EP1748512A1 - Flüssigkeitsgekühlter Hochfrequenzfilter - Google Patents

Flüssigkeitsgekühlter Hochfrequenzfilter Download PDF

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Publication number
EP1748512A1
EP1748512A1 EP05106808A EP05106808A EP1748512A1 EP 1748512 A1 EP1748512 A1 EP 1748512A1 EP 05106808 A EP05106808 A EP 05106808A EP 05106808 A EP05106808 A EP 05106808A EP 1748512 A1 EP1748512 A1 EP 1748512A1
Authority
EP
European Patent Office
Prior art keywords
resonator
high frequency
frequency filter
filter according
cover element
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Withdrawn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
EP05106808A
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English (en)
French (fr)
Inventor
Ivan Milak
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.)
Harris Broadcast Systems Europe
Original Assignee
Harris Broadcast Systems Europe
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 Harris Broadcast Systems Europe filed Critical Harris Broadcast Systems Europe
Priority to EP05106808A priority Critical patent/EP1748512A1/de
Priority to US11/491,707 priority patent/US7864528B2/en
Publication of EP1748512A1 publication Critical patent/EP1748512A1/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Withdrawn legal-status Critical Current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
    • H01P1/207—Hollow waveguide filters
    • H01P1/208—Cascaded cavities; Cascaded resonators inside a hollow waveguide structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/30—Auxiliary devices for compensation of, or protection against, temperature or moisture effects ; for improving power handling capability

