US714831A - Apparatus for selective electric signaling. - Google Patents

Apparatus for selective electric signaling. Download PDF

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US714831A
US714831A US44384A US1901044384A US714831A US 714831 A US714831 A US 714831A US 44384 A US44384 A US 44384A US 1901044384 A US1901044384 A US 1901044384A US 714831 A US714831 A US 714831A
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conductor
circuits
waves
circuit
frequency
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US44384A
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John Stone Stone
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BRAINERD T JUDKINS
LOUIS E WHICHER
ALEXANDER P BROWNE
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ALEXANDER P BROWNE
BRAINERD T JUDKINS
LOUIS E WHICHER
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40Circuits
    • H04B1/50Circuits using different frequencies for the two directions of communication

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  • My invention relates to the art of trans other by means of electromagnetic waves without the use of wires to guide the waves to their destination; and it relates more particularly to the system of such transmission in which the electromagnetic waves are developed by producing electric vibrations in an elevated conductor, preferably vertically elevated.
  • Electromagnetic waves have also been developed by producing natural or forced electric oscillations in loops or coils of wire at the transmittingstation and also by means of the discharge of electricity between two conducting spheres, cylinders, or cones; but in such cases the sphere of influence is so limited as to greatly restrict the commercial utility of these two methods of developing the signal waves.
  • the method of signaling by means of electromagnetic waves between stations not connected by a conducting-wire, in which method the electromagnetic waves are de- 'veloped by electric vibrations in an elevated conductor has great advantages over the other existing or proposed methods for accomplishing this purpose in which the electromagnetic waves are developed byother means, since in thecase of the waves developed by the elevated-conductor method the waves ma y be transmitted to and efiectively received at greater distances than by the other systems, but whereas in the systems employing the other methods of generating the waves the signals developed may, at least theoretically, be directed to the particular receiving-station with whichit is desired to communicate to tions in the .neighborhood. It has heretofore been found impossible, so far as I know, to accomplish this purpose in thesystememploying an elevated conductor or wire as the source of the electromagnetic waves.
  • the object of thisinvention isto overcome the exclusion of other similar receiving-stathan in the case of the horizontal conductor, so that these waves may be transmitted to and it depends upon the fact thatit has not heretothe hereinbefore-described limitation to the l mit their signals each to a particular receiving-station simultaneously or otherwise without mutual interference.
  • the vertical or elevated condoctor in such a system to be made the source of simple harmonic electromagnetic waves of any desired frequency independent of its lengthandothergeometricalconstants.
  • the frequency impressed upon the elevated conductor may or may not be the same as the n'atural period or fundamental of such conductor; but, as will be hereinafter explained, an elevated conductor that is aperiodic may be employed and is best adapted for use when the apparatus is to be used successively for different frequencies, and such aperiodic elevated conductor is likewise the preferred form of elevated conductor when two or more frequencies are to be simultaneously impressed upon or received by a single elevated conductor; but forced simple harmonic electric vibrations of different periodicities may each be separately impressed upon a difierent elevated conductor, and the several energies of the resulting electromagnetic waves may be selectively conveyed each to a separate translating device.
  • These motions may consist either of a .unidirectional displacement or of to-and-fro vibrations of the system or parts of the system, depending upon the relations which sub sist between the principal mechanical constants of the system-i. e., its moments of mass and elasticity and its friction coefficients.
  • the determination of the relations which must subsist in order that an oscillatory restoration of equilibrium shall take place either in an electric or in a mechanical system and the determination of the period of these oscillations is very difficult; but in certain simple cases both the determination of the conditions for an oscillatory restoration of equilibrium and of the period of these oscillations is quite'simple.
  • An example of a simple mechanical system capable of an oscillatory restoration of equilibrium is to be found in the torsional pendulum, which consists of a highly-elastic wire fixed at one end and supporting at its other extremity a heavy mass called the bob. If a torsional stress be imparted to the wire of this pendulum by turning the bob about the axis of the wire and the bob be then abruptly released, the pendulum will in general execute isochronous oscillations about the axis of the suspending-wire in the process of restoration of equilibrium.
  • An example of a simple electrical system capable of an oscillatory restoration of equilibrium is to be found in the case of a circuit consisting simply of a condenser and a coil without iron in its core,
  • n l simple circuits as shown in Fig. 1, be assoand the electric oscillations which it supports as shown in Figure l of the accompanying and if its electrodes be then connected to the 2'.
  • the natural vibrations in such cirharmonic in character but in general consist what are termed forced vibrations, and in elated together in ductive or by inductive connections a system of at least it degrees of freedom results, and
  • the natural oscillations of such a system will therefore consist of the superposition of at least n currents. It is, moreover, a fact that the different simple harmonic components. of the oscillations which together constitute the oscillatory restoration of equilibrium of acornplex system are in general not the same as those of the separate simple circuits when these circuits are isolated from one another;
  • each simple circuit modifies the natural period of each of the other circuits with which it isassociated.
  • circuits when inductively connected may have an oscillatory restoration of equilibrium, of which the simple harmonic. components are .00444 of a second and .00159 of a second, showing that the inductive association of the ,circuits together has increased the natural period of the high-period circuit and decreased the natural period of the low-period circuit.
  • the receiving-station is capable of receiving and'responding to vibrations of a great 'variety of frequencies, so that the electromagnetic waves which emanate from one vertical conductor used as a transmitter are capable of exciting vibrations in any other vertical wire as a receiver, and for this reason any transmitting-station in a system of this character will operate any receiving-station within its sphere of influence, and the messages from the transmitting-station will not be selectively received by the particular receiving-station with which it is desired to communicate, but will interfere with the operation of other receiving-stations within its sphere of influence, thereby preventing them from properly responding to the signals of the transmittingstat-ions from which they are intended to receive their signals.
  • the vertical conductor of the transmitting-station is made the source of electromagnetic waves of but a single periodicity, and the translating apparatus at the receiving-station is caused" to be selectively responsive to waves of but a single-periodicity, so that the transmitting apparatus corresponds to a tuning-fork','sending but a single simple musical tone, and the receiving apparatus corresponds to an acoustic resonator capable of absorbing the energy of that single simple musical t-one only.
  • the elevated conductor is aperiodic, it is adapted to receive or transmit all frequencies, and accordinglysa single aperiodic elevated conductor different frequency after the manner now well known in the art of multiple telegraphy by wire conductors.
  • the vertical conductor-at may be associated with a: plurality of local-circuits. each attuned to a ruptly discharge to earth by mcansof an elecother frequency upon the conductor.
  • the operator at the transmitting or receiving station may at will adjust the apparatus at his command in such a way as to place himself in communication with any one of a number of stations in the neighborhood by bringing his apparatus into resonance with the periodicity employed by the station with which intercommunication is desired.
  • Figures 1 to 4 are diagrams already referred to.
  • Fig. 5 is a diagram illustrating one arrangement of the transmitting-station.
  • Fig. 6 is a diagram illustrating an arrangement of the receiving-station. illustrating another form of the transmittingstation.
  • Fig. 8 is a diagram illustrating another form of the receiving-station.
  • Figs. 9 and 15 are diagrams illustrating a detail of the construction at both transmitting and receiving stations.
  • Figs. 10 and 11 are diagrams illustrative of the connection of the co-. herer at the receiving-stations.
  • Fig. 12 is a diagram illustrating the connection of acoudenser-telephone at the receiving station.
  • FIGS. 13 and 16 are diagrams illustrative of forms of transmitter-stations capable of developing signal-waves of two different frequencies.
  • Figs. 14 and 17 are diagrams illustrative of forms of receiving-stations capable of receiving selectively signal-waves of two different frequencies.
  • V represents a vertical or virtually vertical conductor grounded by the earth connection E.
  • Fig. 7 is a diagram primary-and secondary wires are 1,, 1' 1" v generator at develops an alternating electromotive force of moderate frequency, which when the key It is depressed develops a current in the primary circuit of the transformer M.
  • the transformer M is so designed as'to transform the electromotive force in the primary circuit to a very high electromotive force in the secondary. As the potential difference at the terminals of the secondary I rises the charge in the condenser 0 increases till the potential difference is s'uflicient to break down the dielectric at the spark-gap 3.
  • the condenser O discharges through the spark at s, the primary I ,-and the inductance-coil L.
  • This discharge is oscillatory in character and of very high frequency, as will be explained hereinafter.
  • the highfrequency current so developed passing through the primary I induces a corresponding high frequency electromotive force and current in the secondary I and forced elec-- tric vibrations result in the vertical conductor V, which are practically of a simple harmonic'character;
  • the condenser charges of condensers is approximately infrom which designed that the product of the capacity of the condenser by the inductance of the circuit is made numerically very small.
  • the oscillations in the circuit s I L are approximately simple harmonic in character and are practically unaffected by the inductive association with the vertical wire because of the auxiliary inductance furnished by the coil L, it being capable of demonstration that if by means of the coil L the inductanceof the circuit L I sis rendered large compared to the mutual inductance between the circuit and the vertical wire the natural oscillations which will take place in the circuit s I L will be practically unatfect: ed by the inductive association with the vertical wire and will therefore be practically of a simple harmonic character, as in the case of the isolated simple circuit shown in Fig.
