US1718431A - Radio apparatus - Google Patents

Description

. June 25, 1929. G, w, plCKRD 1,718,431

RADIO APPARATUS Filed Oct, 14, 1921 3 Sheets-Sheet 2 'W' \\l\\ f v RADIO'APPARATUS. Application led October 14, 1921. Serial No. 507,663.v

This invention relates to radio apparatus bodiment of the invention mo for use in radio communication for recepadapted for direction finding; tion and transmission. *The invention in iig. 7 is a diagrammatic view. showing particular relates to Acombined open and the wiring of the construction of Fig. 6;`

closed aerials of the typedescribed in my Fig. 8 is a diagrammatic View .of another Patent 876,996, and in my pending appllcaembodiment of .the invention more especire especially tions, 'Serial No. 368,903 filed March 26, ally adapted for elimination of static than 60 1920, and'Serial No. 379,405 iiled May 6, 4o'r direction nding. 1920, the present application constituting a In Fig. vl` is shown the now-familiar re- 10 continuation in part of application No. 368,- ception curve. of a vertical loop lor closed 903. The apparatus disclosed in the patent aerial, in a. horizontal plane, consisting ofl a andapplicationsabove-mentioned relates to cosine curve drawn in polar co-ordmates. 65 aerials having different directional proper- This 1s an idealcurve; actuall ties in any given plane suchas a closed loop gives a more or less distorted ligure-of* aerial combined with an open vertical aerial eight, sometimes tending to an hour-glass in which the currents set up-in the aerials 4shaptaand usually more or less iinsymmetriare combined for unilateral reception, as in cal. n a vertical plane, including-the plane 70 direction finders and radio Compasses and of the loop itself, reception for a closed loo e for the elim nation of'static as in transatis symmetrical, and the reception curve in Q) lantic'communication,'or both. this plane is a circle, as shown in Fig. 2.' Heretofore, apparatus has been designed If t e loop is near the ground, i't does not fory reception in a'horizontal plane, and the receive from points below the horizon; and 75 reception characteristics of aerials have been the reception curve for a loop in afvertcal studied principally, if not exclusively, 1n plane including the loop is a. semicircle as that plane. illustrated infull lines. f' However, if the An object of the present invention .1s to loop is elevated sufliciently above the surprovide .aerials having three-dunenslonal face of the ground, such reception curve in, 80

characteristics designed to recei-ve useful siga vertical lane including the plane of the --nals directionally in all planes, i. e., a threeloop will e a circle as shown 'in Fig. 2,

3o dimensional direction finder or radio compartly infull and partly in broken lines. pass, and to eliminate static coming from This would be true if the loop is placed aloft any point in altitude or azimuth, i. e., from as on an aircraft. Finally, the complete any direction in space. f' three-dimensional reception surface of the lOn November 5, 1919, I presented a 'paper loop is a torus, -not illustrated, but see article before the Institute of Radio Engineers on above referred to, Fig. 12; that is, a ldough- Static elimination by directional recepnut-'shaped figure with the contracted cen-` ti-on, in which paper I discussed the results tral portion tangent to a line drawn norof my investigations on static'and. the remally thru the center-of the loop. The sigeeption characteristics of aerials not only in .nificanceof the reception curves of Figs. l

40 the horizontal plane, but also inth'ree-diand 2 is obvious; that is, the closed loop can mensions. The paper with li ures Was pub- .receive more or-less from all points in space lished in the Proceedings of the Institute excepting only 'along a line passing no r- 95 of Radio-Engineers,- for October, 1920, butl mally thru'its center. The reception of a f I will briefly outline and discuss the receploop is also dependent upon the plane of potional eharucteristics'of such aerials in so l.larization'of thefwaves; that is, lthe orientafar as they may serve to elucidate and eX- tion of the source or transmitter, and this plain' the present invention.

In the accompanying drawings, and the description thereof. The torus- Figures 1 to 5 inclusiveI are diagrams or shaped figure or surface of rpception is, as

5e reception curves illustna, 'ngthe Vdirectional explained in the articleftrue for sources of .properties of open angl/.closed aerials and Iall possible orientation of the, source of their combinations; i waves. A further meaning of Figs.-1 and 2 10|- Fig. Gis an elevation illustrating one emis that maximum reception for a loop isg in is fully set forth in Fig. 19 of the article,-100

loop; that is, for

- come solely from above,

all directions in the plane including -the a loop having its plane in an east and west direction, the zone of maximum reception is a belt across t-hesky from east to west, reception decreasing to zero on the horizon at points north and south of the loop.

The so-called open antenna, which usually consists ot a vertical wire, short as compared with a wave-length, plane a simple circle recept-ion diagram, that is, it receives equally well from all points on the horizon.l Such a diagram would be such as disclosed in Fig. 2, in which the antenna is arranged vertically ot' the point O, reception being equally. in all directions in the horizontal pla-nc as indicatcd by the circle. In any vertical plane passing thru the antenna, a quite ditl'crent reception curve results, as reception is a maximum on the horizon, and decreases to zero at the zenith. The complete curve in any vertical plane passing thru the antenna, therefore, would be a tigure-of-eight such as disclosed in Fig. 1 and discussed in connection with the loop; that is, when the antenna is near the ground, its reception figure would be so much of the tigure-of-'eight of Fig. 1 as is above the line A, B, Fig. 1. However, if thisantenna were spaced vertically from the earth a sufficient distance, the complete reception curve in a vertical plane would then be a figure-ot'- eight. In other words, the reception curve of an open antenna in a vertical planepassing thru it is the same as the reception curve ot a closed loop in a horizontal plane.. Actually, as with the loopl or coil aerial, and for similar reasons, this ideal curve for the open ant-enna usually suffers considerable distortion, partly be anse actual vertical aerials have an appreciable horizontal length in most cases, and partly beca-usc ot' unsymn'ietrical or electrically-warpcd surroundings. The complete 'direc-dimensional reception surface of the open antenna is therefore just like the closed loop reception surface, being a torus, planes apart.

