United States Patent [191
`Turnhull et al.
`
`Illlllllllllllllllllllllllllll
`US005084864A
`Patent Number:
`5,084,864
`Jan. 28, 1992
`Date of Patent:
`
`[11]
`[45]
`
`[54] BROADBAND, INDUCTIVELY COUPLED,
`DUPLEX, RF TRANSMISSION SYSTEM
`
`FOREIGN PATENT DOCUMENTS
`
`
`
`
`
`[75] Inventors: Thomas H. Turnbull, Everett; James B. Turner, Bothell, Of Wash.
`
`
`
`‘123:: Japan _
`
`[56]
`
`_
`Referenc? (Med
`U.s_ PATENT DOCUMENTS
`
`’
`
`'
`
`[73] Assignee: The Boeing Company, Seattle, Wash.
`Primary Examiner_Douglas w_ Olms
`[211 App]_ No‘; 523,226
`Assistant Examiner-T. Ghebretinsae
`_
`Attorney, Agent, or Finn-Christensen, O’Connor,
`Mi)’ 14, 1990
`[22] F1led:
`Johnson & Kindness
`[51] Int. Cl.5 ........................ .. H04B 1/54; H04B 3/03
`[57]
`ABSTRACT
`[52] US. 01. ........................................ .. 370/24; 455/3;
`'
`,
`_
`.
`455/33; 455/41; 333/4; 333/5; 333/24 R; A broadband, inductively coupled, duplex, radio fl‘C
`333/24 C. 375/36
`quency (RF) transmission system for communcating
`[58] Field of Search ....................... .. 455/3, 33’, 51, 41-
`between a “ma! “Hit (10) and 1* Plmlity °f "mm
`333/4, 5’ 124, 136’ 24 R, 24 C’ 25, 26. 370/24:
`units (31) is dlSClOSCd. The central unit (10) includes an
`'
`375/36
`RF signal source (11) and an RF receiver (21) con
`nected to one end of a balanced transmission line (25)
`via a signal splitter (15) and a transmission line impe
`dance matching network (27). Each remote unit (31)
`includes a receiving section (33) and a transmitting
`section (35) separate from one another. Each receiving
`section (33) and each transmitting section (35) includes
`U-shaped couplers (37,43) positioned so as to overlie the
`balanced transmission 1in=(25)-Th¢ U-shaped couplers '
`(37,43) are oriented such that the cross~members of the
`U-shaped couplers (37,43) lie orthogonal to the bal
`anced transmission line (25) and the legs of the U
`
`,
`
`,
`
`no . . . . . . . .
`
`. . . . ..
`
`~
`
`-
`
`-
`
`_
`
`_
`
`22 Claims, 3 Drawing Sheets
`
`IF / ”
`5/64/44
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`6214444550 MAS/Mu”! : [=1 .
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`53 44/?
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`if
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`xgl'ltg‘gmer ‘ ‘ ' ‘ ‘
`é’égi’iz
`2’419’833 4/1947 Grimes
`2:515:663 7/1950 O'Brien
`3,310,736 3/1967 Bayly et al.
`3,975,594 8/1976 Guntersdorfer
`3,999,015 12/1976 Snyder et a1 . . . . . .
`4,209,663 6/1980 sckiguchl - - - - - -
`
`‘ ' ‘ ‘ ' " 13779765;
`179/8'2
`179/2_5
`324/62
`179/15
`. . . . .. 179/1
`- - - - -- 455/3
`
`shaped couplers (37,43) lie parallel to the balanced
`313g
`i’zééyggg “13232: graham
`13112236 tsrlzlggenilitcoud
`375/36
`4,528,677 7/1985 156 et al. .
`.
`’
`p .
`m .
`a“
`455/41
`4,584,707 4/1986 Goldberg et al. .
`455/41 mm“ “mm RF rece‘vers and Rf s‘gnal mums
`4 736 452 4/1988 Daniels et al.
`455/11
`(41147)’ via impedance mamhing n°tw°rks (39145)
`4,747,158 5/1988 Goldberg et al. .
