EP0487396A1 - Passives Bandpassfilter - Google Patents

Passives Bandpassfilter Download PDF

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Publication number
EP0487396A1
EP0487396A1 EP91403093A EP91403093A EP0487396A1 EP 0487396 A1 EP0487396 A1 EP 0487396A1 EP 91403093 A EP91403093 A EP 91403093A EP 91403093 A EP91403093 A EP 91403093A EP 0487396 A1 EP0487396 A1 EP 0487396A1
Authority
EP
European Patent Office
Prior art keywords
resonator
resonators
filter according
bandpass filter
passive bandpass
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Withdrawn
Application number
EP91403093A
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English (en)
French (fr)
Inventor
Henri Jean-Marie Budan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
VALTRONIC FRANCE
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VALTRONIC FRANCE
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Filing date
Publication date
Application filed by VALTRONIC FRANCE filed Critical VALTRONIC FRANCE
Publication of EP0487396A1 publication Critical patent/EP0487396A1/de
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/201—Filters for transverse electromagnetic waves
    • H01P1/203—Strip line filters
    • H01P1/20327—Electromagnetic interstage coupling
    • H01P1/20336—Comb or interdigital filters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P7/00—Resonators of the waveguide type
    • H01P7/08—Strip line resonators
    • H01P7/082—Microstripline resonators

