US1677956A - Broadside antenna array - Google Patents

Description

July 24, 19:28.

BROADSIDE ANTENNA ARRAY Filed June 5, 1926 3 Sheets-Sheet 1 Single Wwentama,

uonwamfated VMM/remate@ Iii/ale Kronau-:lie in tema,

mu/aw a 1,90' mmmumr/maana A HUH/v5 y 1,677,956 s. w. DEAN July 24, 1928. 1,677,956

S. W. DEAN lS. Weaw 5C ATTORNEY July 24, 1928.

, 1,677,956 s. W. DEAN BRoADsIDE ANTENNA ARRAY Filed June 5, 1926 5 Sheets-Sheet 3 Mgr,

NI/ENTOI? /1 TTOANEY Patented July 34, i923.

UNHTED STTES ,Y senese sintesi?` Vssi-es.

SAMUEL, lW- DEAN. QF HOULTUN, MAINE, ASSIGNQR, e0 Memisa-N "DELEN-Iona AND TELEGBAPH COMPANY;

n connaissaient or new Yoan.

BROADSIDE ANTENNA ARRAY.

Application filed June 3,

This invention relates to radio transmission systems, and more particularly to arrangements for connecting a plurality of antennae in array formation. i

lVhen using a wave antenna it has been customary to make use ot a small traction of the interference or noise voltages develcned in the surge resistance of the antenna to balance out undesired interference or noise received from a direction approximately opposite to that ot the desired signal. lbuch a procedure is termed compensation7 and lserves in effect to deiorm the normally directive curve of the antenna in such manner as to produce zero reception atany desired angle iloehindy the antenna, that is, at any angle greater than 90 degrees measured from the direction of the desired signal which is in linewith the antenna. In particular', compensation is often used to produce Zero reception at an angle of' 180 degrees, or directly opposite to the direction oi' the desired antenna. it is also known that the directivity may be increasedV by the use of a system of parallel wave antenn spaced apart a certain traction of a Wave length in a direct-ion at right angles to that of the desired signal, cach Wave antenna, however, extending in the direction of the desired sig-nal. Such an arrangen'icnt is commonly called a broadside wave antenna system. The eiect ot the broadsidevarrangement in general is to decrease the Width of the directive curve as measured in a direction at right angles to the axis of transmission. In such a system compensa-tion of the individual antennae is capabler ot reducing to a considerable extent the size of the so-called back-end area ot the directive diagram. In other words,` the cception `oit 'interference and noise over the entire semi-circle to the rear ot the antenna system is reduced with a corresponding` iml'irm'ement ot the signal-noise or signal-interference ratio.

in the past this compensation has been accianplishe-d by separate adjustments for cachantenna of the liroadside system, that is, each `antenna has been compensated by itselt as it it vWere to he used alone and the outputs oi the antennae have been subsequently combined in a suitable manner. in accordance with the present invention it is proposed to bring to a central point voltages derived from the surge resistances of 1926. Serial N0. 113,505.

the several antennae of the broadside system and combine them in the same manner as the desired signal (derived from the so-called 4"iront endy oi' the antennae). Having thus combined these interference and noise voltages from the several antennae it is proposed to` utilize, a portion of the resultantvoltage to balance out noise and interference voltages coexistent with the desired signal in the circuit derived :liromthe lfront end77 of the antennae. In doing this the same general result is obtained as in the case of the individual compensating Vmethods previously used, but the result is obtained in a simpler manner. llurthermore,` the proposed compensation has the advantage that it permits ot a very much more accurate adjustment ot the balance thanI has ever been possible Where it was attempted to balance' each antenna separately.

