EP1653552A1 - Abstimmbares Filter mit Mikrostrifenresonators und dazugehöriges Abstimmverfahren - Google Patents

Abstimmbares Filter mit Mikrostrifenresonators und dazugehöriges Abstimmverfahren Download PDF

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Publication number
EP1653552A1
EP1653552A1 EP04425815A EP04425815A EP1653552A1 EP 1653552 A1 EP1653552 A1 EP 1653552A1 EP 04425815 A EP04425815 A EP 04425815A EP 04425815 A EP04425815 A EP 04425815A EP 1653552 A1 EP1653552 A1 EP 1653552A1
Authority
EP
European Patent Office
Prior art keywords
substrate
filter
dielectric
microstrip
distance
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Withdrawn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
EP04425815A
Other languages
English (en)
French (fr)
Inventor
Paolo Bonato
Carlo Buoli
Fabio Morgia
Tommaso Turillo
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.)
Siemens SpA
Original Assignee
Siemens Mobile Communications SpA
Siemens SpA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Siemens Mobile Communications SpA, Siemens SpA filed Critical Siemens Mobile Communications SpA
Priority to EP04425815A priority Critical patent/EP1653552A1/de
Publication of EP1653552A1 publication Critical patent/EP1653552A1/de
Withdrawn legal-status Critical Current

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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
    • H01P1/203—Strip line filters
    • H01P1/20327—Electromagnetic interstage coupling
    • H01P1/20354—Non-comb or non-interdigital filters
    • H01P1/20363—Linear resonators