`455/41
`4,833,337 5/1989 Owens et al. .... ..
`4,835,604 5/ 1939 Kondo et al. ....................... .. 358/86
`
`Petitioners' Ex. 1006 - Page 1
`
`

`
`US. Patent
`
`Jan, 28, 1992
`
`Sheet 1 of 3
`
`5,084,864
`
`MN
`
`Petitioners' Ex. 1006 - Page 2
`
`

`
`US. Patent
`
`Jan. 28, 1992
`
`Sheet 2 of 3
`
`5,084,864
`
`Petitioners' Ex. 1006 - Page 3
`
`

`
`US. Patent
`
`Jan. 28, 1992
`
`Sheet 3 of 3
`
`5,084,864
`
`Petitioners' Ex. 1006 - Page 4
`
`

`
`1
`
`BROADBAND, INDUCI'IVELY COUPLED,
`DUPLEX, RF TRANSMISSION SYSTEM
`
`5,084,864
`2
`tainment systems provide video as well as audio enter
`tainment. Video entertainment requires 6 MHz per
`channel and contemporary FM stereo requires 200 KHz
`per channel. Service data transmission requires a band
`width of 100 KHz per 50 K bit/second channel. Duplex
`communication is required because it is necessary to be
`able to establish two-way communication between the
`seats of an aircraft and central control equipment in
`order for a passenger to initiate action, such as tuning on
`a TV mounted in the seat in front of the passenger, and
`the action to occur.
`High efficiency is required because it is necessary to
`communicate broadband RF signals throughout an air
`craft cabin without interfering with other electronic
`equipment such as the navigational equipment and com
`puter systems of the aircraft. It is also necessary that the
`system operate with minimal interference from outside
`sources. More speci?cally, conventional RF transmit
`ting systems use a high-powered signal to excite an
`antenna. Transmitter power is proportional to the
`square of the distance between the transmitting antenna
`and the receiving antenna. The use of high power cre
`ates a potential interference problem with other elec
`tronic systems that operate in the same area. Con
`versely, a broadband receiving antenna tends to pick up
`interfering signals generated by other signal sources.
`Thus, to be practical a system for use onboard an air
`craft must operate with minimal power and have a
`minimal tendency to pick up interference from external
`sources.
`The present invention is directed to providing a
`highly efficient, broadband, inductively coupled, du
`plex, RF transmission system suitable for use in the
`passenger compartment of aircraft to communicate
`between a central unit and a plurality of remote seat
`units.
`
`15
`
`25
`
`TECHNICAL AREA
`This invention relates to transmission systems and,
`more importantly, to inductively coupled ratio fre
`quency transmission systems.
`BACKGROUND OF THE INVENTION
`When ordering commercial aircraft, airline compa
`nies often specify a number of design options to the
`manufacturer, including passenger seating layouts. The
`manufacturing and inventory costs associated with pro
`viding different seating arrangements and spacing be
`_ tween seats can be signi?cant. These costs will become
`more important to the next generation of aircraft, which
`will offer new personal entertainment and service facili
`ties to each passenger. Designers of such facilities are
`planning to install an entertainment system and passen
`ger service system in the back of each aircraft seat for
`use by the passenger in the following seat. In order to
`communicate with these facilities, conventional wiring
`techniques typically require that each different seating
`arrangement that an airline company speci?es have a
`different length communication lead harness. The costs
`and weight penalty associated with providing commu
`nication for each seat using conventional wiring tech
`niques is likely to be unacceptable to most passenger
`30
`carriers. In addition to unacceptable costs in terms of
`weight, conventional wiring techniques inhibit the abil
`ity to rearrange classes of seating (by sliding seats to
`change seating pitch) in order to maximize the payload
`return on a flight (even within thirty minutes of depar
`35
`ture). The ability to rearrange classes of seating on a
`short-term basis is a profitable feature that is desired by
`most airlines.
