United States Patent [191
`Provencher
`
`[111
`[45]
`
`4,032,922
`June 28, 1977
`
`[54] MULTIBEAM ADAPTIVE ARRAY
`
`[75] Inventor: éoslegh 3- "Wench", San Diego,
`
`a 1 .
`
`.
`_
`.
`.
`[73] Asslgnee' The Umted Smtes of Amen“ as
`represented by the Secretary of the
`Navy, Washington, DC.
`Jan. 9, 1976
`[22] Filed:
`2‘ A l. N A 4
`[
`1
`pp
`0 6 7’828
`[52] US. Cl. ............................. .. 343/854; 343/7 A;
`343/100 SA
`[51] Int. Cl.2 ........................................ .. H01Q 3/26
`[58] Field of Search .... .. 343/854, 853, 7 A, 100 R,
`343/100 SA, lOO LE
`Re‘erences Cited
`
`[56]
`
`UNITED STATES PATENTS
`
`3,868,695
`3,940,770
`
`3,967,279
`
`2/1975 Kadak ............................. .. 343/854
`2 l976 F
`tt t l. . . . . .
`. . . .. 343/854
`
`6‘1976 22:;
`
`....................... .. 343/854
`
`Primary Examiner—Eli Lieberman
`Attorney, Agent, or Firm—R. S. Sciascia; G. J. Rubens;
`H Fendelman
`'
`ABSTRACT
`[57]
`An antenna system utilizing the multibeam‘ advantages
`of the Butler matrix to achieve beam steering with the
`additional capability of placing nulls in the direction of
`undesired radiation. The system comprises essentially a
`Butler matrix with an adaptive circuit interposed be
`tween each of the antenna elements and a correspond
`ing one of the hybrid matrices of the Butler matrix.
`Switch. means are also provided for separating the
`transmit and receive functions.
`
`3,736,592
`
`5/1973 Coleman ......................... .. 343/854
`
`6 Claims, 3 Drawing Figures
`
`3°
`
`4“\
`
`46\
`
`40
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`
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`TO ADAPTIVE CIRCUITS
`TO RECEIVER
`
`WAVES607_1012-0001
`
`Petitioner Waves Audio Ltd. 607 - Ex. 1012
`
`

`
`US. Patent June 28, 1977
`
`Sheet 1 of2
`
`4,032,922
`
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`TO ADAPTIVE CIRCUITS
`TO RECEIVER
`
`WAVES607_1012-0002
`
`Petitioner Waves Audio Ltd. 607 - Ex. 1012
`
`

`
`US. Patent June 28, 1977
`
`Sheet 2 of 2
`
`4,032,922
`
`QUADRATURE
`FROM
`ANTENNA --> HYBR")
`ELEMENT
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`BANDPASS
`FILTER
`
`62
`
`LIMITER
`
`s4
`
`ZONAL FILTER 66
`
`WAVES607_1012-0003
`
`Petitioner Waves Audio Ltd. 607 - Ex. 1012
`
`

`
`1
`
`MULTIBEAM ADAPTIVE ARRAY
`
`4,032,922
`
`5
`
`15
`
`BACKGROUND OF THE INVENTION
`Electronic scanning of corporate structure antennas
`has been greatly simpli?ed in the number of power
`dividing and phasing matrices required by the Butler
`matrix which utilizes the phase shifts occurring in hy
`brid dividers. The theory, construction and operation 10
`of the Butler matrix is well known and is explained in
`detail in the article “Beam-Forming Matrix Simplifiers
`Design of Electronically Scanned Antennas” by Jesse
`Butler and Ralph Lowe, Electronic Design, Apr. 12,
`196i. Although the Butler system is effective for ac
`complishing beam steering it is incapable of minimizing
`the effects of undesired radiation.
`The problem of minimizing undesirable received
`signals has been approached by the use of “adaptive
`arrays.” The design of an adaptive array is dependent
`upon the principles of feedback design. The main ob
`jective of the array is to minimize an undesired signal or
`to maximize the desired signal in a given direction.
