USRE12115E - Receiver for electromagnetic waves - Google Patents

Description

N0.12,115. I v REISSUED MAY 26,1903. R A. EEssENDEN,

RECEIVER FOR ELECTROMAGNETIC WAVES.

APPLICATION FILED MAY 5.190s.

z sBEETssHEnT 1 0 A v 0. m

WITNESSES: INVENTQQ- REISSUED MAY 2a, 1903 E. A. FESSENDEN. RECEIVER FOR ELEGTROMAGNETIG WAVES.

{APPLICATION TILED MAY 5. 1903.

2 SHBETS-SHEET 2.

FHlEL FIGS- was Eases:

RM o n T A N LII No. 12,115. I

UNITED STATES Beissued May 28,1903.

PATENT OFFICE.

REGINALD A. FESSENDEN, OF PlT'lSlJURG, PENNSYLVANIA.

RECEIVER FOR ELECTROMAGNETIC WAVES.-

, SPhZGsEIOAI'lON forming part of Reissued. Letters Patent No. 1Z,L 15, dated May 26. 190 3. Original Nb. 727,831, dated May 5,1903. Applicatiqn fur reissnefiled May 5,1903. arial No. 155,793.

,To (all whom, Lt may concern.-

Be it known that I, REGINALD A. FESSEN- DEN, a citizen of the United States, residing at. Pittsburg,'in the county of Allegheny and State of Pennsylvania, have invented or discovered certain new and useful Improvements in Receivers for Electromagnetic W'aves. of which the following is a specification.

The invention described herein relates to certain improvements in current-actuated. wave-responsive devices of the class or kind described and claimed in Letters Patentltl'o. 706,744, granted to me August 12, 1902, and adapted to be so affected by currents generated by electromagnetic waves as to produce a change in or variation of the conductivity of the receiving-circuit, of which said device forms a part.

The invention is hereinafter more fully described and claimed. I

In the accompanying drawings, forming a pnrtof this specification, Figure 1 is a sectional view of a form of receiver embodying myil-nprovement. Figs. 2, 3, 4. and 5 are simi lar vicwsot' modified forms of receiver, and

. Fig. 6 is a diagrammatic view illustrating the mode of operation of the receiver. Figs. 7 and 8' illustrate further modifications in the construction of the receiver.

It is characteristic of the hot-wire receiver described inthe above patent referred, to and which has been termed a barret'le'r, that the energy of the electromagnetic waves is utilized to heat a body of small mass, and hence requires a small amount of energy to be beated to such an extent as to change its electrical conductivity; Iloretoforc metals, especially platinum and silver, have been used, as described in the patent referred to; but I have found that substances other than metals are available for this purpose, more especially liquids, and of the latter class preferably elcc- Y trolytcs give even better commercial results than metals for the'following reasonsid irst,

liquids are not, by reason of their nature, in-

' jurcd by excessive discharge; second,because the specific resistance of liquids is much higher, in some cases as much as a million times greater, than that of metals, and consequently to obtain the same resistance a very, much smaller mass which is capable of being heated to a. much larger extent may be used; third, because the amount of change of resistance per degree of centigrade is very much greater-for example, the resistance of sulfuric acid when not quite concentrated changes approximately twelve per-cent. per degree centigrade, while'the change in platinum is only about one-third of one per cent. per degree ccnt-igradc. For ail-these reasons the results produced are very much greater. and the action of the receiving device is mu more reliable.