Definitions

  • the present invention relates to a high-frequency filter.
  • the present invention relates to a liquid cooled high-frequency filter, preferably for use in multi-frequency networks (MFNs) or single-frequency networks (SFNs) like digital video broadcasting (DVB) networks, which may include multimedia services like DVB-H or DVB-RCT and the like.
  • MFNs multi-frequency networks
  • SFNs single-frequency networks
  • DVB digital video broadcasting
  • the transmitter has to meet the following spectral characteristics: A f 0 ⁇ 4 , 2 MHz ⁇ ⁇ 50.2 dB ; A f 0 ⁇ 6 MHz ⁇ ⁇ 62 dB ; A f 0 ⁇ 12 MHz ⁇ ⁇ 87 dB , where A is the attenuation at the respective frequency f 0 ⁇ ⁇ .
  • COFDM coded orthogonal frequency division multiplexing
  • a conceivable way to keep intermodulation products due to nonlinearities of the amplifier at a low level or even reduce them while increasing amplification power is the application of highly selective output filter units following the transmitter amplifier in order to linearize the amplified signal before transmission by the transmitter antenna.
  • thermally compensated resonators solves the problem of thermal instability only to a certain extent, particularly in appliances, in which the filter enclosure is subject to changes of the ambient temperature.
  • a high-frequency filter of the invention comprises a filter housing having at least one cover element with at least one resonator positioned therein, a signal input, through which a high frequency signal is coupled to the first resonator, as well as a signal output, through which the filtered high-frequency signal is coupled from the last resonator to downstream appliances.
  • the cover element is made form a thermally conductive material and is in thermal connection with the resonators positioned therein.
  • the cover element has at least one recess arranged therein, along which a liquid coolant is guided in order to absorb thermal energy resulting from feeding the high-frequency signal to the resonator.
  • the high-frequency filter according to the invention comprises a tubing element, through which the liquid coolant flows and which is positioned inside the recess of the cover element, whereby the tubing element is in thermal connection with the cover element.
  • a filter housing having a cover element with a recess, along which a liquid coolant is guided represents a very effective and advantageous way to dissipate thermal energy that is generated in the high-frequency filter and particularly the resonators due to high current and/or field densities.
  • the liquid coolant provides a thermal energy sink having a high thermal capacity such that a sufficiently high amount of thermal energy can be dissipated in order to keep the high-frequency filter, and particularly the resonators, at thermally stable operating conditions, even if the electric current and/or field density is substantially higher when compared to high-frequency filters according to the state of the art.
  • output filters according to the state of the art are generally specified for a maximum input power of 2.5 kW (rms), this limit resulting from a balance between maximally tolerable thermal instabilities or maximally achievable temperature compensation, respectively, and minimally tolerable selectivity of the filter due to an increase in cavity dimensions.
  • a DVB-T UHF bandpass filter according to the state of the art working at an input power of 5 kW (rms), would exhibit a loss of about 500 W of electromagnetic field power, which will almost completely be converted to thermal energy, i.e. heat. According to Applicant's calculations, this would increase the filter enclosure's temperature by more than 50°C, thereby driving the filter's temperature out of the specified operating range.
  • the high-frequency filter according to the invention obviates this problem by providing means for guiding a liquid coolant, wherein the liquid coolant is provided in order to dissipate excess heat, which is generated by the conversion of electric and/or electromagnetic energy into thermal energy.
  • the provision of a recess inside the cover element, along which the liquid coolant is guided allows for a simple construction of the liquid cooled high-frequency filter, for example by fitting a tubing element into the recess, through which the liquid coolant flows and which is in thermal connection with the cover element such that the liquid coolant represents a heat sink in the cover element.
  • the tubing element is positively or non-positively fitted inside the recess of the cover element and/or in a material connection with at least parts of the walls of said recess. This ensures that thermal resistance at the interface of the tubing element and the recess walls is minimized in order to improve heat dissipation.
  • such material connections are made of thermally conductive paste or thermally conductive glue in order to decrease thermal resistance of interfacing portions.
  • the tubing element is made from a different material than the cover element and most preferably from a material selected from a group comprising aluminium, zinc, copper, silver, gold, brass, bronze, alloys thereof or any other metals or alloys having a sufficiently high thermal conductivity, thermally conductive polymers and ceramics and the like, as well as combinations thereof.
  • the tubing element is made from a material having a higher thermal conductivity than the material, the cover element is made from.
  • the recess of the cover element is at least partially covered with a closing element, whereby the closing element is fixed to the cover element by a bonding material, fixing means and/or positive or non-positive fit.
  • the bonding material is of high thermal conductivity in order to maximize dissipation of heat by the liquid coolant.
