USRE12151E - And boston - Google Patents

Description

JHS. STONE. APPARATUS FOR AMPLIPYING ELECTROMAGNETIC SIGNAL WAVES.

APPLICATION FILED AUG. 18. 1903.

May 40y .To all .whom it may concern.-

' U ITED STATES keissuedseptember a 1908;

I PATENT:

JOHN srosn sronn, or BOSTON, M ssnonUsE'rTa AssieNoR, BYMESN ASSIGNMENTS, To THE STONE TELEGRAPH Ann rnnnrnonncoMPAnY; or PORTLAND, MAINE, AND BOSTGN; MASSACHUSETTS; A- coRPoRA;

TION OFaltlAINE.

APPARATUS roR AMPLIFYING"ELECTROIQKGMITIC*SlGNAL-WAYESQL srncrnxcnrron forming part ofne'ilsued Letters Patent no; 12,161; dated memb rs, 1908;;

Original No 714,832, dated December 2;;902 ljhpplicatib n for rsiuue'liled August 18,1908- Beit known that I,' J HN STONE Sronn, a citizen of the United States, residing-at Bus-- ton, in the county of Suifolk' and State of Mes? sachusetts, have invented "certain. new and useful Improvements in Apparatus'for Am plifying Electromagnetic Signal-Waves, of which the following is a specification.

1 The invention relates to the art of wireless or spacetelegraphy, and more particularly to that form of space telegraphy in'which the signals emanate from an elevated conductor 4 in the form of electromagnetic waves. Such systems shall hereinafter be designated as elevated-conductor systems'of space telegraphyfi? v Heretofore, as far as Iain aware, in elevated I conductor systems of spaceteleg'raphy the electromagnetic waves emanating from the elevated conductonhave either been of suchinoderate frequency as those corresponding to" audible sound-waves or of such enormously greater frequencies" .as can at present only be obtained by the discharge of electric conplitude of the vibrations conveyedtotheeledensers through circuits possessing inductQ' ance. The high-frequency waves havecertain advantages-over the comparatively lowfrequency waves for thepurposes'of elevate'd conductor systems of spaceitele'graphwebut whereas heretofore intheelevatedeconductor;

systemsof space telegraphy employing low frequencies the I electrical oscillationsfin, the

primary 'circpitby means Ora step uptrans former, thereby greatly amplifying-the amvat'ed. conductor, itTlia-s; so far as I amaware;

- heretofore been exclusively the'practice'in high-frequency elevatedconductor systems of space telegraphy to develop the electrical oscillations in the elevated conductor by causing an oscillatory discharge to take place at aspark gap in the elevated conductor itself.

This method of developing the electric oscilptial dif' fircnce just snflicient to produce a' lations directly in the vertical conductor'p're sents the disadvantage of limitingthe ampli-' tude of. theresulting oscillations to 'a poten spark' at the spark-gapin the elevated conductor. y The object of the presentiinventionis to -the electric oscillations in the elevated con ductorfl is limited tothe potential diiferenee:

Y oscillations by means of a step-up transformer to produce inductively corresponding oscillaconductor, the amplitude of these'oscillations being'through the intermediary of the stepup transformer much. amplified.

In my application-filed January 23,. 1901,

- overcome in the highfrequencyelevated-con; ductor system'of space'telegraphy'the defect described. above, wherebyitheamplitude of L v required to produce at sparkat the sparligapi contained in. the elevated conductor. This 1 object I attainiby developing the high-free quency oscillationssrequired.for the purposes of high-frequency space telegraphy in a primary circuit by the charge and discharge of; an electric'condenser and then causing thesev tions of increased amplitude in the elevated 1 SerialZNo. 44,384, for improvement in. appa-- ratusfor selective electric signaling','l have ;AZ-neiiibodiment of this invention is depict= ed in the drawing; which accompanies and l ;;forms a part of-this specification. elevated conductor are conveyed 'toi t'froln'i'a The-figure is a diagram illustrating an or ganization of-circuits and apparatus for pro= .ducing electrical oscillations of great ampli= tud'e inian' elevated conductor;

IuiheidiaQram; a is a generator" of current of arelatively moderate frequency.

and vvhereby oscillations maybe developed orlnot in an elevated conductor at the will of 'the operator.

" Mis an induction-coil or step-up transfernamed as Nand N respectively; S is a spark-gap.

10 is a condenser.

his a'keyby'means of which-the operation Q 6f. the apparatus as awhole may be controlled mer vvho'se primary and secondary arefdesig M is a second step-up transformer whose primary and secondary are designated by N and N respectively.

The elevated .conductor V is grounded at the earth connection E.

The operation of the apparatus is as follows: When set in motion in any suitable. manner, the generator a develops an alternating electroinotive forceof relatively moderto spark passes-at-S, and the condenser is there-.

