3,422,378
`R. A. ROSA
`Jan. 14, 1969
`COMPENSATING MEANS FOR MINIMIZING UNDESIRABLE WARATIONS IN
`THE AMPLITUDE OF A REFLECTED WAWE
`Filed Oct. 19, 1965
`
`VARACTOR
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`CONTROL
`SIGNAL
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`HDISTANCE
`X
`-II
`SMNIMUM Cecil
`A non Noeller
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`F.G. 2
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`
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`OUTPUT
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`CONTROL
`SIGNA
`
`FIG 3
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`Page 1 of 4
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`GOOGLE EXHIBIT 1007
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`

`

`United States Patent Office
`
`3,422,378
`Patented Jan. 14, 1969
`
`1.
`
`3,422,378
`COMPENSATING MEANS FOR MINIMIZNG UN
`DESERABLE VARATIONS IN THE AMPLTUDE
`OF A REFLECTED WAVE
`Richard La Rosa, South Hempstead, N.Y., assignor to
`Hazeltine Research, Inc., a corporation of Illinois
`Filed Oct. 19, 1965, Ser. No. 497,889
`U.S. C. 333-28
`7 Claims
`Int, CI. H03h 5/00, 7/38
`
`ABSTRACT OF THE DISCLOSURE
`Disclosed is apparatus capable of compensating for
`variations in the amplitude of the output reflected wave
`signal of a varactor diode phase shifter, for example,
`caused by the variable loss characteristic of the varactor.
`Compensation is achieved by coupling a resistance in the
`transmission line feeding the varactor, at a point where a
`voltage or current null exists when the varactor loss is at
`a relative maximum. Other embodiments are covered.
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`O
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`together with other and further objects thereof, reference
`is had to the following description taken in connection
`with the accompanying drawing, and its scope will be
`pointed out in the appended claims.
`Referring to the drawing:
`FIG. 1 is a diagram, partly schematic, of wave signal
`apparatus embodying the invention in one form;
`FIG. 2 is a table of values helpful in explaining the op
`eration of the wave signal apparatus of FIG. 1; and
`FIG. 3 is a diagram, partly schematic, of wave signal
`apparatus embodying the invention in another form.
`DESCRIPTION OF THE APPARATUS OF FIG. 1
`In FIG. 1 of the drawing there is shown a typical em
`bodiment of wave signal apparatus constructed in accord
`ance with the present invention. Basically, the apparatus
`of FIG. 1 is a conventional varactor diode phase shifter
`consisting of a circulator 10 coupled to one end of a trans
`mission network 11, which is terminated at the other end
`in a variable impedance device, in this case a varactor
`diode 12. While transmission network 11 is shown sche
`matically as a single line in FIG. 1, it will be understood
`to represent any suitable transmission path for supply
`ing an incident wave signal to the varactor and for con
`veying a reflected wave signal therefrom, such as coaxial
`cable, waveguide, stripline, lumped network, etc.
`In the apparatus of FIG. 1, varactor diode 12 has a
`loss characteristic which varies between a relative mini
`mum value and a relative maximum value when the junc
`tion capacitance of the diode is varied correspondingly
`between a first capacitance and a second capacitance.
`This variation in the loss characteristic of diode 12 causes
`the reflected wave signal to be variably attenuated in a
`corresponding manner. That is, when the loss character
`istic of diode 12 is at a maximum value, the reflected
`wave signal will exhibit a maximum attenuation, and like
`wise when the loss characteristic of diode 12 is at a
`minimum, the reflected wave signal will exhibit a mini
`mum attenuation.
`In accordance with the present invention, however,
`there is also included in the wave signal apparatus of
`FIG. 1, compensating means, which in this case is the re
`sistance (R), coupled at a predetermined point in trans
`mission network 11 for minimizing the undesirable effect
`of the variable loss characteristic of varactor 12 on the
`reflected wave signal. As mentioned previously, this unde
`sirable effect is the variable attenuation of the reflected
`Wave signal due to variations in the loss characteristic of
`diode 12, resulting from changes in the diode's junction
`capacitance. More specifically, resistance (R) is coupled
`between transmission network 11 and ground at a point
`X units from the effective location of the diode junction.
`In the embodiment of FIG. 1, the diode junction is as
`Sumed to be directly at the terminated end of transmis
`sion network 11 for ease of illustration. In an actual cir
`cuit, however, those skilled in the art will be readily
`able to determine the actual location of the diode junc
`tion, since this depends on the physical configuration of
`the particular diode and diode mount used.
`OPERATION OF THE APPARATUS OF FIG. 1
`The operating principles of a varactor diode phase
`shifter of the type shown in FIG. 1, are well known and
`will not be described in detail herein. Generally, however,
`a wave signal is supplied via an input of circulator 10 to
`transmission network 11. This incident wave signal is
`shown in FIG. 1 as a dashed arrow pointing toward
`varactor diode 11, since the incident wave signal propa
`gates toward the diode along the transmission network.