  • the closing element may be fixed to the cover element by fixing means such as screws, clips and the like.
  • the closing element may either be used as retaining means in order to hold the tubing element inside the recess of the cover element in place or may function as an upper cover to provide a closed cross section along the total length of the recess, which may be sealed by a bonding material.
  • the recess in its direction of extension, has substantially no sharp edges but extends in a substantially straight and/or continuously curved direction.
  • a tubing element made from a comparatively soft material, such as copper into the recess by bending the copper tubing element along the continuously curved recess and fixing it inside the recess using one or more closing elements.
  • At least one liquid coolant inlet and at least one liquid coolant outlet is provided, through which a liquid coolant is applied to and drained from the liquid coolant pathway, respectively.
  • the liquid coolant inlet and/or outlet port comprises valve means preventing liquid coolant to leak out of the liquid coolant pathway in case the inlet and/or outlet port exhibits a connection fault or the liquid coolant source and/or drain is disconnected from the respective inlet and/or outlet port.
  • the high frequency filter according to the invention comprises at least one resonator cavity, which is associated with said resonator.
  • a multiple resonator filter assembly an equal number of resonator cavities is provided, where each resonator cavity is associated with one resonator.
  • the resonator cavities are of a cubic, cylindrical or spherical shape.
  • the resonator is tuneable, preferably tuneable from 650 MHz to 700 MHz, more preferably tuneable from 600 MHz to 750 MHz, yet more preferably tuneable from 550 MHz to 800 MHz, most preferably tuneable from 500 MHz to 850 MHZ, and particularly preferably tuneable from 470 MHz to 860 MHz.
  • the resonators and, consequently, the high frequency filter can be used in the whole UHF frequency band and are particularly well-suited for DVB-T applications, even if general frequencies are changed by the authorities or coverage constraints require a modification of the operating frequencies of the high-frequency filter.
  • the high-frequency filter according to the invention comprises inductive and/or capacitive coupling means, which are used in order to couple multiple resonator cavities by inductive and/or capacitive coupling.
  • the coupling means have an electrical length of ⁇ /4, i.e. 1 ⁇ 4 of the wavelength corresponding to the center frequency f 0 of the high-frequency filter.
  • the high-frequency filter comprises a multitude of resonators and associated resonator cavities, which are most preferably coupled to form a serial arrangement of preferably three, more preferably four, most preferably five, and particularly preferably six, eight or more cavity resonators.
  • the serial coupling of multiple cavity resonators increases selectivity of the high-frequency filter and, thus, allows for a narrow band filtering of a high-frequency signal.
  • At least two cavity resonators which are not coupled by the serial arrangement of the multiple cavity resonators, are cross-coupled, most preferably by a capacitive coupling of the first and the last cavity resonator, the second and the penultimate cavity resonator, and most preferably the second and the fifth cavity resonator of a serial arrangement of six cavity resonator.
  • Cross-coupling cavity resonator in a serial resonator arrangement leads to an increased attenuation in the upper and/or lower edge region of the passband of the high-frequency filter according to the invention and, thus, an even further increased filter selectivity.
  • a particularly preferred embodiment of the present invention includes at least one and preferably two notch cavity resonators, coupled to at least one other cavity resonators of the high-frequency filter.
  • the first notch cavity resonator is coupled to a first cavity resonator and the second notch cavity resonator is coupled to a last resonator.
  • the first notch cavity resonator is coupled to a second cavity resonator and the second notch cavity resonator is coupled to a penultimate resonator and the like.
  • liquid coolants for a high frequency filter include water, liquid ammonia, liquid carbon dioxide (CO 2 ) or any other liquid, preferably having a high thermal capacity. Further, the liquid coolant may include additives in order to reduce corrosion and precipitation of unwanted material inside the liquid coolant pathway.
  • All embodiments of the present invention as previously described, as well as any combination thereof provide high power high-frequency filters with an increased temperature stability while having a compact design that prevents the development of higher TEM modes. Further, high flexibility regarding operation frequency and power are achieved.
  • Fig. 1 shows a schematic circuit diagram of a liquid cooled high-frequency bandpass filter for DVB-T applications according to the invention
  • Fig. 1 shows a schematic circuit diagram of a high-frequency filter according to the invention, particularly for use in terrestrial DVB appliances.
  • the filter 1 comprises a filter housing 2, having a signal input port 3 as well as a signal output port 4 for coupling a DVB-T UHF signal from an output amplifier to the first resonator 5 via inductive input coupling means 13.
  • the first resonator 5 represents the first resonator element in a serial circuit of six resonator elements represented by resonators 5, 6, 7, 8, 9 and 10, whereby resonator 10 represents the last resonator in the serial resonator circuit.
  • the last resonator 10 is inductively coupled to the signal output 4 resulting in a coupling of the filtered DVB-T UHF signal from the last resonator to downstream appliances, such as antennas and the like.