Another feature oit the present invention relates to the details oif the circuits tor .conihining the outputs oi' several antennae connected in parallel. it, for example, lines from a plurality ot Wave antennae are connected to the pri-maries oi similar transformers Whose secondaries are connected in paralleltol a common receiver, or if the line-s are connected to the primaries ot a multiple.

winding transformer `Whose secondary is connected to. the receiver, the lines will not be terminated in their characteristic impedances. For example, Where we have three antennae each line 1would be terminated in the impedances of the other two lines together Withthe input impedance of the receiving apparatus-Pall in parallel. This would obviously he considerably less than the characteristic impedance ot' the line. In accordance with the present invention it is therefore proposed to correct this dii'iiculty by building out7 'he ytranstormers with impedance networks in such a manner as to terminate all ot the lines in their characteristic impedances.

rihe method of compensation and impedance correction ot the present invention are equally Vapplicable to other types oi: directive antenna systems when arranged in thread-mild?, as ivill be described later.

rEhe invention may new be more fully understood trom the following detailed description when read in connection with the accompanying drawing in which Figure l shows `they invention as applied to a system lill) llU of wave antennae connected in broadside; Figs. 2, 3, l and 5 are curves or directional diagrams illustrating the directive characteristics of wave antenna systems; Figs. 6, 7 and 8 are diagrams showing alternative methods of combining the outputs of a number of separate antenna systems; and Figs. 9 and 10 shoiv the invention applied to broadside arrangen'ients of typical directive antenna ar 'angements other than Wave antennae.

Referring to Fig. 1, a broadside connection, of three Wave-antennee A, B and C is shown although it Will be understood that the principle is applicable to any number of antennae connected in broadside. Each antenna is in the'form of a pair of Wires stretched across the country side in line with the direction from which signals are to be received.y Assuniing that the wires extend from east to West, vfor cxan'iple, a signal coming from the east builds up by increments upon the Awires of the ivave antenna and reaches its maximum value at the West end of the antenna. lt is usually desirable to have the receiving apparatus connected to the end of the antenna which points in the directionV from which the signals arrive. Therefore each pair of Wires comprising an antenna, such as A, terminates at the west end in a Winding l of a transformer whose midpoint is connected to ground. rlhc ground connection includes a primary Winding ll so related to the Winding 10 that the two together constitute a transformer. rlhe transformer impresses the received signal upon the two conductors constituting the antenna` A in such a manner that the conductors function as a transmission line to transmit the signal from the West or back end of the antenna, to the east or front7 end at which the receiving apparatus is located. At the front end the antenna, such as A, for example, is terminated in a similar transformer con'lprising primary Winding 12 and secondary Winding- 13 for associating the antenna with a local line, such as A leading to the receiver. The midpoint of the Winding 12 is connected to ground through a surge resistance 14.

A wave antenna such as above described has a directivediagram of the general form indicated in'F ig. 2, so the niaxin'uim signal .is received in a direction along the axis ab from b-a. No signal is received from a direction along the axis cd. rlhe wave antenna is not, however, purely unidirectional in its action but the directive curve has a small back-end area 15 of somewhat irregular form, as shown in Fig. 2. Conp sequently a certain amount of noise or interference in a direction from a to o or from a direction at an angle somewhat less than 90 degrees on either side thereof Will be superposed on the signal received by the antenna A, for example, as above described. In order to compensate or balance out the noise which is picked up with the signal component due to the back-end area 15 of the directive curve, a transformer having a primary Winding 16 is provided, the secondary l? of the transformer being connected to a local line A2 leading to a. compensator consisting of a suitable phase adjuster '18 and attenuation adjuster 19. The noise from the directionsrepresented by the bachend area 15 will be most eliiciently picked up by the coinluetors on the antenna A, functioning as a wave antenna for the direction from west to east. YThese noise components attain their maximum value at the east or front end of the antenna and flow to ground through the surge resistance 111. By picking up these components through the transforn'iers 1G and 17 and adjusting them with respect to phase by the phase adjuster 18 and With respect to amplitude by the attenuation adjuster 19 these noise components may be impressed upon the receiver in such phase relation and with such value as to oppose the components picked up along vwith the signal due to the bach-end l5 of the directive curve. *When this compensation is properly effected for a sin lewave-antenna the directive diagram assumes the form shown in Fig. t, the bachend arca being reduced to zeroin a direction -from a to but being somewhat increased for directions in the neighborhood of degrees on either side thereof. It Will be understood of course that by suitable phase adjustn'ient the compensation may be made effective for noise arriving from any direction within the so-called bach-end area, the curve of Fig. s merely showing the condition, where the noise arrives in a direction of 1S() degrees from the desired signal.