  • n is the frequency
  • C is the capacity
  • L is the inductance
  • p is the periodicity which equals 21m.
  • the vertical wire may with advantage be so constructed asto be highly resonant to a particular frequency, and the harmonic vibrations impressed thereon may with advantage be of that frequency.
  • the construction of such a vertical wire is shown and described in other applications of mine now pending. 7
  • the inductance coil L is introduced in .order to supply auxiliary inductance and to permit of the circuit CO I, L-being' attuned to a partical conductor and the generating and translating devices, respectively.
  • the circuit C I L I is attuned to the same-period as the circuit C L I s and merely tendsto wee'dout and thereby screen the vertical wire from any harmonics which may exist in the current developed in the circuit C L I, s.
  • This screening action of an interposed resonance-circuitis due to the wellk'nown property of such circuits by which a" resonant circuit favors the development in it of simple harmonic currents of the period to which it is attuned and strongly opposes the development in it of simple harmonic currents of other periodicities.
  • the electric resonator C I, L 1 interposed between the vertical conductor and the circuit containing the coherer, is attuned to the same period as the circuit L O C" I, and acts to screen the coherer-circuit from the effect of all currents developed in the vertical conductor save that of thecurrent of the particular period to which the receiving-station is IIO , i stationsof the type shown in Fig. 7 associated intended to respond.
  • any suitableuumher of resonant circuits serve to screen t therecei'ver from the effects of all currents to p y doctor that are not of the period to which which may be induced in the verticalcom the receiving-station is intended to respond.
  • the function of the condensers shown at C inFig. 6 and at C" in Fig. 8 as those con-v densers are not essentialto the tuning of the circuits in which they are placed, but merely serve to exclude the current of the batteries B from the resonant circuits.
  • these'condensers may not appreciably afiect the tuning of the circuits iri which they are included, and thereby lower the resonant rise of potential at the plates of the condensers C and (shown in Figs. 6 and 8,) they are so constructed as to have large capacities compared to the capacities of C and O in Figs. 6 and 8, respectively.
  • Figs. 6 and 8 the coherers K are shown connected in shunt-circuit to the condensers in shunt-circuit to the coil L Q and C, respectively; but they may be connected serially'in the resonant circuit, as
  • any other suitable electroreceptive device may be employed to receive the signal-as, for example, a condenser-telephone.
  • the receiving resonant circuit may be that illustrated in Fig. 12, in which 0 is the condenser-telephone and also thecapacity by which the circuit L GO I is attuned.
  • each of the transmittingstations in Figs. 13 and 16' is identical with that of the transmitting-station illustrated in Fig. 7, and the operation of each .of the receiving-stations shown in Figs. 14 and 17 is identical with the operation of the receivingstation illustrated in Fig. 8.
  • the step-up transformer or spark-coil M" in Figs. 13 and 16 is equipped with an interrupter p and condenser C', and the current is supplied by the battery B.
  • a high potential is developed in the secondary of M".
  • the condenser C As the potential difiereuce. at the terminals of the secondary of M" rises the condenser C is charged till the resulting potential diflerence at s is sufficient to break down the spark-gap 8.
  • the condenser C" discharges through the spark at s, the primary of M, and the inductance-coil L".
  • This cirwo: receiving-sta cuit is attuned to a given high frequency, and f the oscillatory current which results is therefore of that frequency.
  • This current induces a similar current in the interposed resonant circuit L M G M attuned to the same frequency, which current in turn induces 3. currentof corresponding frequency in the con-* ductorV M E.
  • a coil or solenoid as usually constructed consists of niany turns of cotton or silk insulated wire wound on an .insulating-core,-such as a glass or ebonite tube or a wooden spool, the consecutive turns being separated only by the thin. insulating coating of the wire.
  • These solenoids are in general wound with several layers of wire, the layers also being separated from each other only by the insulating coatings of the wires.
  • Such' solenoids are well adapted to be used in conjunction with condensers having solid dielectries for the purpose of tuning circuits to low frequencies; but neither such coils nor such condensers are available for the purpose of tuning circuits to such high frequencies as are concerned in the present invention.
  • sistance and inductance and no capacity but partake more of the character of conductors having distributed resistance, inductance, and-capacity. In fact, they may insome in-' stances behave with high frequencies more like condensers than like conductors having fixed resistance and inductance and no capacity. Since ajcoil constructed inthe usual way behaves for high frequencies as a coninertia and elasticity ductor having distributed resistance, inductance, and capacity, it follows that such a coil will show for high frequencies the same quasi-resonance as is observed with low frequencies in long aerial lines and cables-4'.
  • a general criterion which determines the utilityof a coil for tuning a circuit to a particular high frequency is thatthe potential energy of the displacement-currents in the coilshall be small compared to the kinetic V 1. energy of the conduction-current flowing through the coil when the coil is traversed by a current of that frequency.
  • the preferred form of support for sucha coil is any skeleton frame which will hold the turns of wire in place without exposing much surface of contact to the wires and affording a minimum of opportunity for the development of displacement-currents within itself.
  • elevated conductors In this specification I have spoken of elevated conductors, vertically-elevated conductors, and vertical conductors. I wish to be understood as including inthe term elevated conductors disposed at an angle to the earths surface ,as distinguished from horizontal. conductors disposed parallel to the earths surface.
  • vertically elevated and vertical I refer to conductors whose disposition with regard to the earths surface is mainly or wholly ata right angle or vertical thereto, which is the particular form of elevated conductor preferred by me for use in connection with my present improvement.
  • the circuit whereby forced simple harmonic electric vibrations are produced in the elevated conductor I have shown as a circuit containing a condenser and a self-induction coil so proportioned as to make the natural vibrations of a frequency which is the frequency of the vibrations to be forced or impressedin an elevated conductor.
  • the circuit whereby the energy of the electromagnetic waves of one frequency is absorbed to the exclusion of that of waves of another frequency is in like manner a circuit containing a condenser and a self-induction coil so proportioned as to make the circuit resonant to a frequency which is the frequency of the waves the energy of which is to be received.
  • Bothof the circuits I have spoken of are tuned circuits, and they may be conveniently distinguished with reference to their respective functions by denominating the circuit employed in the development of the vibrations as an oscillating. or snorous-circuit and by denominating the circuit employed in the reception or absorption of the vibrations as a resonant circuit. 1 preferto make this discrimination in nomenclature for the reason that while both the circuits are resonant circuits, yet functionally only that one employed for receiving or absorbing is accurately so described. Except for this distinction in function it is well to,
  • the vertical metallically'rcontin uous source of radiant energy is a structure the location and func tion of which are confined entirely to the transmitting, or'it may be the receiving, end of a system in which the conductor which connects the transmitting and receiving sta-' tions is the non-metallic non-conducting-in fact, dielectric-medium,whichis commonly called the ether and which is by many assumed to be essential to the theory of the propagation of electrical and magnetic force, radiant light, and radiant heat.
  • I claim- 1 Ina system for developing free or unguided simple harmonic electromagnetic signal-waves of a'definite frequency, an elevated conductor and means for developing therein forced simple harmonic electric vibrations of corresponding frequency.
  • a system for selectively receiving the energy of free or unguided simple harmonic, electromagnetic signal-waves of diEerent frequencies a plurality of elevated conductors elevated conductor, and each attuned to' a different one of the said frequencies. 7.
  • a system for producing free and unguided electromagnetic signal-waves of a definite frequency an elevated conductor, a source of electrical. energy and. a group of resonant circuitsinterposed between said elerial-waves, a condenser,
  • vated conductor and said source of electrical energy said circuits being attuned to the frequency of the waves to be developed.
  • electromagnetic sigmeans for charging and discharging said condenser through a closed circuit having inductance adapted toproduce under such conditions simple harmonic electric vibrations, and means for communicating the vibrations so produced to an open circuit or elevated conductor.
  • a condenser means for charging -and discharging said condenser through a closed circuit having inductance adapted to produce under such conditions simple harmonic electric vibrations, means for communicating said vibrations toa resonant cir- .cuit or group thereof attuned to the frequency of these vibrations and means of communicating the resulting electrical vibrations in said resonant circuit or group thereof to an open circuit or elevated conductor;
  • a circuit resonant to a given High frequency comprising a coil having the amplitude of its potential energy small compared to the amplitude of its kinetic energy when it issupporting a current of said given high frequency
  • a'condenser adapted to balance by its reactance, the reactance of said coil for said given high frequency.
  • a coil having the amplitude of its potential energy small compared to the am- 5 plitude of its kinetic energy when supporting a current of said given high frequency.
  • electromagnetic,signal-waves of different frequencies a plurality of elevated conductors, each associated with a circuit resonant to the particular frequency of the electromagnetic waves, the energy of which it is to receive.
  • a plurality of elevated conductors each associated with a group of circuits resonant to the particular frequency of the electromagnetic waves the energy of which it is to receive.
  • an elevated conductor and an electric translating device forming one of the elements of a resonant circuit associated with said. elevated conductor and resonant to the frequency of the electromagnetic waves.
