US3581246A - Filter arrangement - Google Patents

Filter arrangement Download PDF

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Publication number
US3581246A
US3581246A US681223A US3581246DA US3581246A US 3581246 A US3581246 A US 3581246A US 681223 A US681223 A US 681223A US 3581246D A US3581246D A US 3581246DA US 3581246 A US3581246 A US 3581246A
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United States
Prior art keywords
circuit means
filter arrangement
reactive
power dividing
dividing circuit
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Expired - Lifetime
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US681223A
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English (en)
Inventor
Tore Torstensson Fjallbrant
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Telefonaktiebolaget LM Ericsson AB
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Telefonaktiebolaget LM Ericsson AB
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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
    • H01P1/215—Frequency-selective devices, e.g. filters using ferromagnetic material
    • 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
    • H01P1/209—Hollow waveguide filters comprising one or more branching arms or cavities wholly outside the main waveguide
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/0115—Frequency selective two-port networks comprising only inductors and capacitors
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/01—Frequency selective two-port networks
    • H03H7/09—Filters comprising mutual inductance

Definitions

  • dividing circuit means Including an input port adapted to [52] [1.5. CI 1333/24.], r DCvg signals an output port adapned to transmit signals and 333/731 3. 1 ⁇ two signal-transfer ports. Signals received by the input port [51] [Ill-Cl H03h 13/00, are power divided and fed to the ignal-transfer ports for 1 12 transmission therefrom to a reactive circuit means which 0 Search W, reflects the signals back to the ignaLfl-ansfer ports, The 1 reflected signals received by the signal-transfer ports pass throu h the ower dividing circuit means to the output port [56] Rehrences cued and ar e geom etrically added.
  • Various power dividing circuit means including differential 2,531,447 1 1/1950 Lewis 333/73(W) transformers, magic T devices and 90 hybrid devices are dis- 2,649,576 8/1953 Lewis... 333/73(W) closed.
  • the reactive circuit means include, reciprocal and 2,916,712 12/1959 Artuso Vietnamese 333/73(W) nonreciprocal phase shifters as well as waveguide elements 3,027,525 3/1962 Salberg 333/73(W) having irises and tuning stubs.
  • the present invention relates to filters and more particularly to filters having attenuation and phase characteristics which are not simply realizable with conventional filters.
  • filters are substantially lossless and free of mutual inductances, and at the same time comprise a simple ladder network terminated at both ends by resistances.
  • filters are restricted to certain types of amplitude and phase functions which restrictions can be mathematically formulated.
  • a further object of the invention is to provide filters which while being utilizable at both microwave and low frequencies have very good phase linearity, low time-delay distortion and flat attenuation characteristics within the desired passbands.
  • the invention contemplates a filter or filter arrangement comprising a power dividing circuit means including two external signal-transfer ports and two sum signal-transfer ports and a reactive circuit means.
  • One of the external signaltransfer ports of the power dividing circuit means is the input of the filter and is adapted to receive signals; the other of the external signal-transfer ports of the power dividing circuit means is the output of the filter and is adapted to transmit signals.
  • the reactive circuit means is connected across the sum signal-transfer ports of the power dividing circuit whereby signals received by the reactive circuit means, via the sum signal-transfer ports of the power dividing circuit means, from one of the external signal-transfer ports is reflected by the reactive circuit means and transferred therefrom, via the sum signal-transfer ports of the power dividing circuit means,
  • an cxtert nal signal-transfer port is meant a port which connects to circuits external to the filter.
  • sum signal-transfer ports are meant ports of the power dividing circuit means which are connected to the reactive circuit means for transmitting signals thereto and receiving signals therefrom and wherein the signals received from the reactive circuit means are geometrically (vectorially) added by the power dividing circuit means.
  • FIG. 1 shows schematically a low frequency filter arrangement employing a differential transformer for the power dividing circuit means
  • FIG. 2 shows a filter arrangement with a magic T as the power dividing circuit means
  • FIG. 3 shows amplitude functions and time delay distortions for a conventional filter as well as for a filter arrangement according to the invention
  • FIG. 4 shows a filter arrangement for microwave frequencies
  • FIG. 4a shows as an example a detail of FIG. 4
  • FIG. 5 shows a modification of the filter arrangement ac cording to FIG. 2;
  • FIG. 6 shows a further modification of the filter arrangement according to FIG. 2;
  • FIG. 7 shows a filter arrangement with a 90 hybrid
  • FIG. 8 shows a vector diagram for a magic T
  • FIG. 9 shows a vector diagram for a 90 hybrid
  • FIG. 10 shows a ladder network
  • the filter arrangement schematically shown in FIG. 1 comprises a power dividing circuit means in the form of differential transformer l-2-3-4 with the external signal-transfer ports 1,2,and sum signal-transfer ports 3,4.
  • port I represents the input of the filter arrangement and port 2 represents its output.