`An alternative to wiring each seat to a central com
`munication source utilizing a conventional wire lead
`harness is disclosed in commonly assigned US. Pat. No.
`4,428,078 (C. Kuo). This patent discloses what is re
`ferred to therein as a “wireless” system for communi
`cating with a plurality of multiple-tum coupler coils
`disposed in the base of seats throughout an aircraft
`cabin. Perhaps this technology could more accurately
`be described as a “connectorless” transmission system,
`because communication signals are inductively coupled
`from a transmission line that is disposed in the floor of
`an aircraft cabin to coupler coils attached to each seat
`group. The communication signals are used to commu
`nicate with the passenger entertainment and service
`systems installed in the seats. This wireless system per
`mits seats to be moved about in different arrangements
`as required by individual airlines, without concern for
`providing different length interconnecting wire har
`nesses.
`In order for a connectorless communication system
`to be practical in an aircraft environment, the system
`must meet certain criteria. First, the system must be
`broadband, i.e., operate over a relatively broad band
`width. Second, the system must be duplex, i.e., have the
`capability 'of transmitting and receiving in both direc
`tions from a central unit to a plurality of remote (seat)
`units. Further, the system must be highly efficient, low
`65
`in weight, and highly reliable.
`The development of higher quality entertainment and
`services for aircraft passengers creates the broad band
`width requirement. Present and future aircraft enter
`
`50
`
`45
`
`55
`
`SUMMARY OF THE INVENTION
`In accordance with this invention, a broadband, in
`ductively coupled, duplex, radio frequency (RF) trans
`mission system suitable for communicating between a
`central unit and a plurality of remote units is disclosed.
`The central unit includes an RF signal source and an RF
`receiver connected to one end of a balanced transmis
`sion line via a signal splitter and a transmission line
`impedance matching network. Each remote unit in
`cludes a receiving section and a transmitting section
`separate from one another. Each receiving section and
`each transmitting section includes a U-shaped coupler
`positioned so as to overlie the balanced transmission
`line, in close proximity thereto. The U-shaped couplers
`are oriented such that the cross-members of the U
`shaped couplers lie orthogonal to the balanced trans
`mission line and the legs of the U-shaped couplers lie
`parallel to the balanced transmission line. The legs of
`the U-shaped couplers are connected to electronic
`transmit and receive systems, i.e., RF receivers and RF
`signal sources, via receive and transmit loop impedance
`matching networks, respectively. Because the U-shaped
`couplers are located in close proximity to the balanced
`transmission line, tight signal coupling exists between
`the couplers and the transmission line.
`High efficiency results from the tight signal coupling
`between the couplers and the balanced transmission
`line. The balanced configuration of the transmission line
`minimizes the effect of interfering radio frequency sig
`nals from outside sources and maintains the quality of
`
`Petitioners' Ex. 1006 - Page 5
`
`

`
`20
`
`25
`
`30
`
`5,084,864
`3
`4
`output that might cause interchannel interference be
`the transmitted and received entertainment and service
`signals high. High efficiency allows the radio frequency
`tween the channels of an entertainment and service
`?elds radiating from the system to be of relatively low
`system, or cause electromagnetic interference (EMI)
`intensity, causing minimal radio interference with other
`with respect to the communications and avionic systems
`electronic equipment. More speci?cally, the total radio
`of an aircraft in which the invention is utilized. The
`frequency power needed to transmit signals over a
`central unit 10 also includes an RF receiver 21 con
`broadband, inductively coupled, duplex RF transmis
`nected to the signal splitter 15 via a cable 23, preferably
`a coaxial cable. The signal splitter 15 separates the
`sion system formed in accordance with the invention is
`much lower than would be required by previously de
`transmitted and received signals, which are coupled to
`veloped inductively coupled RF transmission systems.
`a balanced transmission line 25 through a transmission
`line impedance matching network 27, which also forms
`BRIEF DESCRIPTION OF THE DRAWINGS
`part of the central unit 10. Preferably, the signal splitter
`The foregoing and other features and advantages of
`15 is connected to the transmission line impedance
`this invention will become more readily appreciated as
`matching network 27 by a coaxial cable 29.