  • an elevated conductor In a system for receiving the energy of simple harmonic, one frequency, to the exclusion of like waves of difierent' frequencies, an elevated conductor, associated circuits each resonant to the frequency of the electromagnetic waves to be received, and means in each of said circuits for swamping the effect of the mutual inductance between it and the other circuits and between it and the elevated conductor.
  • an elevated conductor In a system for receiving the energy of free or unguided, simple harmonic, electromagnetic signal-waves of a definite frequency, to the exclusion of the energy of signal-waves of other frequencies, an elevated conductor, a resonant circuit associated with said con ducttir and attuned to the frequency of the waves, the energy of which is to be received and means'for swamping the elfect of the mutual inductance between said circuit and the elevated conductor.
  • circuits being attuned to the frequency of the wavesto be developed, and means in each of said circuits for swampingthe effect of the mutual inductance between it and the other circuits and between it and the elevated conductor.
  • an elevated conductor an electrio translating device, a group of resonant circuits interposed between said elevated conductor and said electric translating device, said circuits being resonant to the frequency of the waves, the energy of which is to be received, and means in each of said circuits for swamping the elfectof the mutual inductance between it and the other'circuits and between a it and the elevated conductor.
  • a condenser In a system for developing free or unguided, simple harmonic, electromagnetic signal-waves, a condenser, means for chargmg and discharging said condenser through a closed circuit having inductance adaptedto produce under such conditions simple harmonic, electric vibrations, means for communicating the vibrations so produced to an elevated conductor, and means for swamping the efiect of the mutual indnctancebetween said circuit and the elevated conductor.
  • a condenser means for chargring and discharging said condenser through a closed circuit having inductanceadapted'to produce under such conditions simple harmonic, electric vibrations, means forcommunicating said vibrations to a resonant circuit or group thereof attuned to the frequency of thesevibrations, means of communicating the resultingelectrical vibrations in said resonant circuit or group thereof to an elevated conductor, and means in each of said circuits for swamping the effect of the mutual inductance between it and the other circuits and between it and the elevated conductor.
  • an elevated conductor In a system for selectively receiving the energy of free or unguided, simple harmonic, electromagneticsignal-waves of different frequencies, an elevated conductor, a plurality of resonant circuits associated with said elevated conductor, each resonant to ,the particular frequency, of the electromagnetic waves, the energy of which it'is to receive, and means in each of said circuits for swam ping the effect of the mutual inductance between it and the other circuits and between it and the elevated conductor.
  • a plurality of elevated conductors each associated with a group of circuits resonant'to the particular frequency of the electromagnetic waves the energy of which it is to receive, and means in each of said circuits for swamping the effect of the mutual inductance between it and the other circuits and between it and the elevated conductor.
  • electromagnetic signal-waves of different frequencies an elevated conductor, a plurality of groups of resonant circuits associated with said elevated conductor, each of said groups of circuits being resonant to the particular frequencies of,the electromagnetic waves, the energy of which it is to receive, and meansin each of said circuits for swamping the effect of the mutnal'inductance between it and the other circuits and between it and the elevated conductor.
  • an elevated con ductor In a system for receiving the energy of free or unguided, simpleharmonic, electromagnetic signal waves of a definite frequency, to the exclusion of energyof signalwaves of other frequencies, an elevated con ductor, a group of resonant circuits associated with said conductor attuned to the frequency of the waves, the energy of which is to be received, and means in each of said cir cuits for swamping the eifectof the mutual inductance between it and the other circuits and between it and vthe elevated conductor.
  • electromagnetic signal-waves of diiferent frequencies a plurality of elevated conductors corresponding in number to the number of different frequencies to be received, groups of resonant circuits each associated with a different elevated conductor, and each attuned to a diiferent one of the said frequencies, and

Description

No. 714,83l. Patented Dec. 2,1902? J; S. STONE.
APPARATUS FOR SELECTIVE ELECTRIC- S|GNALlNG-. 1
(Application filed Jan. 23, 1901) (No Model.)
5 Sheets-Sheef In W W JEES E5:
M0. 7l4,83l. Patented Dec. 2. I902. J. S. STONE.
APPARATUS FOB SELECTIVE ELECTRIC SIGNALING. (Application med Jan. 28, 1901.
(NqModeL) 5 Sheets-Sheet 2 Mo. 7l4,83l. Patented Dec. 2.11902.
J. S. STONE.
APPARATUS FOR SELECTIVE ELECTRIC SIGNALING.
(Application filed Jan. 28, 1901.)
woman.)
Fl -IZ WITNESSES: I N'ETu fi wflmm 9 m I MQ M fi wfifly 5 Sheets-Shani 3.
m. 7|4,as|. Patented mung-1.19112.
.u. s. s'mwE.
APPARATUS FOR SELECTIVE ELECTRIC SIGNALING. (Application mod Jan. 28, 1901.)
m @j m (No Model.) fishujs-rslhaai No. 7|4,83|. Patented Dec. 2, I902.
J. S. @TUNE.
APPARATUSIOR SELECTIVE ELECTRIC SIGNALING Application filed Jan flii. 1901.)
(No Model.) 5 shaeisflihaet 5.
%wsr 858. v I V INVENTOR.
UNIT D SirAT s PATEN OFFICE.
a when the stations are not connected by a connatural or forced electric vibrations in a hori- JOHN STONE STONE, OF BOSTQN, MASSACHUSETTS, ASSIGNOR TO LOUIS E. WVHICHER, ALEXANDER P. BROWNE, AND BRAINERD T., JUDKINS,
TRUSTEES.
APPARATUS Fo a SELECTIVE ELECTRIC SIGNALING.
SPECIFICATION forming part of Letters latent No. 714,831, dated December 2, 1902.
Original application filed February 8, 1900. Serial No. 4,505- Divided and this application filed Jaimary 23, 1901. Serial No. 44,384. (No model.) v
To all whom it may concern:
Be it known that I, JOHN STONE-STONE, a citizen of the United States, residing at Boston, in the county of Suffolk and State of Mas- 5 sachusetts, have invented certain new ,and
useful Improvements in Apparatus for Select ive Electric Signaling, of which the following is a specification. 4
My invention relates to the art of trans other by means of electromagnetic waves without the use of wires to guide the waves to their destination; and it relates more particularly to the system of such transmission in which the electromagnetic waves are developed by producing electric vibrations in an elevated conductor, preferably vertically elevated.
Here'tofore in signaling between two stations by means of electromagnetic waves ducting-wire. certain disadvantageous 'limitationshave been observed which greatly militated against the commercial value of the methods employed. When the electromagnetic waves are developed by producing zontal conduct0r,the attenuation of the waves so developed as they travel away from the.
conductor is'found to be so great as to very seriously limit the distance to which they may be transmitted and effectively received, the chief cause of this observed phenomenon probably being that owing to the horizontal position of the conductor the plane of polarization of the waves is such as to cause therapid absorption of theenergy of the waves by .the conducting-surface ot' the earth or ;water over which they travel. This difliculty has been overcome by a method of developing the waves which consists in prod ucing natural electric wibrations in a verticallyelevated conductor, in which case the plane of polarization of the wave so produced is at quadratu rewith that of the waves which may bedeveloped inahorizontalwire, and in case of the vertical conductor theattenuation of the waves is observed to be very much less mitting intelligence from one station .to an effectively received at much greater distances. A limitation of the commercial utility of this system is,however,observed,which fore been found possible, so far as I am aware, to direct signals sent OlllifI'Olll atransmitterstation to the particular receiving-station with which it is desired to'communicate to the ex'- clusiou of other receiving-stations equipped with equally or more sensitive receiving apparatus and located within the radius of influence of the sendingrstation. Electromagnetic waves have also been developed by producing natural or forced electric oscillations in loops or coils of wire at the transmittingstation and also by means of the discharge of electricity between two conducting spheres, cylinders, or cones; but in such cases the sphere of influence is so limited as to greatly restrict the commercial utility of these two methods of developing the signal waves. In fine, the method of signaling by means of electromagnetic waves between stations not connected by a conducting-wire, in which method the electromagnetic waves are de- 'veloped by electric vibrations in an elevated conductor, has great advantages over the other existing or proposed methods for accomplishing this purpose in which the electromagnetic waves are developed byother means, since in thecase of the waves developed by the elevated-conductor method the waves ma y be transmitted to and efiectively received at greater distances than by the other systems, but whereas in the systems employing the other methods of generating the waves the signals developed may, at least theoretically, be directed to the particular receiving-station with whichit is desired to communicate to tions in the .neighborhood. It has heretofore been found impossible, so far as I know, to accomplish this purpose in thesystememploying an elevated conductor or wire as the source of the electromagnetic waves.
The object of thisinvention isto overcome the exclusion of other similar receiving-stathan in the case of the horizontal conductor, so that these waves may be transmitted to and it depends upon the fact thatit has not heretothe hereinbefore-described limitation to the l mit their signals each to a particular receiving-station simultaneously or otherwise without mutual interference.
It is'also the object of the invention to provide means whereby each of a plurality of transmitting and receiving stations in such a system may be enabled to selectively place itself in communication with any other station to the exclusion of all the remaining stations.