. by permitted to discharge through the circuit I 3 N C. Thisdischarge is oscillatory in character, owing to the inductance of the coil N a or to 'the inductance. of an auxiliary coil,

is (shoyvjuiinithe drawing at :L,) whieh is intro ducedin'jthe circuit S N G {for the purpose of; controlling the frequency of the resulting vibrations.

"--.0atio1f:liereiubefore referred tb, and its funcgo' "tionindetermining a; simpleharmonic waye istherein fully described.

primary 'N' induce vibrations-of much gmter; amplitude in the secondary conduc- V N"-E, and-these latter give rise to, electromagnetic waves whose amplitude and fiequency, correspond to the amplitude and 5 frequency: of the, electric oscillations. i ,In this manner electromagnetic waves'are caused to "."emanate from theivertical conductor-which 46; are (If, greater amplitude: than it WouId be "possible'to produce from a corresponding elevated conductor in which theelectr'icoscil- Indians are produced'by, charging the condlmtortoahigh potential and; theniperrnittingzt-he'conductor to discharge to earth ."--'-By manipulating the key is in accordance with a predetermined .code telegraphic messages m y-be transmitted from, the elevated condnctor .by lectromagnetic wavesemanating 5o therefrom, and the messages so transmitted.

maybe received by any suitable elevatedconductor space-telegraph receiver within the rangeriof influence of the transmitting elevated conductor V. V a

a Certain precautions must-beta-ken in, the construction of the coil M in order to over come the effects of dielectric and. magnetic hysteresisagnd the eifectsofcapacity and conductance, leakage between the. various-con- 6o volution's of the coil; but these precautions -are no different from those which have'long been recognized air-necessary in-theeenstruction of inductance-coils to be used; thighmedium the conditions governing conductive and inductive or capacity leakage are'practically identical. The wire must b of rela-- This coil is shownin my appli- The vibrations' in tively small diameter, and the distance separating two convolutions between which a considerable difierence of potential exists during the operation of the apparatus should be relatively large. For this purpose fiat spirals have been employed; but any other convenient form may be employed, provided such proportions are taken as will sufliciently diminish'the' electrostatic capacity of the convolutions between which high differences of potential occur during the operation of the apparatus. The necessity of avoiding dielectric and magnetic hysteresis makes it necessary to avoid as much as possible the use of solid andliquid dielectricshaving great dielectric hysteresis, and also imposes the condition that no iron shall be placed in or about the coils except-it be so placed as tovhave but slight induction developed in it by the current I and it is there that the displacement-current is greatest. For this reason it is necessary to so construct the condenser C that there shall be a minimum of dielectric hysteresis.

This; may be most easily accomplished by usingan air-condenser, though it is possible that some other dielectric, either solid or liq- .rience extends, air is the preferred dielectric to em ploy in the condenser. When the ciredit 8 G N is supporting the oscillating discharge of the condenser O, the greatest magnetization occurs in the said coil' N or in the here-inbefore mentioned auxiliary coil employed to control the frequency of the oscilla-' tions. For-this reason it is necessary to so construct the coil N and the auxiliary coil as to minimize the magnetic hysteresis in them.

This result may be accomplished by excluding -iron or other paramagnetic materials from these coils and from their immediate neighborhood. Though itmay be-possible to employ finely-divided soft iron embedded in a dielectric matrix to enhance the magnetization in these coils, I am not prepared to recommend netic material is excluded are the preferred coils toemploy in the circuit S O N. Though the displacement-currents are greatest at the condenser, there is nevertheless, as hereinbefore stated, inductive or capacity leakage between the turns of the coil--11 9., displacement-currents flow between the convolutions of the coil, and these displacement-currents,

as well as the hysteretic losses which they may involve, should be minimized in the manner hereinbefore described; but it is not necfrequency circuits; For a= given d electric essaryto indefinitely diminish these displacemerit-currents, audit is sufficient to so design thejc'oils that they shall behave for currents of tor having a fixed inductance and a fixed resistance, but devoid of appreciable capacity.

-Coils constructed in the usual way do not behave for high frequencies as if. they had a fixed resistance and inductance-and no ca pacity, but partake more of the character of conductors having distributed resistance, in-- dhctance, and capacity. In fact, they may in some instances behave with high frequencies more like condensers than like conductors having fixed resistance and inductance and no capacity. Since a coil constructed in the usual way behaves for high frequencies as a conductor having distributed resistance, ins

ductance, and capacity, it follows that such I a coil will show for high frequencies the same quasi resonance as is observed with low frequencies in long aerial lines and cables-t. e. that it will per se and without the intermediary of a condenser'show a slight degree of selectivity for'some particular frequency and for certain multiples of that frequency, just as a stretched stringwhich has distributed inertia and elasticity 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 withsuch quasi resonance that the present invention is carried into effect. A general criterion which determines the utility of a coil for tuning a circuit to a particular high frequency is that the potential energy of the displacement-currents in the coil shall be small compared to the kinetic energy of the frequency.