`the same becomes better understood by reference to the
`- The impedance matching network 27 transforms or
`following detailed description when taken in conjunc
`matches the characteristic impedance of the connecting
`tion with the accompanying drawings wherein:
`coaxial cable 29 to that of the balanced transmission line
`FIG. 1 is a partially block, partially pictorial diagram
`25 in a conventional manner. For example, the transmis
`of a broadband, inductively coupled, duplex, RF trans
`sion line impedance matching network 27 may trans
`mission system formed in accordance with the inven
`form or match the 75 ohm characteristic impedance of
`tion;
`one type of standard coaxial cable to the 380 ohm impe
`FIG. 2 is an enlarged, plan view of a U-shaped cou
`dance of a suitable balanced transmission line. In addi
`tion, the transmission line impedance matching network
`pler positioned so as to overlie the balanced transmis
`sion line of a broadband, inductively coupled, duplex
`converts the unbalanced signal carried by the coaxial
`RF transmission system of the type illustrated in FIG. 1;
`cable 29 into a balanced signal suitable for application to
`FIG. 3 is an elevational view of the U-shaped coupler
`the balanced transmission line 25.
`illustrated in FIG. 2; and
`The balanced transmission line 25 conveys radio fre
`FIG. 4 is a schematic diagram of an equivalent circuit
`quency signals between the central unit 10 and a plural
`of the major components of a broadband, inductively
`ity of remote units 31, only one of which is illustrated in
`coupled, duplex, RF transmission system formed in
`FIG. 1. In an aircraft system incorporating the inven
`accordance with the invention, namely, a balanced
`tion, the remote units 31 are located in the passenger
`transmission line coupled to a U-shaped transmit or
`seat groups located within the cabin of the aircraft.
`receive coupler.
`Each of the remote units 31 includes a receiving section
`33 and a transmitting section 35. Each of the receiving
`DETAILED DESCRIPTION OF THE
`sections includes a U-shaped coupler 37, a receiver loop
`PREFERRED EMBODIMENT
`impedance matching network 39, and an RF receiver
`As will be better understood from the following de
`41. Each of the transmitting sections includes a U
`shaped coupler 43, a transmit loop impedance matching
`scription, the present invention provides a broadband,
`inductively coupled, duplex, radio frequency (RF)
`network 45, and an RF signal source 47. The U-shaped
`couplers 37 and 43 each include a pair of parallel legs
`transmission system for communicating between a cen
`4-0
`tral unit and a plurality of remote units. The invention is
`joined by cross-members. The cross-members are
`straight and unitarily join the legs at right angles.
`ideally suited for use onboard an aircraft for communi
`The legs of the U-shaped coupler 37 of the receiver
`cating between a central unit that provides control,
`video and audio signals to a plurality of remote units
`section 33 are connected to the input of the receiver
`loop impedance matching network. The output of the
`installed in passenger seat groups located within the
`cabin of the aircraft. Radio frequency signals pass
`receiver loop impedance matching network 39 is con
`through a balanced transmission line extending between
`nected to the RF receiver 31 via a cable 49, preferably
`the central unit and the seat group located remote units
`a coaxial cable.
`where signals transmitted by the control unit are picked
`The output of the RF signal source 47 is connected to
`'up by U-shaped couplers disposed at the base of each
`the input of the transmit loop impedance matching net
`group of seats, above the balanced transmission line.
`work 45 via a cable 51, preferably a coaxial cable. The
`output of the transmit loop impedance matching net
`Signals transmitted by the seat groups are applied to the
`balanced transmission line via separate U-shaped cou
`work 45 is connected to the legs of the U-shaped cou
`plers.
`pler of the transmit section 35.