  • the sum signaltransfer ports 3,4 and connected to a reactive circuit means or link 5 comprising reactive elements. The construction of this link is determined by the desired transfer function for the filter arrangement.
  • the differential transformer works as a power dividing circuit and divides the power supplied to the port 1 between the two ports 3,4.
  • the link 5 reflects to a large extent the signals supplied through the ports 3,4, and the differential transformer has the property of transmitting to the port 2 of the filter the geometric sum of the signals reflected from the link 5 to the ports 3,4.
  • the arrangement shown in FIG. 2 comprises a magic T as the power dividing circuit means, the ports 2 and A of which, represents the external signal-transfer parts and are the input and output respectively of the filter arrangement, while the link is connected to the sum signal-transfer ports 8, and 8
  • FIG. 3 where the curve A2 shows the amplitude characteristic and B2 the time delay distortion characteristic as a function of the relative frequency w, for a conventional filter, while the corresponding curves A1 and BI relate to similar characteristics of a filter arrangement designed according to the invention.
  • the frequency is normalized with respect to the 3 db. bandwidth.
  • the filter arrangement shown in FIG. 4 is comprised of microwave elements and has a magic T 40 with four ports 31,
  • Externalsignal-transfer port 31 represents the input (2) of the filter arrangement
  • external signal-transfer port 32 represents the output (A) of the filter arrangement.
  • the sum signal-transfer ports 33 (8,) and 34 (8 are connected to a link 50 (a reactive circuit means).
  • Link 50 in principle, represents a wave guide constructed in such a way that its two ends lie close to each other. The detailed construction of this link is also determined by the desired transfer function for the filter arrangement, according to a well known technique. As an example, the construction of this link will be described in a few words. It may be presumed that the filter arrangement is intended for a center frequency of 9 MHZ, with a 3 db.
  • the openings of which into the branch in the longitudinal direction are 4.6 mm. and 3.7 mm. respectively and in the latitudinal direction 18.0 mm. and 7 mm. respectively, and a M4-transformer 507.
  • the space between the centers of the stubs 505 and 506 is 36.5 mm.
  • a nonreciprocal phase shifting element (not shown) can be connected between the magic T and. the link 50.
  • the phase shifting element can be for example a ferrite element under the influence ofa magnetic field.
  • the amplitude function of the filter arrangement may in some cases be affected while its phase function remains unaffected.
  • phase linear filters used, for example, in systems for transfer of frequency modulated signals. These filters may be constructed in such a way that a variation of the nonreciprocal phase shift changes the size of the frequency band within which the amplitude characteristic of the filter is flat without affecting the phase function of the filter.
  • the arrangement shown in FIG. 5 is comprised of a magic T and a link 5 consisting of a nonreciprocal phase shifter SI, having a phase shift of I for signals in one direction and a phase shift of I for signals in the opposite direction.
  • the link 5 is constructed in such a way that its input impedance Z (jw), starting from a region between the power dividing circuit (the T-circuit) and the link 5, for example at the sum signal port 3, is defined by the expression:
  • V M, and M being even functions of the angle frequency w and N, and N being odd functions of the angle frequency a).
  • the arrangement shown in FIG. 7 has a 90 hybrid as a power dividing circuit means, and a reactive circuit means or link 5 consisting of a nonreciprocal phase shifter 71, as well as a reciprocal phase shifter 72.
  • the link 5 is constructed in such a way that its input impedance Z( w) corresponds to the expression (1) above when the transfer function t(j w) of the filter arrangement is defined by the expression:
  • the link 5 must be constructed in such a way that its input impedance z(j w) corresponds to the expression (I) above when the transfer function t(j w) of the filter arrangement is to be:
  • a filter arrangement comprising a power dividing circuit means including a single input port, a single output port and two sum signal-transfer ports wherein signals received by said input port are power divided and transmitted to each of said sum signal-transfer ports and signals received by said sum signal-transfer ports are geometrically added and transmitted to said single output port, and reactive circuit means for partially reflecting signals received thereby, said reactive circuit means being connected across said sum signal-transfer ports for partially transmitting signals between said sum-signaltransfer ports, and so dimensioned that only signals within a given single frequency range are transmitted to said single output port.
  • the power dividing circuit means comprises a hybrid
  • the reactive circuit means comprises reactive elements, a nonreciprocal phase shifter having a phase shift I and a reciprocal phase shifter having a phase shift 11:
  • the reactive circuit means is constructed in such a way that its input impedance, starting from a region between the power dividing circuit means and the reactive circuit means is defined by the expression:
  • Filter arrangement according to claim 4 characterized in that the quantities N, and N are such that the input impedance constitutes the impedance of a simple ladder network.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Networks Using Active Elements (AREA)
  • Treatment Of Water By Ion Exchange (AREA)
US681223A 1966-12-07 1967-11-07 Filter arrangement Expired - Lifetime US3581246A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE16806/66A SE315963B (enrdf_load_stackoverflow) 1966-12-07 1966-12-07

