US1567204A - Radio transmitting system - Google Patents

Description

Dec. 29 1`925- J. S. STONE RADIO TRANSMITTING SYSTEM 2 Sheets-Sheet l Filed Jan. 29, 1925 ATTORNEY Dec. 29 1925- 1,567,204

J. S. STONE RADIO TRANSMITTING SYSTEM Filed Jan, 29 1925 '2 Sheets-Sheet 2 R 5 i l t Patented Een. 29, i925.

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JOHN STONEl STONE, 0F SAN DEGO, CALFFCRNA, A.SSIGNGR TO AMERICAN TELE- PHONE AND TELES-BAPE. COMPANY, A GORLDGRATION OF NEW YORK.

RADIO TRANSMTTTING- SYSTEM.

Application filed January 29, 1925.

T0 all whom t may concern.'

Be it known that T, JOHN S'roNn STONE, residing at San Diego, in the county of San Diego and State of California, have invented certain Improvements in Radio Transmitting Systems, of which the following is a specification.

An object of my invent-ion is to provide a new and improved system of radio transmission by which interference between one transmitting system and another may be obviated. Another object of my invention is to provide for two independent radio transmissions in the same neighborhood and on the same frequency without objectionable interference. Another object of my invention is to provide a receiving system by which a receiver can get the radiated waves of a certain frequency from a certain transmitteiand exclude the waves of the same frequency from another transmitter. These and various other objects of my invention will become apparent on consideration of eX- amples of the invention which I have chosen for presentation in the following specification and in the accompanying drawings. It willbe understood that the description that follows relates more particularly to these eX- amples of the invention and that the detinition of the invention will be given in the appended claims.

Referring to the drawings, Figure l is a plan diagram of a system embodying my invention; Fig. 2 is a diagram showing a certain functional relation that will be referred to in explaining the principle of my invention; Fig. 3 is a diagrammatic elevation of a relaying station that may be employed 1n this connection; Fig. t is a plan diagram of -a modication in which the output from the relaying station goes to metallic conductors; and Fig. 5 is a diagram that will be used 1n explaining the principles involved in the invention.

The arrow in the upper part of F ig. l shows the direction of incoming waves from a transmitter T2. The horizontal lines in Fig. l represent the magnetic lines of the waves from T2, and the arrowheads on these horizontal lines are directed alternately right and left, so that the space between two successive horizontal lines indicates a half wave length.

At S1 there is a relaying station which Serial No. 5,580.

radiates waves of the same frequency, that is, the same wave length as those which it receives. These radiated waves are represented by the circles, and the equivalence ot' wave length just mentioned is indicated by the same spacing for the circles as for the parallel lines. The plane waves represented by the horizontal lines and the waves of curved front represented by the circles will form an interference pattern producing enforcement at certain points marked by os and annulment at points marked by s Accordingly a receiving station R1, placed at one of the ws as shown, will not be affected by the waves from the transmitter T2, but the receiving station R2 at one of the os will be affected by the waves from the transmitter T2.

The angle from the point S, between the two receiving stations R1 and R2 is q2. Let the waves of equal length from another transmitter T1 come in a direction making the same angle cp with the direction of the transmitter T2. It will at once be evident that the relations already pointed ont are reciprocal and that R2 will be blind to the transmission from T1 but will receive from Thus it is established that each receiver R1 or R2 receives only from its intended transmitter T, or T2 and is blind to the transmission from the other transmitter T2 or T1.

While the receivers R,L and R2 havev been placed each at a particular point of the interference pattern in Fig. l, it will readily be seen that there are many other points where they might have been placed and that appropriate points can be selected corresponding to different values of the angle e between the two transmitting stations.

ifrt increasing distances from the relaying station S2 the radiation will fall off in intensity as shown by the diagram in Fig. 2, whereas the radiation from the transmitters T1 and T2 will be of substantially uniform intensity within the limited area involved in the diagram of Fig. 1. Accordingly the intensity of radiation from the relaying station S1 should be adjusted, so that at the distance of the receivers R, and R2 the relayed waves will have the same intensity as the direct waves. This condition is fulfilled in Fig. 2 because at the distance from S1 of the stations R1 and R2, the curves aa intersect with the line bb whose ordinates represent the intensity of the waves from T1 and T2.