In this connection, there has been milch discussionas to the direction or directions from which static comes. However, if static the zenith, a symmetricalopen antenna would make a perfect static eliminator. Equally, if static came in on the receiving point with the same intensity from all points in altitude and azimuth, it would be difficult to account forthe wellf known freedom of the loop from static. But if we assume in general that static is at its worst near the horizon rather than the zenith and comesfrom a point or a small arc instead of from'all around ,the horizon, it will be obvious why the loop is a much bet-ter stat ic eliminator than vthe open aerial.

It is now known, as a result of careful' has in the horizontal' but arranged 1n 'surface is difficult to measurements, that static waves come in on the receiving station from the horizon, ife., with a iiractically vertical wave l'ront. See L. W. Austin, The lVavc-Itrout Radio-'llelegraphy \Vashington Acad. Sci. J. II, pp.101-106, March t, 1921.

As disclosed in my patent above referred to and also in thc applications above rcerred to, itis my practice to couple the open aerial and the 'closed loop together with the open and closed acrials at approximately the same point in space 'relative to the transmitted wavelength,-(i. c., the open and the loop acrialsarc either at thc same point in space, or are but a very small fraction ot a wave-length a.par t),-a1nl to add the currents received in the open and closed aerials in -phase in a secondary cir- ,cuit for affecting -a detector or indicator.

lIn such coupled or combined arrangements,

loop and open aerial ot it' (by vproviding a Angle in,

equivalent dimensions or by coupling ad` j'ustment, or by both), the currents open antenna are made `equal, in their effect upon the secondary, to those 'from the loop, the result of this addition may be illustrated by a reception curve on the horizontal plane, as shown in'Fig. 3. As there illustrated, it will be seen that reception is at. a 1na. \'imum from thel direction C A, is zero from the direction O-B, and has intermediate values from other directions, the complete curve being a cardioid, it heilig assumed that the distant transmitter is at a point at the right of the figure and that the. coupling between the 4open and closed aeria-ls and sccondary is so arranged as to add the currents in the open and closed aerials. Such a circuit, employed as a direction tinder, givesthe. true bearing of the distant station, and does not, as with the simple loop, lea-ve the direction indeterminate by 180. In a vertical plane including the loop, the reception curve forfthe coupled loop and open/ aerial is also a cardioid, as shown in Fig. Lt. with a maximum on the horizon at Z, and zero on the horizon at B. Reception from the zenith, that is, along the line OZ, being limited to the loop, has half the value of reception along the line O-L In a vertical plane at right angles with the loop and, passing thru the vert-icall antenna, the reception curve of the-combined system is a circle, `as indicated at Y, Fie. 5.

The complete three-dimensional reception show in a two-dimensional tigure or plan. In Fig. 5, however, I have illustrated the three principal sections of thisreception surface. This rece )tion surface section, it willbe noted, is ma e up of a combination of the figures of Figs. 3 and 4 arranged at right angles to each other, plus the surface Y, arranged in a plane at right angles and passing thru line Z-N This -gure is a cardioid -of revolution,

from the apple.,

pending which may be. moresimply described as anwith the pit at the origin O. From a conslderat-ion of the three-dimensional unilateral reception figure .of the combined open and loop aerials,

be seen that static originating at oints other than on thehorizon in the direction of will either be Wealgthe distant transmitter ly received, or, if it ha pens to originate on the horizon at a point 180 from the-transmitter, it will not be received at all.

As fully discussed and disclosed in my coapplications above mentioned, the combined openaerial and loop such as shown in myPatent 87 6,996 is not at present,

. however, the best arrangement for kreducing static. 'As the effect of static on a receiving circuit is practically pure impact excitation, complex Waves will be s .et up in the two coupledcircuits-the loop and the open antenna-With the result that. the ideal diagrams illustrated in Figs. 1 to 5 are but roughly approximated. Y These diagrams are, ofcourse, only true for steady state undamped wave reception, or for static reception on substantially aperiodie circuits.

The' types of combined closed loop andl open aerials as disclosed in my applications above mentionedand in use at Otter' Cliffs near Bar Harbor, Maine, for transatlantic communication, are lconstructed .and designed primarily with reference to the hori- 'zontal characteristics of reception-andnot inregard to the three-dimenslonal receptlon.

Such apparatus, however, Was found to bel very satisfactory in. reception and inhthe` elimination of static, especially when used with a variable resistance inserted in 'either or both aerials such as disclosed in Fig. 8, this resistance being for the purpose ofl damping, the oscillations caused' by static upon the coupled circuits of the receiving apparatus as more fully described in said applications and hereinafter, such resistance being generally of the order of 'thousands of ohms; for example, 1,000 to 10,000 ohms,

its exact .value depending upon the circuit ycharaeteristics, wave-length, etc.