  • the resonators 5, 6, 7, 8, 9 and 10 of the serial resonator circuit are inductively coupled by coupling means 14, 15, 16, 17 and 18.
  • the resonators 5, 6, 7, 8, 9 and 10 of the serial resonator circuit are bandpass resonators such that a signal, having substantially the center frequency of the respective resonator, passes said resonator from its input coupling to its output coupling.
  • the high-frequency filter according to the embodiment of Fig. 1 is designed in ⁇ /4 technology, i.e. the electrical lengths of inductive couplings 13, 14, 15, 16, 17, 18, 19 are such that they correspond to 1 ⁇ 4 to the wave length of the center frequency f 0 , in order to maximize impedance matching, which results in an optimized coupling between the cavity resonators and, thus, in a minimization of the total insertion loss of the filter.
  • the filter according to the embodiment of Fig. 1 further comprises a capacitive cross coupling between resonators 6 and 9, i.e. the second and fifth resonator of the serial arrangement of six resonators. This leads to an increased selectivity for f 0 ⁇ 6 MHz of about 7 dB (see Fig. 4, B).
  • notch cavity resonators 11, 12 are inductively coupled by coupling means 20, 21 to the first and last resonator 5, 10, respectively, of the serial resonator assembly.
  • the provision of notch resonators 11, 12 leads to an increased selectivity of f 0 ⁇ 4,2 MHz ⁇ 15 dB (see Fig. 4, C), resulting in a frequency characteristic of the bandpass filter according to the embodiment of Fig. 1, which meets ETSI standard EN 300 744.
  • inductive coupling means 20 As in the case of inductive coupling means 13 - 19, inductive coupling means 20, 21 have an electrical length of ⁇ /4, in order to optimize the coupling between the notch cavity resonators and the respective bandpass resonators 5 and 10.
  • all resonators and coupling means are tuneable, which allows the filter to be used in the UFH frequency range, i.e. 470 to 862 MHz, by adjusting the center frequencies of the resonators as well as the electrical length of the coupling means.
  • Fig. 1 schematically shows a liquid cooling pathway 30, having an input port 31 and an output port 32.
  • the liquid coolant pathway is constructed to be in good thermal conductivity with the resonators 5 to 12.
  • Fig. 2 shows a side view of a high frequency output filter according to the invention.
  • the filter housing consists of a bottom element 2c, side elements 2b and 2d, as well as a cover element 2a.
  • the elements 2a, 2b, 2c and 2d define an inner volume of the high-frequency filter, which is subdivided by longitudinal and lateral partition walls 2e, defining multiple cavities of the filter enclosure of substantially identical volume.
  • the cavities 5a, 6a, 9a, 10a define resonator cavities which, in combination with resonators 5, 6, 9 and 10, form cavity resonators as is known to the skilled person.
  • the resonator cavities are of substantially rectangular shape.
  • Signal input and output ports 3, 4 are arranged at opposed sidewalls 2b of the filter housing.
  • the bottom, side and cover elements 2c, 2b, 2d and 2a are made of sheet metal plates and most preferably aluminium or aluminium alloy plates. These sheet metal plates are interconnected and fixed in place by fixation means and most preferably metal screws. Likewise, the partition elements 2e, which are arranged inside the volume defined by the sheet metal plates 2a - 2d, are connected and fixed in place by fixation elements, such as screws or the like. The interconnection of the sheet metal plates is preferably sealed by a sealing/bonding material, which provides good electrical conductivity between the metal plates.
  • cover element 2a is made of a sheet metal plate having a greater thickness than bottom and side elements 2c, 2b and 2d, in order to enable for good thermal conductivity as well as provide sufficient material thickness in order to house recess 23.
  • Fig. 3 shows a top view of the filter assembly according to Fig. 2.
  • the resonator cavities are arranged in two adjacent rows of four resonators.
  • the serial resonator arrangement of six bandpass cavity resonators 5, 6, 7, 8, 9, 10 is folded to extend longitudinally and laterally across the cross section of the resonator housing defined by sidewalls 2b and 2d.
  • Notch cavity resonators 11 and 12 are arranged adjacent to the respective first and last resonator of the serial resonator arrangement 5 - 10 such that the filter assembly has a substantially rectangular outer shape.
  • the resonators 5 - 12 are arranged substantially centered with reference to the resonator cavities 5a to 12a. Again, the substantially rectangular shape of the resonator cavities 5a to 12a is shown in Fig. 3.
  • Fig. 3 also shows recess 23 in the covering element 2a of the high-frequency filter device, in which a tubing element 30 is arranged and fixed by closing elements 33.
  • closing elements 33 are fixed to cover element 2a by fixing elements, such as screws, clips or the like.
  • Tubing element 30 comprises inlet and outlet ports 31 and 32, which, in the present case, include automatic valve means sealing the tube element 30 as soon as connecting means of a liquid coolant source and drain, respectively, are disconnected from the inlet and outlet ports 31, 32.
  • a high-frequency filter as shown in Fig. 3, dissipating excess heat from the cavity resonators using a liquid coolant allows to use the high-frequency filter in 5 kW applications.
  • the maximum input power specification of bandpass filters for use in DVB-T transmitter applications is doubled, while the physical dimensions of the filter assembly are kept constant, thus, ensuring increased selectivity and stability of the filter by omitting the development of higher harmonic TEM modes.

