US1696249A - Antenna system - Google Patents

Description

Dec. 25, 1928. 1,696,249

H. w. NICHOLS ANTENNA SYSTEM Filed Jan. 16, 1924 lfl Van for. Harold WM'c/ro/s.

Patented Dec. 25, 1928.

UNITED STATES PATENT OFFICE. 7

HAROLD W. NICHOLS, OF MAPLEWOOD, NEW JERSEY, ASSIGNOR T0 WESTERN ELEC- TRIO COMPANY, INCORPORATED, OF NEW YORK, N.

YORK.

Y., A CORPORATION OF NEW ANTENNA SYSTEM.

Application filed January 16, 1924. Serial No. 686,472.

This invention relates to radio signaling and more particularly to a radiating network for use at the terminal station of a multiplex radio system.

The invention will be described as applied to a communicating system in which a carrier line system is associated with a radio system, including a plurality of stations any one of which is adapted to maintain a plu rality of simultaneous two-way communications with one or more distant stations. In 7 the frequencies used for radio communica- I tions.

At a terminal radio station, the selecte line carrier frequency is supplied to an antenna for radiation to the remote stations. At the terminal station, and also at the re mote stations the control frequency is supplied to a device for multiplying this frequency to supply any number of desired fre quencies. The different multiple frequencies are used as carrier transmitting waves or as oscillations to be combined with incoming waves to effect detection. In this manner,

the carrier system for the whole country could be tied together. One standard carrier frequency would be continuously radiated over the whole area affected so that there could never be any disagreement in frequency betweenany two points in the wire or radio network. The difiiculties, attendant upon maintaining individual oscillators supplying oscillations of desired frequencies at the different radio stations, will be avoided, and the frequency spacing between all of the channels of the radio system will be accurately fixed. With a system of this type it would be possible to obtain the well-known advantages accruing from the transmission of one carrier side fre uency for each message, whereby the amp ifiers used for com munication purposes could be operated at maximum efficiency so that the number f amplifiers required in the system would be reduced to a minimum, the frequency range for a single communication would be a minimum and successive detection receiving sets could be used with aresultant decrease in interference due to strays and static.

When used for communication with a number of nearby stations, such as ships, it is desirable that the radio terminal stat-ions should be adapted for multiplex operation.

In accordance with this invention the radiating network comprises a plurality of antennas carried by a supporting structure to constitute the sides of a regular geometric figure and associated with each other in such manner that carrier waves eachmodulated by a separate message may be radiated from the respective antennae without causing interference or crosstalk.

A feature of the invention relates to the provision of an antenna system which is especially adapted for multiplex operation. Another feature is an antenna system of polygon form having a number of impedance minima equal to the number of sides of the polygon. I

For a complete understanding of the present invention reference should be made to the following description read in conjunction with the attached "drawing which shows one arrangement whereby the invention maybe carried into effect. y

Referring to the drawing there is shown a communicating system comprising a carrier line 1,'coupled to a terminal station TS for multiplex operation by means of which a plurality of simultaneous two communications may be held with a plurality of remote stations RS and RS The system will be described as applied to' radio telephony.

In the arrangement illustrated the trans mitting apparatus is shown at TS and the receiving apparatuses at stations RS and RS...

ceiving apparatus similar to that shown at However, it. is-tobeunderstood that the station TS will beprovided with a rethe other stations and that RS and RS will a each be provided with apparatus for trans mitting'speech modulated carrier waves simithe device 2 will be supplied to an antenna 3 and also to a harmonic generator The generator 4 may be any well known arrangement for producing, from a current .of one frequency, a number of current components of harmonically related frequencies. A typical example of a generator which may be used for this purpose is disclosed in Kendall U. S. Patent No. 1,446,752, February 27, 1923.

The output circuit of the generator 4 is provided with a plurality of selective circuits,

one of which 5 is shown adapted to select one of the harmonic current components, for example the sixteenth harmonic,-which is supplied to the coil 6 included in the circuit of the modulator 7.

A speech current supply circuit, including a transmitter 8, battery 9 and coil 100, is also associated with the coil 6. It is to be understood that the local speech current circuit is intended to represent any type of telephone system over which a subscriber may be connected to the radio apparatus. a

With this arrangement a carrier wave of frequency 16C and speech currents are supplied to the modulator 7 to produce in its output circuit a speech modulated carrier wave.