It is further the object of the present invention to enable the vertical or elevated condoctor in such a system to be made the source of simple harmonic electromagnetic waves of any desired frequency independent of its lengthandothergeometricalconstants. Thus the frequency impressed upon the elevated conductor may or may not be the same as the n'atural period or fundamental of such conductor; but, as will be hereinafter explained, an elevated conductor that is aperiodic may be employed and is best adapted for use when the apparatus is to be used successively for different frequencies, and such aperiodic elevated conductor is likewise the preferred form of elevated conductor when two or more frequencies are to be simultaneously impressed upon or received by a single elevated conductor; but forced simple harmonic electric vibrations of different periodicities may each be separately impressed upon a difierent elevated conductor, and the several energies of the resulting electromagnetic waves may be selectively conveyed each to a separate translating device.
Before proceeding to describe the invention certain fundamental principles relative to electrical vibrations should be stated, as these principles are involved in the art of signaling by means of what. may be called unguided electromagnetic waves.
'Ifthe electrical equilibrium of a conductor be abruptly disturbed and the conductor thereafter be left to itself, electric currents will flow in the conductor, which tend to ultimately restore the condition of electrical equilibrium. These currents may be either unidirectional or oscillatory in character, dependingupon the relation between the principal electromagnetic constants of the conductor-t'.. e.., upon its electromagnetic and electrostatic capacities and its resistance. These phenomena are analogous to the mechanical phenomena which are observed when the mechanical equilibrium of a system is abruptly disturbed and the system is thereafter left to itself. In the case of a mechanical system motions re sult which tend to restore the mechanical equilibrium of the sys: tern. These motions may consist either of a .unidirectional displacement or of to-and-fro vibrations of the system or parts of the system, depending upon the relations which sub sist between the principal mechanical constants of the system-i. e., its moments of mass and elasticity and its friction coefficients. In general the determination of the relations which must subsist in order that an oscillatory restoration of equilibrium shall take place either in an electric or in a mechanical system and the determination of the period of these oscillations is very difficult; but in certain simple cases both the determination of the conditions for an oscillatory restoration of equilibrium and of the period of these oscillations is quite'simple.
An example of a simple mechanical system capable of an oscillatory restoration of equilibrium is to be found in the torsional pendulum, which consists of a highly-elastic wire fixed at one end and supporting at its other extremity a heavy mass called the bob. If a torsional stress be imparted to the wire of this pendulum by turning the bob about the axis of the wire and the bob be then abruptly released, the pendulum will in general execute isochronous oscillations about the axis of the suspending-wire in the process of restoration of equilibrium.- An example of a simple electrical system capable of an oscillatory restoration of equilibrium is to be found in the case of a circuit consisting simply of a condenser and a coil without iron in its core,
drawings, in which 0 is a condenser, and I is a coil without iron in its core. If a charge of electricity be imparted to the condenser coil, as shown in Fig. 1, an isochronous oscillatory current will in general be developed in the circuit in the process of restoration of its electrical equilibrium. Such a simple circuit asthat shown in Fig. 1 is known as a system with a single degree of freedom,
when its equilibrium is abruptly disturbed and it is then left to itself are known as the natural vibrations or oscillations of the system. These vibrations begin with a maximum of amplitude and gradually die away i accordance withwhat is known as an exponential law and are what are known as f. simple harmonic vibrations. They may be represented graphically, as in Fig. 2, in which A is a curve drawn to rectangular coordinates, in which the ordinates represent instantaneous values of current strength and the abscissae represent times. When two suchsimple circuits are associated together inductively, as shown in Fig. 3, the system so formed is known as a system of two degrees of freedom, and in the oscillatory restorations of equilibriumcurrents, as shown in Fig. 4. In general if n l simple circuits, as shown in Fig. 1, be assoand the electric oscillations which it supports as shown in Figure l of the accompanying and if its electrodes be then connected to the 2'. e., in the natural vibrations in such cirharmonic in character, but in general consist what are termed forced vibrations, and in elated together in ductive or by inductive connections a system of at least it degrees of freedom results, and
the natural oscillations of such a system will therefore consist of the superposition of at least n currents. It is, moreover, a fact that the different simple harmonic components. of the oscillations which together constitute the oscillatory restoration of equilibrium of acornplex system are in general not the same as those of the separate simple circuits when these circuits are isolated from one another;
but the presence of each simple circuit modifies the natural period of each of the other circuits with which it isassociated. Thus in a particular case if there be two simple circuits, the first with a natural period of .004
of a 'secoud when isolated and the second with a period of .0025 of a second when isolated, these circuits when inductively connected, as shown in Fig. 3, may have an oscillatory restoration of equilibrium, of which the simple harmonic. components are .00444 of a second and .00159 of a second, showing that the inductive association of the ,circuits together has increased the natural period of the high-period circuit and decreased the natural period of the low-period circuit. It
is, moreover, to be remembered that during the restoration of electric equilibrium cur-4 rents of each of the periods are found'in each of the circuits of the connected system.-
Sofar we have considered the natural vibrations of electric systems-i. a, the electric vibrations by means of which the electric been abruptly destroyed and the circuits are that'complex circuits-will in general have.
complex electric'oscillations. We have, moreover, seen that the natural period of oscillations depended upon the electromagnetic constantsof the circuit in the case of a simple circuit and thateach of the periods of oscillation in the case of a complex or of interrelated circuits depended upon the electromagnetic constants, of each of the interrelated circuits but besides the ability to execute natural vibrations or oscillations both electric and mechanical systems are capable of supporting a system either by con- 7 equilibrium of circuits is restored after it has i the case of forced vibrations the period of the whether, it be a simple circuit or a complex the forced vibrations or of simple circuits,
will also be simple harmonic and of the same period as that of the impressed force. 7 In present systems of signaling by means conductor is employed as the source of electromagnetic radiations the electric oscillations are of the kind hereinbefore described as natural vibrations, the vertical conductor being charged to a high potential relative to the surrounding earth and permitted to ab tric' spark between two ball-electrodes. In such a. method of developing the electromagneticwaves the oscillations are necessarily of a complex character, and therefore the resulting electromagnetic waves are of a complex character and consist of a great variety of superimposed simple harmonic vibrations of difierent frequencies. sist of a simple harmonic vibration of lower periodthan all the others, known as the fundamental, with a great variety of simple harmonies of higher periodicity superimposed thereon. the receiving-station is capable of receiving and'responding to vibrations of a great 'variety of frequencies, so that the electromagnetic waves which emanate from one vertical conductor used as a transmitter are capable of exciting vibrations in any other vertical wire as a receiver, and for this reason any transmitting-station in a system of this character will operate any receiving-station within its sphere of influence, and the messages from the transmitting-station will not be selectively received by the particular receiving-station with which it is desired to communicate, but will interfere with the operation of other receiving-stations within its sphere of influence, thereby preventing them from properly responding to the signals of the transmittingstat-ions from which they are intended to receive their signals.
By my invention the vertical conductor of the transmitting-station is made the source of electromagnetic waves of but a single periodicity, and the translating apparatus at the receiving-station is caused" to be selectively responsive to waves of but a single-periodicity, so that the transmitting apparatus corresponds to a tuning-fork','sending but a single simple musical tone, and the receiving apparatus corresponds to an acoustic resonator capable of absorbing the energy of that single simple musical t-one only. When, how-' ever, the elevated conductor is aperiodic, it is adapted to receive or transmit all frequencies, and accordinglysa single aperiodic elevated conductor different frequency after the manner now well known in the art of multiple telegraphy by wire conductors.
When a single-elevated conductor is who made a source of a plurality of single waves currents resulting from this impressed forts of electromagnetic waves in which a vertical 7 The vibrations con- Similarly the vertical conductor-at may be associated with a: plurality of local-circuits. each attuned to a ruptly discharge to earth by mcansof an elecother frequency upon the conductor.
of difierent frequencies and when, moreovert these signal-waves are to be simultaneously developed, it is obviously necessary that the trains of waves of different frequencies developed in the elevated conductor shall be independent of each other-i. e., it is necessary that the electric vibrations of one freless be hereinafter fully described in order to add to the completeness of the specification. When the apparatus at a particular station is attuned 'to the same periodicity as that of the electromagnetic waves emanating from a 0 I particular transmitting-station, then this receiving-station will respond to and be capable of selectively receiving messages from that particular transmitting-station to the exclusion of messages simultaneously or otherwise sent from other transmittingstations in the. neighborhood which generate electromagnetic waves of dilferent periodicities. Moreover, by my invention the operator at the transmitting or receiving station may at will adjust the apparatus at his command in such a way as to place himself in communication with any one of a number of stations in the neighborhood by bringing his apparatus into resonance with the periodicity employed by the station with which intercommunication is desired.
' In order that the vertical conductor at the transmitting-station shall generate harmonic electromagnetic waves of but a single frequency, I cause the electric vibrations in the conductor to be of asimple harmonic character, and this in turn I-accomplish by producing what are substantially forced electric vibrations in the vertical conductor in lieu of producing natural vibrations in the conductor, as has heretofore been practiced. In order that the electric translating apparatus at the receiving station shall be operated having reference to the drawings which accompany and form a part of this specification.