. As a result 'of my investigations at Otter. Cliffs andstudy of aerials in three dimensions, I have devised the arrangement of open and closed aerialsvdisclosed in@ Fig. 8

- as the most satisfactory, primarily for the elimination of static. Examination `of Fig. 5,wi1l show if this figure is turned thru 90 `(lockwiseso that the vertical plane Y becomes the horizontalplane, a veryfavorable reception surface results.' No energy such as static would bereeeived from the zenith and a very little' from the rest of the hemisphere until theyhorizon was reached On the horizon, from static sources having all possible planes ofv polarization, there would be reception from' all directions, but

for signals from distant transmitters the.

as shown in Fig. 5, it Will y ltally relatively to the l'metrically with the loo as to the reception surface.

the transmitter,`so that signal reception would be directional, and so that the circle Y of Fig. 5 would be eight'such as derto turn through face of al circuit, such as changed to a figure of the reception sura combined closed.

that shown in Fig. 1. In orloop and open vertical antenna adjacent the earth, and to obtain `the ladvantages of this invention, I found it necessary t0 shift such vertical antenna thru 90 in the plane of the loop. This results in the construction illustrated ldiagnammatically in Fig. l8- in which A' is a closed loop therewith a tuning justable resistance aerial 'having in, series condenser C and an ad- R. Arranged -horizonground and `sym- A v but -insulated therefrom is an open aerial B having inserted centrally thereof an adjustable con# denser C around the terminals of which is a shunt having a coil L" coupled to a coil Ls'in the closed' loop A forming an adjustable coupling M for transferring in phase the energies received in the closed loop and 1n the open aerial to one or the other, combimng them, and constituting means for eliminating static. 'A secondary circuit S having a coil L2 therein is adjustably coupled as indicated at N to coil L3, or, if so desired,to coil L". The circ-uit S includes an suitable detecting means and indicator (not illustrated) and may also include any amplifying means. I have found it best to remove the cn'cnitllsclosed 1n Fig-8, somewhat from theearths'surface, and I have observed that 1n general, 1f the lower part of the loop is'elevatcd some .five or slx meters from the ground, the arrangement Will func'- tion sa.tisfa'ctorily.` In this connection, 1t must be remembered that, overland at least, Wave-fronts are not vertical, but are tilted forward somewhat `in i the direction of propagation. F or example, I- have found that at Otter Cliffs the waves arriving fromfEur'opean stations were in'- elined approximately 15 from the vertical. Vhcn a tilted wave-front of Fig. 8, it is equivalent to tilting the`horizon of this figure, with all that' that implies Returning to the plane Y,

Fig. 5, Iit will be seen that if passes, the circuit.-

assuming that 'it is. now in a horizontalI plane, be rotated slightl Acounter clockwise around- C-z-'D as an axis, one-half of the reception surface will bemore or less subm'erged (below ground), so that reception will be unilateral. This change of position of the reception surface' is secured in the" physical" embodiment of the invention by angle, thereby suppressing practically encircuit free from disturbance.

.swlnglngthe c ircuitI of Fig. Sthru a slight all by the combination,

Cil

source of static tending vzontal antenna B is either condenser C inserted at its center. coils L In the construction of Fig. 8, the horifeebly receptive or non-receptive as to the transmitted signal, the loop B being so positioned, with its plane in line with the distant transmitter, Aas to receive the signal with maximum intensity. Static wavesl coming from overhead are received by both collectors A and B and are equalized and opposed by couplings L L3 L2 which are adjustablel and reversible. Static impulses originating near the horizon at lpoints at right angles to theantenna B will be received by the open antenna only when their plane of polarization is other than vertical, and I have found that in general all waves arriving from the horizon are vertically polarized, perhaps due to-attachment to the earth, and hence are either not received at or at most but eebly. On the lother hand, static impulses arising at points near the horizon in the plane of the loop will not affect aerial B, and hence cannot be eliminated without so tilting the apparatus that the horizontal aerial B' is affected and the static energizes in the two aerials then equalized and opposed by the couplings. In the latter case, inasmuch as the horizontal aerial B is tilted relative to the ground to cause it to be normal to the tilted transmitted waves, Vstatic waves coining from these directions will also strike the open aerial B at an angle and set up 'oscillations which can be made equal to and opposed with the static oscillations in the loop.

In an embodiment of the invention of Fig. 8 as actually constructed and used, the loop `Alconsisted of seventurns of number 16 Brown & Sharp gauge ,copper wire (1.3 mm. diameter) spaced 10 cm. (4; inches) apart in a solenoidal coil, 30 meters (91.5 feet) long, 7 meters (21.4 feet)I high and i with the lower conductors of the loop about 4 meters (12.2 feet) above the ground. The open horizontal antenna single wire meters long, with a Variable The were 2O millihenrys each,

Pre-

and L and the resistance R was 1000 ohms.

liminary tests having indicated that the open antenna. B received materially less energy `than the loop A, the resistance R was therefore placed in the loop in order to render thecurrents in the loop and open aerial more nearly equal, thereby requiring and adjustment of the couplings.

The apparatus of Fig.' 8 may be mounted,

if so desired or convenient, on suitable universal mountings such as disclosed in Fig. 6, which 4will be more fully described `hereinafter, inorder that the combined closed loop and `open antenna may be located in the most advantageous to*the-transmitteror with reference to the to preventthe clear reception of the'signal, and if so'desired the able' or required it. Conductors 16 B consisted ot a. j

tuning condenser C less variation equal, and added together any relation with reference and reversible for the purpose of equalizing and concelling the static energies, and for this purpose it is'advisable that reversing switches such as disclosed in my above-mentioned co-pending applications be employed.

