US1740370A - Directive radio transmitting system - Google Patents

Description

Dec. 17, 1929. c, w, RICE DIRECTIVE RADIO TRANSMITTING SYSTEM Filed Nov. 25, 1924 J. e H 1 m 0 r tw o n H we MA mus s e i %H W Patented Dec. 17, 1929 PATENT OFFICE CHESTER W. RICE, OF SGHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK DIRECTIVE RADIO TRANSMITTING SYSTEM:

Application filed November 25, 1924. Serial No. 752,237.

My present invention relates to directive systems for radiating energy, and more particularly to systems in which the greater part of the effective radiation will be in one direction only.

Many arrangements have been proposed in the past whereby directive radiation of energy can be obtained, but none of these systems have been employed to any great extent in actual practice. Most of the systems proposed have not furnished means for producing a radiation which is sharp enough in its directivity to offer any material advantage over a radiating system in which the radiation is produced in all directions equally.

One of the objects of my invention is to provide a system whereby the sharpness of the directivity obtained may be "made as great as may be desired. Another object of my invention is to provide a directive system which radiates in only one direction in which the effective radiation is practically all confined to an angle of less than 90, together with means for supplying currents to the various elements of the radiating system in such a way that the desired result is obtained.

All useful radiation in radio communication takes place from a vertical conductor carrying high frequency current. All directive transmitting systems which have been proposed heretofore comprise two or more vertical conductors separated in space and carrying currents having such phase relation that the radiated waves add in certain directions and partially or completely interfere with one another in other directions. For point to point communication the sharper the directivity (i. e. the smaller the solid angle in which the radiation is concentrated) the more efficiently the power output will be utilized.

The problem of providing an efficient directive tranmsitter therefore requires for its solution the selection of the best arrangement of the radiating vertical conductors and the supplying of power to the various vertical conductors in such a way that each will carry its due proportion of current in the proper phase relative to the currents in the other verical conductors.

One of the requirements for obtaining extremely sharp directivity is that the radiating system must have a dimension of the order of one or more wave lengths. Many of the directive systems proposed in the past have failed in their accomplishment because of the fact that they have fallen short of this requirement.

Another requirement for obtaining sharp directivity is the use of a considerable number of vertical conductors. Here again many of the arrangements proposed in the past have failed in their practical accomplishment because of the fact that they have proposed to use only a few, and in many cases, only two vertical conductors.

One of the specific arrangements which may be used in attaining the object of my invention comprises a single unit or plurality of units which are structurally similar to a transmitting loop. By certain modifications, however, in the arrangement of a loop and in the method employed for tuning, I produce a system in which the efiective radiation instead of being in the direction of the loop is in a direction at right angles to the direction of the loop.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, my invention itself, however, both as to its organization and method of operation will best be understood by reference to the following description taken in connection with the accompanying drawing in which I have illustrated diagrammatically a system which may be employed for producing unidirectional radiation.

I have indicated in the drawing as a radiating unit a loop structure 1 which extends in a direction at a right angle to the desired direction of radiation. This loop should preferably have a horizontal length greater than the wave length of the waves to be diated although useful directive results may be obtained with a length less than a wave length.

The loop 1 is so tuned that the apparent velocity of wave propagation along its length is substantially infinite. To accomplish this the IOU from one another by a distance equal to series inductance on .each horizontal side of the loop is neutralized by series condensers 2 distributed uniformly along its length. The shunt capacity between the two horizontal sides of the loop is neutralized by shunt inductances 3 which are uniformly distributed along its length, as indicated. By this method of tuning the loop when considered as a transmission line has the characteristic of a circuit of low series resistance and high shunt resistance. The tuning condensers and inductions should be close enough together to give the elfect of uniformly distributed capacity and inductance. To fulfill this requirement the distance between adjacent condensers 1 and lnductances should not be greater than 77 times the wave length although I have found that these elements may to advantage be lo cated even closer together than this distance. Energy is supplied to the loop structure described from a source of high frequency current 4, which supplies energy to coupling coil 5 to which is coupled the coil 6 which in turn is connected to the transmission line 7. Err ergy is fed from this transmission line to one of the tuning inductances 3. To accomplish this the transmisison line is directly connected to points in the inductance so chosen that the impedance through which energy is fed will be substantially equal to the surge impedance of the transmission line whereby wave reflections will be prevented. With a structure such as that described it will be r found that the current produced in the vertical connections between the two sides of the loop, whlch include thetunmg lnductances 3,

will all be in phase with one another and of the sameorder of magnitude. Each one of these cross-connections therefore acts as a radiating unit and the combined radiations from the different units will add in directions at right angles to the directions of the loop structure, but will oppose one another in the direction of the loop and substantially neu tralize each other.

