EP 89306771A EP 0350256 A2 EP0350256 A2 EP 0350256A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- band elimination
- capacitor
- elimination filter
- resonator
- filter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- 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
- H01P1/205—Comb or interdigital filters; Cascaded coaxial cavities
- H01P1/2056—Comb filters or interdigital filters with metallised resonator holes in a dielectric block
Definitions
- the present invention relates to a band elimination filter, and more particularly, it relates to a band elimination filter utilizing resonators such as dielectric resonators.
- Fig. 10 shows exemplary structure of a conventional band elimination filter which is disclosed in Japanese Patent Laying-Open Gazette No. 193501/1986, for example.
- dielectric resonators 1 are connected in series with capacitors 2.
- a transmission line 3 has an inductor 4.
- the capacitors 2 and the resonators 1 are connected between the transmission line 3 and earthing means 15, while other capacitors 5 are connected in parallel with the same.
- the band elimination filter shown in Fig. 10 generally exhibits frequency-signal attenuation characteristics shown in Fig. 11, assuming that f2 represents a trap frequency.
- the aforementioned conventional band elimination filter requires the capacitors 5 which are directly connected to the earthing means, in addition to the capacitors 2 for attaining filter characteristics.
- the filter structure is inevitably complicated.
- the aforementioned conventional band elimination filter cannot be regarded as having excellent filter characteristics, since the signal attenuation amount is gradually reduced from the trap frequency f2 toward zero.
- An object of the present invention is to provide a band elimination filter, the filter structure of which is simplified to reduce the manufacturing cost as well as to improve mass productivity.
- Another object of the present invention is to provide a band elimination filter which can improve filter characteristics.
- a band elimination filter includes a filter circuit and an input/output transmission line having inductance means.
- the aforementioned filter circuit has a resonator and capacitance means which is connected in series with the resonator. Only the aforementioned filter circuit is connected between each end of the aforementioned inductance means and earthing means.
- the band elimination filter according to the present invention requires no capacitor, which has generally been directly connected between the transmission line and the earthing means in the prior art. Consequently, the filter structure is simplified to reduce the manufacturing cost and to improve mass productivity.
- change in signal attenuation amount is abruptly inclined around a trap frequency, thereby to enable implementation of excellent filter characteristics as the result.
- Fig. 1 shows an embodiment of a band elimination filter according to the present invention.
- filter circuits 10 are formed by dielectric resonators 11, which are examples of resonators exhibiting inductiveness at a frequency f2, and capacitors 12 which are connected in series with the resonators 11.
- the dielectric resonators 11 are formed by internal conductors 111, external conductors 112 and dielectric members 113 of TiO2-ZrO2-SnO2 ceramic dielectric material etc. which are disposed between the internal and external conductors 111 and 112.
- the internal conductors 111 are electrically connected to first electrodes 121 of the capacitors 12.
- an input/output transmission line 13 has an inductor 14. Second electrodes 122 of the capacitors 12 of the filter circuits 10 are connected to respective ends (points A and B) of the inductor 14. The external conductors 112 of the resonators 11 of the filter circuits 10 are connected to earthing means 15.
- the band elimination filter according to this embodiment can be regarded as comprising a circuit in which a distribution constant line 18 is arranged between the points A and B while inductors 19 are arranged between the points A and B and earthing means, as shown in Fig. 3.
- a distribution constant line 18 is arranged between the points A and B while inductors 19 are arranged between the points A and B and earthing means, as shown in Fig. 3.
- an equivalent circuit thereof is as shown in Fig. 4.
- a capacitor 20 and an inductor 21, which are connected in parallel with each other, are arranged between the capacitor 12 and the earthing means 15.
- FIG. 5 shows the relation between the frequency and the admittance in this case.
- the relation between the frequency and the signal attenuation amount is as shown in Fig. 6.
- the signal attenuation amount is nearly zero at the antiresonance frequency f1. Therefore, as obvious from comparison with Fig. 11 showing the characteristics of the conventional band elimination filter, the signal attenuation amount is more abruptly changed around the trap frequency f2 according to this embodiment.