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EP05106808A 2005-07-25 2005-07-25 Flüssigkeitsgekühlter Hochfrequenzfilter Withdrawn EP1748512A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP05106808A EP1748512A1 (de) 2005-07-25 2005-07-25 Flüssigkeitsgekühlter Hochfrequenzfilter
US11/491,707 US7864528B2 (en) 2005-07-25 2006-07-24 Liquid cooled high-frequency filter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP05106808A EP1748512A1 (de) 2005-07-25 2005-07-25 Flüssigkeitsgekühlter Hochfrequenzfilter

Publications (1)

Publication Number Publication Date
EP1748512A1 true EP1748512A1 (de) 2007-01-31

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Family Applications (1)

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EP05106808A Withdrawn EP1748512A1 (de) 2005-07-25 2005-07-25 Flüssigkeitsgekühlter Hochfrequenzfilter

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111697296A (zh) * 2020-07-20 2020-09-22 成都锐明合升科技有限责任公司 一种强迫液冷非互易性微波器件
CN114050843A (zh) * 2021-10-28 2022-02-15 广东宽普科技有限公司 一种vhf信号模块式通信设备

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4712158A (en) * 1985-03-28 1987-12-08 Fujitsu Limited Cooling system for electronic circuit components
US5675473A (en) * 1996-02-23 1997-10-07 Motorola, Inc. Apparatus and method for shielding an electronic module from electromagnetic radiation
US5960861A (en) * 1995-04-05 1999-10-05 Raytheon Company Cold plate design for thermal management of phase array-radar systems
EP1253639A2 (de) * 2001-04-27 2002-10-30 Aavid Thermalloy S.r.l. Flüssigkeitsgekühlte Wärmesenke für elektronische Bauteile
WO2003096473A1 (en) * 2002-05-07 2003-11-20 Microwave And Materials Designs Ip Pty Ltd Filter assembly

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4712158A (en) * 1985-03-28 1987-12-08 Fujitsu Limited Cooling system for electronic circuit components
US5960861A (en) * 1995-04-05 1999-10-05 Raytheon Company Cold plate design for thermal management of phase array-radar systems
US5675473A (en) * 1996-02-23 1997-10-07 Motorola, Inc. Apparatus and method for shielding an electronic module from electromagnetic radiation
EP1253639A2 (de) * 2001-04-27 2002-10-30 Aavid Thermalloy S.r.l. Flüssigkeitsgekühlte Wärmesenke für elektronische Bauteile
WO2003096473A1 (en) * 2002-05-07 2003-11-20 Microwave And Materials Designs Ip Pty Ltd Filter assembly

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
MILAK I ET AL: "Synthesis of output filter unit for terrestrial digital video broadcasting", VIDEO/IMAGE PROCESSING AND MULTIMEDIA COMMUNICATIONS, 2003. 4TH EURASIP CONFERENCE FOCUSED ON 2-5 JULY 2003, PISCATAWAY, NJ, USA,IEEE, vol. 2, 2 July 2003 (2003-07-02), pages 857 - 862, XP010650196, ISBN: 953-184-054-7 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111697296A (zh) * 2020-07-20 2020-09-22 成都锐明合升科技有限责任公司 一种强迫液冷非互易性微波器件
CN114050843A (zh) * 2021-10-28 2022-02-15 广东宽普科技有限公司 一种vhf信号模块式通信设备

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