`Typically, a broad beam is formed by using a small
`number of elements. When an undesired signal is inci
`dent on the antenna, it is split into in-phase and quadra
`ture components, compared with a reference signal and
`integrated. If no correlationn is achieved, the weights
`or excitation coefficients, W, in each of the in-phase
`and quadrature are adjusted to place a minimum in the
`direction of the undesired signal. Adaptive antenna
`systems are further described in the article by Robert
`L. Riegler and Ralph T. Compton, Jr., “An Adaptive
`Array for Interference Rejection,” Proc. IEEE, Vol
`ume 61, No. 6, June 1973 and also in the article
`"Adaptive Antenna Systems,” by B. Widrow, P. E.
`Mantey, L. J. Griffiths, and B. B. Goode, Proc. IEEE,
`Volume 55, No. 12, December 1967, both articles
`incorporated herein by reference. The disadvantage of 40
`the adaptive systems heretofore described is basically
`that the systems are receive only and, thereby, require
`a separate system for transmission.
`
`20
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`25
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`30
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`SUMMARY OF THE INVENTION
`The present invention relates to a low cost, light
`weight, compact multi-simultaneous beam antenna
`system for minimizing undesired signals and radiation
`by self adapting through feedback circuits, for provid
`ing multiple beams which can also self adapt and for
`providing multiple beams for transmission if desired.
`More speci?cally, adaptive circuits are used in con'
`junction with the basic Butler matrix to achieve multi
`ple beam capability, nulling and/or jamming capabili
`ties and high‘power concentration (directivity) on a
`target all in a single radiating structure.
`
`45
`
`50
`
`55
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`Statements of the Objects of the Invention
`Accordingly, it is the primary object of the present
`invention to disclose a single antenna system providing
`a plurality of simultaneous beams for receive, null
`steering in selected directions and maximum transmit
`power in selected directions.
`Other objects, advantages and novel features of the
`invention will become apparent from the following
`detailed description of the invention when considered
`in conjunction with the accompanying drawings.
`
`65
`
`2
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a circuit schematic diagram of the mul
`tibeam adaptive array of the present invention.
`FIG. 2 is a circuit schematic diagram of an exemplary
`adaptive circuit suitable for use in the present inven
`tion.
`FIG. 3 is a block diagram of a reference signal gener
`ator suitable for use in the present invention.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`Referring now to FIG. 1 there is illustrated the an
`tenna system 10 of the present invention. Beginning
`with the Butler matrix portion, the antenna system 10
`includes ?rst and second 90° hybrid couplers l2 and 14
`having input ports denoted as port 12,, port 122, port
`14, and port 14,. The input ports are connected to
`microwave signal generator 16 through switch 18
`which may comprise a T-R switch, a diode switch, a
`ferrite switch, a reed switch, a multiple pole muliple
`throw switch or any other switching means for permit
`ting selective inputs to any of the input ports, to all the
`input ports or any combination thereof and that has the
`capability of isolating the generator 16 from the ports
`12,, 12,, 14, and 142 during the receive mode opera
`tion. Port 123 is connected through 45° phase shifter 20
`to port 22, of 90° hybrid coupler 22 and, Iikeile, port
`14, or 90° hybrid coupler 14 is connected through 45
`degree phase shifter 24 to port 262 of 90° hybrid 26.
`Ports l2, and 14,, are cross connected to the ports 26,
`and 222, respectively, as illustrated. Port 223 or 90°
`hybrid 22 is coupled through switch 28 to the input of
`antenna element 30. Similarly, port 264 is coupled
`through switch 32 to the input of radiating antenna
`element 34. Ports 224 and 26,, are cross coupled
`through switches 36 and 38, respectively, to radiating
`antenna elements 40 and 42. Switches 28, 32, 36 and
`38 may comprise T-R switches or multi-pole multi
`throw switches, diode switches, ferrite switches, or reed
`switches with the appropriate associated control cir
`cuits and serve to isolate the transmit and receive func
`tions of the system 10.
`The operation of the device thus far described is the
`same as that of a conventional Butler matrix. Brie?y
`and by way of example, assuming an input at port 12,
`from switch 18, the input signal would be divided into
`two equal outputs at ports 12,, and 124 with a 90° phase
`shift being introduced by the hybrid l2 therebetween.