- the passing characteristic is improved in a frequency domain below the trap frequency f2. Utilizing the frequency f1 as a passing band, on the other hand, insertion loss is reduced.
- a plurality of capacitor electrodes 31 and 32 are provided on an upper surface of a substrate 30.
- Inductor electrodes 33 which are integrally formed with the capacitor electrodes 31, are arranged between the capacitor electrodes 31.
- Central conductors 35 provided in opening ends 341 of resonators 34 are connected to the capacitor electrodes 32. Electrostatic capacitance is implemented by the capacitor electrodes 31 and 32.
- inductors 36 may be connected between capacitor electrodes 31 which are adjacent to each other, as shown in Fig. 8.
- disc-type capacitors 37 may be connected to opening ends 341 of resonators 34 while connecting a transmission line 39 having an inductor 38 to electrodes of the capacitors 37 as shown in Fig. 9, without employing the substrate 30 etc.
- capacitors 37 may be replaced by terminals which are inserted in bushing members of synthetic resin while leaving parts of metal pins, to implement electrostatic capacitance between the metal pins and internal conductors of resonators.
- dielectric resonators may be replaced by LC resonators or stripline resonators.
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Control Of Motors That Do Not Use Commutators (AREA)
- Filters And Equalizers (AREA)
Abstract
Description
- The present invention relates to a band elimination filter, and more particularly, it relates to a band elimination filter utilizing resonators such as dielectric resonators.
- Fig. 10 shows exemplary structure of a conventional band elimination filter which is disclosed in Japanese Patent Laying-Open Gazette No. 193501/1986, for example.
- Referring to Fig. 10,
dielectric resonators 1 are connected in series withcapacitors 2. Atransmission line 3 has aninductor 4. On respective ends of theinductor 4, thecapacitors 2 and theresonators 1 are connected between thetransmission line 3 and earthing means 15, whileother capacitors 5 are connected in parallel with the same. - The band elimination filter shown in Fig. 10 generally exhibits frequency-signal attenuation characteristics shown in Fig. 11, assuming that f₂ represents a trap frequency.
- The aforementioned conventional band elimination filter requires the
capacitors 5 which are directly connected to the earthing means, in addition to thecapacitors 2 for attaining filter characteristics. Thus, the filter structure is inevitably complicated. - Further, the aforementioned conventional band elimination filter cannot be regarded as having excellent filter characteristics, since the signal attenuation amount is gradually reduced from the trap frequency f₂ toward zero.
- An object of the present invention is to provide a band elimination filter, the filter structure of which is simplified to reduce the manufacturing cost as well as to improve mass productivity.
- Another object of the present invention is to provide a band elimination filter which can improve filter characteristics.
- A band elimination filter according to the present invention includes a filter circuit and an input/output transmission line having inductance means. The aforementioned filter circuit has a resonator and capacitance means which is connected in series with the resonator. Only the aforementioned filter circuit is connected between each end of the aforementioned inductance means and earthing means.
- The band elimination filter according to the present invention requires no capacitor, which has generally been directly connected between the transmission line and the earthing means in the prior art. Consequently, the filter structure is simplified to reduce the manufacturing cost and to improve mass productivity.
- According to the inventive band elimination filter, change in signal attenuation amount is abruptly inclined around a trap frequency, thereby to enable implementation of excellent filter characteristics as the result.
- These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
-
- Fig. 1 is a circuit diagram showing an embodiment of the present invention;
- Figs. 2, 3 and 4 are equivalent circuit diagrams of the circuit shown in Fig. 1 as viewed from different points;
- Fig. 5 is a graph showing frequency-admittance characteristics;
- Fig. 6 is a graph showing frequency-signal attenuation amount characteristics;
- Figs. 7 and 8 are partially fragmented plan views showing other embodiments of the present invention;
- Fig. 9 is a partially fragmented perspective view showing a further embodiment of the present invention;
- Fig. 10 is a circuit diagram showing a conventional filter in correspondence to Fig. 1; and
- Fig. 11 is a graph showing the characteristics of the conventional filter in correspondence to Fig. 6.
- Fig. 1 shows an embodiment of a band elimination filter according to the present invention.
