EP0127527B1 - Einstellungsverfahren, besonders Frequenzeinstellungsverfahren eines gedruckten Mikrostreifenleitungsfilters, und Filter nach dieser Art - Google Patents

Einstellungsverfahren, besonders Frequenzeinstellungsverfahren eines gedruckten Mikrostreifenleitungsfilters, und Filter nach dieser Art Download PDF

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Publication number
EP0127527B1
EP0127527B1 EP84401028A EP84401028A EP0127527B1 EP 0127527 B1 EP0127527 B1 EP 0127527B1 EP 84401028 A EP84401028 A EP 84401028A EP 84401028 A EP84401028 A EP 84401028A EP 0127527 B1 EP0127527 B1 EP 0127527B1
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EP
European Patent Office
Prior art keywords
filter
low dielectric
dielectric loss
resonators
loss material
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.)
Expired - Lifetime
Application number
EP84401028A
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English (en)
French (fr)
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EP0127527A1 (de
Inventor
Marcel Motola
Jean René Jecko
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Thales SA
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Thomson CSF SA
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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

Definitions

  • the present invention relates to filters with elements with distributed constants, such as filters printed in "microstrip" lines.
  • the invention relates more particularly to an adjustment process, in particular in frequency of a filter printed in "microstrip" lines, and the filter obtained by this process.
  • Such filters comprise a dielectric support, on which have been, for example etched, metallizations. These metallizations can have different shapes.
  • a first way is to vary the length of the microstrips, for example by cutting part of these microstrips with a scalpel.
  • This way of adjusting a filter has the serious disadvantage of being irreversible. This is particularly serious in the event that the desired adjustment value has been exceeded.
  • cutting a part of these microstrips with a scalpel risks damaging the support on which they are deposited, which can lead to an immediate change in its electrical characteristics and chemical degradation in the long run.
  • Another way to adjust the frequency of the filters printed in microstrip lines, illustrated in Figure 1 is to solder capacitors at the ends of the strips. The process which is the subject of the present invention allows filter adjustment, not having these drawbacks.
  • the main object of the invention is a method for adjusting the electrical characteristics of a filter comprising metal resonators, known from document DE-B-1228011 characterized in that the filter being a printed filter with distributed constants comprising a dielectric substrate and comprising on a first face a ground plane and on a second face the resonators, at least one dielectric material with low losses of a given geometry is deposited on the resonators.
  • FIG. 1 is a top view of a filter with distributed constants, equipped with a frequency adjustment device of known type;
  • FIG. 2 is a top view in section of a filter with distributed constants comprising an adjustment device according to the invention
  • FIG. 3 is a view of another embodiment of the frequency adjustment device according to the invention.
  • FIG. 1 we can see a filter with distributed constants with alternating fingers, called interdigitated filter.
  • the filter comprises, etched on a dielectric support 1 of the microstrips 2, 3 and 4.
  • the microstrips 2 and 3 respectively constitute the electrical input and the output of the filter.
  • the microstrips 4 constitute resonators allowing filtering.
  • the ends of the microstrips 4 are grounded 6.
  • the filter illustrated in FIG. 1 is a bandpass filter. It may be interesting to adjust the center frequency of such a filter. This adjustment can be made necessary by manufacturing tolerances, for example the variation of the dielectric constant of the support 1 or the variation of its thickness.
  • the variations of the central frequency of the filter can also come from the etching of the microstrips 2, 3 and 4.
  • FIG. 2 an example of a bandpass filter according to the invention can be seen.
  • the filter is called the hairpin type because it has 7 microstrip U-band resonators that propagate the signal, the shape of which resembles that of hairpins.
  • the L-shaped microstrips 2 and 3 respectively constitute the electrical input and output of the filter.
  • On the microstrips is placed a dielectric element 8.
  • the presence of an element 8 has the effect of modifying the behavior of the filter.
  • the invention proposes to use these modifications of the behavior of the filter to carry out an adjustment either to modify the behavior of the same filter during its operation, or to adjust a filter, for example at a predetermined central frequency to overcome d '' a dispersion of the center frequencies due to too large manufacturing tolerances.