Referring to Figs. 6 and 7, I have illustrated a form of the invention which is primarily adapted for use as a radio compass or direction finder on airplanes or balloons or for the purpose of determining from any station the location of distant- 'airplanes or other airships when transmitting.

Fig. 7 is a diagram of the circuits involved in the mechanical arrangement of Fig. 6. In Fig. 6 I have illustrated a frame 11 of insulating material, having crossp-ieces 12 of similar insulating material. On cross-pieces 12 is secured a loop vA of wire forming a multiturn loop of any suitdimension. As here illustrated, this loop A is so wound lthat the several turns thereof same plane and spaced from .each other, altho they. may be wound in any suitable manner as conditions may require. The ends of the loop A extend atv points 13 and 14 into shieldingl box 15 secured to frame 11 and containing the adjustable. elements of the apparatus as disclosed diagrammatically in Fig. 7. Mounted at diametrically opposite lpoints on the n alined two metal rodsi B constituting an open' aerial structurally distinct from closed. loop A in the sense of being insulated from and 17 electrically connected to the rods B extend into the box 15 points 18 and 19 within which they are associated with the adjustable devices more fully illustrated in Fig. 7. 'The loop A has in series with it an adjust: ble tuning-condenser G (Fig. -7) and an inductance L .(Fig. 7) within box 15, (Fig. (3), while the open aerial B has a similar inductan'ce L (Fig. 7) shunted around which is a variable all /within box 15 (Fig. 6). The inductances L and L (Fig. 7 constitute an adjustable and reversible coupling M, whereby the signal currents set up in the open and closed aerials are made and the static currents are made equal and opposed if for reason this is advisahle. I have not illustrated the specific means the condensers C and C' and couplings L and L3, as any well-known means may be .'utilized, such as knobs` or handles projecting open aerial v added together thru couplings. L and L*l lie substantially in the 10o frame 11 (Fig. 6) are t or adjusting.

and are then transfer-red to a secondary circuit S thru an inductance L2 pled at N to inductance L3. The secondary circuit S has associated therewith any suitable detector and usual condenser 21, which parts are located within casing 15, (Fig. 6) and leads 22 therefrom extend outside of the casing and are provided with a filter, diagrammatically illustrated as choke- 'coils23, these being connected by leads 22 to a telephone receiver 24, Fig. 6.- This filter, which for some purposes may consist simply of a pair of choke coils, acts toprevent any disturbing action either from the capacity-of the telephone receiver 24 to the operators body, or from any energy which might be picked up by these` leads or by means of any high frequency energy drainage from the system contained'in the box 15. The fral'ne 11-12 supporting the erials A and B is mounted on an axis journaled in a yoke 25, the frame being rotated about its horizontal axis by turning knob 26 which is attached to frame 1112 and rotatable therewith. A suitable dial 27 attached to frame .l1-12 and rotating therewith co-operates with an indicator 28 fixed. to yoke 25 for indicating the angular positionin degrees of the loop and'aerial assembly carried by the frame. The yoke'25 is rotatable about a vertical axis 29, which in turn is rotatably mounted on a base 30. The position of the rotatable yoke 25.

served by frame 11 and its aerials in azimuth is obmeans of a dial or graduated circle 31 fixed to the axis 29 and therefore fixed with respect to the base 30. The dial 3l co-operates with an index 32 fixed to the It will be s'een that the aerials are mounted rotatably'on both a horizontal and a vertical axis. Both rotations can be imparted to the system by suit-1 ably manipulating knob 2G.

In the practice of my invention, unless the loop A is. of unusually large enclosed area or the sending station is nearby, the secondary circuit S preferably is supplemented by a suitable number of steps of amplification in the manner now well-known in the art. 4After both the open and closed circuits are tuned together and to the distant transmitter, the couplings M and N are adjusted by successive trial so that when the I loop and open aerials are in their position of maximum reception, the energy delivered to the secondary circuit is the same from each. the apparatus into the null reception position Where the currents are equal and opposite in phase and should then have no leffect upon the secondary circuit.

Inasmuch as the open circuit collector B leads the loop 'A in phase by 90, these two circuits are coupled together as Well as to the`secondary circuit-AS to preserve this phase relation; The currents are first added variably cou-- bearing of the sired.

This is best determined by swingingtogetherin'phasein the closed circuit'A, and then the combined energy is transferred to the secondary S, where it actuates any suitable indicator 24 (Fig. 6). For maxi-A mum reception, with Vadditive coupling the apparatus when-mounted as in Fig. 6 is so swung that'the plane of the loop'includes the distant transmitter (except under such circumstances as obtain when the transmitter is in the same vertical plane as both the loop and the open aerials and is horizontally displaced With respectto the axis of knob 26) and at the same time the open antenna B is normal to a line joining the receiving apparatus and transmitter. Similarly, the position of noreception is 180 from that,

such position being secured 'by swinging the loop thru 180 on the open antenna as an axis without changing the position of the open antenna. As is common practice with two-dimensional direction finders employing my loop, the null point preferably is. used for determining the bearing of the distant station. The apparatus is swung in altitude and azimuth until a point of zero signal is reached, and this determines the distant transmitter in three dimensions, i. e., its 'altitude rand azimuth.

