EP0396430A2 - Réseau radiofréquence - Google Patents

Réseau radiofréquence Download PDF

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Publication number
EP0396430A2
EP0396430A2 EP90304909A EP90304909A EP0396430A2 EP 0396430 A2 EP0396430 A2 EP 0396430A2 EP 90304909 A EP90304909 A EP 90304909A EP 90304909 A EP90304909 A EP 90304909A EP 0396430 A2 EP0396430 A2 EP 0396430A2
Authority
EP
European Patent Office
Prior art keywords
branch
node
input
common
radio frequency
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Withdrawn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
EP90304909A
Other languages
German (de)
English (en)
Other versions
EP0396430A3 (fr
Inventor
Clement Peter Burrage
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.)
BAE Systems Electronics Ltd
Original Assignee
Marconi Co Ltd
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 Marconi Co Ltd filed Critical Marconi Co Ltd
Publication of EP0396430A2 publication Critical patent/EP0396430A2/fr
Publication of EP0396430A3 publication Critical patent/EP0396430A3/fr
Withdrawn legal-status Critical Current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
    • H01P5/00—Coupling devices of the waveguide type
    • H01P5/12—Coupling devices having more than two ports
    • H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port

Definitions

  • This invention relates to a radio frequency network usable for splitting an r.f. signal or for combining a plurality of r.f. signals.
  • a particular application for a combiner is in transmitters, for example television transmitters.
  • a television transmitter uses a klystron in the r.f output stage to amplify the signal to be passed to the antenna. While klystrons generally perform this function satisfactorily and reliably, they require complex cooling arrangements, usually employing circulating water, and these require regular maintenance. In addition, failure of the klystron renders the transmitter inoperative.
  • the present invention provides a radio frequency network, comprising a first common node connected to a common input or output port, a second common node, and at least three identical branches therebetween, each branch comprising a first branch node, to which is connected a balance load, and a second branch node spaced therefrom and connected to a branch output or input port, the network being dimensioned and arranged such that an r.f. signal of a specific frequency input at the common input port is divided equally between all the branch output ports, and a plurality of identical r.f. signals of the specific frequency applied in phase to all the branch input ports appear combined at the common output port.
  • All the inter-nodal distances are preferably equal to one quarter of the operating wavelength of the input signal or signals.
  • a narrow network bandwidth is unsatisfactory. It has been found that the values of the impedances of the portions of the branches between the second common nodes and each first branch node have some influence on the bandwidth of the network. By selection of suitable impedances for these portions, the bandwidth may be increased.
  • the impedance is preferably low relative to the other portions of the network.
  • a greater increase in bandwidth may be achieved by providing a quarter wavelength transformer between the first common node and the common input/output port, the length of the line added being a quarter of the wavelength at the centre of the bandwidth. Still further improvement of the bandwidth may be obtained by connecting to the first common node a short circuited stub, preferably having a length equal to a quarter wavelength.
  • a twenty way combiner with a bandwidth of 88 to 108 MHz for an input VSWR of less than 1.02:1 can be achieved.
  • the network of the invention may be formed of coaxial cable, multi-wire cable, waveguide, or even LC circuits to give a 90° phase shift.
  • the quarter wavelength lines may conveniently be any odd multiple of quarter wavelengths where this makes the network physically easier to realise.
  • the use of greater lengths carries the disadvantage, however, that the operating bandwidth becomes narrower.
  • the network comprises sixteen identical branches 1a to 1p extending between a first common node 2 and a second common node 3.
  • Each branch 1 comprises three equal lengths of coaxial cable joined at a first branch node 4 and at a second branch node 5.
  • a balance load 6 is connected to the first branch node 4, while a branch input port 7 is connected to the second branch node 5.
  • the inter-nodal length is in each case one quarter of the wavelength at the centre of the operating bandwidth for the network, thus giving a 90° phase shift in each portion of the network for that wavelength.
  • the first common node 2 is connected to an output port 8.
  • sixteen identical r.f. signals are applied in phase to the branch input ports 7a to 7p.
  • the signal appearing at the output port 8 is substantially the sum of the input signals.
  • the bandwidth of the network may be increased by connecting a quarter wavelength transformer 9 between the first common node 2 of the network illustrated in Figure 1, and the output port 8.
  • a further improvement may be achieved by connecting a short circuited quarter wavelength stub 10 to the first common node 2.
  • Adjustment of the impedances of the lines extending between the second common node 3 and each of the first branch nodes 4a to 4p can also improve the bandwidth. The effects of these modifications are illustrated by Figures 3, 4 and 5.
  • Figure 3 illustrates insertion loss and input VSWR against frequency for the network illustrated in Figure 1, where, in each branch, the impedance of the line from the second common node 3 to the first branch node 4 is 280 ohms, the impedance of the line between the two branch nodes 4 and 5 is 50 ohms, and the impedance of the third line is 12.5 ohms. It will be seen that, moving away from the central frequency of approximately 670 MHz, one encounters rapidly increasing loss and VSWR.
  • Figure 4 shows the effect of a circuit in accordance with Figure 2, but without the short circuited stub.
  • the impedances are set in each branch, from the second common node 3 to the first common node 2 as 5 ohms, 50 ohms and 100 ohms respectively.
  • the quarter wavelength transformer has an impedance of 25 ohms. It will be seen that the bandwidth over which very low loss is experienced is very much greater, extending from about 470 MHz to about 860 MHz the VSWR over this range is also substantially reduced.
  • Figure 5 shows the effect of adding a short-circuit stub, having an impedance of 49 ohms.
  • the impedance of the line in each branch extending from the second common node to the first branch node is increased to 50 ohms, with all other impedances remaining the same. It will be seen that, while the loss is very slightly increased over the bandwidth of 470 to 860 MHz, the VSWR is significantly reduced further.
  • the network of the application although particularly described with reference to television transmitters, will find application in many other types of transmitter, and generally where a plurality of r.f. signals are to be combined together or produced from a single such signal.