`The incident wave signal is reflected by varactor diode 12
`in accordance with the reflection coefficient (p) present
`
`In general, the present invention is concerned with
`Wave signal apparatus. More particularly, the invention
`concerns a compensating means which is included in such
`apparatus to provide compensation for an otherwise vari
`able loss characteristic of the apparatus.
`In prior art, it is common practice to use wave signal
`apparatus consisting of a transmission network coupled at
`one end to a circulator and terminated at the other end in
`a variable impedance device, such as a varactor diode, to
`serve as a phase shifter, for example. As the impedance
`of the device is varied, the reflection coefficient (p) of
`the termination varies accordingly. In this manner, an
`incident wave signal traveling toward the termination on
`the transmission network is reflected therefrom with a
`phase shift determined by the reflection phase angle of the
`termination. Until now, the inherent drawback of this
`type system has been the fact that loss in the variable
`impedance device varied with variations in its impedance.
`This, in effect, caused amplitude modulation of the re
`flected signal in accordance with variations in the mag
`nitude of the reflection coefficient of the termination,
`which is a highly undesirable effect.
`It is therefore an object of the present invention to
`provide wave signal apparatus of the type described
`wherein a compensating means is included to minimize
`said amplitude modulation.
`It is another object of the present invention to pro
`50
`vide wave signal apparatus of the type described, where
`in a resistance is coupled in the transmission network at
`a predetermined point to provide compensation for the
`variable loss characteristic of the variable impedance de
`WC
`In accordance with the present invention wave signal
`apparatus comprises a variable impedance device having
`a loss characteristic which varies with variations in the
`impedance of the device and a transmission network
`for supplying an incident wave signal to the device and
`for conveying a reflected wave signal therefrom, the level
`of the reflected wave signal being undesirably attenuated
`in accordance with the varying loss characteristic of the
`device. The wave signal apparatus also includes compen
`Sating means coupled in the transmission network and
`jointly responsive to the incident and reflected wave sig
`nals for producing an attenuation of the reflected wave
`signal which varies inversely with the attenuation caused
`by the varying loss characteristic of the device, thereby
`developing an output reflected wave signal wherein unde
`sirable variations in level are minimized.
`For a better understanding of the present invention
`
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`Page 2 of 4
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`5
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`3,422,378
`4.
`3
`magnitude (K), and undesirable amplitude variation in
`ed by the diode termination, thus undergoing a phase
`the final reflected wave signal appearing at the output of
`shift dependent upon the reflection phase angle 0, where:
`circulator 10 will be minimized.
`(1)
`In accordance with another embodiment of the present
`invention shown in FIG. 3, it will be appreciated that the
`Likewise, in the illustration of FIG. 1 the reflected wave
`same form of loss compensation can be obtained by cou
`signal is shown as a dashed arrow pointing away from
`pling a resistance (R') in series with the transmission net
`the varactor diode. Those skilled in the art will recognize
`work at a point where a current minimum exists in the
`the fact that the incident and reflected wave signals com
`standing wave pattern when the variable impedance de
`bine to form a standing wave pattern in the transmission
`vice is providing maximum loss. Just as described above
`network 11. The reflected wave signal is eventually separ
`for the shunt resistance-voltage minimum case, here also,
`rated from the incident wave signal by circulator 10 in
`as the reflection coefficient (p) of the termination is
`a conventional manner, and is presented at the output of
`varied, likewise, the current minimum will move away
`the circulator.
`from the series resistance (R') thus permitting the re
`Since the impedance of the varactor diode may be
`sistance to compensate for the decreasing loss in the vari
`varied by varying a bias control signal supplied thereto,
`able impedance device. By proper selection of the Series
`then, the reflection coefficient (p) will vary accordingly,
`resistance (R') the increasing attenuation of the reflected
`thereby providing a controlled variable phase shift of the
`wave signal produced by the resistance, as the current
`reflected signal.
`minimum moves away from it, may be made to compen
`Ideally, in such a phase shifter, any variation in the re
`sate for the decreasing loss in the diode. Thus, here again
`flection coefficient (p) should involve only a variation in
`20
`the effective reflection coefficient produced by the diode
`the phase angle (0) thereof, and not a variation in the
`acting in conjunction with the series resistance, will have
`magnitude (K), since a variation in the magnitude (K)
`a substantially constant magnitude (K), and undesirable
`will cause a corresponding amplitude variation in the re
`amplitude variation in the final reflected wave signal ap
`flected signal. However, due to the presence of series re
`pearing at the output of the circulator will be minimized.