`In operation, signals transmitted by the RF signal
`FIG. 1 illustrates the presently preferred embodiment
`of a broadband, inductively coupled, duplex, radio fre
`source 11 of the central unit 10 and applied to the bal
`quency transmission system formed in accordance with
`anced transmission line 25 are detected by the U-shaped
`coupler 37 of the receiver section 33. The signals de
`the invention. More speci?cally, FIG. 1 illustrates a
`tected by the U-shaped coupler 37 of the receiver sec
`central unit 10 formed by an RF signal source 11 con
`nected through an RF power ampli?er 13 to a signal
`tion 33 are applied to the RF receiver 41 of the receiver
`splitter 15. The RF signal source creates RF signals,
`section via the receiver loop impedance matching net
`preferably lying in the 40 MHz to 300 MHz band. Pref
`work 39. The combination of the U-shaped coupler 37
`erably, the cables 17 and 19 connecting the RF signal
`and the receiver loop impedance matching network 39
`provide an ef?cient, low distortion method of coupling
`source to the RF power ampli?er and the RF power
`ampli?er 13 to the signal splitter 15, respectively, are
`signals from the balanced transmission line 25 to an
`65
`coaxial cables. Also, preferably, the RF power ampli?er
`unbalanced cable 49, which forms an unbalanced trans
`13 is a low distortion power ampli?er designed to avoid
`mission line, without a physical connection between the
`creating harmonics or intermodulation products on its
`two transmission lines.
`
`35
`
`45
`
`50
`
`55
`
`Petitioners' Ex. 1006 - Page 6
`
`

`
`21
`F-
`0
`= T ('- ‘n n" - ' )
`
`(3)
`
`where:
`[an is again the permeability of free space
`- l is the length of the strips
`D is the separation of the strips
`1n indicates the natural logarithm
`The high frequency self-inductance of a ?at, rectangu
`lar printed circuit coil can be de?ned by the following
`equation:
`
`)+ .u in (
`
`ZS: 82
`we: + g)
`
`(4)
`
`D
`b+c
`
`in)
`
`no is again the permeability of free space
`s1 is the average width of the loops in the x direction
`s2 is the average width of the loops in the y direction
`g is the square root of s12+s22
`b is the width of the turn traces
`c is the thickness of the turn traces
`n is the number of turns
`The mutual inductance between a ?at, rectangular coil
`and a parallel wire transmission line, including the ef
`fects of a nearby conducting ground plane can be de
`?ned by the following equation:
`
`5,084,864
`5
`6
`Signals produced by the RF signal source 47 of the
`l is the length of the strip
`receive section 35 are coupled to the transmit U-shaped
`w is the width of the strip
`coupler 43 via the transmit loop impedance matching
`t is the thickness of the strip
`network 45. The transmit loop impedance matching
`Provided l is much greater than d, the mutual induc
`network 45 impedance matches the unbalanced cable 51
`tance between two identical parallel conductor strips
`that connects the RF signal source 47 to the transmit
`can be defined by the following equation:
`loop impedance matching network 45 to the U-shaped
`coupler 43. The combination of the U-shaped transmit
`coupler 43 and the transmit loop impedance matching
`network 45 provides an efficient, low distortion method
`of coupling signals from the unbalanced cable 51 to the
`balanced transmission line without the use of physical
`connectors. i5 The use of separate transmit and receive
`sections and separate transmit and receive couplers 37
`‘and 43 provides a substantial amount of isolation be
`tween the receive and transmit sections 33 and 35. In
`one actual embodiment of the invention, this arrange
`ment provided more than 30 db isolation between the
`receive and transmit sections. This substantial amount
`of isolation greatly reduces interference between the
`20
`RF signal source 47 and the RF receiver 41 of each
`remote unit 31. It should be noted that, while illustrated
`as very similar, the transmit and receive sections need
`not have the same design. Ef?ciencies can be realized
`by optimizing the loops and their associated networks
`to provide only the necessary bandwidth.