Any well known system for producing the modulated carrier wave may be used, including any well known form of modulator. However, since at the receiving station detectionis effected by supplying oscillations to combine with the incoming modulated wave,

transmission of the carrier component is not essential to the operation of the system, and hence any wellknown type of balanced modulator, such as, for example, that shown in Carson Patent No. 1,343,307, J unelfi, 1920 may be used. 2

Included in the output circuit of the modulator 7 is a band filter BF, which is adapted to pass substantially without attenuation one side frequency component ofthe modulated wave. The output side of; the band filter is coupled by a transformer 101 to the antenna circuit including the radiating. element 10 connected through the inductance 11, and condenser 12 to a ground system at 13.

Apparatus similar to that described above, is provided to supply a single: side band modulated carrier wave of different frequency to each of the antenna elements 14 and 15. In each case the carrier wave will be supplied by the harmonic. generator .4. The seventeenth harmonic may be supplied to the modulating apparatus associatedwith the antenna element 14, and the eighteenth harmonic to the modulator associated with the antenna element 15.

Assuming that S represents the essential frequencies of the speech band, and the upper side band is transmitted in each case, there will be radiated from the antenna element 10 In order that three channels may be simultaneously operated without interference, it is essential that the transmitting antenna sysstem should be designed to have an impedance minimum for each frequency band assigned to the different channels, and that the resonance conditions or points of minimum impedance for each band should be independently controllable.

A system which meets these requirements and which is simple and economical to corn struct is shown at the transmitting station TS. In this system the antenna sections 10, 14 and 15 which are electrically or reactivcly unequahare suspended from masts or towers .16 by supporting cable 17 The antenna system is connected to a common ground system 18 through separate down leads. When hoisted into position, the antenna sections constitute the sides of an equilateral triangle having. the towers at its verticcs.

IVith this construction it has been found that by making the towers of the proper heights,-spacing them a sufiicient distance apart, and using supporting cables of the proper lengths the antenna sections were so situated relatively to each other that three different signal modulated carrier waves could be simultaneously radiated without in terference.

It has also been found that, under certain conditions, three different carrier modulated waves can be simultaneously supplied. through a sin le down lead to the antenna system and radiated therefrom without causing interference. One condition under which this can be done is to provide antenna sections which are electrically or rear-lively uuequal.

For the purpose of disclosing one practical embodiment of the invention, the antenna system used with the three channel terminal station will he described. The antenna systemwas supported-on towers 130 feet high. the sides of the equilateral triangle were 100 feet long and the supporting cables between each tower and the adjacent ends of the antenna was feet. The carrier frequencies used in the three channels were respectively 775,000 cycles, 750,000 cycles and 725,000 cycles.

In :1 second triangular system the lowers were 165 feet hight, 500 feet apart and the supporting cables were 5200 feet long from the tower to the adjacent end of the antenna. The carrier frequencies used in the different channels were 700,000 cycles, 730,000 cycles and 760,000 cycles.

With both of these systems reactions between the antenna sect-ions was practically negligible.

The antenna system for a three channel station has been described above, but the principles'of this'featureof the invention may be applied to a system having any number of antenna sections. In all cases the sections would be arranged inthe form of a polygon, i. e. a four, five, etc. sided figure, with the towers at its angles and should be so supported that the reactions between the antenna sec-. tions do not exceed a definite value.

The control frequency C will be continuously radiated from the antenna The different stations of the system are each provided with a receiving antenna 19 adapted to selectively receive one of the incoming carrier modulated waves radiated from the terminal station.

For the purpose of disclosing the operation of the radio system let'it be assumed that RS and RS are distant stations adapted to co-operate with the terminal stat-ion described above, that the antenna 19 of RS is tuned to receivethe signal wave 160 S, the antenna 19 of BS, is selective of the signal wave 18C+S, and a third station having a receiving antenna tuned to the frequency 17C+S is provided.