So far the apparat-us has been described for al single Wave-antenna. lli/hen a plurality of antennae are arranged in broadside the other wave antennae, such as B and C, will be provided with equipment similar to that described in connection with the ant-enna A. lThe signal from the antennae B and U Will be transmitted from the bach ends to the front ends thereof over the conductors of the antennae connected as transmission lincs, and the front ends of these antennae will be connected to the receiver through lines such as B, and C1. Similarly the balancing components will be taken from .the surge resistance ofantenn B and C through transformers similar to transformers 16 and 17 and combined in the com]L ensating circuit through lines B2 and C2.

The signal components from the several antennae transmitted over the line circuits A'l, B1 and C, may be combined in a common circuit such as RL by a compound t ansformer such as RT, having individual lill) primary windings in the circuits A1, B1 and C, and a common secondary in the circuit RL. lt is ofcourse. necessary thatA the signal components i'roni the several circuits should he impressed upon the circuit RL in phase with each other. This resultI will be readily obtained where the line circuits A1, l, and C, are of equal length. lV here the geographical situation is not such that these .lines would he normally oi equal length they may he made ot the same length by building the lines which would otherwise be short along indirect routes to; the antenna terminals. As an alternative the shorter lines may he made electrically ot the same length as the longest line hy includingl in the shorter lines artilicial line sections equivalent to the diil'erence in length between any given line and the longest line.

In a similar` manner the noise components talren from the surge resistances o'i the sew eral antennae may he combined in a compensatin'gl circuit CL `through a compound transformer CT having primary windings associated with each ot' the lines A2, B, and C2 and a common winding in the circuit CL. Here again components taken from several antenna; must he impressed upon the common circuit CL in phase with each other. The lines A2, B2 and C2 must there fore either be equal in length or be made electrically equal in length', as just described. The common circuit CL includes the phase adjuster 1S and attenuation adjuster 19, hoth ot which `are well known in the art. he former element serves the purpose of adjusting the phase of the compensating current due to noise arriving from a given direction in the hack-end area so as to oppose the corresponding component received over lines A1, B1 and CV Similarly, the attenuation adjuster i9 may he adjusted un. til the compensating current is just equal in value to the noise current component in the circuit RL due to noise arrivingl from the particular direction ,tor which compensation is to he made. As already stated the compensation will he for noise arrivin from a. sector in the ncighhorhood of i8() degrees from the direction ot' the signal.

As above described, the signal components are combined in a common circuit RL together with noise currents which are inherently picked up from the back-end area of the antenna system. rhe compensatingnoise con'iponents are combined in a common circuit CL. vIn order that the signal currents with their associated noise and the compensating noise currents 'trom the circuits RL and CL, respectively, may be combined in the receiver, a compound transformer T may be employed. rihis transformer has separate primaries in the circuitsl'ii and CL and a common secondary in the circuit `leading to the receiver. The compensating current is therefore combined with the currentto he compensated in the same manner, so tar as electrical connections are concerned, as the several components of the signal were combined, except that the compensating currentpis 180 degrees out of phase fit-h the current tohe compensated.