`The balanced transmission line 25 terminates in a
`characteristic impedance 53, which may be coupled to
`the end of the balanced transmission line 25 via an impe
`dance matching transformer 55, if desired. In addition
`to the U-shape of the coupler, critical parameters in the
`design of a broadband, inductively coupled, duplex, RF
`transmission system formed in accordance with the
`invention are the physical and electrical relationships
`between the balanced transmission line, the U-shaped
`couplers, and the metal structure of the aircraft. FIGS.
`2 and 3 illustrate how a transmission line and U-shaped
`couplers formed in accordance with the invention
`should be mounted in an aircraft. The mounting ar
`rangement is best described using certain mathematical
`relationships, set forth next.
`The characteristic impedance of a balanced transmis
`sion line is de?ned by the following equation:
`
`25
`
`30
`
`35
`
`2,- = 120 in
`
`2W
`d '
`
`1
`
`2
`
`l 211 )
`
`1+
`
`45
`
`(1)
`
`where, as shown in FIG. 3:
`Z,- is the characteristic impedance of the balanced
`transmission line
`W is the spacing between conductor centers of the
`balanced transmission line
`d is the diameter of the balanced transmission line
`wire
`h is the vertical distance between a ground plane and
`the centers of the balanced transmission line wires
`The inductance of a single strip of copper at high
`frequencies can be de?ned by the following equation:
`
`50
`
`55
`
`P0
`
`2" (I'ln
`
`41
`
`2
`
`—I+"w)
`
`(2)
`
`65
`
`where:
`no is the permeability of free space
`
`Petitioners' Ex. 1006 - Page 7
`
`

`
`5,084,864
`8
`transmission line impedance matching network. Each
`remote unit includes a receiving section and a transmit
`ting section separate from one another. Each receiving
`.section and each transmitting section includes a U
`shaped coupler position so as to overlie the balanced
`transmission line, in close proximity thereto. The U
`shaped couplers are oriented such that the cross-mem
`bers of the U-shaped couplers lie orthogonal to the
`balanced transmission line and the legs of the U-shaped
`couplers lie parallel to the balanced transmission line.
`The legs of the U-shaped couplers are connected to
`electronic transmit and receive sections, via impedance
`matching networks. The U-shaped couplers are formed
`of ?at, rectangular, conductor strips having a U shape,
`i.e., a pair of parallel legs and a cross-member.
`A transmission system formed in accordance with the
`invention is highly ef?cient'due to the tight signal cou
`pling between the U-shaped couplers and the balanced
`transmission line. The balanced con?guration of the
`transmission line
`the effect of interfering
`radio frequency signals from other sources and main
`tains the quality of the transmitted and received signals
`high. High ef?ciency allows the radio frequency ?elds
`radiating from the system to be of relatively low inten
`sity, causing minimal radio interference with other elec
`tronic equipment.
`While a preferred embodiment of the invention has
`been illustrated and described, it is to be understood
`that, within the scope of the appended claims, various
`changes can be made therein.
`The embodiments of the invention in which an exclu
`sive property or privilege is claimed are de?ned as
`follows:
`1. A broadband, inductively coupled, duplex, RF
`transmission system comprising:
`a central RF communication unit for transmitting and
`receiving RF signals;
`a balanced transmission line, said balanced transmis
`sion line including a pair of parallel, spaced-apart
`wires coupled to said central RF communication
`unit; and
`at least one remote unit, said at least one remote unit
`including a receiving section for ~ receiving RF
`signals and a transmitting section for transmitting
`RF signals, each of said transmitting and receiving
`sections including a U-shaped coupler and other
`elements, said U-shaped couplers positioned so as
`to overlie the pair of parallel, spaced-apart wires of
`said balanced transmission line, in close proximity
`to both wires of the balanced transmission line, said
`U-shaped couplers being oriented such that the
`cross-members of said U-shaped couplers lie or
`thogonal to the longitudinal axis of said pair of
`parallel, spaced-apart wires and such that the legs
`of said U-shaped couplers lie generally parallel to
`said pair of parallel, spaced apart wires, the legs of
`each of said U-shaped couplers being electrically
`connected to other elements of the receiving and
`transmitting section that includes said U-shaped
`coupler.