`25
`sistance in the varactor diode, loss in the diode will vary
`While there have been described what are at present
`with variations in its junction capacitance, causing at
`considered to be the preferred embodiments of this inven
`tendant variations in the magnitude (K) of the reflection
`tion, it will be obvious to those skilled in the art that vari
`coefficient presented by the diode. In accordance with one
`ous changes and modifications may be made therein with
`aspect of the present invention, however, this variation
`out departing from the invention and it is, therefore,
`in loss within the diode may be compensated for in an
`aimed to cover all such changes and modifications as fall
`exceedingly simple manner by shunting a resistance (R)
`within the true spirit and scope of the invention.
`across the transmission network at a distance (X) units
`What is claimed is:
`from the diode junction, where (X) is measured in units
`1. Wave signal apparatus, comprising:
`of the wavelength (A) of the incident Wave signal.
`a variable impedance device having a loss charac
`In describing now the operation of the present inven
`teristic which varies with variations in the impedance
`tion, it will be assumed that the junction capacitance (C)
`of said device;
`of diode 1 may be varied from a first value (C1) to a
`a transmission network for supplying an incident wave
`second value (C2), where C1<C2, presenting reflection
`signal to said device and for conveying a reflected
`coefficients of Ip-KZOil and (p2=K2/02 respectively,
`wave signal therefrom, the level of said reflected
`where K1)K2; 61<62.
`wave signal being undesirably attenuated in accord
`When the diode junction capacitance is (C2), diode
`ance with the varying loss characteristic of said de
`loss is greatest as indicated by the reflection coefficient
`VIce;
`(p2) since Kaki. At this reflection coefficient (p), those
`and compensating means coupled in said transmission
`skilled in the art will recognize that a voltage minimum
`network and jointly responsive to said incident and
`exists in the standing wave pattern in transmission net
`reflected wave signals for producing an attenuation
`work at a distance (X--n2r) from the diode 11, assum
`of said reflected wave signal which varies inversely
`ing a frequency (f) and corresponding wavelength (A)
`with the attenuation caused by the varying loss
`for the incident wave signal, where:
`characteristic of said device, thereby developing an
`output reflected wave signal wherein undesirable
`180°--9X.
`variations in level are minimized.
`X2
`(2)
`7200
`2. Wave signal apparatus constructed in accordance
`If a resistance (R) is shunted across the transmission net
`with claim 1 wherein said incident and reflected wave
`work at the distance (X) from the diode, for example,
`signals combine to establish a standing wave in said trans
`it will have little effect so long as the reflection coefficient
`mission network which varies in accordance with varia
`(p) remains the same. However, it will be appreciated
`tions in the impedance of said device, and wherein said
`that as that diode junction capacitance SWings to (C1),
`compensating means is responsive to variations in the
`and the reflection coefficient to p1=K1 Z61), diode loss
`standing wave for producing said attenuation of the re
`decreases, and at the same time, the voltage minimum in
`flected wave signal.
`transmission network 11 moves away from point (X2) to
`3. Wave signal apparatus constructed in accordance
`(X) as shown in the table of FIG. 2, where:
`with claim 2, wherein said compensating means is solely
`resistive in nature and is coupled at a predetermined point
`in said transmission network so as to be responsive to the
`standing wave pattern at said point, and wherein said
`(3)
`7200
`1
`output reflected wave signal is of a substantially uniform
`Since there is no longer a voltage minimum at point
`level, regardless of variations in the loss characteristic
`(X), resistance (R) becomes effective in providing loss.
`of said device.
`4. Apparatus constructed in accordance with claim 3
`Thus, while diode loss decreases in going from (C2) to
`(C), the loss provided by shunt resistance (R) increases.
`wherein said resistive means is a single resistance coupled
`By proper selection of the resistance (R), the increasing
`at said predetermined point between said transmission
`attenuation of the reflected wave signal produced by the
`network and ground.
`resistance may be made to compensate for the decreasing
`5. Apparatus constructed in accordance with claim 3
`wherein said resistive means is a single resistance coupled
`loss in the diode. Thus, the effective reflection coefficient
`produced by the diode acting in conjunction with the
`at said predetermined point in series with said transmis
`shunt resistance (R), will have a substantially constant 75 Sion network.
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`Page 3 of 4
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`

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`3,422,378
`5
`6. Apparatus constructed in accordance with claim 4
`wherein said resistance is coupled in said transmission
`network at a predetermined point where a voltage mini
`mum exists in said standing wave when the loss charac
`teristic of said device is at a maximum.
`7. Apparatus constructed in accordance with claim 5
`wherein said resistance is coupled in said transmission net
`work at a predetermined point where a current minimum
`exists in said standing wave when the loss characteristic
`of said device is at a maximum.
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`5
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`6
`References Cited
`UNITED STATES PATENTS
`10/1949 Bradley ----------- 333-28 X
`2,485,029
`8/1965 Bachnick.
`3,204,198
`HERMAN KARL SAALBACH, Primary Examiner.
`PAUL L. GENSLER, Assistant Examiner.
`U.S. C. X.R.
`
`l0 333-31
`
`Page 4 of 4
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