US1569835A

US1569835A - Radio transmission system

Info

Publication number: US1569835A
Application number: US5737A
Authority: US
Inventors: Edward W Kellogg
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1925-01-30
Filing date: 1925-01-30
Publication date: 1926-01-12
Anticipated expiration: 1943-01-12
Also published as: GB246816A; FR610223A; BE331756A

Description

E. W. KELLOGG RADIO TRANSMISSION SYSTEM Jan. 12 ,1926.

Filed Jan. 1925 [724 AMP 2.95 am: 4/4 "g AMP 1m" 2420 OHHS I000 0/1376 9 QZ :3 o r Win u M v s .3 H W m Patented .Jan.-.12, 1926.

1 UNITED STATES.

EDWARD W. KELLQ GG, OF SGHENECTADY,

PATENT. OFFICE.

NEW YORK, ASSIGNOR TO GENERAL ELEG- TRIO COMPANY, A GQRPORATION or NEW YORK.

RADIO TRANSMISSION SYSTEM.

Application filed J aniiary ticularly to transmitting systems of the directive type.

It has been proposed to employ a pluralityof individual radiating'units arranged in a row and by proper adjustment of the phase relation of the currents supplied to the different units to produce radiation, the

reater part of which will be effective only in one of, the directions between which the row extends.

One of the objects of my present invention is to provide a simple and effective means for supplying currents to the different radiating unitsin a system of the class described in such a way that the phase relations between the different currents will be those necessary for producing the desired directive effect.

In attaining this object of my invention, I provide a single transmission line for supplying currents to all of the radiating units. For producing the desired directive effect the radiating units should be separated from. one another by distances of the order of a quarter wave length and the currents in the different units must differ in phase by similar fractions of a cycle. If the transmission line is so constructed that waves are propagated thereon at substantially light velocity the base differences of the currents supplied at t e different feeding points along its length will be correct for a unidirectional system. This will be true, however, only in case there are no reflections over the line from the .feed points and the line carries waves in one direction only. If a number of loads are connected to a transmission line either as shunt or series loads, reflections will result and the proper phase "relations will not be secured.

A more specific; object of my invention is to provide, means whereby current may be.

supplied from a transmission line at a plura ity of points along its length without producing any reflections.

so, 1925. Serial No. 5,737.

Inattaining this object of my invention I provlde means at each feeding point wherer by the loadsare a combination of shunt and series loads. By proper proportioning of the shunt and series loads in a manner which will be more fully described, .I am able to prevent reflections over the transmission line.

In the case of directive transmission it is desirable that equal currents be supplied to all of the radiating units. In case enough units are used to, provide very sharp directivity the last units to be supplied will not, on account of line attenuation receive the due proportion of the total energy supplied unless suitable precautions are taken. .7

Still another object of my invention is to provide means whereby the energy supplied y the transmission line will be equally divided among the different radiating units.

This object may be attained by suitable proportionin of the load resistances at the different fee ing oints in a manner which will also be more ully described.

The novel features which I believe to be characteristic of my invention are set forth with partioularit in the appended claims; my invention itse f, however, will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figs. 1 and 2 are diagrammatic. representations of networks having suitable constants for obtaining the results of my invention, and Fig.3 is a diagrammatic representation of the application of my invention toa radio transmitti-ng system. v Thenormal high 'efliciency unloaded line has a characteristic or surge impedance which is practically equivalent toa pure to construct afladder type network of SQ:

rice and shunt resistances which has the same characteristic impedance ,as the transmission line. The transmission line may then be cut and as many sections of this network as desired introduced and no reflections will result, but attenuation will take place in the resistance network, depending on'the number of sections introduced, or on the ratio of series to shunt resistance. By this means any desired fraction of the power carried by t the line may be absorbed in a local network,

and not give rise to reflections. It h attention;

nation per section is small, say not over 20% reduction in current, the following relations hold:

in which R is the series resistance per sec- R is the shunt resistance per section;

Z is the line surge resistance;

K is the ratio of the current on the two sides of a section or the square-root of the ratio of power received to power passed on.