The relaying station S is shown in Fig. 3. The three antenn V0, V11 and V2 are placed in a plane transverse to both the sets of wave fronts from T2 and T2. Accordingly there will be a periodic difference of potential on the antennae V1 and V2, and the corresponding electromotive torce drop in the resistances r1 and r2 will be applied to the grid ot the three-electrode vacuum tube. The corresponding plate circuit current goes to the middle antenna V0 which is caused thereby to radiate waves of the same frequency.

Since-V1 and V2 are equidistant from V0, the effect of the waves radiated from V0 is null on the input side of the vacuum tube. With the resistances r, and r2 as shown, the radiation from antenna V0 will be in phase with the incident waves. When some other phase relation is required, these resistances may be replaced in whole or in part by inductance capacities, or transformers.

As shown in Fig. l, the radiation :trom the secondary source Sl proceeds equally on all sides, although it is utilized only at the receivers R1 and R2. Instead of radiating to the ether from .SM the transformer secondary of the antenna V0 of Fig. 3 may be bent down and connected to conductors such as S, R1 and S2 R2 of Fig. a, so that the currents from the secondary source S1 will be conveyed in this manner to the receiving` stations R1 and R2.

In general, the speed of propagation along such a conductor may be different from. that through the ether thus giving rise to a diterent interference pattern from that shown in F ig. l. The diagram in Fig. 4 has been prepared for the case in which the propagation along the conductors is at half the velocity of that through the ether. The wider spacing of the horizontal lines, as compared with the circles, exhibits this difference of velocity to which allusion has just been made. IN ith the pattern in Fig. 4L it will be seen that various locations are possible for the two receiving stations, one at an -point and the other at an o-point. For any given angular separation between the transmitting directions from T1 and T2, there will be a variety of possible locations for the two receiving stations It, and R2, and further flexibility will be obtained by varying the retardation in the conductors from S1 to R1 and R2.

To Jfacilitate the employment of the principle of my invention in any special case, certain appropriate formulas involved will now be pointed out. The station S, is shown in Fig. 5, and a receiver is shown at R in the lower right-hand quadrant of the interference pattern of Fig. l or Fig. e. Let the plane waves of periodicity c) and wave length from a distant transmitter be traveling in the direction of the arrow. Let these waves be of phase a at the line aa. Then the phase of these waves at R will be where 7c is an odd integer. For Z) in the foregoing equation substitute its obvious equivalent value,-11 sin te), where is the complement of cp, and the equation becomes By similar reasoning it can readily be.

shown that when the sum of the waves is to be a maximum at R, the equation of condition is I claim:

1. In a radio transmission system, two` transmitters and two receivers on the same frequency, and a secondary relay station, each receiver being at a point where the waves build up from a respective transmitter and the said relay station and where they are null from the other transmitter and said relay station.

2. In a radio transmission system, two

transmitters on the same frequency, a re-y ceiver and a relay station whose radiation annuls the effect of one transmitter at the receiver and enforces the eliect of the other transmitter at the receiver.

3. In a radio transmission system, two transmitters in diii'erent directions from a certain locality', a relay station in that locality to set up an interference pattern with the Waves from the distant transmitters, and a receiving station at a null point with respect to one transmitter and a point of maximum intensity with respect to the other transmitter.

t. In a radio transmission system, two transmitters in different directions fromla certain locality, a relay station in that` locality to set up an interference pattern with the waves from the distant transmitters, and two receiving stations, one of them locate-d at a null point with respect to'one transmitter' and a point of maximum intensity with respect to the other transmitter, and the other receiving station at a point of maximum intensity for the first mentioned transmitter and a null point for the other transmitter.

5. The method of receiving respectively from two transmitters on the same frequency, which consists in relaying from a secondary station and thereby establishing an interfering pattern with enforcement oi' the Waves from one transmitter and annulment from the other transmitter at one receiver, and vice versa at the other receiver.

6. The method of receiving Without interference from one of tWo transmitters on the same frequency, which consists in relaying from a secondary station and thereby establishing an interfering pattern With enforcement of the Waves from one transmitter and anulment from the other.

7 The method of preventing interference from one of tWo radio transmitting stations on the same frequency, which consists in relaying from a secondary station and thus establishing an interference pattern, With the receiving station at a null point with respect to the radiation from the said transmitter.

In testimony whereof, I have signed m name to this speciiication this 21st day of January, 1925.

JOHN STONE STONE.

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