  • the element 8 consists of a low loss dielectric, such as for example PTFE (polytetrafuoroethylene).
  • the element 8 has a constant thickness.
  • the element 8 has a constant width in the plane of the resonators 2, 3 and 7.
  • the microstrips which constitute the resonators 2, 3, 4 and 7 will bear the reference 9.
  • the element 8 is a rectangular parallelepiped ribbon.
  • the width of the dielectric element 8 decreases as one moves away from the microstrips 9.
  • the ribbon 8 is arranged perpendicular to the resonators of the filter.
  • the ribbon 8 is deposited on all the resonators of the filter.
  • the ribbon 8 is deposited so as to respect the symmetry of the distribution of the lines of the fields of the filter. In Figure 2, this has was achieved by superimposing the axis of symmetry of the filter with the axis of symmetry of the ribbon 8, which covers all the resonators 7. This facilitates the prediction of the influence of the ribbon 8 on the behavior of the filter. Thus the frequency displacement of the filtering curve is effected without the latter changing shape.
  • the invention is particularly advantageous for filters of this type having for example the bandwidth ratio at 3 decibels on the center frequency less than 0.1. Indeed, the adjustment values are limited by the dielectric materials currently available. For such filters, it is possible to obtain a frequency displacement of the filtering curve without the latter changing shape.
  • the filter is made from a PTFE substrate 1 loaded with ceramic sold by the company ROGERS under the reference DUROID 6010.
  • the substrate has a 35um copper deposit on both sides. One operates on one of these copper deposits the etching of the microstrips, the other deposit constituting the mass of the filter.
  • the filter of figure 2 has a central frequency of 1000MHz and a bandwidth for an attenuation of 3 decibels of 50MHz.
  • the filter is covered with a cover, for example made of stainless steel.
  • the cover makes it possible to close to the ground the field lines which are not captive of the dielectric substrate.
  • the cover for example, provides a space of 3mm above the pattern of the filter.
  • this space is filled with the ribbon 8.
  • the filter is adjusted by selecting the width L of the ribbon 8.
  • the ribbon 8 is formed by a low loss dielectric, for example the PTFE sold by DUPONT DE NEMOURS under the reference dielectric constant TFE 5 teflon close to 2.
  • the adjustment is effected either by reducing the width of the ribbon 8, for example by cutting with a scalpel until the desired value is obtained, or by having a set of ribbon 8 of various widths.
  • the ribbon 8 of desired width is then placed on the filter to be adjusted. The adjustment thus operated is reversible, since it suffices to remove the ribbon 8. If the value of the desired central frequency is exceeded, it is sufficient to replace the ribbon 8 without touching the filter.
  • FIG. 3 an alternative embodiment of the filter according to the invention can be seen.
  • the frequency displacement is obtained by the placing on the microstrips 9 of a ribbon 8 of fixed width, the thickness of which is varied either by machining or by stacking a certain number of dielectric elementary plates 10, 11, 12.
  • the plates 10, 11, 12 do not have the same dielectric constant. The adjustment then takes place, not only by the thickness and the number of plates, but also by their arrangement in the stack. The influence of the dielectric plates 10, 11, 12 is linked to the distance separating them from the microstrips. Thus, placing the wafers with a high dielectric constant near the microstrips 9 increases the value of the corrections made by the adjustment.
  • Figure 4 is a figure illustrating the result of the adjustments obtained with the device of Figure 2.
  • Curve 16 represents the insertion losses as a function of the frequency of the filter without the ribbon 8.
  • the central frequency (A) of the filter equipped with its cover is 1025 MHz.
  • Curve 17 represents the insertion losses as a function of the frequency of the filter fitted with a PTFE tape with a width of one centimeter.
  • the central frequency (B) of the filter is then 1013 MHz.
  • Curve 18 represents the insertion losses as a function of the frequency of a filter fitted with a 2 cm wide PTFE tape.
  • the central frequency (C) of the filter is then 999MHz.
  • the displacement of the central frequency is proportional to the width of the bar, with a sensitivity in the illustrated example of 13 MHz per cm.
  • the adjustment of the center frequency is possible up to at least 3%. This makes it possible to shelter from manufacturing dispersions, mainly due to the substrate and whose influence on the central frequency of the filter for, for example, DUROID 6010 is of the order of + 1.5%.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)

Claims (12)