Landscapes

  • Microwave Amplifiers (AREA)
  • Amplifiers (AREA)
  • Transmitters (AREA)
EP19900304909 1989-05-05 1990-05-04 Réseau radiofréquence Withdrawn EP0396430A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8910410A GB2232028B (en) 1989-05-05 1989-05-05 Radio frequency network
GB8910410 1989-05-05

Publications (2)

Publication Number Publication Date
EP0396430A2 true EP0396430A2 (fr) 1990-11-07
EP0396430A3 EP0396430A3 (fr) 1992-02-05

Family

ID=10656307

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900304909 Withdrawn EP0396430A3 (fr) 1989-05-05 1990-05-04 Réseau radiofréquence

Country Status (5)

Country Link
EP (1) EP0396430A3 (fr)
JP (1) JPH0388402A (fr)
AU (1) AU625827B2 (fr)
CA (1) CA2015945A1 (fr)
GB (1) GB2232028B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0508662A3 (en) * 1991-04-11 1993-04-14 Harris Corporation N-way power combiner/divider
WO2001061780A1 (fr) * 2000-02-16 2001-08-23 Signal Technology Corporation Circuit combineur d'emission de puissance f.r.

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5223809A (en) 1992-04-24 1993-06-29 At&T Bell Laboratories Signal isolating microwave splitters/combiners

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4156212A (en) * 1977-12-19 1979-05-22 Nautical Electronic Laboratories, Ltd. Combiner system
US4163955A (en) * 1978-01-16 1979-08-07 International Telephone And Telegraph Corporation Cylindrical mode power divider/combiner with isolation
GB2069244A (en) * 1980-02-11 1981-08-19 Decca Ltd Radio frequency zero phase power combiner
DE8816832U1 (de) * 1988-04-30 1990-09-20 Grundig E.M.V. Elektro-Mechanische Versuchsanstalt Max Grundig holländ. Stiftung & Co KG, 8510 Fürth Hybrid-Leistungsteiler, insbesondere dreitoriger Hybrid

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0508662A3 (en) * 1991-04-11 1993-04-14 Harris Corporation N-way power combiner/divider
WO2001061780A1 (fr) * 2000-02-16 2001-08-23 Signal Technology Corporation Circuit combineur d'emission de puissance f.r.

Also Published As

Publication number Publication date
GB2232028B (en) 1992-12-09
AU5467590A (en) 1990-11-08
JPH0388402A (ja) 1991-04-12
GB8910410D0 (en) 1989-06-21
GB2232028A (en) 1990-11-28
CA2015945A1 (fr) 1990-11-05
AU625827B2 (en) 1992-07-16
EP0396430A3 (fr) 1992-02-05

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