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US3581246A true US3581246A (en) 1971-05-25

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US681223A Expired - Lifetime US3581246A (en) 1966-12-07 1967-11-07 Filter arrangement

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US (1) US3581246A (enrdf_load_stackoverflow)
DE (1) DE1566013A1 (enrdf_load_stackoverflow)
GB (1) GB1187790A (enrdf_load_stackoverflow)
NO (1) NO119749B (enrdf_load_stackoverflow)
SE (1) SE315963B (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2463500A1 (fr) * 1979-08-07 1981-02-20 Sits Soc It Telecom Siemens Dispositif pour l'accord electronique d'un magnetron de puissance
GB2184607A (en) * 1985-12-24 1987-06-24 Plessey Co Plc Microwave beamforming lens

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2531447A (en) * 1947-12-05 1950-11-28 Bell Telephone Labor Inc Hybrid channel-branching microwave filter
US2649576A (en) * 1949-10-07 1953-08-18 Bell Telephone Labor Inc Pseudohybrid microwave device
US2916712A (en) * 1954-07-09 1959-12-08 Sperry Rand Corp Microwave diplexer
US3027525A (en) * 1958-04-28 1962-03-27 Microwave Dev Lab Inc Microwave frequency selective apparatus
US3042883A (en) * 1953-07-24 1962-07-03 Philips Corp Frequency wave-filter
US3337821A (en) * 1963-12-26 1967-08-22 Bell Telephone Labor Inc Transmission line tuning arrangement
US3384841A (en) * 1966-03-10 1968-05-21 Bell Telephone Labor Inc Ferrite phase shifter having longitudinal and circular magnetic fields applied to the ferrite

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2531447A (en) * 1947-12-05 1950-11-28 Bell Telephone Labor Inc Hybrid channel-branching microwave filter
US2649576A (en) * 1949-10-07 1953-08-18 Bell Telephone Labor Inc Pseudohybrid microwave device
US3042883A (en) * 1953-07-24 1962-07-03 Philips Corp Frequency wave-filter
US2916712A (en) * 1954-07-09 1959-12-08 Sperry Rand Corp Microwave diplexer
US3027525A (en) * 1958-04-28 1962-03-27 Microwave Dev Lab Inc Microwave frequency selective apparatus
US3337821A (en) * 1963-12-26 1967-08-22 Bell Telephone Labor Inc Transmission line tuning arrangement
US3384841A (en) * 1966-03-10 1968-05-21 Bell Telephone Labor Inc Ferrite phase shifter having longitudinal and circular magnetic fields applied to the ferrite

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Pascalal, H.G., Strip Line Hybrid Junction, IRE Trans. on Microwave Theory & Techniques Jan. 1957 pp. 23 30 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2463500A1 (fr) * 1979-08-07 1981-02-20 Sits Soc It Telecom Siemens Dispositif pour l'accord electronique d'un magnetron de puissance
GB2184607A (en) * 1985-12-24 1987-06-24 Plessey Co Plc Microwave beamforming lens
GB2184607B (en) * 1985-12-24 1989-10-11 Plessey Co Plc Microwave beamforming lens

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Publication number Publication date
DE1566013A1 (de) 1971-02-18
GB1187790A (en) 1970-04-15
SE315963B (enrdf_load_stackoverflow) 1969-10-13
NO119749B (enrdf_load_stackoverflow) 1970-06-29

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