Neglecting for the moment the compensa- Y from a direction 135 degrees away from the signal will be decreased. i j

As has been previously stated, the-practice heretofore hasiheen to attempt tofcompen-k sate each wave antenna separately. TWhile such compensation can he made it sutlicient tirnerand trouble be taken, as a practical matter it has been found very diiiicult. This will he clear if we consider the form of the directional diagram ot a single compensated wave antenna, as shown in Figi. et. 'As has been previously pointed out such an antenna, when uncompensated, has a hack-end area such as shown at l5 in Fig. 2. lt the antenna he compensated *for noise arriving iii-om a direction 180 degrees away from the direction of the signal, the back-end area is as shown in F el. N ow it will he obvious that if the only noise or interference is. trom a direction 180 degrees away from the direction oit the signal, the operator who maires the compensating adjustments can readily determine when the circuit is proper.- ly compel-mated at 15%() degrees. Since the noise from that direction is the only noise present, the tact of its disappearance will he at once apparent.

n practice, however, the situation is not so simple. Static and other iormsof noise and interference will usually he 'found coming from various directions hroughout the entire haelt-end area. rThe operator listening on an uncompensated wave antenna hears all ot these noises. It now the ogiierator. begins to malte compensating adjustments the situation will he that when the l" circuit is properly adjusted for compensation the noise component arriving' from a d'ection 180 degrees away from the signal will disappear hut noise components 'troni' a direction 45 degrees on either side thereof, for example, will have heenk increased. In short, noise will he heard representing a large number oit components even though the single wave-antenna is properly `compensated.V rIhe result is that it is difficult,

r of Fig. 5.

and under certain conditions practically impossible, for the operator to determine by the difference in the noise effects produced on the receiver, when a single wave-antenna has been properly compensated.

The effect of the broadside connection (neglecting compensation) is,. as already stated, to malte the diagram of less width. The back-end area, which assumed the form shown at 15 in Fig. 2 for a single wave antenna, becomes of the general shape shown at 15 of Fig. 3 for an uncompensated triple broadside antenna. IVhere all of the noise components are combined in a single circuit, and phase and attenuation adjustments are made for all of the antennae at the same time, as is the case with the present invention, the noise compenents arrivingl in a direction 180 degrees from the signal will disappear when the proper compensating adjustment has been made. The back-end area, which in the 'uncompensated condition has the form shown in 15 of Fig. 3, will be reduced to two small loops, as shown at 15 in Fig. 5. The operator will have no didiculty whatever in determining when the circuit is properly compensated because even assuming that noise is coming from a great many directions within the back-end area the total noise will be very materially decreased when the components in the neighborhood of 180 degrees away from the signal direction have been balanced.

In other words, an operator attempting to compensate a single wave-antenna would have great difficulty, when noise is coming in from a great many directions, in determining by hearing methods the difference between the back-end area 15 of Fig. 2 and the corresponding back-end area` of Fig. 11 which represents the saine antenna compensated. On the other hand, the same operator would have no difliculty whatever in determining the difference between the backend area 15 of Fig. 3 and the back-end area j This sharpness and definiteness of the balance obtained in accordance with the present invention is due to the fact that there is one and only one adjustment of the compensation that markedly re-` duces the area of the so-called back-end diagram. Hence this adjustment is the only one which will materially reduce noise originating from a relatively broad sector behind the antennae.

In using the system of the present invention it is possible to reach this adjustment with a minimum eifort at times when with the older system it could only be reached by a-laborious process of cut and try if indeed it could be reached at all. The present invention has the additional advantage that the adjustments for proper combination of the signal currents as well as for proper combina-tion of the noise currents will be relatively stable and fixed in their nature, so that there only remains a single adjustment which need be made from time to time. Due to the varied direction of noise and interference waves it is necessary at intervals to readjust the compensating' apparatus to preserve the desired degree of bala-nce against these waves. In accordance with the present invention this is accomplished in a` minimum of time, whereas in systems previously used the broadside array must be separated into its component antennae and each antenna adjusted for proper balance by itself. This complicated procedure necessarily entailed an interruption of service involving a considerable length of time. Obviously of course the apparatus necessary to make the adjustments is in the present case materially simpler and cheaper' than with the old system, particularly if a. large number of antennae are to be used in broadside.