`The signal departing from port 123 would be further
`phase shifted by the phase shifter 20 and further split
`and phase shifted by the 90° hybrid coupler 22 between
`ports 223 and 22,. Similarly, the signal departing from
`port 12, would be inputted to port 26, and divided and
`phase shifted by 90° hybrid 26 between ports 26;, and
`26,. The signals then pass through the respective
`switches 28, 32, 36 and 38, propagate along the path
`denoted as “TRANSMIT" and are radiated by the
`respective antenna elements 30, 34, 40 and 42, the
`radiated signals being separated by equal phase shifts.
`It is to be understood that the Butler matrix shown in
`FIG. 1 and described herein is exemplary only and that
`any size Butler matrix could be utilized in the present
`invention, i.e., the system 10 of the present invention
`could be built for an array having 8, l6 . . . 2" (N =
`integer), radiating elements.
`The remaining elements of the system 10 of the pre
`sent invention will now be described. An adaptive cir~
`
`WAVES607_1012-0004
`
`Petitioner Waves Audio Ltd. 607 - Ex. 1012
`
`

`
`20
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`25
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`4,032,922
`4
`pass ?lter 62 is chosen to be wide enough to pass the
`desired signal but not wide enough for the full interfer
`ence bandwidth. The limiter 64 establishes the refer
`ence signal amplitude and the zonal ?lter 66 removes
`unwanted spectral products from the limiter. Interfer
`ence spectral components outside the ?lter pass band
`will not be present in the reference signal. Hence the
`error signal will contain these components. As a result,
`the array will null the interference. During transmis
`sion, switch 18 couples the microwave signal generator
`16 to the Butler matrix which is coupled to the output
`antenna element by means of switches 28, 38, 36 and
`32 by means of the alternate TRANSMIT path around
`the adaptive circuits as illustrated in FIG. 1.
`Obviously many modi?cations and variations of the
`present invention are possible in the light of'the above
`teachings. It is therefore to be understood that within
`the scope of the appended claims the invention may be
`practiced otherwise than as speci?cally described.
`I claim:
`1. A system comprising:
`a Butler matrix including at least a plurality of input
`ports, a ?rst plurality of hybrid couplers coupled to
`said input ports, a plurality of phase shifters cou
`pled to said ?rst plurality of hybrid couplers, a
`second plurality 'of hybrid couplers coupled to said
`plurality of phase shifters;
`a plurality of antenna elements; and
`a plurality of adaptive means, each being coupled
`between one of said plurality of antenna elements
`and a corresponding one of said second plurality of
`hybrid couplers for minimizing the amplitude of an
`undesired signal received by said one of said plural
`ityof antenna elements to which it is coupled, each
`adaptive means including means for comparing
`said received signal with a reference signal to de
`velop an error signal for feedback control.
`2. The system of claim 1 wherein said second plural
`ity of hybrid couplers includes a plurality of output
`ports and further including a plurality of output ports
`and further including a plurality of switch means, each
`for selectively coupling one of said output ports di
`rectly to a corresponding one of said plurality of an
`tenna elements during transmission and each for selec
`tively coupling one of said plurality of antenna ele
`ments through a corresponding one of said plurality of
`adaptive means, during reception, to a corresponding
`one of said output ports.
`'
`' 3. The system of claim 2 further including:
`a signal summer connected to said plurality of input
`‘ports for outputting a signal indicative of the sum
`of the signals received by each of said antenna
`elements as processed by said plurality of adaptive
`
`3
`cuit 44 is connected between radiating element 30 and
`switch 28. Similarly, adaptive circuits 46, 48 and 50 are
`coupled between radiating elements 42, 40 and 34 and
`the respective switches 38, 36 and 32. An adaptive
`circuit is de?ned herein to be any circuit for tending to
`minimize an undesired signal. Each of the adaptive
`circuits 44, 46, 48 and 50 receives a feedback signal
`from summer 52, the inputs to which are derived from
`ports 12,, 122, 14,, and‘142 during the receive mode of
`operation.
`The adaptive circuits are well known and are shown
`and described in detail in the aforementioned IEEE
`articles except for the modi?cation necessitated by the
`unique combination of the present invention described
`below. Referring now to FIG. 2 there is illustrated a
`well known adaptive circuit modi?ed as described
`below that is suitable for use in the present invention.