A liquid barretter or curren t-actuatod wave; responsive device maybe constructed in sev-- em] ways. For instance, it is found that it the loop of ametal barretter'snch as described" in the patentbe broken while it is immersed in' nitric acid it will nevertheless act event? more elficiently than before, syn hencea'bar- 7o rett er may be formed consisting of two thin, platinum wires 2 and 3, as shown in Fig. 1, having their ends immersed in a liquid contained in a suitable vessels and farming, together with-such liquid, 2. part of a receivim, 7 circuit,includingnuindicatingdevicefi. This barretter may be connected either directly or indirectly with a receiving-vertical 1. .A second method is to moisten aminute fiber-for example, a cotton thread -an to use it as the loop of a barretter. A desirable construction for this form'of barretter is shown in Fig. 2 and consists of a iiber loop 6, having one end immersed in a liquid, which will be caused to travel along the libel bycapiiiary action and 85, maintain the fiber in saturated. condition. A third method consists in forming a minute,- hole through a d iaphragm 7, conveniently done by drawing down a very thin capillary tube to about three thousandths (.003). of an inch internal diameter, cementing it into a 7 hole in the center of a thick glass disk, and Q then grinding ed the ends of the glass. tube: until they are flush with the surface of the diaphragm, The diaphragm is so arranged in a suitable vesscl as to form a partition between two portions of the solution in the cup or holder shown in Fig. 3, said portions being thus-separated except by the thin columu of the lion id contained in the capillary I00 tube. said column forming the barretter. A terminal 9, preferably of platinum, connected side of the hemisphere 15.

ner described in prior patents granted tome.

A fourth method is to connect two platinum wires by a thin film or small body of cond ncting liquid, as indicated in Fig.4. This can be done conveniently by inserting the wires into a bubble 11, formed of such liquid.

A fifth method is to insert a small piece 12,

of platinum orsimilar material, into aliquid, such as nitric acid, so that it is onlyimmerscd ashort distance. Fig. 5 shows such an arrangement, the platinum wire being covered with silver. The silver wire has a diameter. of about .003 of an inch, and the platinum core inclosed therein has a diameter-of about .0000 of an inch. The silver is removed or eaten oil? from .the lower extremity, and the platinum core projects into the solution of nitric acid. This solution of nitric acid, which preferably contains nitrous acid, is covered by a layer of kerosene-oil, so as to prevent evaporation of the acid and to pre-v vent the platinum from being fused. Asceond platinum wire 13 is also im mersedin the liquid, preferably by inserting it through the hottom of the vessel 4, and these wires are connected to'the vertical and to ground and .also included in the indieating-circuit. It follows from the well-known electricalformula giving the resistance of a cylindricalbody in a conducting medium that practically all the resistance is localized and concentrated within a short distance 'of the point where the platinum wire'lZ projects into the acid. For example, if platinum of a diameter of .0000; of an inch should be immersed in acid t9 a depth of .00002 of an inch, practically all the temperature effects would be local or take place inside of a hemisphere of liquid whose radius would be .OOOOtofan inch. Such an imaginary hemisphere is indicated in Fig. 6, where 12 represents the tip of the platinum, and 15 represents the hemisphere referred to. That this is true will be seen by considering a second hemispheric shell 14, having the thickness of .(JOOlH of an inch out The quantity of liquid in this shell 14- will be more than eight times that in the shell 15, and consequently it will take eight times the amount of heat .to raise it to this same extent. At the same the li uid within tin.- boundary of 15 does not vary much and all parts are almost equally eflicient as soon as we pass the boundary of the effect of the variations of liquid beyond Fig. 6 a depth of immersion of'a terminal equal to half its diameter, the immersionof the terminals should be such as to insurewhat is known in the art asa perfect contact between the terminals and liquid, even though somewhat greater than what I have stated as theoretical, as illustrated in Figs. 5, 7,-and 8. As shown in Fig. 7, the terminal 12 may be inserted through the bottom of the-vessel 4, in which case an insulating liquid-such as bisulfid ofcarbon, having greater specific gravity than the nitric acid or other liquid is used in connection with the latter. As indicated in Fig. 8, the wire 12 may be so surrounded with glass as to preventany gas given off from adhering to the wire, and thereby decreasing its effective area.

The arrangement of circuits used with the liquid ba rretter is practically the same as that with the metal barretter described in the patent referred to.