- Referring to Fig. 1,
filter circuits 10 are formed bydielectric resonators 11, which are examples of resonators exhibiting inductiveness at a frequency f₂, andcapacitors 12 which are connected in series with theresonators 11. Thedielectric resonators 11 are formed byinternal conductors 111,external conductors 112 anddielectric members 113 of TiO₂-ZrO₂-SnO₂ ceramic dielectric material etc. which are disposed between the internal andexternal conductors internal conductors 111 are electrically connected tofirst electrodes 121 of thecapacitors 12. - On the other hand, an input/
output transmission line 13 has aninductor 14.Second electrodes 122 of thecapacitors 12 of thefilter circuits 10 are connected to respective ends (points A and B) of theinductor 14. Theexternal conductors 112 of theresonators 11 of thefilter circuits 10 are connected to earthing means 15. - In the band elimination filter shown in Fig. 1, no conventional capacitors (
capacitors 5 in Fig. 10) are connected to the points A and B. Considering a given frequency f₁, therefore, it can be regarded that antiresonance is caused to develop opening states in the points A and B at the frequency f₁. With reference to the points A and B, it can be regarded that LCparallel circuits 16 are formed as shown in Fig. 2, to be in resonant states. Referring to Fig. 2,capacitors 17 of the LCparallel circuits 16 and theinductor 14 can be regarded as π-type distributed constant lines. - Thus, the band elimination filter according to this embodiment can be regarded as comprising a circuit in which a distribution
constant line 18 is arranged between the points A and B whileinductors 19 are arranged between the points A and B and earthing means, as shown in Fig. 3. Considering eachresonator 11 of the circuit shown in Fig. 3 as an LC parallel circuit, an equivalent circuit thereof is as shown in Fig. 4. Referring to Fig. 4, acapacitor 20 and aninductor 21, which are connected in parallel with each other, are arranged between thecapacitor 12 and the earthing means 15. Admittance Y between the point A and the earthing means 15 is obtained as follows:
Y = {ω⁴L₁L₀C₁C₀ - ω²(L₀C₀ + L₁C₁ + L₀C₁) + 1}/jωL₁(1 - ω²L₀C₀ - ω²L₀C₁)
where L₀ represents inductance of theinductor 21, L₁ represents inductance of theinductor 19, C₀ represents capacitance of thecapacitor 20, and C₁ represents capacitance of thecapacitor 12 respectively. Assuming that f₁ represents an antiresonance frequency and f₂ represents a trap frequency, the admittance Y is zero at the antiresonance frequency f₁, while the admittance Y is infinite at the trap frequency f₂. Fig. 5 shows the relation between the frequency and the admittance in this case. Regarding this as the passing characteristic of the transmission line, the relation between the frequency and the signal attenuation amount is as shown in Fig. 6. As understood from Fig. 6, the signal attenuation amount is nearly zero at the antiresonance frequency f₁. Therefore, as obvious from comparison with Fig. 11 showing the characteristics of the conventional band elimination filter, the signal attenuation amount is more abruptly changed around the trap frequency f₂ according to this embodiment. In other words, the passing characteristic is improved in a frequency domain below the trap frequency f₂. Utilizing the frequency f₁ as a passing band, on the other hand, insertion loss is reduced. - Concrete structure of the band elimination filter according to this embodiment is now described.
- For example, the structure shown in Fig. 7 is employable. Referring to Fig. 7, a plurality of
capacitor electrodes substrate 30.Inductor electrodes 33, which are integrally formed with thecapacitor electrodes 31, are arranged between thecapacitor electrodes 31.Central conductors 35 provided inopening ends 341 ofresonators 34 are connected to thecapacitor electrodes 32. Electrostatic capacitance is implemented by thecapacitor electrodes - In place of the
aforementioned inductor electrodes 33,inductors 36 may be connected betweencapacitor electrodes 31 which are adjacent to each other, as shown in Fig. 8. - Alternatively, disc-
type capacitors 37 may be connected toopening ends 341 ofresonators 34 while connecting atransmission line 39 having aninductor 38 to electrodes of thecapacitors 37 as shown in Fig. 9, without employing thesubstrate 30 etc. - Further,
such capacitors 37 may be replaced by terminals which are inserted in bushing members of synthetic resin while leaving parts of metal pins, to implement electrostatic capacitance between the metal pins and internal conductors of resonators. - In addition, the dielectric resonators may be replaced by LC resonators or stripline resonators.
- Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
Claims (8)
a filter circuit (10) formed by a resonator (11, 34) and capacitance means (12, 31, 32) connected in series with said resonator (11, 34);
inductance means (14, 33, 36, 38) having an end portion;
an input/output transmission line (13, 39) connected to said end portion of said inductance means (14, 33, 36, 38); and
earthing means (15),
only said filter circuit (10) being connected between said end portion of said inductance means (14, 33, 36, 38) and said earthing means (15).
said band elimination filter has a trap frequency (f₂),
a signal attenuation amount being abruptly changed at said trap frequency (f₂).
said band elimination filter has an antiresonance frequency(f₁),
a signal attenuation amount is small at said antiresonance frequency(f₁).
said resonator (11, 34) has an opening end (341),
said capacitance means is a disc-type capacitor (37) which is connected to said opening end (341), and
said inductance means is an inductor (38) which is connected to said capacitor (37).
said resonator (11, 34) is a dielectric resonator (11, 34).
a resonator (34) having an opening end (341) and a central conductor (35); and
a substrate (30) being provided in the vicinity of said opening end (341) of said resonator (34),
said substrate (30) essentially comprising a first capacitor electrode4 (32) being electrically connected to said central conductor (35), a second capacitor (31) being paired with said first capacitor electrode (32) and inductor means (33, 36) being electrically connected to said second capacitor electrode (31).
said inductor means is an inductor electrode (33) which is integrally formed with said capacitor electrode (31).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP63166580A JPH0216802A (en) | 1988-07-04 | 1988-07-04 | Band elimination filter |
JP166580/88 | 1988-07-04 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0350256A2 true EP0350256A2 (en) | 1990-01-10 |
EP0350256A3 EP0350256A3 (en) | 1990-11-28 |
Family
ID=15833909
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19890306771 Withdrawn EP0350256A3 (en) | 1988-07-04 | 1989-07-04 | Band elimination filter |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0350256A3 (en) |
JP (1) | JPH0216802A (en) |
FI (1) | FI893231A (en) |
NO (1) | NO892754L (en) |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0444948A2 (en) * | 1990-03-02 | 1991-09-04 | Fujitsu Limited | Dielectric resonator and a filter using same |
EP0472319A1 (en) * | 1990-08-16 | 1992-02-26 | Nokia Mobile Phones (U.K.) Limited | Tunable bandpass filter |
FR2680605A1 (en) * | 1991-07-22 | 1993-02-26 | Motorola Inc | MULTI-STAGE MONOLITHIC CERAMIC STRIP CUTTER, WHERE THE STAGES ARE INSULATED FROM EACH OTHER. |
US5293141A (en) * | 1991-03-25 | 1994-03-08 | Sanyo Electric Co., Ltd. | Dielectric filter having external connection terminals on dielectric substrate and antenna duplexer using the same |
WO1999052208A1 (en) * | 1998-03-18 | 1999-10-14 | Conductus, Inc. | Narrow-band band-reject filter apparatus and method |
US6529750B1 (en) | 1998-04-03 | 2003-03-04 | Conductus, Inc. | Microstrip filter cross-coupling control apparatus and method |
US7317364B2 (en) | 2000-08-07 | 2008-01-08 | Conductus, Inc. | Varactor tuning for a narrow band filter including an automatically controlled tuning system |