The arrangement thus far described will, as indicated, produce radiation in two directions at right angles to the direction of the loop structure. To produce radiation in one direction only additional loop structures may be provided extending parallel to one an- ;other, each being constructed 1n the manner already described. In the figure I have indicated another such loop structure 8. The individual loop structures should be separated or some other odd multiple of 2, A being the second loop of energy received from the first loop. When the two loops are separated only 7 by 2 quite effective results may be obtained in this way, the currents flowing in the vertical conductors of the second loop being of nearly the same order of magnitude as the currents flowing in the vertical conductors of the first loop. In some cases, however, it will be desirable to supply energy also to the second loop. In the case illustrated, I have in dicated a second transmisison line 9, which is supplied with current from a coupling coil 10, which is also coupled with the coil 5. Transmission line 9 should have an electrical length such that the current supplied to the second loop will be 90 in phase ahead of the current supplied to the first loop. This condition will result in radiation in the direction indicated by the arrow as in that direction the waves radiated from the two loops will combine, whereas in the opposite direction waves radiated by the two loops will largely oppose each other and be neutralized.

The sharpness of directivity obtained by a system such as that described may be increased to practically any order desired by increasing the length of the loops and by the addition of other parallel loops besidesthose indicated.

lVhen the separation between the adjacent loops is only equal to 2 the operation may be complicated by reason of the coupling between the adjacent loops. This element of complication may be obviated by making the height of the loop equal to a half wave length in which case the electrostatic and magnetic couplings balance each other. As an alternative the loops may be separated by a distance greater than 2 and thereby the coupling between adjacent loops will be reduced to such a {value as to produce no appreciable effect inthe operation of the system. 7

What I claim as new and desire to secure by Letters Patent of the United States, is

1. A radiating loop system having the series inductance of each horizontal side neutralized by a plurality of series condensers distributed along its length and the shunt capacity between the two horizontal sides neutralized by shunt inductances connected at a plurality of points along its length, said system having such an arrangement and distribution of impedanc-es that a standing wave of current is built up therein.

2. A radiating antenna system comprising a loop, a plurality of cross connections which include inductances extending between the horizontal sides of said loop and means for producing substantially in phase currents in all of said cross-connections, said system having such an arrangement and distribution of impedances that a standing wave of current is built up therein.

8. A radiating antenna system comprising a loop, a plurality of cross-connections which include inductances extending between the horizontal sides of said loop, means for feeding energy to one of said cross-connections, and means for producing substantially in phase currents in all of said cross-connections, said system having such an arrangement and distribution of impedances that a standing wave of current is built up therein.

4. A radiating antenna system comprising a loop, a plurality of series condensers included in each horizontal side of said loop for neutralizing the series inductance thereof, a plurality of inductances connected in shunt to the horizontal sides of said loop for neutralizing the shunt capacity, and means for feeding energy to one of said inductances, said system having such an arrangement and distribution of impedances that a standing wave of current is built up therein.

5. A radiating antenna system comprising a plurality of parallel loops, each of said loops having its series inductance neutralized. by series condensers uniformly distributed along its horizontal sides and its shunt capacity neutralized by shunt inductances distributed uniformly along its length, said loops being separated from one another by a distance equal to an odd multiple of 6. A radiating antenna system comprising a plurality of parallel loops, each of said loops having its series inductance neutralized,series condensers uniformly distributed along its horizontal sides and its shunt capacity neutralized by shunt inductances distributed uniforml along its length, said loops being separatec from one another by a distance equal to an odd multiple of 2, and means tance equal to an odd multiple ofi, and

means for supplying currents to one inductance in each of said loops of such phase that the greater part of the effective radiation will be in one direction which is at a right angle to the direction of the loops.

8. A radiating antenna system, comprising a plurality of parallel loops, each of said loops having its series inductance neutralized by series condensers uniformly distributed along its horizontal sides and its shunt capacity neutralized by shunt inductances distributed uniformly along its length, said loops being separated from one another by a distance equal to an odd multiple ofg, a

distance equal to an odd multiple ofg, a

source of high frequency current and a separate transmission line for supplying energy from said source to a shunt inductance of each loop, each of said transmission lines being arranged to feed energy to its respective loop through an impedance substantially equal to the surge impedance of the transmission line whereby reflections of energy over the transmission lines will be avoided.

In witness whereof, I have hereunto set my hand this 24th day of November, 1924.

CHESTER 4V. RICE.

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