It is found that certain liquids act better than others-as, for example, though carbonate of soda, caus'ic soda, nitrate of potash,- and other substances give good results it is preferred to use nitric acid, for the reason that the effects are stronger with it than with most other liquids, and in the case of a'burn-out it is sulficient'to screw down the platinum wire until it is again immersed. The burnout is not liable to occur on account of the cooling effect of the liquid 'onthe wire. When using silver-coated platinum wire, the screwing down of the wire into the nitric acid will subject the silver to the action of the acid, which will remove it from the platin um. If, however, a high voltage-e. 1., seven or eightbe used in the local cit-cut, carbonate of soda will give larger effect than nitric acid. v

It is to be noted that in the case of the liq- .uid barretter the action of the electromagnetic waves is to cause a greater current to pass in the local circuit, owing tothe fact that the conductivity of electrolytes increases instead of decreases with heat. With liquid barretter having a resistance of between six hundred and two thousand ohms the increase of conductivity when 'the liquid is heated is so marked as to permit of the operation of a siphon recorder or relay, though a telephone may be used. 1

It is tube noted that there are several distinct methods in which metal and liquid can ICC absorbed none of it can be rectified.

gbealsed in conjunction to form a receiver for electromagnetic waves. First, the case of i a conductor, such asoxidized silver, in coniactwith a liquidv like mercury, where the .action is appareutlya true coherr action caused by the voltage produced by the electromagnetic waves breaking down the insulating oxid and makinga good electrical con.-

tact between" the silver and mercury. This effect does not occur and is not utilized in my form of liquid barretter, for, in the first place, the resistance of my apparatus is constant and definite, does not alter by shock or jar, returns to the same value no matter what the strength of the wave, and an entirely new piece of wire immersed to the same depth when a burn-out has occurred allowsthe same current to pass as any other similar piece of wire; Again, the increase of con.- ductivity is always the same in amount under the same conditions and is exactly what ealculationsshow should be produced by the heating of the liquid. Secondly, the change of resistance is exactly proportional to the energy of the electromagnetic waves, thus diit'ering from the operation of the coherer. Third, it the size of the platinum wire be increased the efiect falls oti: very rapidly, as it should do according to theory, while in the caseof coherer this is not true.

A second method of using liquid and metal is illustrated in Fig. 3 of Letters Patent No.

706,738, dated August 12, 1902, the apparatus described therein being capable of rectifying the' alternating currents produced by the electromagnetic waves. This elt'ect does not occur when using my improved form of receiver, as may be readily shown by substitilting such receiver for the electrolytic cell showuin the patent, in which case no such rectification will be found to occur. The evident reason for this is the fact that the resistance of the liquid barretter is so arranged as to absorb the energy ant not to allow any of it to pass through. The energy by being A seeo'ud'reason is that the polarization capacity of the barretter is too small to permit of such rectification. A third proof of this consists in the fact that the signals are obtained almost as well when both terminals consist of similar pieces of platinum, in which case, according to theory, there should be no recti ficatiou.

A thirdmet-hod consists in utilizing the depolarization of the electrode caused by the heating of the liquid. While there is no doubt that such effectis probably prod need, it is masl-rcd, and when in actual working practically the entire effect seems to be due to the change in resistance. An effect which appears when the voltage of thejocal circuit .is raiscd'to such a point as to t ttase the gases to bubble oil too freely from the point gives rise to a fourth method. Then this is the case, the waves eil'cct an increase in resistance instead of a diminution possibly by. first causing the bubble of gas to be deposited, which decreases the area of contact between the liquid and the platinum wire. This action is, however, irregular, and occurs only at a certain critical point, and as it "does not always occur and regularly'it is not available for actuating an indicating mechanism.

While the liquid receiver will work well no matterwhich pole is connected to the platinum, it is found inpractice that better results-are obtained when the platinum point is made negative, probably because bubbles of gas which may come off are dissolved in the liquid and tend to maintain. the conductivity. I I I claim herein as my invention- 1., A receiver for electromagnetic waves having a small heat capacity and consisting of a small quantity of liquid, substantially as. set forth.

2. Areceiverfol-electromagnetic waves consisting of a small quantity of liquid, theconductivity of which is affected by thotiqiition of electromagnetic waves, substantiallyias set forth.

3. A receiver for electromagnetic waves consisting of a small quantity of liquid adapted to have its resistance decreased by the action of electromagnetic waves, substantially as set forth.

4. A receiver for electromagnetic waves consistiug of a material increasable in conductivity by currents produced by electromagnetic waves, substantially as set forth.

5. Areceiver fol-electromagnetic waves com sisting of a liquid, and rapidly responsive as regards temperature to effects. produced by electromagnetic forth.