  1. Verfahren zur Einstellung der elektrischen Kenndaten eines metallische Resonatoren enthaltenden Filters, dadurch gekennzeichnet, daß auf den Resonatoren (7) wenigstens ein verlustarmes dielektrisches Material (8, 10, 11, 12) mit gegebener Geometrie abgelagert wird, wobei das Filter ein gedrucktes Filter mit verteilten Leitungskonstanten ist, das ein dielektrisches Substrat (1) enthält und auf einer ersten Seite eine Masseebene und auf einer zweiten Seite die Resonatoren aufweist.
  2. Verfahren gemäß Anspruch 1, dadurch gekennzeichnet, daß die gewünschte Geometrie durch ein Schneiden der verlustarmen Materialien (8, 10, 11, 12) erhalten wird.
  3. Verfahren gemäß Anspruch 1 oder 2, dadurch gekennzeichnet, daß die eingestellten elektrischen Kenndaten von der Bandmittenfrequenz des Filters gebildet werden.
  4. Verfahren gemäß einem der vorangehenden Ansprüche, dadurch gekennzeichnet, daß die Einstellung durch die Wahl der Dicke des verlustarmen dielektrischen Materials (8, 10, 11, 12) erreicht wird.
  5. Verfahren gemäß einem der vorangehenden Ansprüche, dadurch gekennzeichnet, daß die Einstellung durch die Wahl der Breite des verlustarmen dielektrischen Materials erreicht wird.
  6. Verfahren gemäß einem der vorangehenden Ansprüche, dadurch gekennzeichnet, daß die Einstellung durch die Wahl der dielektrischen Konstanten des verlustarmen dielektrischen Materials (8, 10, 11, 12) erreicht wird.
  7. Gedrucktes Filter, das durch das Verfahren gemäß einem der vorangehenden Ansprüche erhalten wird, dadurch gekennzeichnet, daß das abgelagerte, verlustarme dielektrische Material eine im wesentlichen konstante Dicke besitzt.
  8. Gedrucktes Filter, das durch das Verfahren gemäß einem der Ansprüche 1 bis 6 erhalten wird, dadurch gekennzeichnet, daß das abgelagerte, verlustarme dielektrische Material eine im wesentlichen konstante Breite besitzt.
  9. Gedrucktes Filter, das durch das Verfahren gemäß einem der Ansprüche 1 bis 6 erhalten wird, dadurch gekennzeichnet, daß das verlustarme dielektrische Material senkrecht zu den Resonatoren (2, 3, 4, 7) abgelagert wird.
  10. Gedrucktes Filter, das durch das Verfahren gemäß einem der Ansprüche 1 bis 6 erhalten wird, dadurch gekennzeichnet, daß das verlustarme dielektrische Material auf sämtlichen Resonatoren (2, 3, 4, 7) abgelagert wird.
  11. Gedrucktes Filter, das durch das Verfahren gemäß einem der Ansprüche 1 bis 6 erhalten wird, dadurch gekennzeichnet, daß die Ablagerung des verlustarmen dielektrischen Materials die Symmetrie der Verteilung der Feldlinien des Filters einhält.
  12. Gedrucktes Filter, das durch das Verfahren gemäß einem der Ansprüche 1 bis 6 erhalten wird, dadurch gekennzeichnet, daß die Breite des auf den Resonatoren (2, 3, 4, 7) abgelagerten, verlustarmen dielektrischen Materials (8, 10, 11, 12) gemäß der Entfernung von den Mikrostreifenleitern (9) abnimmt.
EP84401028A 1983-05-31 1984-05-18 Einstellungsverfahren, besonders Frequenzeinstellungsverfahren eines gedruckten Mikrostreifenleitungsfilters, und Filter nach dieser Art Expired - Lifetime EP0127527B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8309008A FR2547116B1 (fr) 1983-05-31 1983-05-31 Procede d'ajustage notamment en frequence d'un filtre imprime en ligne " microbandes ", et filtre obtenu par ce procede
FR8309008 1983-05-31

Publications (2)

Publication Number Publication Date
EP0127527A1 EP0127527A1 (de) 1984-12-05
EP0127527B1 true EP0127527B1 (de) 1991-02-27

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EP84401028A Expired - Lifetime EP0127527B1 (de) 1983-05-31 1984-05-18 Einstellungsverfahren, besonders Frequenzeinstellungsverfahren eines gedruckten Mikrostreifenleitungsfilters, und Filter nach dieser Art

Country Status (5)

Country Link
US (1) US4638271A (de)
EP (1) EP0127527B1 (de)
JP (1) JPS59230302A (de)
DE (1) DE3484149D1 (de)
FR (1) FR2547116B1 (de)

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Also Published As

Publication number Publication date
JPS59230302A (ja) 1984-12-24
EP0127527A1 (de) 1984-12-05
FR2547116A1 (fr) 1984-12-07
DE3484149D1 (de) 1991-04-04
FR2547116B1 (fr) 1985-10-25
US4638271A (en) 1987-01-20

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