US7437187B1 (en) | 2000-10-30 | 2008-10-14 | Conductus, Inc. | Superconductive filter with capacitive patches providing reduced cross-coupling |
US7610072B2 (en) | 2003-09-18 | 2009-10-27 | Superconductor Technologies, Inc. | Superconductive stripline filter utilizing one or more inter-resonator coupling members |
GB2512032A (en) * | 2013-01-31 | 2014-09-24 | David Clive Baty | Filter |
Families Citing this family (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH03181205A (en) * | 1989-12-11 | 1991-08-07 | Fuji Elelctrochem Co Ltd | Dielectric filter |
JPH03247001A (en) * | 1990-02-23 | 1991-11-05 | Fuji Elelctrochem Co Ltd | Dielectric filter |
JPH0824243B2 (en) * | 1990-03-02 | 1996-03-06 | 富士通株式会社 | Dielectric filter |
JPH03254202A (en) * | 1990-03-02 | 1991-11-13 | Fujitsu Ltd | Dielectric resonator and filter using same |
JPH0490602A (en) * | 1990-08-03 | 1992-03-24 | Fuji Elelctrochem Co Ltd | Dielectric resonator and dielectric filter |
JPH04103201A (en) * | 1990-08-22 | 1992-04-06 | Fuji Elelctrochem Co Ltd | Dielectric band stop filter |
JPH04196829A (en) * | 1990-11-28 | 1992-07-16 | Hitachi Ltd | Branching filter device and mobile radio equipment using same |
WO1992012546A1 (en) * | 1990-12-26 | 1992-07-23 | Ube Industries, Ltd. | Dielectric filter |
JP2643634B2 (en) * | 1991-04-10 | 1997-08-20 | 株式会社村田製作所 | Dielectric coaxial resonator and dielectric filter |
JPH054603U (en) * | 1991-06-27 | 1993-01-22 | 京セラ株式会社 | Band elimination filter |
JP2811382B2 (en) * | 1991-12-11 | 1998-10-15 | 富士電気化学株式会社 | Dielectric filter |
JPH05167309A (en) * | 1991-12-11 | 1993-07-02 | Fuji Elelctrochem Co Ltd | Dielectric filter |
JP2899210B2 (en) * | 1994-05-20 | 1999-06-02 | 国際電気株式会社 | Variable frequency band filter |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1568141A (en) * | 1920-08-13 | 1926-01-05 | American Telephone & Telegraph | Frequency selective circuits |
JPS61105901A (en) * | 1984-10-30 | 1986-05-24 | Sumitomo Electric Ind Ltd | Notch filter |
JPS61191101A (en) * | 1985-02-19 | 1986-08-25 | Murata Mfg Co Ltd | Filter |
JPS61193501A (en) * | 1985-02-21 | 1986-08-28 | Murata Mfg Co Ltd | Filter |
US4703291A (en) * | 1985-03-13 | 1987-10-27 | Murata Manufacturing Co., Ltd. | Dielectric filter for use in a microwave integrated circuit |
US4730173A (en) * | 1983-06-23 | 1988-03-08 | Murata Manufacturing Co., Ltd. | Asymmetrical trap comprising coaxial resonators, reactance elements, and transmission line elements |
EP0312011A2 (en) * | 1987-10-15 | 1989-04-19 | Murata Manufacturing Co., Ltd. | Dielectric filter |
-
1988
- 1988-07-04 JP JP63166580A patent/JPH0216802A/en active Pending
-
1989
- 1989-07-03 NO NO89892754A patent/NO892754L/en unknown
- 1989-07-03 FI FI893231A patent/FI893231A/en not_active Application Discontinuation
- 1989-07-04 EP EP19890306771 patent/EP0350256A3/en not_active Withdrawn
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1568141A (en) * | 1920-08-13 | 1926-01-05 | American Telephone & Telegraph | Frequency selective circuits |
US4730173A (en) * | 1983-06-23 | 1988-03-08 | Murata Manufacturing Co., Ltd. | Asymmetrical trap comprising coaxial resonators, reactance elements, and transmission line elements |
JPS61105901A (en) * | 1984-10-30 | 1986-05-24 | Sumitomo Electric Ind Ltd | Notch filter |
JPS61191101A (en) * | 1985-02-19 | 1986-08-25 | Murata Mfg Co Ltd | Filter |
JPS61193501A (en) * | 1985-02-21 | 1986-08-28 | Murata Mfg Co Ltd | Filter |