The same letters, so far as may be, regresent similar parts in all the figures.
Figures 1 to 4 are diagrams already referred to. Fig. 5 is a diagram illustrating one arrangement of the transmitting-station. Fig. 6 is a diagram illustrating an arrangement of the receiving-station. illustrating another form of the transmittingstation. Fig. 8 is a diagram illustrating another form of the receiving-station. Figs. 9 and 15 are diagrams illustrating a detail of the construction at both transmitting and receiving stations. Figs. 10 and 11 are diagrams illustrative of the connection of the co-. herer at the receiving-stations. Fig. 12 is a diagram illustrating the connection of acoudenser-telephone at the receiving station. Figs. 13 and 16 are diagrams illustrative of forms of transmitter-stations capable of developing signal-waves of two different frequencies. Figs. 14 and 17 are diagrams illustrative of forms of receiving-stations capable of receiving selectively signal-waves of two different frequencies.
In the drawings, V represents a vertical or virtually vertical conductor grounded by the earth connection E. v
M, M, M,and M are ind action-coils whose Fig. 7 is a diagram primary-and secondary wires are 1,, 1' 1" v generator at develops an alternating electromotive force of moderate frequency, which when the key It is depressed develops a current in the primary circuit of the transformer M. v The transformer M is so designed as'to transform the electromotive force in the primary circuit to a very high electromotive force in the secondary. As the potential difference at the terminals of the secondary I rises the charge in the condenser 0 increases till the potential difference is s'uflicient to break down the dielectric at the spark-gap 3. When this occurs, the condenser O discharges through the spark at s, the primary I ,-and the inductance-coil L. This discharge is oscillatory in character and of very high frequency, as will be explained hereinafter. The highfrequency current so developed passing through the primary I induces a corresponding high frequency electromotive force and current in the secondary I and forced elec-- tric vibrations result in the vertical conductor V, which are practically of a simple harmonic'character;
These simple harmonic vi'-.
,"bratio'ns'ih the conductor V develop electro- "si'mpl turn, on impinging upon the vertical con-- magnttic waves, which are also practically harmonic in character, andthese, in
doctor at the receiving-station develop therein corresponding simple harmonic vibrations i; oflike frequency.
In the organization illustrated in Fig. -6 the simple harmonic electromagnetic waves of a given frequency or periodicity impinging upon thevertical conductor V develop thereincorrespouding electrical vibrations of like frequency.- By means of the induction-coil M avibratory electrom otive force corresponding in frequency to the electric'vibrations in t the conductor V is induced in the secondary circuit I L C 0'.
If the frequency of this induced electromotive force is that to which the circuit I, LO 0' is attuned,-there will-be a maximum potential difference developed at theplates of the condenser O, and this potential will operate the coherer K. vWhen the coherer K operates, the resistance of the circuit B R K is enormously diminished and the battery B develops acurrent which operates the translating device R. The decoherer (not shown in the drawings) is thereby set in operation, and as soon as the impulse passes the coherer is restored to its sensitive condition. If, however, the frequency of the electromagnetic waves which impinge upon the veltical conductor V of the receiving station depicted in Fig. 6 is not the same as that'to which thecircuit I L C Ois attuned, the electromotive force induced in this circuit will be dilferent from thatto which the circuit will respond by virtue of resonance, and there will be but a negligible potential difference developed at the plates of the condenser 0. Under these circumstance the coherer K will not be operated and the-signals will not actuate the translating device B.
When transmitting-stations and a corvesponding number of receiving-stations are employed, by adjusting the electromagnetic constantsof the circuits atthe various stations these circuits maybe so proportioned or tuned that the energy of the electromagnetic waves emanating from any given transmitting-station will be selectively received and absorbed at a given receiving-station.
Before proceeding to a description of the operation of the other two forms of transmitting and receiving stations (shown'in Figs.
7 and 8) it is to be noted that the condenser charges of condensers is approximately infrom which designed that the product of the capacity of the condenser by the inductance of the circuit is made numerically very small. Moreover, the oscillations in the circuit s I L are approximately simple harmonic in character and are practically unaffected by the inductive association with the vertical wire because of the auxiliary inductance furnished by the coil L, it being capable of demonstration that if by means of the coil L the inductanceof the circuit L I sis rendered large compared to the mutual inductance between the circuit and the vertical wire the natural oscillations which will take place in the circuit s I L will be practically unatfect: ed by the inductive association with the vertical wire and will therefore be practically of a simple harmonic character, as in the case of the isolated simple circuit shown in Fig. 1. The principlemay for the present purpose'be stated oscillators, each such as that shown in Fig.1, are inductively associated with each other, as in Fig. 3, the system is a system of two degrees of freedom, and the natural period of oscillation of each simple circuit is modified by the presence of the other; but if the pro- .versely proportional to the square root of the ,go I thus: that when two simple 1 portions of the circuits be such that the prodnot of the inductance of the two circuits is large compared to the mutual inductance between the circuits the natural period of oscillation of each of the circuits becomes practically the same as if the circuits were isolated. It, further, the electric equilibrium of the circuit .9 I L be abruptly disturbed and the circuit be then left without impressed force-,the oscillations whichare developed in it induce corresponding oscillations in the vertical wire, which oscillations are virtually forced vibrations corresponding in frequency with the natural oscillations developed in the circuits I L and being practicallyindlependcut as regards their frequency of the constants of the second circuit in which they are induced.
The mathematical expression for the frequencyto which a circuit is resonant when it is isolated from all. other circuits-4 e., ,has but a single degree of freedom-is well known and may be stated as follows:
where n is the frequency, C is the capacity, L is the inductance, and p is the periodicity which equals 21m. In the case of a circuit of two degrees offreedom, however, in order. to make the component circuits each responsive to the. same frequency as when isolated-in other words, to overcome the modifying effect of the mutual inductance of each circuit upon the other-4t is necessary to consider in the case of inductive relation the expression:
. M (L a M; 0,10 2 l) where C, L, are the capacity and inductance of the first circuit 0 L R are the capacity, inductance, and resistance, respectively, of the second circuit and M, is the mutual inductance of the circuits. From these expressions careful consideration will show that the effective inductance of the first circuit has been modified by its inductive relation with the second circuit, and it is:
7 M2 IW L 121 11 1 1" 2 1 1p C1 Similarly we have to consider the expression:
1 M2 I12 p(L1p 01 p) from which it will be seen that the effective inductance of the second circuit has been modified by its inductive relation with the first circuit and is These two ind-uctances L, and L are the apparent inductanoes which each of these circuits would have if acting as a primary to induce simple harmonic vibrations of frequency 11. in the other. It is therefore necessary in order to overcome the modifying eflect of the mutual inductance on either circuit to add to that circuit an auxiliary inductance-coil of inductance large compared to the term of the form a 1 b t) BM 1.)
' or at least so large that when it is added to I The vertical wire may with advantage be so constructed asto be highly resonant to a particular frequency, and the harmonic vibrations impressed thereon may with advantage be of that frequency. The construction of such a vertical wire is shown and described in other applications of mine now pending. 7
At the receiving-station shown in Fig. 6 the inductance coil L is introduced in .order to supply auxiliary inductance and to permit of the circuit CO I, L-being' attuned to a partical conductor and the generating and translating devices, respectively.
Inthe transmitter arrangements illustrated in Fig. 7 the circuit C I L I, is attuned to the same-period as the circuit C L I s and merely tendsto wee'dout and thereby screen the vertical wire from any harmonics which may exist in the current developed in the circuit C L I, s. This screening action of an interposed resonance-circuitis due to the wellk'nown property of such circuits by which a" resonant circuit favors the development in it of simple harmonic currents of the period to which it is attuned and strongly opposes the development in it of simple harmonic currents of other periodicities. In this organization an ordinary spark-coil, (shown at M':,) equipped in the usualway with an interrupterp and condenser C",is employed, the current being supplied by the battery B. The operation of this organization is substantially the same as that of the organization shown in Fig. 5, hereinbefore described,except for the screening action of the circuit C I L I, and need not,therefore,' be further described. Suffice it to say that when the source of vibratory currents is particularly rich in harmonics any suitable number of resonant circuits each attuned to the desired frequency may be connected inductively in series, as shown in Figs. 9 and 15, and interposed between the generating device and the vertical conductor for the purpose 'of screening the vertical conductor from the undesirable harmonics.
In the organization illustrated in 'Fig. 8 the electric resonator C I, L 1,, interposed between the vertical conductor and the circuit containing the coherer, is attuned to the same period as the circuit L O C" I, and acts to screen the coherer-circuit from the effect of all currents developed in the vertical conductor save that of thecurrent of the particular period to which the receiving-station is IIO , i stationsof the type shown in Fig. 7 associated intended to respond. 'Asin the case of the" transmitting-station, any suitableuumher of resonant circuits,,each attuned to the particular period to which the station is desired fSuchci-rcuits so interposed serve to screen t therecei'ver from the effects of all currents to p y doctor that are not of the period to which which may be induced in the verticalcom the receiving-station is intended to respond. No mention has heretofore been made of ,the function of the condensers shown at C inFig. 6 and at C" in Fig. 8, as those con-v densers are not essentialto the tuning of the circuits in which they are placed, but merely serve to exclude the current of the batteries B from the resonant circuits. In order that these'condensers may not appreciably afiect the tuning of the circuits iri which they are included, and thereby lower the resonant rise of potential at the plates of the condensers C and (shown in Figs. 6 and 8,) they are so constructed as to have large capacities compared to the capacities of C and O in Figs. 6 and 8, respectively. p
In Figs. 6 and 8 the coherers K are shown connected in shunt-circuit to the condensers in shunt-circuit to the coil L Q and C, respectively; but they may be connected serially'in the resonant circuit, as
shown in Fig. 10,0r they maybe connected 7 and condenser O, as shown in Fig. 11.