The description of the invention up to this point ha been concerned with the arrangements for effecting a balance against the interfering components impressed upon the receiver. rIhe method of obtaining this result, above described7 involves combining signal components from several antennae arranged in broadside in a common circuit. Similarly interference components from the SQVGI'Il 311141211132@ 2LT@ COlDblHGd 2].- COH11DOI1- circuit. These combinations are effected through parallel connections extending between the common circuit and each of the antennae. @ne of the simplest parallel combination systems is that in which the lines from the several antennae are connected to the primaries of a number of 'dentical transformers whose secondaries connected in parallel as shown in Figs. 6 and 8. An alternative is the use of a multiple winding transformer as described in connection with Fig. 1 and as illustrated in Fig. 7. The secondai'ies, or secondary, as the case may be, may supply energy to the receiving equipment which may or may not have a high input impedance, as is most convenient. A parallel system of this type is adapted to supply energy to a filter or similar device which has a characteristic impedance of the saine order as an open-wire line, thus conforming to standard telephone practice. Of course other combining systems will readily suggest themselves and may be used if necessary.

If the lines from several rantennae are directly connected to the several primaries, however, they cannot be terminated in their characteristic impedances. For instance, take the case of three antennae as shown in Fig. 6. Here the line from each antenna would be terminated in the impedances of the other two lines together with the input impedance of the receiving apparatus, all

being in parallel. This impedance would obviously be considerably less than the characteristic impedance of the line.

In accordance with the present invention it is proposed to overcomey this difliculty by building out the transformers with impedance networks in such a manner as to t minatefall theplines in their `characteristic impedances. In Fig. G `the combination is effected by three transformers RTA, RTB and RTC, in parallel. These transformers supply the receiving apparatus whose input impedance is K2. The impedance networks for building out the transformers are shown as H networks Comprising resistances r1, r2 .and r3. Since the characteristic impedance of most lines at radio frequencies is very nearly equal to pure,resistance2 onlyv resista-nce con'iponents need be used in the net-works in most cases. y The characteristic iinpedances of the lines will be the same and equal to K1. The 'values of the resistance elements `of an H network which will satisfy' the theoretical requirements may he Vobtained mathematically although the proc-- ess is somewhat complicated. The adjustments of the resistance elements of such a network may also be obtained empirically Vwithin a fairly close approximation. or

example, if the two resistance elements r1' and the resistance element 71 have a total value equal to the impedance K1, the `actual impedance of the networks as seen fromthev line will not n'iaterially vary from that of 2r=-K2ip\,/K12+(n where n is the number of antennzefto be conibined and the 'other symbols are as previously defined.

lf K2 and K1 are the same this becomes If the common circuit in which. the lines are combined works directly into af vacuinn tube the in'ipedance looking .into the common circuit may be made very large. Vln this case K2 approaches infinity `and .theequation for r aen-1f (s) l Al/Jecomes wave antennae, yis equally applicable to broadthe line even though the combined impedances of the other two lines and the :receiver quite small, if the resistances 912 be made very large. In other words, if the resistances r2 are very large the shunting effect of these resistances upon the resistance r3 will be relatively small. 1 i

The circuit in which the signal is combined andthe circuit in which' the compensatingcurrent is combined may be brought together through similar individual transformers T s and TC whose seeondariesare 4coma'ecte'd `in parallel, these transformers being built out .by networks similar to "those just described. Instead of using separate transformers for combining signals a single compound transformer, having a plurality of primaries and a secondary, may' be used,

shown inFig. 7. Other ,combining arrangements, of course, may be used. A similar type of transformer may he used for ,combining the total Vsignaling current with the total compensating current. Here again ifi-type networks are used for building out' the transformers in the individual lines.