The tuning of the several aerials to the desired wave length may be done substantially as follows. lFirst, cut, out the closed loop circuit as by looseningthe coupling between it and the open circuit or by di.- rectly opening the loop circuit at some point (not illustrated). Then vary the condenser C (or its equivalent inductance) until the maximum signal is obtained in the open aerial. Then lopen or otherwise remove from the circuit the open aerial vvandtune the lclosed circuit by means of the conenser 'C until maximum response is obtained. Then restore the open circuit, and the combined system is ready for use. The tuning can be done in the reverse order if so de- In each case the a'erials should be receptively positioned relative to the distant transmitter. Altho I have illustrated inductances L', L2 andL3 as being more sat-isfactory and easier to manipulate, yet it is to be understood that any.. suitable means of coupling the open and closed circuits may be employed. The Aopen aerial may be tuned by an inductance if so desired such asthe inductance L.

It is necessary that the currents in the two circuits A and B when at their maximum Y,be equal in their effect upon the secondary S in order to secure a null point on opposition orthe maximum signal upon addition of the equal currents. Otherwise, the reception characteristic curves disclosed in Figs. 1 to 5 will not apply. A change in degree lof coupling, of course, changes the amount of energy transferred from one circuit to theother (Figs. 6, 7, and 8), and' sistanee R therefore per whereby the altlio it would be possible to' so proportion the dimensions of the open and closed circuits that their reception wouldbe equal, it is much easier to make the adjustment by simple change in coupling. Furthermore,- inasmuch as the received current in a loop follows a different law of variation upon change of wavelength from that of an autenna, a given loop and open aerial would he in adjustment only at one wave-length, however carefully they were constructionally proportioned. lVhen the combinedj open and closed'aerials of the present invention are so located as to give a null point or. no response with reference to a distant transmitter( this means that the current in the loop and open aerial are equal and opposite and they cancel out in respect to the secondary and no signal results. single simple loop has two null points in a horizontal plane, Fig. 1, which are', of course, the two lilies 'normal to the loop; but when the single loop-is combined with an open antenna, there results but one null point, and this is 90 from the null points of the loop alone, Fig. 3.

The function of the resistance R in series with the loop, Fig. 8, if used, is to prevent the impact excitation of static or other disturbances from setting up complex or coupling waves inthe system as a whole. Such complex'oscillations result from the successive transfer and retransfer of energy between coupled circuits` of feeble damping and :gre objectionable in my invention because they tend to destroy or impair the directional reception of the system on which the elimination of disturbances depends. By increasing the damping of the loop aerial, which is most readily done by the insertion'of the resistance R as. shown in Fig. 8, such transfer and retransfer of energy is prevented and no coupling waves are formed. The preferred place for the insertion of the res'. tance R is in the aerial insertion of the resistance the currents in the two aerials When the open antenna it is preferable to the loop. 'Phe reforms two functions: first, the damping of the system to' prevent complex wave formation, and second, the reduction of the current. in the closed circuit to approximate equality with that .in theo en circuit.

In using t e circuits disclosed Vi'n Fig. 8, -the operator lfirst opens the antenna circuit, then tunes the closed circuit.' to the desired distant station by first coupling the .loop with the secondary S and noting the signal strength as the capacity C is varled. During this tuning, it is advantageous to reduce the resistance R to zero in order to note the effect of the tuning more readily. When the maxitends to make more nearly equal. is horizontal, Fig. 8, insert the resistance in A wavelength and constants -and finally slightly retunes as that of Figs. 6 and 7 telephone, the magnetic loop of circuit A is opened andi the open lantenna closed.v The open antenna circuit is then timed to the same distant station by varying inductances L or L'-l until maximum' response is obtained in the secondary circuit S. After both open antenna and magnetic loop circuits are tuned, the resistance R is increased from zero until the maximum static elimination is obtained, this resistance R beingl a non-inductive variable resistance having a range say from zero to some thousands or tens of thousands of ohms. In aerials of the size and dimensions herein specified, this resistance will be, when in use, of the order of some 'hundreds or thousands of ohms, depending upon the of the circuits. Then the operator varies the coupling between the inductances L and L until au is reached, the loop and open antenna circuit.. These steps may be performed in any desired order and may be repeated until the best reduction of disturbance is noted. r[he effect of these various adjustments seems to be to produce in the two aerials currents due tostatic which are opposite `in effect upon the secondary, so that when they are For this purpose, where the aerials are not further reduction in disturbance added, their effect is nil. 1

rotatable, it is preferable that the coupling coils be reversible, so thatthe static energies can be opposed, reversing switches for this purpose being shown in my co-pending application, `Serial No. 379,405, above-mentioned. to the directional properties vof the system, are not in' general equal and opposite in their effects upon the secondary but add to produce a useful signalthe currents due to staticdisturbances in the two aerials be opposed in their effect upon the secondary, or otherwise they would add to produce a strong disturbance. To en sure this, the operator may reverse one aerial with respect to the other by reversing the coupling coils as by switches illustrated in said application. y

The circuit arrangement of Fig. '8 as well sirable effects of out-of-phase current in the system present 'when the open aerial is di rectly connected, to and forms a part of the loop, as disclosed in Fig. 3 of my Patent 876,996 above-mentioned. In thepresent invention, out-of-phase currents are prevented by noty connecting the magnetic loop to' earth at all, but employing an open antenna which forms no part of the loop, altho it is within the scope ofthe invention to use any combination of closed aerialy securing unilateral reception and a null point from overhead.