Though a coherer has been shown and described in the specification as the means'of detecting the presence of oscillations in the receiving resonant circuits, under which circumstances it operates as a telegraphic relay to control a local-battery circuit including an electric translating device, any other suitable electroreceptive device may be employed to receive the signal-as, for example, a condenser-telephone. When a condenser-telephone is employed as a receiver, the receiving resonant circuit may be that illustrated in Fig. 12, in which 0 is the condenser-telephone and also thecapacity by which the circuit L GO I is attuned.
and 17 illustrates methodsof associating the apparatus hereinbefore described, and illusalready described in connection with Figs. I
6, 7, 8, and 9. For the sake of clearness only trated inyFigs. 5-, 6, 7, 8, and 9, when two or more stations are to be associated with a common elevated conductor. The operation of each individual station is the same as that two stations are shown associated with the common elevated conductor V in the draw- An inspection of thed rawings will show that Figs. 13 and '16 illustrate two transmitting- .with a common elevated conductor, whereas The apparatus shown in Figs. 13, 1 4, 15, 16,-
letters of reference in the case ofone of the.
stations and not to the letters ofreference of the other station.
The operation of each of the transmittingstations in Figs. 13 and 16'is identical with that of the transmitting-station illustrated in Fig. 7, and the operation of each .of the receiving-stations shown in Figs. 14 and 17 is identical with the operation of the receivingstation illustrated in Fig. 8.
To illustrate, the step-up transformer or spark-coil M" in Figs. 13 and 16 is equipped with an interrupter p and condenser C', and the current is supplied by the battery B. When the key It: is depressed, a high potential is developed in the secondary of M". As the potential difiereuce. at the terminals of the secondary of M" rises the condenser C is charged till the resulting potential diflerence at s is sufficient to break down the spark-gap 8. When this occurs, the condenser C" discharges through the spark at s, the primary of M, and the inductance-coil L". This cirwo: receiving-sta cuit is attuned to a given high frequency, and f the oscillatory current which results is therefore of that frequency. This current induces a similar current in the interposed resonant circuit L M G M attuned to the same frequency, which current in turn induces 3. currentof corresponding frequency in the con-* ductorV M E. I
Passing now to the operation of the receivbe-remarked that since the operation of each of these. stations is identical with the operation of the receiving-station shown in Fig. 8 the energy of the waves of one particular frequency will be absorbed by one of the receiving-stations and the energy of the waves of another particular frequency will be absorbed by the other receiving-station. This selective reception of the energy of waves of a particular frequency is independent of thenumber of Waves of difierent frequencies which may be simultaneously present.
It is to be here noted that the above-described methods of simultaneouslytransmittingand receiving space-telegraph messages by a common elevatedconductor are not de scribed as the preferred methods, but that any way of associating a plurality of the stations .shown in Figs. 5, 6, 7, and 8 with a vertical conductor will result in a system for simultaneously transmitting and receiving space-telegraph signals, owingto the fact that these staling-stations shown in Figs. 14 and 17, it may tions are in themselves inherently selective and dove opment of vibrations of diiferent froquenciesin the'elevated conductor and of selectively absorbing the energy of different frethe branch circuits M M in quencies, since .Figs. 16 and 17 are not in themselves selective and since the elevated conductors in Figs. 13
- them in single inverse proportion to their electromagnetic impedances and are not selective except for a slight reaction due to the associated circuits 0 M L and C M L,. These reactions, so far from tending to make the branches selective to the frequencies to which their associated circuits are intended to respond, will, in fact, cause them to oppose more strongly currents of these frequencies than those to which the associated circuits are not attuned. Again,itisobviousthattheinductance of the coil M in Fig. 13 is merely an additional impedancein the elevated conductor, which, to say the least, cannot assist in the development of vibrations in the elevated conductor impressed by circuit 0' M L M The same is obviously true of the coil M in the elevated conductor with reference to the operation of the circuit C M L. Now passing to the transmitting-station shown at Fig.
' 16, it is obvious that the vibrations communicated by the circuit C M L to the elevated conductor V are subject to a shunt due to the coil M in the other branch of the elevated conductor, and, conversely, the vibrations developed in the elevated conductor by the as sociated circuit O M L are subject to a shunt due to the coil-M in the other branch of the elevated conductor. Finally, the coil M in the elevated conductor in Fig. 14 can at best only present an impedance to the waves intended to be received by the circuit O M L,, and, conversely, the coil M,in the elevated conductor can at best only present an impedance to the vibration s'intended to be received by the circuit C M L. 4
In constructing the various parts of the apparatus shown and described in this specification there is great latitude as to the special forms that may be given them; but it must be remembered that when a circuit is to be tuned and it is desired to gain a high degree of resonance both electrostatic and magnetic hysteresis must be carefully excluded from the resonant circuit. For this reason alliron should be excluded from the coils in the resonant circuits, and solid dielectrics shouldnot ordinarily be employed in the condensers. These injunctions apply to the construction of resonant circuits attuned to vry high frere capable of causing the independent quencies, but not with the same force to the construction of resonant circuits .to be tuned to low frequencies. Another precaution to be taken in the construction of the apparatus included in the resonant circuits when very high-frequency currents are employed is that conductors between which there exists-a considerable potential difierence during the op eration of the apparatus shall be kept as" far apart as practical, because of the excessive displacement-currents which tend to flow in the case of high-frequency currents. For this reason it will often be found to be convenient to build the coils the form of flat spirals instead of long spirals of several layers, as is the usual construction of coils. Flat spirals with the turns well separated in orderto ininimize the displacemen t-currents between the turns are, however, by no means the only forms of coils adapted to be used in conjunction with air-condensers for the purpose of tuning circuits to high frequencies andmay often be neither. the best nor most convenient form of coil to employ. Therefore in defining the character of thecoils to be employed for this purpose it will be of advantage to first give the general theoretical considerations which lead to a special construction of the coils and to then give a practical guide to the manner of designing the coils for a particular f requencyor range of frequencies.
A coil or solenoid as usually constructed consists of niany turns of cotton or silk insulated wire wound on an .insulating-core,-such as a glass or ebonite tube or a wooden spool, the consecutive turns being separated only by the thin. insulating coating of the wire. These solenoids, moreover, are in general wound with several layers of wire, the layers also being separated from each other only by the insulating coatings of the wires. Such' solenoids are well adapted to be used in conjunction with condensers having solid dielectries for the purpose of tuning circuits to low frequencies; but neither such coils nor such condensers are available for the purpose of tuning circuits to such high frequencies as are concerned in the present invention. In
sorbed in the solid dielectric of the condenser due to dielectric hysteresis is excessive and the displacement-currents between the adjawell-defined selectivity for that frequency to the exclusion of other frequencies,even to the exclusion'of frequencies difiering but slightly from the predetermined frequency, it is necits the case of high frequencies the energy abt high frequencies as if they had a fixed re-.
sistance and inductance and no capacity, but partake more of the character of conductors having distributed resistance, inductance, and-capacity. In fact, they may insome in-' stances behave with high frequencies more like condensers than like conductors having fixed resistance and inductance and no capacity. Since ajcoil constructed inthe usual way behaves for high frequencies as a coninertia and elasticity ductor having distributed resistance, inductance, and capacity, it follows that such a coil will show for high frequencies the same quasi-resonance as is observed with low frequencies in long aerial lines and cables-4'. e., that it will per se and without the intermediary of a condenser show a slight degree of selectivity for some particular frequencyand for certain multiples of that frequency just as a stretched string which has distributed will respond to a particular tone called its fundamental and to all other tones whose periods are aliquot parts of the periods of that fundamental;
but it is not with such quasi-resonance that the present invention is carried into effect, and I wish it understood that I here disclaim any system employing distributed inductance and capacity as a means of tuning the reso-' nant circuits described in this specification.
,A general criterion which determines the utilityof a coil for tuning a circuit to a particular high frequency is thatthe potential energy of the displacement-currents in the coilshall be small compared to the kinetic V 1. energy of the conduction-current flowing through the coil when the coil is traversed by a current of that frequency.
I have found that for asingle-layercoil the following procedure is sufficient for practical purposes. Determine the inductance of the coil by 5.