Definitions

  • the invention relates to microstrip resonator tunable filters.
  • the invention has been developed by paying specific attention to the possible application to microwave transceivers such as e.g. outdoor unit microwave transceivers.
  • microwave transceivers such as e.g. outdoor unit microwave transceivers.
  • reference to this preferred field of application is in no way to be construed in a limiting sense of the scope of the invention.
  • Microstrip multi-resonator filters are well known in the art as witnessed e.g. by SU-A-1 026 203.
  • the prior art document in question discloses a filter including quarter wavelength strip resonators.
  • Each quarter wavelength strip resonator is comprised of several coupled conductors, the shorted ends of which are connected to an earthing base, which is positioned on the opposite side of the dielectric substrate.
  • the input signal is applied to one outer (edge) conductor, and the output signal is derived from the second edge conductor.
  • a nominal 50 Ohm load is matched by a partial insertion (conductive coupling), and the filter selectivity is defined by the mutual positions of the conductors.
  • Each resonator with shorted and open ends has two attenuation poles.
  • Microstrip tunable filters are typically used in the place of mechanical filters and antenna diplexers in microwave transceivers up to the 80 GHz frequency range.
  • An antenna circulator and a proper number of filters arranged in a line-up front-end circuit permit the required selectivity to be reached while reducing the final insertion loss and the noise figure.
  • BST elements are ferroelectric elements that may change their permittivity as a function of a field to which they are exposed. Varying appreciably the dielectric constant of these elements requires electrical fields of the order of some tens Kvolt/mm. Machining and depositing these materials with thicknesses of the order on one micron is difficult due to the high crystallization temperature with the ensuing diffusion of the underlying conductive materials that form the transmission lines.
  • the object of the invention is thus to provide an improved arrangement that effectively dispenses with the drawbacks intrinsic to the prior art considered in the foregoing.
  • a particularly preferred embodiment of the invention is based on the concept of changing the effective dielectric constant of a set of microstrip multi-resonator filters by placing a dielectric planar material in close proximity of the filter surface, and varying the central working filter frequency by selectively changing the distance of the dielectric material to the filter surface.
  • a single tuning element may uniformly tune all the resonators, while preserving the other electrical characteristics of the filters. Such operation can be easily performed whenever required, without having to disassemble, re-assemble, test and measure again the filter arrangement.
  • PCB printed circuit board
  • the claimed method is particularly adapted to tune a plurality of microstrip resonators, but without departing from the ambit of the invention may be profitably used for tuning a single microstrip resonator.
  • Figure 1 of the annexed drawings shows a microstrip filter F including a dielectric substrate 1 - e.g. an alumina (AL 2 O 3 ) substrate - having a conductive (e.g. metal) ground plane 2 on is bottom face.
  • a dielectric substrate 1 - e.g. an alumina (AL 2 O 3 ) substrate - having a conductive (e.g. metal) ground plane 2 on is bottom face.
  • One or a plurality of coupled microstrip resonators 3 are laid e.g. by resorting to thin or thick film technology on the top surface of the substrate 1.
  • a tuning dielectric element 4 comprised of a thin parallelepiped body of FR4 (a current designation for glass-fiber based material used e.g. in manufacturing printed circuit boards or PCBs), polytetrafluoroethylene (PTFE or Teflon), or quartz is arranged parallel to the substrate 1 facing the resonators 3.
  • FR4 a current designation for glass-fiber based material used e.g. in manufacturing printed circuit boards or PCBs
  • PTFE or Teflon polytetrafluoroethylene
  • quartz is arranged parallel to the substrate 1 facing the resonators 3.
  • the distance between the substrate 1, namely the resonators 3, and the tuning element 4 can be selectively varied in order to change the central working filter frequency and thus uniformly tune all the resonators 3.
  • Figure 2 is exemplary of an arrangement for mechanical continuous tuning of the filter F.
  • the substrate 1 carrying the resonators 3 is arranged between a base plate 12 and a lid 14.
  • the plate 12 and the lid 14 are maintained at a fixed distance by spacers 16, as schematically shown in Figure 2a.
  • Figure 2a is a cross sectional view along line II-II of Figure 2.
  • a screw 18 in the form of e.g. a flat-tip dielectric screw or dielectric-ended metal screw is arranged in a threaded hole formed in the lid 14. Tightening or loosening the screw 18, that in any case represents a planar-ended dielectric element, causes a variation of the distance of the dielectric or dielectric-ended screw 18 to the substrate 1 in the region where the resonators 3 are arranged.
  • the dielectric or dielectric-ended screw 18 thus plays the role of the dielectric element 4 of Figure 1.
  • Tightening or loosening the screw 18 causes the resonating frequencies of the filters provided on the substrate 1 to be uniformly varied as a result of uniformly increasing/decreasing the effective dielectric constant associated with each and every resonator 3.
  • Figure 3 is exemplary of an arrangement for piezoelectric tuning of the filter F.
  • elements or parts identical of equivalent to elements or parts already described in connection with Figure 2 are indicated by the same reference numerals.
  • the screw 18 of Figure 2 is replaced by a piezoelectric element 20 carried by the lid 14.
  • the element 20 is mounted at the lower surface of the lid 14 and carries in turn at its lower a dielectric plate comprising the dielectric element 4 of Figure 1.
  • Controlling the piezoelectric element 20 in a manner known per se, e.g. by controlling the voltage applied across its opposed surfaces via a bias line 20a - see Figure 4a) produces a controlled deformation of the element 20 and thus a controlled variation of the distance of the plate 4 to the substrate 1.
  • Figure 3a is a cross sectional view along line III-III of Figure 3.
  • Figure 4 is exemplary of another arrangement for tuning the filter F. Again, in Figure 4 elements or parts identical of equivalent to elements or parts already described in connection with Figures 2 and 3 are indicated by the same reference numerals. Similarly, Figure 4a is a cross sectional view along line IV-IV of Figure 4.
  • a source of electromagnetic force 22 acts on a ferromagnetic disc or plate 24 placed at the upper end of a dielectric element 4, here in the form of a small cylinder of a dielectric material.
  • a helical spring 26 interposed between the magnet 22 and the disc 24, having preferably associated a centering ferrule 28, allows two stable configurations of the magnet/disc assembly, namely:
  • the two resulting positions of the dielectric 4 to the substrate 1 essentially correspond to a bi-stable tuning of the filter F at two extreme tuning frequencies. These positions and thus the resulting frequencies can be adjusted and switching between the two can thus be easily obtained.
  • the diagrams of Figure 5 report the result of measurements performed by the Applicants. Specifically, the diagram in question shows the tuning frequency f (MHz - ordinate scale) of a filter F as shown in Figures 1 to 4, as a function of the distance D (mm - abscissa scale) between the substrate 1 and the dielectric tuning element 4. Specifically, three curves are shown for a tuning element of a glass-fiber based material (FR4), a polytetrafluoroethylene (PTFE or Teflon) tuning element and a quartz tuning element. The experimental measures clearly confirm that the tuned filter frequency is a function of the proximity of the dielectric element 4 to the surface of the microstrip resonators 3.
  • FR4 glass-fiber based material
  • PTFE or Teflon polytetrafluoroethylene
  • the measurements were performed on existing circuits designed to have very small size and not minimum losses and good selectivity.
  • the measurements show that the appreciable tuning properties of the filter arrangements shown herein do in no way adversely affect the electrical characteristic thereof.
  • a small increasing loss (0.3 dB) has been observed in the case of a dielectric tuning material of poor quality such as FR4.
  • No additional losses were measured if PTFE (Teflon) or quartz are used as the tuning dielectrics.
  • the measurements thus confirm the possibility of effectively controlling the tuned filter frequency by acting on the dielectric proximity to the microstrip resonator surface.
  • Tuning up to 10% of the central frequency was shown to be feasible depending on the permittivity of the moving element used for tuning.
  • the dielectric constant or permittivity of the moving element used for tuning determines, all the other parameters remaining the same, a smaller or larger frequency shift.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
EP04425815A 2004-10-29 2004-10-29 Abstimmbares Filter mit Mikrostrifenresonators und dazugehöriges Abstimmverfahren Withdrawn EP1653552A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP04425815A EP1653552A1 (de) 2004-10-29 2004-10-29 Abstimmbares Filter mit Mikrostrifenresonators und dazugehöriges Abstimmverfahren