It is important that avoids the undeloop and open horizontal' The signal waves, however, owing in the loop circuit 15 In the systems illustrated in the accompanying figures, means for bringing into phase' both sets of currents in their action on the receiving apparatus consists in employing the coupling between coils L and L3 and L2, the two tuned circuits being coupled together, energy in the form of oscillating or alternating current ofcone circuit being transferred to the other by means of such coupling. In the transfer, the phase is changed by 90, so that in this system the currents flowino` in the open circuit normally 90 out ofgphasewith currents flowing transferred by Way of the couplings between coils L and L3 to the loop `circuit are changed in the phase by90. and are-so made equal in phase with the currents already existing in the loop circuit.

In theuse of combined openfian'dfclosed aerials, primarily for the reception of signals and the elimination of static (Fig. 8) as or radio coinpasses.

in Fig. 6 will serve as a distinguished from purely'direction finding (Figs. 6-7), the dimensions arc the closed coil distant transmitter Vor transmitters; the static being preferably eliminated by an uadjustment or manipulation of'the coupling coils as described in m copending application, Serial` No. 379,405. The same and possibly more satisfactory results as to the elimination of static may be obtained .by mounting the' combined open and closed "aerials in the manner disclosed in Fig. 6, but this method is adapted for the smaller-sized aerials such as direction finders preferably so located that. isl in line with the ciples involved, however, are the same, and bythe addition of the resistance R disclosed in Fig. 8 to the circuitsof Fig. 7, the device very useful eliminator of static whenever necessary. When the construction of Fig. 6 is rotated to bring the open aerial into the horizontal and clirected toward the distant transmitter, we havethe positions of' aerials as shown in F1g.'8. VThe construction shown in Fig. 8 is .therefore preferably fixed on account of the over-all size of the aerials, altho even in the lack of a universal mounting as in Fig. 6

the openaerial Bof Fig. 8 may be and preferabl istiltable about a horizontal axis in order to submerge its characteristic curve, Fig. 5, as described above so as to further decrease the effects of static. I

The aerials above-described are .adapted for use not' only in4 receiving but also in transmitting. In receiving, any welleknown receiving apparatus or detector, such Vas crystal detector or audion, may be used, either with or without association therewith of steps of amplification as is well known in the art, the detector and amplifier equipment used depending upon the dimensions of the receiving aerials and the^power and .dis-

The action and prin-y tance of the transmitting station. vWhen used for transmitting, afsuitable source of high frequency current replaces the detector circuit.

' It is believedthat while static disturbances may arrive at a receiving station from .various directions in altitude'and aximuth, the greater part of the disturbance coincs in on the receiving station from thehorizon. According to my observation on y the North Atlantic coast, the lessl bothersome form of static appears to come indeterminately from many points in the hemisphere, altlio with a preponderance toward the horizon. more bothersome forms of static, however, are localized and on the North Atlantic coast come mainly` from the southwest, so that by adjustment of the apparatus as described, their effects are greatly diminished. 4

In the use of a universally-mounted aerial The as shown in Fig. '6 asa static eliininator ,'.it

may be preferable under some circumstances to so locate the loop and open antenna with reference to the-source of static that it is in large measure eliminated. This can be determined by so positioningthe loop and open aerial,'by moving them on It-he'iraxes, that the static effects are-the least noticeable. 'Thereafter the static-can'be totally eliminated by equalizing and opposing the static currents in the two aerials by manipulation and adjustnient of coupling coils, leaving a suiiicient amount of useful the loop' and open used as a direction finder,

their vertical axis,

aerial are/ rotated around orv horizontal axis, heard, that is, when (Fig. 5) the pit or null point of the cardioid reception surface is.

signal energyto bei audible.- Where the, apparatus of Fig. 6 is or both, untitno signal is f In lorder Ito obtain neutralization and opposition of static, it is necessary that the static currents received by the collectors A and B when. combined musthave substantially the same amplitude, frequency and decrement -or'l damping. `In other words, neutralization only takes .place when the energies are at every instant during the wave train produced by static equal and opposite. This result is secured byl the present invention.

It is to be understood that the invention is not limitedto the embodiments and fea-- tures specifically shown and described herein, but that such embodiments and features are. subject to Ichanges and modifications without invention.

any departure from the spirit of the and an open antenna ing disposed in substantially the same plane I claim 1. Three-dimensional directive radio apparatus comprising aerials having different directional properties but arranged in the same plane; means'for pivoting said aerials permitting their simultaneous movement to any angular position in space. \\'liile. 1m\in Vtaining them in their said common plane; and a local circuit coupled to said aerial system.

2. Three-ilimensional directive radio re.- ceiving apparatus comprising open and closed aerials, means for adding and detect` ing currents` therein; and a universal mounting for both said aerials whereby they may be simultaneously shifted into' any desired angular' position in space. while, maintaining their relation to one. another.