If the coil does not meet This willenablethe kin formulae to be found in the text-books and treatises on electricity and magnetism.
coil to be determined for any particular. ourjrent and will also permit of the determination of what would be the potential gradient along ,the coil for the current tof the fre-i quencyto be employed if the coil were devoid of distributed electrostatic capacity. Next calculate the electrostatic capacity between an end turn and each of the remaining turnsof the coil. These capacities, together with the potentialgradient found,will enable the potential energy to be determined, and if the ratio of the potential energy to the kinetic energy sofound be negligible compared to unity the coil will practically satisfy the requirements hereinbefore mentioned. the requirements,
etic energy of the Regarding the effect of a dielectric core in a coil to be used for tuninga circuit to a high frequency, it is sufiicientto state that the preferred form of support for sucha coil is any skeleton frame which will hold the turns of wire in place without exposing much surface of contact to the wires and affording a minimum of opportunity for the development of displacement-currents within itself.
In this specification I have spoken of elevated conductors, vertically-elevated conductors, and vertical conductors. I wish to be understood as including inthe term elevated conductors disposed at an angle to the earths surface ,as distinguished from horizontal. conductors disposed parallel to the earths surface. By the terms vertically elevated and vertical I refer to conductors whose disposition with regard to the earths surface is mainly or wholly ata right angle or vertical thereto, which is the particular form of elevated conductor preferred by me for use in connection with my present improvement.
In this specification I have deseribed the development of free or unguided electromag netic signal-waves of a given frequency by employing in association with an elevated conductora circuit such as to produce therein forced simple harmonic electric vibrations of the frequency desired. I have also described a method of receiving .or absorbing the energy of free or unguided simple harmonic electromagnetic waves of one frequency to the exclusion of waves of a different frequency by associating with an elevated conductor a circuit made resonant to the frequency of the waves whose energy is to be absorbed. The circuit whereby forced simple harmonic electric vibrations are produced in the elevated conductor I have shown as a circuit containing a condenser and a self-induction coil so proportioned as to make the natural vibrations of a frequency which is the frequency of the vibrations to be forced or impressedin an elevated conductor. The circuit whereby the energy of the electromagnetic waves of one frequency is absorbed to the exclusion of that of waves of another frequency is in like manner a circuit containing a condenser and a self-induction coil so proportioned as to make the circuit resonant to a frequency which is the frequency of the waves the energy of which is to be received. Bothof the circuits I have spoken of are tuned circuits, and they may be conveniently distinguished with reference to their respective functions by denominating the circuit employed in the development of the vibrations as an oscillating. or snorous-circuit and by denominating the circuit employed in the reception or absorption of the vibrations as a resonant circuit. 1 preferto make this discrimination in nomenclature for the reason that while both the circuits are resonant circuits, yet functionally only that one employed for receiving or absorbing is accurately so described. Except for this distinction in function it is well to,
note that all oscillating or sonorous circuits are resonant circuits, but only such resonant circuits as have their resistance less than the square root of the ratio of four times their inductance by their capacity are oscillating or sonorous circuits. t I
Also throughout this specification I have describedthe electrical oscillations or vibrations and the free or unguided electromagnetic waves or radiations as simple harmonic.
It is the object of my present invention to approach as nearly as possible to the perfect tion.
simple harmonicwave',and such object is attained to within such a degree of precision as to preclude any possible interference with the operation of the system by any departure that can exist in the wave from the absolute simple harmonic form. My reason for conevery precaution to obtain a true or absolute simple harmonic wave form.
Specifically,.though it may be possible to employ for the purpose of multiple and selective wireless telegraphy electric vibrations and radiations departing considerably from the simple harmonic type by employing at the receiving end circuits selective to the fundamental of such vibrations and radiations, yet it will only be through the selective reception of that simple harmonic component 0f the vibrations or radiations which is their inndamental that the system will be operat1ve.. The other simple harmonic components of the vibrations or radiations add nothing to the operation of the system. Moreover, if such overtones exist in the waves emanating from a transmitting-station their presence will preclude the possibility of placing receiving-stations in the immediate neighborhood of such transmitting-station for the reception of signal-waves of frequencies cor- It is for this reason that I have taken.
responding to the frequencies of such overtones.
Whereas in the present specification I have used the term elevated conductor todescribe the source of radiation of electromagnetic waves developed by forced electric vibrations impressed thereon, yet I deem it proper to point out that this expression should not be confused with the term conductor when used in connection with systems wherein that term is employed to denote a wire or other metallically-continuous conductor extending from a transmitting to a receivingstation. It is of course obvious that in the art to which the present specification relates such a conductor is wholly absent. The vertical metallically'rcontin uous source of radiant energy is a structure the location and func tion of which are confined entirely to the transmitting, or'it may be the receiving, end of a system in which the conductor which connects the transmitting and receiving sta-' tions is the non-metallic non-conducting-in fact, dielectric-medium,whichis commonly called the ether and which is by many assumed to be essential to the theory of the propagation of electrical and magnetic force, radiant light, and radiant heat.
Having described my invention, I claim- 1. Ina system for developing free or unguided simple harmonic electromagnetic signal-waves of a'definite frequency, an elevated conductor and means for developing therein forced simple harmonic electric vibrations of corresponding frequency.
2. In a system for receiving the energy of free or unguided simple harmonic electromagnetic signal-wavesof a definite frequency, to the exclusion of the energy of signal-waves of other frequencies, an elevated conducto and a resonant circuit associated with said conductor and attuned to the frequency of the waves, the energy of which is to' be received.
3. In a system for independently developing free or unguided simple harmonic electromagnetic signal-waves of dilferent frequencies, an elevated conductor and means for independently developing therein forced, simple harmonic, electric vibrations of different and corresponding frequencies.
4. In a system for selectively receiving the energy of free or unguided, simple harmonic, electromagnetic signal-waves of difierent frequencies, each to the'exclusion of the test, an elevated conductor, and resonant circuits associated with said conductor and each atof said conductors forced simple harmonic elect ic vibrations corresponding to a differout o e of the said frequencies.
i6. In a system for selectively receiving the energy of free or unguided simple harmonic, electromagnetic signal-waves of diEerent frequencies, a plurality of elevated conductors elevated conductor, and each attuned to' a different one of the said frequencies. 7. In a system for producing free and unguided electromagnetic signal-waves of a definite frequency, an elevated conductor, a source of electrical. energy and. a group of resonant circuitsinterposed between said elerial-waves, a condenser,
vated conductor and said source of electrical energy, said circuits being attuned to the frequency of the waves to be developed.
8. In a systemfor receiving the energy of free or unguided simple harmonic, electromagnetic signal-waves of one frequency to the exclusion of the energy of those of other frequencies, an elevated conductor, an electric translating device, and a group of resonant circuits interposed between said elevated condevice,
of the waves, the energy of which is to be received.
9. In a system for developing free or unguided simple harmonic, electromagnetic sigmeans for charging and discharging said condenser through a closed circuit having inductance adapted toproduce under such conditions simple harmonic electric vibrations, and means for communicating the vibrations so produced to an open circuit or elevated conductor.
10. In a system for developing free orunguided, simple'har'monic, electromagnetic signal-waves, a condenser, means for charging -and discharging said condenser through a closed circuit having inductance adapted to produce under such conditions simple harmonic electric vibrations, means for communicating said vibrations toa resonant cir- .cuit or group thereof attuned to the frequency of these vibrations and means of communicating the resulting electrical vibrations in said resonant circuit or group thereof to an open circuit or elevated conductor;
11. A circuit resonant to a given High frequency comprising a coil having the amplitude of its potential energy small compared to the amplitude of its kinetic energy when it issupporting a current of said given high frequency,
and a'condenser adapted to balance by its reactance, the reactance of said coil for said given high frequency.
12. In a circuit resonant to agiven high frequency, a coil having the amplitude of its potential energy small compared to the am- 5 plitude of its kinetic energy when supporting a current of said given high frequency.
13. In a system for selectively receiving the free or unguided,
energy of free or unguided simple harmonic,
electromagnetic,signal-waves of different frequencies, a plurality of elevated conductors, each associated with a circuit resonant to the particular frequency of the electromagnetic waves, the energy of which it is to receive.
15. In a system for selectively receiving the energy of free or unguided simple harmonic, electromagnetic,signal-waves of difierent frequencies, a plurality of elevated conductors, each associated with a group of circuits resonant to the particular frequency of the electromagnetic waves the energy of which it is to receive. 1 r
16; In asystem for selectively receiving the energy of free or unguided simple harmonic, electromagneticsignal-waves of different frequencies, an elevated conductor and a plurality of groups of resonant circuits'associated with said elevated conductor, each of said groups of circuits being resonant to the particular frequencies of the electromagnetic waves, the energy of which it is to receive.
17. Ina system for receiving the energy of simple harmonic, electromagnetic signal-waves of a definite frequency to the exclusion of energy of signal-waves of other frequencies, an elevated conductor and a group of resonant circuits associated with said conductor and attunedto the frequency the energy of whichis to be reof the waves, ceived.
and a plu- 18. In a system for selectively receiving the energy of free or unguided, simple harmonic, electromagnetic signal-waves of different frequencies, eachto the exclusion of the rest, an
elevated conductor and a plurality of resonant circuits associated with said conductor and each attuned to the frequency of adifferent' one of the trains of Waves, the energy of which is to be received.