6. Areceiver for electromagnetic wavesonsist'ing of a small quantity of nitric acid, substantially as set forth. 7. A receiver for electromagnetic waves, having in combination a small quantity of nitric acid, and terminals formed of platinum immersed in said liquid subsiantiallyas set forth.

waves, substantially as set 8. A receiver for electromagnetic waves.

having all its contacts perfect contacts and formed of a material increasjable in conductivity by currents produced by electromagnetic waves, substantially asset forth.

9. A receiver for electromjagnetic waves,

having in combination a suiall quantity of nitric acid, and terminals formed of platinum immersed in said liquid, thejpositive terminal having an external covering, substan' tially as set forth.

10. An'e ectrical receiver,jconsisting of a liquid and a terminal projecting into the liquid and forming a substantiall perfect con tact therewith, substantially) set forth.

11. An el ctrical receiver; consisting of a liquid and art-e115; Lmely-fine terminal projectinginto the liquid, substantially as set forth. 12. As a means for utilizing the energy of waves, the combination of a liquid adopted 1 to have a condition or characteristic changed or modified by energy produced by waves and meansforlocalizin gin the liqnidsuch change or modification, substantially as described.-

13. As a means for utilizing the electrical energy of waves, the combination of a liquid adapted to have a condition or characteristic changed or modified by energy produced by waves and means for localizing in the liquid such change or modification, Substantially as described.

14. As a means for detecting electric waves,

the combination of a liquid adapted to have one or more of its characteristics changed or modified by electric waves and means for localizing in the liquid such changes or modifications, substantially as described.

15. As a means for utilizing electrical energy, a liquid capable of being affected by said energy to change its condition in combination with means for localizing such change in the liquid, substantially as described.

' lb. As a'mean's for utilizing received electroradiant energy, the combination of a liquid adapted to have one or more of its characteristics changed or modified by said received energy, and means for localizing in said liquid such change or modification, substantlally as set forth.

17. As arneans for detecting waves in space telegraphy, the combination of a liquid, and

means for producing an elfiect. or indication operative on a. change or modification produced in the liquid by electric waves, sub stantially as set forth.

18. As a means for detectingwaves in space telegraphy, the combination of a liquid and means for localizing in the liquid the effect produced by the waves in the liquid whereby the waves'may be detected, substantially as set forth.

telegraphy, the combination of a liquid and means whereby the energy of the waves transformed into another form of energy in the liquid, sul'istantially as set forth. 22. Asa meansfordetectingwavesin space telegraphy, the combination of a liquid and means for enabling it transformation of the energy of lhe'waves to take place in the iiquid, substantially as described.

23. In an electrical wavedeteeior, tie cou1- bination of aliquidand aterminai projecting; thercinto and having in the liquid so small an immersed area that a highly-resistau t'layer is formed about the terminal, substantially as described.

24. In an electrical Wave-detector, the corn bination of a liquid wi ill a terminal projecting" thereinto and having so small an immersed area. that a highly-resistant layer of liquid is formed about the terminal, substaniiallyasdescribed.

25. Asa telegraphic receiver, the eombinw tionof a liquid and an extremely-tine terminal projecting into the liquid and so arranged that the passage of an electric current will produce thermal effects in the liquid, substantially as described.

26. An electrical receivercomnrisicg a liquid and means for transforming the electrical energy received into energy of different form in a localized part of the liquid, said means being adapted to receive and accumulate such transformed ener y, substantially as described.

27. As a means tor utilizing electrical energy, the combination 0E s. liquid and means for localizing the efiect of the energy in the liquid, substantially as described.

- 28. As a. means for detecting received elec tric waves, a liquid adapted to have its resistance changed by the received. energy, 1 combination with means for localizing said change of resistance in said liquid, substantially as described.

99. As a in cans for detecting received electric waves, aliqnid adapted to have its resistance changed by the received energy, in combination with the terminal projecting into said liquid and adapted to localize the resistan ce change, substantially as described.

REGINALD A. FESS ENDEN.

\Vitnesses:

MARY ApUonsmu'r, (inn'rnnon Len lmnooczt.

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