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
• • 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

Definitions

• This invention relates to microwave and millimeter wave integrated circuits and more particularly to a planar power divider/combiner circuit which may be used to divide an RF signal into a plurality of signals or combine a plurality of RF signal sources into a single signal.
• RF signal includes both microwave and millimeter wave signals.
• Power divider circuits have been developed to divide RF signals into a number of signals to feed multi-element antennas.
• power combiner circuits were developed to combine the output of a number of solid state amplifiers, chip transitors or oscillators.
• Several different circuit geometries have evolved to accomplish this power dividing or combining such as: The circular-geometry Wilkinson power divider disclosed in G. J. Wilkinson, "An-N Way Hybrid Power Divider," IRE Trans. on Microwave Theory and Tech. , MTT-8 No.l, 116-19 (Jan 1960); the fork power divider disclosed in an article by A. Saleh entitled "Planar, Electrically Symetric N-Way Hybrid Power Dividers/Combiners," IEEE Trans. Microwave Theory
• a power divider/combiner circuit comprises a flat tapered strip of electrically conductive material with a plurality of slots therein extending from the wide end of the tapered strip toward the narrow end of the strip such that the strip defines a plurality of fingers.
• the narrow end of the tapered strip forms one port, either an input or an output port, and the respective tips of the fingers form a plurality of ports which can be either input ports or output ports.
• Isolation resistors connect adjacent fingers at quarter wavelength distances along the fingers.
• the tapered strip is mounted on a dielectric substrate.
• An input signal from an RF signal source may be fed into the single port at the narrow end of the tapered strip.
• the input signal will be divided into a plurality of RF signals of equi-amplitude and equal phase at the finger ports.
• these signals will combine into a single RF signal at the single port at the narrow end of the tapered strip.
• FIG. la is a top plan view of a power divider/ combiner circuit according to the principles of the present invention.
• FIG. lb is a cross-sectional view taken along line lb-lb of FIG. la;
• FIG. 2 is an enlarged perspective view partly broken away, illustrating a portion of a power divider/ combiner circuit according to another embodiment of the invention.
• FIG. 3 is a top plan view illustrating still another embodiment of the invention using a pair of power divider/combiner circuits. It will be appreciated that FIGS. 1-3 are not drawn to scale.
• a power divider/combiner circuit 10 may include a tapered strip of electrically conductive material 1 with a narrow end 2 and a wide end 3.
• the tapered strip 1 is preferably made of a metal such as gold, but may be made of any other good electrically conductive material.
• the strip may be about 2-3 skin depths thick for the lower frequency of the desired bandwidth of operation.
• the tapered strip 1 provides a tapered transmission line in which the contour of the taper is selected to match the impedance at the narrow end 2 of the tapered strip to the impedance at the wide end 3 of the tapered strip over the desired bandwidth of operation.
• the contour and lengths of the taper determine the maximum inband reflection coefficient and the lower cut off frequency, respectively. While many taper geometrices are available, such as an exponential taper or a hyperbolic taper, a Dolph- Tchebycheff taper has been found to afford optimum performance because it provides a minimum length for the transmission line for a specified maximum magnitude reflection coefficient in the passband.
• the design equations for the Dolph-Tchebycheff taper may be found in an article authored by R. W. Klopfenstein entitled “A Transmission Line Taper of Improved Design," 44 Proc. IRE 31-35 (Jan. 1956), which is incorporated herein by reference.
• the tapered strip 1 has a plurality of slots 4 therein extending from the wide end 3 of the strip toward the narrow end 2 of the strip which define a plurality of conductor fingers 5.
• the narrow end 2 of the tapered strip 1 thus defines a single port 2 which can be either an input port or an output port depending on whether the circuit is used as a power divider or combiner, respectively.
• the tips of the conductor fingers 5 at the wide end 2 of the strip 1 define N ports 6, where N is an integer greater than 1, which can be either output ports or input ports depending on whether the circuit is used as a power combiner or divider, respectively.
• N is an integer greater than 1
• 5 ports are shown FIGS la and lb, any number of ports are possible.
• the slot width i.e. the spacing between the adjacent fingers 5, should be kept small to enhance coupling between adjacent fingers and thus ensure that the structure retains the characteristics of a DolphTchebycheff tapered transmission line.
• a slot width of about 1.5 mil has been typically used.
• the fingers 5 function as strip line conductors.
• Isolation resistors 7 connect adjacent conductor fingers 5.
• the resistors 7 absorb signals that are reflected back into the power divider/combiner circuit, the odd mode propagation.
• These resistors may be chip resistors 7 disposed on top of the strip as illustrated in FIG. 1, or thick or thin film resistors 7* located between the fingers 5 in the slots 4 on the substrate 8, as illustrated in FIG. 2.
• the number of isolation resistors 7 disposed along each pair of adjacent fingers 5 should preferably be one less than the total number of finger ports in the circuit to effectively absorb the propagation of odd modes.
• la and lb where 5 ports are used there are 4 resistors along each pair of adjacent fingers.
• additional or fewer resistors also may be employed. Several methods are available for determining the resistance value for the isolation resistors 7.
• the tapered strip 1 may be adhesively mounted onto a dielectric substrate 8 which is generally a thin flat plate of dielectric material.
• the substrate for example, may be made of sapphire, berryllium oxide, quartz, or alumina.
• the adhesive material 9 may be chrome or ti-tungsten or any other good conductive adhesive material.
• the dielectric substrate may be grounded at the bottom surface 11 of the substrate 8.
• FIG. 3 illustrates a power divider/combiner circuit according to a further embodiment of the present invention.
• the circuit of FIG. 3 includes an RF signal source 30 which may be an oscillator or amplifier, for example. The signal from the source 30 is fed into the single port 2a of a power divider/combiner circuit 31.
• This single RF signal is divided into a plurality of RF signals at the finger ports 6a.
• These signals are amplified by respective amplifiers 32, which may be hybrid amplifiers, pre-matched chips, microwave monolithic integrated circuit chips, transitor chips, for example, and fed into respective finger ports 6b of power divider/ combiner circuit 33 according to the invention which, in turn, combines these N amplified RF signals into a single RF signal at port 2b.
• the resultant output signal is the summation of the various output signals from the amplifiers 32.

Priority Applications (4)

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Publications (1)

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Cited By (1)

Citations (3)

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• 1987
  • 1987-03-30 AU AU73572/87A patent/AU581817B2/en not_active Ceased
  • 1987-03-30 KR KR1019880700086A patent/KR900008628B1/ko not_active IP Right Cessation
  • 1987-03-30 DE DE8787902973T patent/DE3779269D1/de not_active Expired - Fee Related
  • 1987-03-30 JP JP62502712A patent/JPS63503429A/ja active Granted
  • 1987-03-30 EP EP87902973A patent/EP0271505B1/en not_active Expired - Lifetime
  • 1987-03-30 WO PCT/US1987/000681 patent/WO1987007438A1/en active IP Right Grant
• 1988
  • 1988-01-14 NO NO880153A patent/NO171580C/no unknown
  • 1988-01-26 DK DK035988A patent/DK35988D0/da not_active Application Discontinuation

Patent Citations (3)

Non-Patent Citations (4)

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