Definitions

  • the present invention relates to a passive bandpass filter made of micro-bands deposited on a first face of a dielectric substrate.
  • a first type of filter consists of two "combs" of interdigitated micro-bands deposited on a substrate.
  • This type of filter notably has the drawback of occupying a relatively large place in a hybrid circuit, which harms the densification constraints sought for such circuits. In addition, it has low breaking and rejection powers insofar as the response curve of the filter does not have sufficiently steep sides.
  • This type of filter makes it possible, compared to the previous one, to reduce the size of the filter and to improve the cutting and rejection powers of the filter.
  • the present invention therefore aims in particular to provide a filter overcoming the above drawbacks without affecting its size.
  • the present invention relates to a passive bandpass filter produced in micro-bands deposited on a first face of a dielectric substrate and comprising at least three resonators, characterized in that each resonator has a general trapezoidal shape and in that the guideline of a longitudinal edge of a resonator is parallel to the guideline of the longitudinal edge of the resonator which is adjacent to it, the top of each resonator constituting an open circuit.
  • each resonator is connected in the region of its base to a ground plane carried by a second face of the substrate by suitable means.
  • the overvoltage coefficient is significantly increased to the extent that, in such a resonator, the current is maximum in the region where the resonator is connected to ground and is minimum in the region of the open circuit formed through the other end of the resonator.
  • the base of the resonator being wider, the overvoltage coefficient is higher by decreasing the resistance.
  • the insertion losses which depend mainly on the conductor losses, and incidentally on the dielectric losses and radiation losses are significantly lower for a filter according to the invention. Indeed, the region of maximum current in a resonator of this type being that where the most conductive losses occur, the fact of having a wide base in this region reduces the impedance and ensures a good connection with the ground, which leads to a reduction in the insertion losses.
  • the present invention not only makes it possible to reduce the insertion losses and to increase the overvoltage coefficient, but preserves the filter a good efficiency by not increasing the average width of the resonators. Likewise, it preserves the possibility of fixing the standing wave rate in a large value range according to the desired result.
  • the invention makes it possible to produce filters of small bulk insofar as the resonators are somehow nested.
  • At least two of said resonators not adjacent to one another are coupled by a self-coupling and / or capacitive coupling impedance (Z).
  • This coupling makes it possible in particular as will be seen later to improve the selectivity of the filter.
  • the coupling impedance is carried out on a microstrip line, which eliminates at this impedance the dielectric and radiation losses, and thereby improves the general characteristics of the filter.
  • the first face of the substrate comprises metallized portions in electrical connection with the ground plane.
  • Said metallized portions are affixed to the lateral edges of the substrate substantially parallel to the longitudinal direction of the resonators and in that two of said portions constitute input and output terminals of the filter by being electrically connected, via of said micro-bands, one at the first resonator and the other at the last resonator.
  • the resonators are dimensioned so that the ratio of the base to the top is between 0.5 and 3, this ratio preferably being 2.
  • the metallized holes are arranged in an arc of a circle in the region of the base of the resonator with which they are associated so that the distance between each hole and the top of the resonator is constant and equal to a quarter of the guided wavelength which corresponds to the center frequency.
  • the passive bandpass filter shown diagrammatically in FIG. 1 comprises three resonators 1, 2 and 3 of generally trapezoidal shape and produced in micro-bands on a first face 4 (FIG. 3) of a dielectric substrate 5 (FIG. 2).
  • a first 1 and a third 3 resonator are arranged on the substrate so that their respective bases 6,7 are aligned while a second resonator 2 is interposed between the two preceding ones in an inverted position relative to the latter so that the edges longitudinal opposite 9, 10 and 11, 12 of two neighboring resonators 1, 2 and 2, 3 are parallel.
  • Each resonator is connected by its base 6, 7, 8 to ground.
  • This connection to ground can be achieved in practice by metallized holes 13 (FIG. 2) formed in the region of the base of each resonator and opening onto a second face 14 (FIG. 3) of the substrate carrying a ground plane 15.
  • the two resonators 1 and 3 are coupled by a coupling impedance Z for this capacitive and / or inductive effect whose purpose is to define the response curve of the filter.
  • This impedance Z can in practice be advantageously carried out in microstrip lines affixed to the first face 4 of the substrate 15.
  • such an impedance consists of a first microstrip line 16 in electrical contact with the first resonator 1 and a second microstrip line 17 in electrical contact with the third resonator 3, the two microstrip lines 16 and 17 being arranged relative to each other, so as to achieve the 'coupling impedance sought.
  • the input 18 and the output 19 of the filter are produced by micro-ribbon lines 20 and 21 respectively in electrical contact with the first 1 and the third 3 resonator and serving to apply the input signal to filter and take the signal filtered output.
  • the microstrip lines 20 and 21 are each by their free end electrically connected to a metallized portion 22 affixed on the first face 4 of the substrate 15 on an edge of the latter. As can be seen in FIG. 2, two series of metallized portions are affixed to the substrate on either side of the resonators. These metallized portions are electrically connected to the ground plane 15 (FIG. 3).
  • the dimensioning of the constituent elements of the filter and the relative positioning of these elements is fixed as a function of the different operating characteristics desired for the filter.
  • Such a passive bandpass filter is defined inter alia by its guided wavelength ⁇ , its passband, its response curve and therefore its selectivity, and its input and output impedances.
  • the bandwidth of the filter is adjusted by the average width "l" of the resonators and by the spacing "d” between two resonators.
  • the average width "l” is identical for all the resonators and the spacing "d” between two neighboring resonators 1,2 and 2,3 is also identical for the entire filter.
  • This average width and this spacing also influence the efficiency and the TOS of the filter.
  • the higher the average width and / or the narrower the spacing the lower the TOS. Conversely, the greater the average width and / or the greater the spacing, the greater the TOS.
  • the distance "e” representing the offset between the base 8 of the second resonator 2 and the vertices of the first and third resonators also influences the bandwidth of the filter insofar as the smaller the distance "e", the more the coupling between the resonators 1,2 and 2,3 is important.
  • the selectivity of the filter is fixed inter alia by the coupling impedance Z.
  • the response curve of the filter has the form of a Gauss curve and therefore the filtering n ' is not selective.
  • the coupling impedance Z by its value affects the cut and rejection power of the filter.
  • An increase in the value of the coupling impedance Z leads to an increase in the breaking capacity of the frequencies higher than the central frequency of the filter while a reduction in the value of the coupling impedance Z leads to an increase in the power rejection frequencies below the central frequency of the filter.
  • the coupling between the two resonators 1 and 3 is optimized by the position of the electrical contact of the micro-ribbon lines 16 and 17 with their respective resonator. This position is defined by the height respectively h1 and h2, between the electrical contact of line 16 or 17 and the base 6 or 7 carried by the mass of the resonator 1 or 3. These heights respectively define the related input and output impedances at the coupling impedance Z. Therefore the choice of heights hke and h2 also influences the response curve and the selectivity of the filter.
  • the input and output impedances of the filter depend on the position of the electrical contact of the microstrip lines 20 and 21 with the resonators 1 or 3. This position is defined by the height respectively he or hs between the electrical contact of the line 20 or 21 and the base 6 or 7 brought to the ground of the resonator 1 or 3.
  • the trapezoidal shape of the resonators makes it possible in particular, with respect to a filter comprising resonators of parallelepiped shape, that for the same desired input or output impedance, the height he or hs is greater. This results in the width of the input and output tracks having less influence on the operation of the filter. Indeed, we see that the greater this height, the more the width of the input and output tracks has a negligible influence, in particular on the insertion losses of the filter.
  • a filter according to the invention having the following parameters:

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
EP91403093A 1990-11-21 1991-11-18 Passives Bandpassfilter Withdrawn EP0487396A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9014514A FR2669476A1 (fr) 1990-11-21 1990-11-21 Filtre passif passe-bande.
FR9014514 1990-11-21

Publications (1)

Publication Number Publication Date
EP0487396A1 true EP0487396A1 (de) 1992-05-27

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP91403093A Withdrawn EP0487396A1 (de) 1990-11-21 1991-11-18 Passives Bandpassfilter

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EP (1) EP0487396A1 (de)
FR (1) FR2669476A1 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0627781A1 (de) * 1993-06-04 1994-12-07 Valtronic Industrie S.A. Passives Filter und Verfahren zu seiner Herstellung
US5648747A (en) * 1995-03-15 1997-07-15 Grothe; Wolfgang Planar filter having an overcoupling stripline an integral multiple of a half wavelength in length
ES2143964A1 (es) * 1998-09-15 2000-05-16 Univ Catalunya Politecnica Diplexor dual para telefonia celular gsm y dcs.
US6549093B2 (en) * 2000-05-22 2003-04-15 Murata Manufacturing Co. Ltd. Dielectric filter, duplexer, and communication apparatus incorporating the same
EP1349232A2 (de) * 2002-03-27 2003-10-01 Tesat Spacecom GmbH & Co. KG Mikrowellenresonator

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3451015A (en) * 1966-03-21 1969-06-17 Gen Dynamics Corp Microwave stripline filter
FR2499786A1 (fr) * 1981-02-09 1982-08-13 Radiotechnique Compelec Filtre hyperfrequence a large bande d'attenuation et systeme hyperfrequence comportant ce filtre
US4418324A (en) * 1981-12-31 1983-11-29 Motorola, Inc. Implementation of a tunable transmission zero on transmission line filters
EP0373028A1 (de) * 1988-11-30 1990-06-13 Thomson Hybrides Passives Bandpassfilter

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3451015A (en) * 1966-03-21 1969-06-17 Gen Dynamics Corp Microwave stripline filter
FR2499786A1 (fr) * 1981-02-09 1982-08-13 Radiotechnique Compelec Filtre hyperfrequence a large bande d'attenuation et systeme hyperfrequence comportant ce filtre
US4418324A (en) * 1981-12-31 1983-11-29 Motorola, Inc. Implementation of a tunable transmission zero on transmission line filters
EP0373028A1 (de) * 1988-11-30 1990-06-13 Thomson Hybrides Passives Bandpassfilter

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
IEEE REGION 5 CONFERENCE 1988, Colorado Springs, 21-23 mars 1988, pages 68-72, IEEE, New York, US; D.W. GARDNER et al.: "Microwave filter design using radial line stubs" *
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. AP-29, no. 1, janvier 1981, pages 2-24, New York, US; K.R. CARVER et al.: "Microstrip antenna technology" *
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, vol. MTT-26, no. 2, février 1978, pages 95-100, New York, US; J. HELSZAJN et al.: "Planar triangular resonators with magnetic walls" *
IRE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, vol. 10, no. 2, mars 1962, pages 124-132, New York, US; C.P. WOMACK et al.: "The use of exponential transmission lines in microwave components" *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0627781A1 (de) * 1993-06-04 1994-12-07 Valtronic Industrie S.A. Passives Filter und Verfahren zu seiner Herstellung
FR2706084A1 (fr) * 1993-06-04 1994-12-09 Valtronic Ind Sa Filtre passif et procédé de fabrication d'un tel filtre.
US5648747A (en) * 1995-03-15 1997-07-15 Grothe; Wolfgang Planar filter having an overcoupling stripline an integral multiple of a half wavelength in length
ES2143964A1 (es) * 1998-09-15 2000-05-16 Univ Catalunya Politecnica Diplexor dual para telefonia celular gsm y dcs.
US6549093B2 (en) * 2000-05-22 2003-04-15 Murata Manufacturing Co. Ltd. Dielectric filter, duplexer, and communication apparatus incorporating the same
EP1349232A2 (de) * 2002-03-27 2003-10-01 Tesat Spacecom GmbH & Co. KG Mikrowellenresonator
EP1349232A3 (de) * 2002-03-27 2003-11-12 Tesat Spacecom GmbH & Co. KG Mikrowellenresonator

Also Published As

Publication number Publication date
FR2669476A1 (fr) 1992-05-22

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