US4703291A (en) * | 1985-03-13 | 1987-10-27 | Murata Manufacturing Co., Ltd. | Dielectric filter for use in a microwave integrated circuit |
EP0312011A2 (en) * | 1987-10-15 | 1989-04-19 | Murata Manufacturing Co., Ltd. | Dielectric filter |
Non-Patent Citations (3)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 10, no. 285 (E-441)(2341) 27 September 1986; & JP-A-61 105 901 (SUMITOMO ELECTRIC IND LTD) 24 May 1986, * |
PATENT ABSTRACTS OF JAPAN vol. 11, no. 20 (E-472)(2467) 20 January 1987; & JP-A-61 191 101 (MURATA MFG CO LTD) 25 August 1986, * |
PATENT ABSTRACTS OF JAPAN vol. 11, no. 23 (E-473)(2470) 22 January 1987; & JP-A-61 193 501 (MURATA MFG CO LTD) 28 August 1986, * |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0444948A3 (en) * | 1990-03-02 | 1992-05-27 | Fujitsu Limited | Dielectric resonator and a filter using same |
EP0444948A2 (en) * | 1990-03-02 | 1991-09-04 | Fujitsu Limited | Dielectric resonator and a filter using same |
EP0472319A1 (en) * | 1990-08-16 | 1992-02-26 | Nokia Mobile Phones (U.K.) Limited | Tunable bandpass filter |
US5227748A (en) * | 1990-08-16 | 1993-07-13 | Technophone Limited | Filter with electrically adjustable attenuation characteristic |
US5422612A (en) * | 1991-03-25 | 1995-06-06 | Sanyo Electric Co., Ltd. | Dielectric filter having corresponding individual external and ground electrodes formed on a dielectric substrate |
US5293141A (en) * | 1991-03-25 | 1994-03-08 | Sanyo Electric Co., Ltd. | Dielectric filter having external connection terminals on dielectric substrate and antenna duplexer using the same |
US5345202A (en) * | 1991-03-25 | 1994-09-06 | Sanyo Electric Co., Ltd. | Dielectric filter comprising a plurality of coaxial resonators of different lengths all having the same resonant frequency |
DE4292384C2 (en) * | 1991-07-22 | 1995-10-05 | Motorola Inc | Monolithic, ceramic multi-stage notch filter with decoupled filter stages |
FR2680605A1 (en) * | 1991-07-22 | 1993-02-26 | Motorola Inc | MULTI-STAGE MONOLITHIC CERAMIC STRIP CUTTER, WHERE THE STAGES ARE INSULATED FROM EACH OTHER. |
WO1999052208A1 (en) * | 1998-03-18 | 1999-10-14 | Conductus, Inc. | Narrow-band band-reject filter apparatus and method |
US6529750B1 (en) | 1998-04-03 | 2003-03-04 | Conductus, Inc. | Microstrip filter cross-coupling control apparatus and method |
US7317364B2 (en) | 2000-08-07 | 2008-01-08 | Conductus, Inc. | Varactor tuning for a narrow band filter including an automatically controlled tuning system |
US7738933B2 (en) | 2000-08-07 | 2010-06-15 | Conductus, Inc. | Varactor tuning for a narrow band filter having shunt capacitors with different capacitance values |
US7437187B1 (en) | 2000-10-30 | 2008-10-14 | Conductus, Inc. | Superconductive filter with capacitive patches providing reduced cross-coupling |
US7610072B2 (en) | 2003-09-18 | 2009-10-27 | Superconductor Technologies, Inc. | Superconductive stripline filter utilizing one or more inter-resonator coupling members |
GB2512032A (en) * | 2013-01-31 | 2014-09-24 | David Clive Baty | Filter |
GB2512032B (en) * | 2013-01-31 | 2020-07-29 | Clive Baty David | Filter |
Also Published As
Publication number | Publication date |
---|---|
NO892754L (en) | 1990-01-05 |
JPH0216802A (en) | 1990-01-19 |
FI893231A0 (en) | 1989-07-03 |
EP0350256A3 (en) | 1990-11-28 |
NO892754D0 (en) | 1989-07-03 |
FI893231A (en) | 1990-01-05 |
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