`2. A broadband, inductively coupled, duplex, RF
`transmission system as claimed in claim 1, wherein said
`U-shaped couplers are formed of a thin, ?at piece of
`metal having a rectangular shape and include a pair of
`elongate parallel legs and a cross-member unitarily
`formed with said pair of elongate parallel legs and lying
`orthogonal thereto, the longitudinal axis of said elon
`
`R
`
`M
`
`2
`
`Z0
`Z:
`
`(
`
`(6)
`
`where:
`G is the transfer characteristic
`Zais the series impedance of the unbalanced transmis
`sion line, which is known
`Rp is the parallel resistance of the impedance match
`ing network, which is known
`at is the angular frequency in radians per second
`C0 is the series capacitance of the impedance match
`ing network, which is known
`M is the mutual inductance de?ned by Equation (5)
`L, is the inductance of a ?at, rectangular coil de?ned
`by Equation (4)
`Z,- is the characteristic impedance of the parallel wire
`(balanced) transmission line
`See FIG. 4 which, for ease of illustration, does not
`include the circuitry coupling the RF signal source 11
`to the balanced transmission line 25 or the RF receiver
`21.
`The circuit illustrated in FIG. 4 has an optimally ?at
`frequency response if for a given RP and Z0, and for an
`L, value determined by Equation (4) the series capaci
`tance, C0, of the impedance matching network can be
`de?ned by the following equation:
`‘
`
`30
`
`35
`
`40
`
`45
`
`55
`
`7
`-continued
`
`2
`
`where, as shown in FIG. 3:
`no is again permeability of free space
`q is Q the length of the loops in one direction
`p is i the length of the loops in the other direction
`(centerline to centerline)
`W is the spacing between the conductor centers of
`the parallel wire transmission line
`'
`y is the vertical distance between the ?at, rectangular
`coil and the parallel wire transmission line
`x is the offset between the centerline between the flat,
`rectangular coil and the parallel wire transmission
`line
`h is the distance between the wire transmission line
`and the nearby conducting ground plane
`In indicates the natural logarithm
`The transfer characteristics between a parallel wire
`transmission line and a coupler coil is:
`
`15
`
`20
`
`25
`
`co
`
`(L
`
`(7)
`
`As will be readily appreciated from the foregoing
`description, the invention provides a broadband, induc
`tively coupled, duplex, RF transmission system suitable
`for communicating between a central unit and a plural
`ity of remote units. Preferably, the central unit includes
`an RF signal source and an RF receiver. In any event,
`the central unit is connected to one end of a balanced
`transmission line, preferably via a signal splitter and a
`
`65
`
`Petitioners' Ex. 1006 - Page 8
`
`

`
`25
`
`5,084,864
`10
`formed with said pair of elongate parallel legs and lying
`gate parallel legs lying parallel to said pair of parallel,
`orthogonal thereto, the longitudinal axis of said elon
`spaced-apart wires.
`gate parallel legs lying parallel to said pair of parallel,
`3. A broadband, inductively coupled, duplex, RF
`spaced-apart wires.
`transmission system as claimed in claim 1, wherein said
`11. A broadband, inductively coupled, duplex, RF
`central RF communication unit includes:
`transmission system as claimed in claim 5, wherein said
`an RF signal source;
`other elements of each of said transmitting sections
`an RF receiver;
`includes:
`a signal splitter coupled to said RF signal source and
`an RF signal source; and
`said RF receiver; and
`a transmit loop impedance matching network for
`a transmission line impedance matching network for
`coupling said RF signal source to a U-shaped cou
`coupling said signal splitter to one end of said bal
`pler.
`anced transmission line.