I to
19 In a system for selectively receiving the I energy of free or unguided simple harmonic, electromagnetic signal-waves of difierent frequencies, a plurality of elevated conductors corresponding in.n umber to the n umber of different frequencies to be received, and groups a of resonant circuits each'associated with a different elevated conductor, and each attuned to a dilferent one of the said frequencies.
. 20 In a system for developing free or un guided simple harmonic, electromagnetic signal-waves or radiations, anelevated conductor, associated closed oscillating. circuits,
means for disturbing the eleetricalequillbrium of said oscillating circuits, and means for swamping the effect of the mutual inductance between said circuit and the elevated conductor.
7 22. In a system for receiving the energy of 7 simple harmonic, electromagnetic waves of a given frequency, to the exclusion of like waves of different frequencies, an elevated conductor, a circuit associated with said elevated conductor and made resonant to the frequency of the electromagnetic-waves, the energy of which is to be received, by the condenser and an auxiliary inductance-coil whose inductance is suflicient to swamp the effect of the mutual inductance between the associated circuit and the elevated cond ctor.
23. In asystem for recei yng the energy-of simple harmonic, electromagnetic waves of one frequency, to the exclusion of like waves of difierent frequencies, an elevated conductor, associated circuits each resonant to the frequency of the electromagnetic waves to be received, and each having sufficient auxilia'ry inductance to swamp the efiect of the mutual inductance between it and the other associated circuits and between it and the elevated conductor.
24. In a system for developing simple harmonic, electromagnetic signal-waves or radiations of a given frequency,- a metallicallycontinuous-vertical oscillator and means for impressing thereon simple harmonic, electrical, oscillations of the same frequency. I 25. In a system for simultaneously developing simple harmonic, electromagnetic, signal-waves of dilferent frequencies, a metallically continuous vertical, oscillator, and means for impressing thereon simple harmonic, electrical oscillations of the same frequencies.
26. In a system for receiving the energy of free or unguided, simple harmonic, electromagnetic waves, an elevated conductor, a circuit associated with said elevated conductor and resonant to the frequency of the electromagnetic waves, and'an electric translating device shunted around free or unguided,
the terminals of one of the elements of said resonant circuit.
27. In a system for receiving the energy of simple harmonic, electromagnetic waves, an elevated conductor, a group of resonant circuits associated with said resonant conductor, resonant to the fre-. quency of the electromagnetic waves, and an electric: translating device shunted around the terminals of that one-of said resonant cir-,
cuits which is farthest removedfrom the ele- -vated conductor.
28. In a system for receiving the energy of free or unguided, simple harmonic, electromagnetic waves, an elevated conductor and an electric translating device forming one of the elements of a resonant circuit associated with said. elevated conductor and resonant to the frequency of the electromagnetic waves.
29. In a system for receiving the energy of simple harmonic, electromagnetic waves of a given frequency, to the exclusion of like waves of different frequencies, an elevated conductor, a circuit associated with said elevated conductor and made resonant to the frequency of the electromagnetic waves, the energy of which is to be received, and means for swamping the effect of the mutual inductance between said circuit and the elevated conductor.
30. In a system for receiving the energy of simple harmonic, one frequency, to the exclusion of like waves of difierent' frequencies, an elevated conductor, associated circuits each resonant to the frequency of the electromagnetic waves to be received, and means in each of said circuits for swamping the effect of the mutual inductance between it and the other circuits and between it and the elevated conductor.
31. In a system for receiving the energy of free or unguided, simple harmonic, electromagnetic signal-waves of a definite frequency, to the exclusion of the energy of signal-waves of other frequencies, an elevated conductor, a resonant circuit associated with said con ducttir and attuned to the frequency of the waves, the energy of which is to be received and means'for swamping the elfect of the mutual inductance between said circuit and the elevated conductor.
32. In a system for selectively receiving the energy of free or unguided, simple harmonic,
electromagnetic signal-waves of dilferent frequencies, each to the exclusion of the rest, an
elevated conductor, resonant circuits associated with said conductor and each attuned to the frequency of a different one of the trains of waves, the energy of which is to be received,
and means for swamping the effect of the mutual inductance between said circuit and the elevated conductor.
33'. Ina system for selectively receiving theenergy of free or unguided, simple harmonic,
electromagnetic, signal-waves of different frequencies, a plsrality of elevated conductors corresponding in number to the number of difierent frequencies to be received, resonant circuits each associated with a different ele-- vated conductor and each attuned to a different one of the said frequencies, and meansina each of said circuits for swamping the eifect' of the mutual inductance between'it and the other circuits and between it and the elevated conductor. t
34. Ina system for'producing free and unguided, electromagnetic signalwaves of a definite frequency, an elevated conductor, a
source of electrical energy,
a group of resonant circuits interposedbetween said elevated conductor and said source of electrical energy,
said circuits being attuned to the frequency of the wavesto be developed, and means in each of said circuits for swampingthe effect of the mutual inductance between it and the other circuits and between it and the elevated conductor. U
In a system for receiving the energy of free or unguided, simple harmonic, electrounagnetic signal-waves of one frequency, to
the exclusionof the energy of those of other frequencies, an elevated conductor, an electrio translating device, a group of resonant circuits interposed between said elevated conductor and said electric translating device, said circuits being resonant to the frequency of the waves, the energy of which is to be received, and means in each of said circuits for swamping the elfectof the mutual inductance between it and the other'circuits and between a it and the elevated conductor.
36. In a system for developing free or unguided, simple harmonic, electromagnetic signal-waves, a condenser, means for chargmg and discharging said condenser through a closed circuit having inductance adaptedto produce under such conditions simple harmonic, electric vibrations, means for communicating the vibrations so produced to an elevated conductor, and means for swamping the efiect of the mutual indnctancebetween said circuit and the elevated conductor.
37. In a system for developing free or unguided, simple harmonic, electromagnetic signal-waves, a condenser, means for chargring and discharging said condenser through a closed circuit having inductanceadapted'to produce under such conditions simple harmonic, electric vibrations, means forcommunicating said vibrations to a resonant circuit or group thereof attuned to the frequency of thesevibrations, means of communicating the resultingelectrical vibrations in said resonant circuit or group thereof to an elevated conductor, and means in each of said circuits for swamping the effect of the mutual inductance between it and the other circuits and between it and the elevated conductor.
' 38 In a system for selectively receiving the energy of free or unguided, simple harmonic, electromagneticsignal-waves of different frequencies, an elevated conductor, a plurality of resonant circuits associated with said elevated conductor, each resonant to ,the particular frequency, of the electromagnetic waves, the energy of which it'is to receive, and means in each of said circuits for swam ping the effect of the mutual inductance between it and the other circuits and between it and the elevated conductor.
" 39,. In a system for selectively receiving the energy, of free or unguided, simple harmonic, electromagnetic signal-waves of different he quencies, a plurality of elevated conductors, each associated with a circuit resonant to the particular frequency of the electromagnetic waves, the energy of which it is to receive, and means ineach of said circuits for swamping the eifectof the mutual inductance between it and the other circuits and between it and the elevated conductor.' a
40. In a system for selectively receiving the energy of free or unguided, simple harmonic, electromagnetic signal-waves of different frequencies, a plurality of elevated conductors, each associated with a group of circuits resonant'to the particular frequency of the electromagnetic waves the energy of which it is to receive, and means in each of said circuits for swamping the effect of the mutual inductance between it and the other circuits and between it and the elevated conductor.
41. In a system for selectively receiving the .energy of free or unguided, simple harmonic,
electromagnetic signal-waves of different frequencies, an elevated conductor, a plurality of groups of resonant circuits associated with said elevated conductor, each of said groups of circuits being resonant to the particular frequencies of,the electromagnetic waves, the energy of which it is to receive, and meansin each of said circuits for swamping the effect of the mutnal'inductance between it and the other circuits and between it and the elevated conductor.
42. In a system for receiving the energy of free or unguided, simpleharmonic, electromagnetic signal waves of a definite frequency, to the exclusion of energyof signalwaves of other frequencies,an elevated con ductor, a group of resonant circuits associated with said conductor attuned to the frequency of the waves, the energy of which is to be received, and means in each of said cir cuits for swamping the eifectof the mutual inductance between it and the other circuits and between it and vthe elevated conductor.
43. In a system forselectively receiving the energy of free or unguided, simple harmonic, electromagnetic signal-waves of diiferent frequencies, each to the exclusion of the rest, an elevated conductor, a plurality of resonant circuits associated with said conductors and each attuned to the frequency of a diiferent one of the trains of waves, the energy of which is to bereceived, and means in each of said circuits for swamping the eifect of the mutual inductance between it and theother circuits and between it and the elevated conductor.
44. In a system for selectively receiving the energy of free or unguided, simple harmonic,
electromagnetic signal-waves of diiferent frequencies, a plurality of elevated conductors corresponding in number to the number of different frequencies to be received, groups of resonant circuits each associated with a different elevated conductor, and each attuned to a diiferent one of the said frequencies, and
means in each of said circuits for swamping the eifect of the mutual inductance between it and the other circuits and between it and the elevated conductor.
JOHN STONE STONE. In presence of- ALEX. P. BROWNE, ELLEN B. TOMLINSON.
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