In actual practice 'H networks or other forms inyol vine shunt kelements. arenot necessari., as lsimple seriesresistanees fr may be used for building vout the transformer-sas shown in 8. 'l iis ligure issiinilar to 6 the use of individual transformers foreach line. The resistances,la7V should `have the valuegivcn ybythe"eqinition,

side arrangements of other types of direc-y tive antenna systems. For example, '1T-ig. 9

shows .howthe invention inightbe applied 'to a lbroadside combination ofindividual directive antennae .units each comprising a` loop such as LA( worled in connection with a vertical antenna such as VA. The ceinbination of a loop and a vertical antenna, is well known, Ahas a one-'way directive edect somewhat similaritothat of a wave antenna. Ilff new we provide a number of such combinations side by side and separated from each 'other'by a fraction of a wave :length in a direction at right angles `to the Idirection of maximum directiyity, each vertical antenna Vof the broadside arrangements may be connected over a separateline.through buildingout resistances" to a l'compound con'ibining *transformer suoli as .describes in connection with Fig. 1. Likewise, each of Athe 'loops` of 'the broadside arrangement may beconnected over separate 4lines through building-out resista'nces to a Vcompound transforn'iein he outputs of the vertical antennae are thus coin- -bined in a `comi'non circuit RL, andthe outputs ofthe loops are thus combined in a connnoncireuit GL. lf a-.phafse adjusting device 18 and an attenuation adjusting device 19 be included in the circuit CL the circuit may be so adjusted as to balance out noise arriving from a sector in the neighborhood ot 180 degrees away 'from the direction ot' the desired signal.

It is true that in this arrangement the phase and atenuation adjustments aifect both signal and interference components,

Vfor both signal and interference components are received by the loops and by the verticals. However, due to the reversal of phase ot the loop current with reversal. of signal direction it is possible, as is well known, to obtain a unidirectional characteristicas described. above. rllhe eii'ect of such a broadsirle array ot looi-and-vertical antenna groups is to secure a much sharper unidirectional characteristic than can be obtained by using a single group oi this type.

llt is'also well known that two loops situated in tandem in the saine plane and a fraction ot a wavelength apart may be made to have a one-way directional effect. It a plurality ot such combinations are arranged in broadside along an axis at right angles to the planes ot the loops the method ot con'ibiiiing, heretofore described, may be applied, as shown in Fig. l1. Here the individual units comprise two loops, such as LA and LA, separated from each other by a distance which may be, for example, about one-twelfth ot the wave length in the direction ot the plane ot' the loops. Each combination of this kind may be separated 'from the adjacent combination in a direction at right angles to the plane ot the two loops by some fraction ot' wave length, such, for eX- ample, as one-half wave length. The loops7 such as LA, LB and LC, may be combined in a common circuit RL by means of separate lines including resistance building-out units through com pound. transformers of the type already described. Similarly the'outputs of the loops LA', LB and LC may be combined in a common circuit CL through similar individual lines leading to a. compoundtransformer through building-out rcsistances. The circuit GL includes a phase adjuster andv attenuation adjuster whereby the noise in the sector 180 degrees away from the signal direction may be balanced out without at the same time balancing` out the signal from the desired direction. The principle in accordance with .which this result occurs will be similar to that already disclosed in connection with Fig. 9. The result accomplished is a more sharply unidirectional characteristic than can be obtained from a single twoloop system, while retaining the facility of balance against interferenceand noise as disclosed above in connection with the application of the invention to wave antennae.

In addition to the advantages already re- :teired to the arrangements ot the present inventionhave certain other advantages. The use ot' vacuum tubes and other more oi less complicated apparatus which has been used or suggested heretofore in connection with other systemsV combining the outputs of anteiin is eliminated. in this connection it is assumed ot' course that the proper phase and amplitude relations are obtained by means oi suitable apparatus preceding the final combining apparatus. Aside 'from the question of siinplicity'it is ot course desirable to eliminate all vacuum tubes previous to the selective circuits ot the receiver. The reason for this is that such tubes are liable to be overloaded by interfering signals not in the lrequency range ot Ahe receiving apparatus.

rlhe system ot' the present invention may vbe' extended to any number ot' antennae and is adapt ble tor use with only one iilter preceding the receiving apparatus.