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP04425815A EP1653552A1 (de) 2004-10-29 2004-10-29 Abstimmbares Filter mit Mikrostrifenresonators und dazugehöriges Abstimmverfahren

Publications (1)

Publication Number Publication Date
EP1653552A1 true EP1653552A1 (de) 2006-05-03

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EP04425815A Withdrawn EP1653552A1 (de) 2004-10-29 2004-10-29 Abstimmbares Filter mit Mikrostrifenresonators und dazugehöriges Abstimmverfahren

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EP (1) EP1653552A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2546578C2 (ru) * 2013-08-09 2015-04-10 Федеральное Государственное Бюджетное Образовательное Учреждение Высшего Профессионального Образования "Саратовский Государственный Университет Имени Н.Г. Чернышевского" Широкополосная микрополосковая согласованная нагрузка
WO2015076212A1 (en) * 2013-11-20 2015-05-28 Kabushiki Kaisha Toshiba Tunable filter apparatus

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04368006A (ja) * 1991-06-14 1992-12-21 Nippon Telegr & Teleph Corp <Ntt> 酸化物超伝導マイクロ波部品
EP1202375A2 (de) * 2000-10-30 2002-05-02 Kabushiki Kaisha Toshiba Hochfrequenzvorrichtung
US20030122635A1 (en) * 2001-12-31 2003-07-03 Valery Borzenets Resonator tuning assembly and method
EP1376745A1 (de) * 2002-06-27 2004-01-02 Harris Corporation Hocheffizientes "stepped-impedance" Filter

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04368006A (ja) * 1991-06-14 1992-12-21 Nippon Telegr & Teleph Corp <Ntt> 酸化物超伝導マイクロ波部品
EP1202375A2 (de) * 2000-10-30 2002-05-02 Kabushiki Kaisha Toshiba Hochfrequenzvorrichtung
US20030122635A1 (en) * 2001-12-31 2003-07-03 Valery Borzenets Resonator tuning assembly and method
EP1376745A1 (de) * 2002-06-27 2004-01-02 Harris Corporation Hocheffizientes "stepped-impedance" Filter

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 017, no. 241 (E - 1364) 14 May 1993 (1993-05-14) *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2546578C2 (ru) * 2013-08-09 2015-04-10 Федеральное Государственное Бюджетное Образовательное Учреждение Высшего Профессионального Образования "Саратовский Государственный Университет Имени Н.Г. Чернышевского" Широкополосная микрополосковая согласованная нагрузка
WO2015076212A1 (en) * 2013-11-20 2015-05-28 Kabushiki Kaisha Toshiba Tunable filter apparatus

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