3. 'llmee-dimensional directive radio apparatus which comprises an aerial system including two aerials of ditlerent directional characteristics, namely a closed loop aerial aerial, said aerials beand syn'nnetrically with respectl to onel another and inductively coupled together, the coupling being adjustable and reversible to permit equalization and cancellation of static energies, the open aerial forming no par-t'of the closed aerial, the closed aerial being in-A sulated from earth, and the open aerial being arranged generally parallel to the earth; and meansfor tilting the opemaerial about a horizontal axis to submerge its charactei-istie curve and decrease the etlects ot static` 4. Directional radio/apparatus comprising a base, a yoke pivoted toV said base on a vertical axis, a fram-e pivoted to said yoke on an axis at right angles to the first-mentioned axis, open and closed acrials having variable coiuilings and tuning devices supported by said trame, and a bof; mounted 'on said frame and containing said -\-'a.riable couplings and tuning devices. V

5. 'lhree-dimensional directive. radio apparatus'which comprises an aerial system including two aerials ot different. directional characteristics, namely a. closed loop aerial and an open antenna aerial, said aerials being disposed in substantially and symmetrically with respect to one another, and being indue-tively coupled toeether but each insulated from earth and from one another, the-open'aerial forming no part of the -closed aerial and being erally parallel to the earth; and means moving the open aerial. Y

l6. .Tlnee-dimensional directive radio receiving apparatus comprisinga loop aerial, an open aerial, a secondary circuit` coupling means tor said aerials and circuit, and a universally movableiramc on which said aerials, circuit and coupling means are mo'unted.

'i'. Three-dimensional directive radio apfor ft'rame, couplings between said and means the same plane 'system comprising paratus comprising a frame, a loop aerial and open aerial mounted on said frame, tuning devices :tor said aerials mounted onthe frame, a secondary circuit mounted on the aerials and circuit and mounted on the frame, and means for supporting said frame for substantially universal movement. r 8. 'lhree-dimensional directive radioapparatus comprising a frameloop aerial mounted thereon, an open aerial also mounted on said trame and insulated from said loop, means for combining the currents set up in said aerials and detecting .the same, and a substantially universally movable mounting for said aerials.

9. Three-dimensional directive radio apparatus comprising open and closed aerials mounted tor movement substantially uniersally, means for combiningthe curr-,ents set up in said aerials and detecting the saine,

for inox-'ing said aerials simultaneously and substantially universally..

` l0. Three-dimensional directive radio apparatus comprising a. frame having a closed loop aerial mounted thereon, an open aerial comprising a pair of rods mounted in alinementon said frame, means forcoupling said serials together and tuning the same and mounted -centrally on said frame, a secondary circuit coupled to said aerials and mounted onthe frame, and a mounting for substantially universally pivot-ing said `frame and aerials.

ll. A three-dimensional directive radio system comprising a closed loop aerial, two metal rods mounted substantially diametrically ofthe loop aerial and arranged symmetrically therewith about a common point and constituting parts of an open aerial; means for coupling such closed and open 'aerials with one another; means sired angular' position circuit coupled tosaid system and .containing a telephone receiver; and means in the telephone circuit'for preventing disturbing action on said aerial system bythe ytelephone leads.

12. A three-dimensional directive radio a closedloop aerial, an open aerial arranged substantially horizontally relative to ground and v symmetrical with the loop aerial about a common point, the. two aerials beinglocated at aproximately the same point in space relative to the length ot the transmitted Waves; means ,for

" coupling said loop and open aerials; means permitting thel simultaneous tilting of said aerials to cause the open aerial tobe normal to tilted transmitted waves; said open aerial being insulated fromthe loop aerial; and an operating circuit coupled to said combination ot loop and open aerialsl- 13. Three-dimensional directive radio aphaving a closed for sWing- `ing said aerlals simultaneously to any de- 1n space; a secondary paratusjcomlprising open and closed aerials symmetrical y disposed with respect to one another about a common aerial being arranged in a substantially hor- -izontal plane and normal to the transmitted wave-front, a coupling between said aerials, and a secondary coupling. i

14. A three-dimensional directive radio directive system comprising a closed loop aerial; an open aerial normally arranged substantially horizontally relative to the ground and symmetrically with said loop aerial about a common point, said open aerial beingcoupled to but `otherwise insulated from the loop aerial; means for moving said aerials simultaneously to any desired angular position in space; means for equalizing the currents in t e loop and open aerials, comprising a resistance of the general order of a 'thousand ohms connected in the loop aerial; and an operating circuit coupled to said symmetrical combination of loop and open aerials.

15. Three-dimensional directive radio receiving apparatus comprising a closed loop aerial, an open aerial adjacent thereto; means for moving said aerials simultaneously to any desired angular position in space; anf adjustable coupling between said aerials for equalizingv Yandopposing the static energies received bythe aerials; and a receiving circuit `coupled to said 'aerial system.

16. Directional'radio receiving apparatus comprising a closed loop aerial, an open aerial; means for moving said aerials simultaneously to position the'opeii aerial normal to the transmitted wave-front; said open aerial having a .lumped capacity intermediate its ends; adjustable coupling means between said aerials for equalizing and opposing the static energies received thereby; andA areceiving circuit coupled with said aerial system. l

17. A three-dimensional directive radio lsystem comprising a closed loop aerial, an' open aerial inductively coupled to but otherwise insulated from said loop aerial; means permitting simultaneousy movement of said point, said open 'aerials to any' desired angular position in space; and an operating circuit coupled to said coupled aerials.