`The signal received by the appropriate antenna ele
`ment is inputted to quadrature hybrid 54 which splits
`the signal into n-phase and quadrature components x,
`(1). Each x, (t) is weighted by a real coef?cient w, at
`units 55 and 57. Whereas the prior art adaptive circuits
`use a single summer to sum the inputs from each of the
`weighting units w, from all of the antenna elements in
`the system, the adaptive circuit for purposes of the
`present invention is modi?ed such that a separate sum
`mer 56 is used in each of the adaptive circuits 44, 46,
`48 and 50. Rather than receiving signal inputs from
`each of the antenna elements as in the prior art adap
`tive circuits, the summers 56 utilized in the present
`invention each receive inputs only from their corre
`sponding antenna element, i.e., summer 56 in adaptive
`circuit 44 receives inputs only from the in-phase and
`quadrature channels derived from antenna element 30,
`summer 56 in adaptive circuit 46 receives input signals
`only from the in-phase and quadrature channels de
`rived from antenna element 42, etc.
`The outputs of each adaptive circuit 44, 46, 48 and
`50 are processed through the corresponding switches
`28, 38, 36 and 32, during the receive mode of opera
`tion, through the Butler matrix and outputted at ports
`12,, 122, 141 and 142 from which they are inputted
`through switch 18 to summer 52 which outputs the sum
`signal S(t). The difference between the array output
`S(t) and a reference signal R(t) is the error signal e(t)
`and is formed by the substraction unit 58. The error
`signal £(t) is used in the feedback control network 60
`that adjusts the weights w,(t). The feedback control
`may be designed to adjust the antenna excitation coef
`?cients (weights) so that the mean square value of 6(1)
`is minimized. This has the effect of forcing the output
`of the array to approximate the reference signal R(t). It
`is noted, however, that any other adaptive algorithm
`could be used in the present invention.
`Thus, during the receive mode of operation the adap
`tive circuits 44, 46, 48 and 50 are, by operation of the
`corresponding switches 28, 38, 36 and 32, in the re- .
`ceive signal processing network. Each antenna element
`receives a portion of the received signal which is
`matched with the reference signal generated. The ref
`erence signal R(t) may be generated by any known
`technique. In practical communication systems, this
`signal is obtained by processing the array output S(t).
`The details of this processing depend on the particular
`design problem. For example, if it were desirable to
`reject interference whose bandwidth is much wider
`than that of the desired signal, a processing loop such
`as that illustrated in FIG. 3 could be utilized. The band
`
`35
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`means.
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`4. In a Butler matrix and antenna system wherein said
`Butler matrix includes ?rst and second pluralities of
`input-output ports and wherein said antenna system
`includes a plurality of antenna elements, each of said
`antenna element being associated with a corresponding
`oneof said second plurality of input-output ports, the
`improvement comprising:
`a plurality of adaptive circuit means, each coupling
`one of said second plurality of input-output ports to
`its said associated antenna element for minimizing
`the amplitude of an undesired signal received by
`said associated antenna element, each adaptive
`circuit means including means for comparing said
`
`WAVES607_1012-0005
`
`Petitioner Waves Audio Ltd. 607 - Ex. 1012
`
`

`
`4,032,922
`6
`5
`received §ignal with a referellce Signal to develop
`pling one of said plurality of antenna elements
`an em" signal for feedback control‘
`'
`directly to a corresponding one of said second
`5. In the Butler matrix and antenna system of claim 4,
`plurality of input-output ports during signal trans
`the improvement further comprising:
`.
`.
`.
`.
`a plurality of switch means each for coupling one of 5
`mission‘
`Said plurality of antenna elements thomgh one of
`6. in the Butler matrix and antenna system of claim 5,
`said plurality of adaptive circuit means to the cor-
`the ‘mpmvemem further comprising a Summer con‘
`responding one of said second plurality of input-
`nected to said ?rst plurality of input-output ports.
`output ports during reception and each for cou-
`* * *
`*
`*
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`I5
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`65
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`WAVES607_1012-0006
`
`Petitioner Waves Audio Ltd. 607 - Ex. 1012