If each section is a T network (i. e., two equal series resistances and one shunt resistance), as much as 50% of the power may be absorbed in a single section, the above formulas may be used without material error. Assume, for example, that the hue surge resistance is 1000 ohms and that 11: is desired to use up equal amounts of power at a series of points, A, B, C, etc. Fig. 1 represents a line with a series of networks introduced. The losses in the line itself are neglected. At the end, A, the load reslstance must be equal to Z or 1000 ohms 1f reflection is to be avoided. Taking the current at A as 1 ampere the power absorbed will be 1 k. w. An equal amount of power must be absorbed at B or power received- ,IR R, 1000 The network at G is to receive 3 k. w. and pass on 2 k. w., whence K z3/2,

I Thevoltages and currents, calculated step by step, are shown on Fig. 1. It is seen that the interposition of one of the T networks leaves the ratio of voltage to current prac- The series resistances can be divided between the two sides of the line to give balance.

The networks might consist of simple L sections, but in this case a different formula is-required. If the forward moving wave encounters first the series resistance R, and then the shunt resistance R, as in Fig. 2.

in which K is the current ratio on the two sides of the network, or the square root of the power ratio.

In order to apply the principles above outlined to the feeding of a series of radiating units the units must be coupled to the transmission line in such a way that they become the equivalent of pure resistance loads the values of which depend upon the mutual inductance of the primary and secondary circuitv In the arrangement shown in Fig. 3 I have indicated a method of coupling which may be made to give a load on the transmission line analogous to that represented in the network of Fig. 1. In this case the transmission line having conductors 1 and 2 is supplied with current from a high frequency source 3. Energy is supplied from the transmission line to a series of radiating units 4 to 8, which in the case illustrated are represented as vertical conductors having both ends insulated from ground. Each unit except 8 is coupled to the transmission line by series coupling transformers 9 and 10 and a shunt coupling transformer 11. The last unit 8 requires only the single coupling transformer 12. In the absence of reflected waves the current through the series coils and the voltage across the shunt coil are in phase. It the latter constitutes a resistance load the current through it will be in phase with that through the series coils. Under these circumstances both can be coupled to the same secondary circuit and each can be made to contribute its share to the power in the secondary circuit.

'What I claim as new and desire to secure by Letters Patent of the United States, 1s:- a

1. The combination in a radio transmitting system of a radiating system comprising a plurality of radiating units separated from one another by an appreciable fraction of a wave length of the waves to be radiated, a single transmission line for supplyin to said radiating units currents having p ase displacements corresponding to the geographical dis lacements of the units from one another, an means for preventing wave reflections over said transmission line from 1,5ee,sss

the points ,at which energy is supplied to the radiating units.

2. The combination in a radio transmitting system of a radiating system comprising a plurality of radiating units separated from one another by an appreciable fraction of a wave length of the waves to be radiated, a single transmission line for supplying to said radiating units currents havplyingto said radiating units currents having p ase displacements corresponding to the geographical displacements of the units from one another, means for preventing wave reflections over said transmission line from the points at which energy is supplied to the radiating units, and means for roducing a substantially uniform. distrlbu-- tion of power to all of said radiating units.

4. The combination in a radio transmitting system of a radiating system comprising a plurality of radiating units separated from one another by an appreciable fraction of a wave length of the waves to be radiated, a single transmission line. for supplying to said radiating units currents having phase displacements corresponding to. the geographical displacements of the units from one another, and means for feeding energy to said radiating units by both series and shunt transformer connections to said transmission line.

5. The combination in a radio transmitting system of a radiating system comprising a plurality of radiating units se arated from one another by an appreciab e fraction of a wave length of the waves to be radiated, a single transmission line for supplying to said radiating units currents having phase displacements corresponding to the geographical displacements of the units from one another, and means for feeding energy to said radiating units by both series and shunt transformer connections to said transmission line, said transformer connections being so proportioned that the power supplied by the transmission line w1ll be substantially uniformly distributed among the difl'erent radiating units. a

6. The combination in a radio transmitting system of a radiating system comprising a plurality of radiating units separated from one another by an a preciable fraction of a wave length of t e waves to be radiated, a single transmission line for supplying to said radiating units currents having phase displacements corresponding to the geographical displacements of the units from one another, and means for feeding