18.- A three-dimensional directive radio system comprising acl'osed loop aerial; an

' about a common open' aerial; and means for aerial about its diameter, said diameter being at right angles tothe open aerial itself, said aerials' being symmetrically` disposed point and means permitting the'simultaneous movement of -the open aerial to any-desired angularlrposition in space. 19. A three-dimensional j directive radio system com rising a closed loop -aerial and an open aerial) arrangedsymmetrically about a common point; the loop aerial being swinging the loop .aerial being mounte the horizontal and vertical axes respectively circuit associated with lsaid A mounted to be rotatable about its horizontal and vertical axes res ectively; and the open to be rotatable4 about of the loop andsimultaneously tation of the loop aerial.

20. A three-dimensional directive radio system comprising a an openaerial arranged symmetrically about a common point; the loop aerial being mounted to be swung about anpaxis substantially `a't'right angles' to the vopen aerial itself; and the open aerial being mounted to be swun bodily and simultaneously with the loop aerial about'avdiametrical axis of the oop. l'

21. A'three-dimensional directive radio with said roclosed loop' aerialV and system comprising a closed loop aerial and an open aerial symmetrically arranged together about a common for. simultaneously swinging both the aerials about the horizontal and vertical axes ofthe loop aerial. f

22. A three-dimensional directive radio system comprising a closed loop aerial and an open aerial arranged symmetrically together about a common point; and means for swinging'the loop aerial about its horizontal and vertical axes respectively, and for simultaneously movin the open aerial while preserving its relation with the loop'v aerial.

23. AVthree-dimensional directive radio point; and means system comprising a closed loop aerial and an open aerial arranged together symmetrically about a'cmmon point; and means for swinging both aerials simultaneously within a ran of 360 to any desired angular position in space.

24. A three-dimensional directive, radio system comprising-a closed loop aerial; two metal rods mounted substantially diametri-- cally of the loop aerial and symmetrically thereto about a common point, said rods constituting parts of an open aerial; means for couplin the closed and open aerials; and means or swin 'ng both aerials simultaneously to any gl space.

25. Directional radioapparatus comprising' two aerials, one being of the closed condenser-tuned loop type, and another being of the open antenna type, said two aerials beinglocated at approximately the same point in space relative to the length of transmitted esired 'angular position in lll ranged h orizontall relative to earth and symmetrically relative to the loop aerial; the4 open antenna aerial also being insulated from the loop aerial but coupledthereto; and anv operating circuit-coupled with vsaid aerial system. t .l

26. Directional radio apparatus compris ing two aerials, one being of the closed'condenser-tuned loop type, and another being of two aerials,

system including the open antenna type; said two aerials being located at approxlmatelythe same point in space relativeto the length of transmitted waves; the open antenna aerial being arranged horizontally7 relative to earth and symmetrically relative to the loop aerial; the loop aerial containing a' lumped resistance; the open antenna aerial being insulated from the lpop aerial but coupled thereto; and an operating circuit coupled .with said aerial system.

27. Radio receiving apparatus comprising two aerials, one being of the closed condenser-tuned loop type, and another being of the open antenna type, said two aerials being located at approximately the same point in space relative to the length of transmitted waves; means for moving the open antenna relative tothe earth to causefit to be normal to tilted transmission; the open antenna aerial being insulated from the-loop aerial but coupled thereto; and an operating circuit coupled to said aerial system.

28. Radio receiving apparatus comprising ser-tuned loop type, and another being an open antenna, said two aerials being located at approximately the same point in space relative to the length of transmitted waves; means for tilting the open antenna relative to the earth to cause it to be normal to tilted transmission; the open aerial being insulated'from the loop but coupled thereto; means permitting rotation of the loop aerial; and an operating circuit coupled with said aerial system.

29. Three-dimensional directive radio receiving apparatus which comprises an aerial two aerials of different directional characteristics, namely a closed loo aerial and an open antenna aerial, said aerialsbeing vdisposed symmetrically with respect to one another and the open aerial being in substantially the same planel with the closed aerial; the two aerials being inductively connected together; the open aerial forming no part of the closed aerial; the closed aerial being insulated from earth; the open aerial being arranged generally parone being of the closed condenallel tc the earth; means for tilting the open aerial about a horizontal axis to submerge its characteristic curve and decrease the effects of static; said arrangement securing uni-lateral reception and a null point from overhead; said apparatus including also a third circuit, of reception by the above aerial system* and an inductive coupling between said thlrd circuit and said system and transerring currents in phase between said third circuit and the two aerials; said last named coupling and the coupling between the two aerials, being reversible and adjustable and v permitting equalization and concellation of static energies.

30. Directional radio apparatus comprising two aerialsof different directional characteristics coupled together, and means permitting simultaneous movement of both said aerials to desired positions of the aerial system as positions `relative to one another.

31. Three-dimensional directive radio receiving apparatus comprising two aerials of different irectional characteristics coupled together; means permitting simultaneous movement of both aerials to any desired angular position in space while preserving' their positions relative to onev another; and means for observing reception by said aerial system when the latter is in any' such angular position.

32. Directional radio apparatus comprising two aerials of different directional characteristics insulated from one another but coupled together; and means permittin simultaneous movement of both couple aerials to any desired angular position in ,space while preserving their vpositions relativ'e to one another; the coupling between said aerials being adjustable and reversible.

33. Directional radio apparatus comprising two aerials of different directional characteristics mounted in fixed relation to one another and coupled together; and means for simultaneously moving said aerials to any desired angular position in space while reservin their fixed relation to one anot er. GRE NLEAF -WHITTIER PICKARD.

a whole while preserving theirl

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