T4. 'l l K 1l l l 1 is will be oovious that the principles .ieierfi disclosed may be embodied in many other i aiiiaations widely dii'lerent troni those strated without departing from the spirit delined in the *l'ollowing illu of the invention as claims.

wWhat is claimed is: Y

l. ln a transmission system, a plurality of substantially one-way directive antenna combinations arranged side by side a fraction ot a wave length apart in a direotionat rightV angles to the direction from which signals are to be received, a receiving circuit, a separate connection from each antenna combination to said receiving circuit over which the desired signal may be transmitted together with noise lfrom a sector in the neighborhood of 180 degrees from the direction of the signal, means to combine the currents transmitted over said connections in substantially the same phase relation in said receiving circuit, arcontrolling circuit, separate vconnections from each antenna combination to said controlling circuit over which noise currents corresponding to noises from a sector in the neighborhood of 180 degrees from the desired signal may be transmitted, means to combine said noise currents in said controlling circuit, means in said controlling circuit to adjust the phase and amplitude of the currents conibined therein until the noise currents are substantially equal in amplitude but opposite in phase to the noise currents in said receiving circuit, and means to impress the currents of said controlling circuit upon said receiving circuit.

2. In a transmission system, a plurality of wave antennae arranged parallel to each other and a fraction of a wave length apart in a direction at right angles to the direction from which signals are to be received, a

receiving circuit, a separate connection from each antenna to said receiving circuit over a sector in the neighborhood of 180 degrees from the desired signal, a controlling circuit, separate connections from eachA of said conductors to said controlling circuit, means i'or combining the currents `flowing over said last mentioned connections in said control-` circuit so that the noise currents Will be oil substantially the same amplitude but opposite in phase to the corresponding noise currents in the receiving circuit, and means to impress the currents from said controlling circuit upon the receiving circuit.

3. ln a transmission system, a plurality of -vavo antennae arranged parallel to each other and a traction of a Wave length apart in a direction at right angles to the direction from which signals are to be received, each oi" said Wave antennae comprising a. pair of conductors extending from itsiiront'end toits back end, means at the back end of each antenna to transmit to the conductors of the antenna acting as a transmission line the desired signal Wave built up at that end ot the antenna together With a. residuuni of noise from` a sector in the neighborhood of 180 degrees from the direction ot the desired signal, a receiving circuit, aseparate line associated with the front end oi each antenna in such manner as to act as a continuation oi' the antenna as a line, each of said lines extending to said receiving circuit, means to combine the currents from each of said lines upon the receiving circuit in substantially the same phase relation, a surge resistance associated with the front end of each antenna, a controlling circuit, separate desired amount of noise currents flowing in such surge resistances upon said last inentioned connections, means to combine the noise currents thus transmitted over the connections in said controlling circuit, means to adjust the phase and amplitude of the combined current in said controlling circuit so that the noise currents Will be substane tially equal in amplitude but opposite in phase to the corresponding noise currents in the receiving circuit, and means to impress the current from said controlling circuit upon said receiving circuit.

si. In a transmission system, a plurality of directive antenna combinations arranged side by side and a fraction of a Wave length apart in a direction at right angles from the direction in which signals are to be received, a common receiving circuit, a `separate line extending trom each antenna combination to said Vreceiving circuit, a transformer arrangement or connecting said lines to said receiving circuit, means associated With each line for eiiectively building out the trans- :tormer so as to terminate each line in a combined impedance including that of the receiving circuit and other lines substantially equivalent to its own impedance.

5. 1n a transmission system, a plurality of directive antenna combinations arranged side by side and a fraction of a Wave length apart in a direction at right angles from the direction in which signals are to be received, a common receiving circuit, a separate line extending from each antenna combination to said receiving circuit, a transformer arrangement for connecting said lines to said receiving circuit, and resistance combinations associated With each line having such values as to in elifect build out the trans- .former arrangements so that each line Vis terminated in a combined impedance including that of the receiving circuit and other lines substantially equal to its own impedance.

In testimony whereof, I have signed my name to this specification this 2nd day oic June, 1926.

SAMUEL WV. DEAN.

Sti

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