`12. A broadband, inductively coupled, duplex, RF
`4. A broadband, inductively coupled, duplex, RF
`transmission system as claimed in claim 11, wherein said
`transmission system as claimed in claim 3, wherein said
`U-shaped couplers are formed of a thin, ?at piece of
`U-shaped coupler are formed of a thin, ?at piece of
`metal having a rectangular shape and include a pair of
`metal having a rectangular shape and include a pair of
`elongate parallel legs and a cross-member unitarily
`elongate parallel legs and a cross-member unitarily
`formed with said pair of elongate parallel legs and lying
`formed with said pair of elongate parallel legs and lying
`orthogonal thereto, the longitudinal axis of said elon
`orthogonal thereto, the longitudinal axis of said elon
`gate parallel legs lying parallel to said pair of parallel,
`gate parallel legs lying parallel to said pair of parallel,
`spaced-apart wires.
`spaced-apart wires.
`13. A broadband, inductively coupled, duplex, RF
`5. A broadband, inductively coupled, duplex, RF
`transmission system as claimed in claim 11, wherein said
`transmission system as claimed in claim 3, wherein said
`RF signal source is connected to said transmit loop
`signal splitter is coupled to said transmission line impe
`impedance matching network via an unbalanced trans
`dance matching network by an unbalanced transmission
`mission line and wherein said transit loop impedance
`line impedance matching network by an unbalanced
`matching network converts unbalanced signals carried
`transmission line and wherein said transmission line
`by said unbalanced transmission line into balanced sig
`impedance matching network converts unbalanced sig
`nals prior to the application of said signals to said U
`nals carried by said unbalanced transmission line into
`shaped coupler.
`balanced signals and vice versa.
`30
`14. A broadband, inductively coupled, duplex, RF
`6. A broadband, inductively coupled, duplex, RF
`transmission system as claimed in claim 13, wherein said
`transmission system as claimed in claim 5, wherein said
`U-shaped couplers are formed of a thin, ?at piece of
`U-shaped couplers are formed of a thin, ?at piece of
`metal having a rectangular shape and include a pair of
`metal having a rectangular shape and include a pair of
`elongate parallel legs and a cross-member unitarily
`elongate parallel legs and a cross-member unitarily
`35
`formed with said pair of elongate parallel legs and lying
`formed with said pair of elongate parallel legs and lying
`orthogonal thereto, the longitudinal axis of said elon
`orthogonal thereto, the longitudinal axis of said elon
`gate parallel legs lying parallel to said pair of parallel,
`gate parallel legs lying parallel to said pair of parallel,
`spaced-apart wires.
`spaced~apart wires.
`15. A broadband, inductively coupled, duplex, RF
`7. A broadband, inductively coupled, duplex, RF
`40
`transmission system as claimed in claim 1, wherein said
`transmission system as claimed in claim 5, wherein said
`other elements of each of said receiving sections in
`other elements of each of said receiving sections in
`cludes:
`cludes:
`an RF receiver; and
`an RF receiver; and
`a receiver loop impedance matching network for
`a receiver loop impedance matching network for
`coupling a U-shaped coupler to said RF receiver.
`coupling a U-shaped coupler to said RF receiver.
`16. A broadband, inductively coupled, duplex, RF
`8. A broadband, inductively coupled, duplex, RF
`transmission system as claimed in claim 15, wherein said
`transmission system as claimed in claim 7, wherein said
`U-shaped couplers are formed of a thin, ?at piece of
`U-shaped couplers are formed of a thin, ?at piece of
`metal having a rectangular shape and include a pair of
`metal having'a rectangular shape and include a pair of
`elongate parallel legs and a cross-member unitarily
`elongate parallel legs and a cross-member unitarily
`formed with said pair of elongate parallel legs and lying
`formed with said pair of elongate parallel legs and lying
`orthogonal thereto, the longitudinal axis of said elon
`orthogonal thereto, the longitudinal axis of said elon
`gate parallel legs lying parallel to said pair of parallel,
`gate parallel legs lying parallel to said pair. of parallel,
`spaced-apart wires.
`spaced-apart wires.
`55
`17. A broadband, inductively coupled, duplex, RF
`9. A broadband, inductively coupled, duplex, RF
`transmission system as claimed in claim 15, wherein said
`transmission system as claimed in clai