conduction-current flowing through the coil when the coil is traversed by a current of that I have found that for a singlelayer coil the following procedure is sutlicient for practical purposes: Determine the inductance of the coil by formulas to be found in the text-books and treatises on electricity and magnetism. This-will enable the kinetic energy of the coil to be determined for any particular current and will alsofpermit of the determination of what would be the potential gradient along the coil for the current of the frequency to be employed'if, the coil were devoid of distributed electrostatic capacity. Next calculate the electrostaticv capacity betweenan end turn and each of the remaining turns of the coil. These capacities, together with the potential gradient found, will enable the potential energy to. be determined, and

if the ratio of the potential energy to the kinetic energy so foundbe'negligible compared to un ity -the-co-il will practically satisfy the requirements 1 hereinbefore mentionedf If the coil does not-meet the requirements,-lhe design should be so changed as to increase the separation between the turns, or the size of the wi-re'should be diminished or the di:

inensjons of the coil so otherwise altered as to decrease "the distributed capacity-without proportionately diminishing the inductance.

The'calculations may be greatly abbreviated and theliability to'error greatly reduced if the results of the computations he plottediu to a high frequency it is sufficient to" state that the preferred form of support for such a coil is any skeleton frame which will hold the turns of wire inplace without exposing much surface of contact to the wires and affording alminimum of opportunity for the develop-- ment of displacement-currents within itself.. Thisform of skeleton frame is well known in. the art, having been fully described in Vol. 49

curves. Regarding the eifect of a dielectric-I corein a coil to. be used for tuning a circuit.

(1900-1901) of the Journaljof the Society of Arts, London, in the report of a lecture by said result.

The injunctions hereinbeforegiven regarding the construction of the coils to beem 'ployed in'circuit S G N' apply'with equal force to both the coil'M -and the auxiliary coil used to control the frequency of the os-' cillations in this resonant circuit; butthe 'coil N may be made to perform thefunction of the auxiliary coil and control the frequeney of the oscillations, or, what amounts. to the same thing, the auxiliary coil may be *made a part of the coil N, which then performs both functions-4'. e., of controlling the frequency of the oscillations and of impressing these oscillations upon the elevated'coni ductor. This double function mayhe'per-' formed by the coil N if it be so designed that Prof. J. A. Fleming. It is by no means necf essary to use this report,but I find'it ja'con-I venient means for accomplishing theafore its'self-induction is made large compared- 110 the ratio of the mutual induction between the coils tothe. product of the inductance of the primary coil-by the inductance of the sec- 1 ondary-'i. 6., M L L that the inductance of the auxiliary coil'must be added to the inductance of N without appreciably increasing the mutual inductance This simplyme ans between that coil and the'second'ary coil N The-performance of the apparatus is the same be located ina separate coil or incorporated in the coilN' of the transformer M, though it will be found in practice more convenient to locatethexauxiliary inductance in a separate coil, owing to thegreater complexity of r the numerical calculations which have to be.

"made when the auxiliary induct'anceis to ,be furnishedby thecoil NY.

' I am aware ofPatents Nos; 645,576 and j 649,621 to Nikola Tesla, which discl'ose a method and apparatus forimpressing on an aerial conductor oscillations of high frequency by means ofa transformer but in said patentsno means are disclosed for producing 'simple'harmonic waves, and,furthermore, as

the system therein disclosed isf'for'the trans mission-of electrical-energy by conduction -througha rarefied atmosphere a simple hers moni'c wave is not; necessary; but as I am the first todiscover'the utility of a; simple harmonic wave in. the transmission of intel ligence by electromagnetic waves by the sys-' imwhether the auxiliary inductance necessary 'to control. the-frequency of the oscillations tem disclosed in my application aforesaid and am the first to discover the means for producing said wave form effectively I claimherein, broadly, an apparatus for amplifying said electromagnetic waves.

It is to be definitely understood that the present invention is not confined to the specialform of apparatus shown and described in this specification as means of developing simple harmonic electric vibrations in the primary circuit of the coil M, any suit-able means of developing simple harmonic electric vibrationsiirthe primary of the coil M being consistent with the invention.

What I claim is- 1; In an apparatus for producing high-frequency simple harmonic electromagnetic signal-waves, means of developing simple harmonic electric oseillations of high frequency J in a primary circuit, an elevated conductor and a step-up transformer having its primary helix associated with said primary circuit and its secondary helix associated with said elevated conductor.

2. In a transmitter of electromagnetic sig-' rial-waves, a closed oscillating electric circuit containing the primary of a stepup transformcr,an elevated conductor associated with the secondary of said transformer, and a JOHN STONE S'IUNIC.

Witnesses:

ALEX. P. BROWNE, G. A. HIGGINS.

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