Each of these stations is also equipped with an auxiliary arrangement for receiving the control frequency. The auxiliary receiver comprises an antenna 20 connected to a harmonic generator 21 the output of which is coupled to a circuit 22 including a plurality of circuits tuned to certain of the harmonics of the control frequency.

Since the receivers operate in the same manner, though the frequencies dealt with in each case are different, the following description of the receiving apparatus at RS will serve to illustrate the method of operation of all the receivers used in the system.

The incoming carrier modulated Wave 16C+S is received by the antenna 19 and impressed upon the circuit including the input terminals of the detector 23, herein shown by way of example, as a three-element space d ischarge device.

The circuit 22, coupled to the harmonic generator 21, includes a circuit 24 tuned to the fourteenth harmonic of the control frequency and a circuit 25 tuned to the second harmonic of the control frequency.

The tuned circuit 24, adapted to supply a frequency of 14C is coupled by a circuit 26 to the input circuit of the detector 23. The signal wave of frequency 16C+S and the wave of frequency 140 are combined in the detector 23 to produce in its output circuit an auxiliary carrier modulated wave of inaudible frequency 2C+S which is selected by device 27 and supplied to a circuit including the input terminals of a second detector 28.

Oscillations of the frequency 2C are supplied through the coupling circuit 29 to theinput terminals of the detector 28 in which they are combined with the auxiliary carrier 20+ S to produce the speech currents. Speech currents traversing the output circuit of the detector 28 are transferred by the contransmission such as, for example, the 19th harmonic. The circuit 33 is coupled by a tra sformer 3% to a modulator 35, having associated therewith a circuit 36 for supplying speech currents.

Speech modulated carrier waves produced in the output circuit of the modulator 35 and having the carrier component as well as one side band component suppressed are supplied through a transformer or repeating coil 37 to a transmittingantenna.

It is to be understood that the modulators, harmonic generators and filters shown schematically in the drawing may include separate amplifying devices if desired.

By adjusting the tuning of the antenna 19 of station RS to receive the waves radiated from station RS and vice versa and using the proper harmonic components at these stations to cooperate with the incoming wave to produce an intermediate modulated Wave of frequency 2C+S, two-way communications may be established between the stations RS and RS Since RS and RS are typical of the complete arrangements used at any of the stations of the system described, they may represent the apparatus of two channels of the terminal station ofwhich the transmitter TS is the transmitting terminal. In this case, the transmitting apparatus of each channel is coupled to either the antenna section 10, 14 or 15, and generator 4t supplies to the input circuit of the detector 23 harmonic components, of the proper frequency to produce an intermediate modulated carrier of 20+ S.

lVhile a radio system embodying a single multichannel terminal station has been described, it will be apparent that the carrier line could be connected to any number of similar s-tationsadapted for single or multichannel operation, and that apparatus for continuously radiating the control frequency may be used at any one or more of the terminal stations.

Although certain circuit arrangements and specific details have been described for the purpose of completely and clearly disclosing the invention, it is to be Ill'lClGl'SllOOCl that this invention is not limited to th specific features described, but only by the scope of the attached claims. i

What is claimed is:

1. An antenna system comprising a plurality of antennae, means for supporting said antennae to constitute the sides of a regular geometric figure, means for holding said antennm spaced apart to maintain the reactions between said antennae at a low value, whereby EGO the system possesses a number of impedance minima equal to the number of antennae.

An antenna system comprising a plurality of antennae, means for supporting said antennae to constitute the sides of a regular geometric figure, means for holding said antennae spaced apart to maintain the reactions between said antennae ata low alue, whereby the system possesses a number of impedance minima equal in number to the number of antennae, and means for independently controlling said impedance minima.

3. an antenna. system comprising a plurality of antennas which are electrically unequal. means for supporting said antennae to constitute the sides of a. regular geometric figure, means for maintaining sai d antennae so positioned with reference to each other that the mutual reactions between said antennae is relatively low, whereby the system is given a number of impedance minima equal to the number of antennae.

4. An antenna system comprising a plurality of antennas, means for supporting said antennae to constitute the sides of a polygon, and having supports at the angles of the polygon, means for suspending said antenme spaced apart from said supporting means and from each other to determine a low value of mutual reactions between said antennae. whereby the system possesses a number of impedance minima equal to the number of autenme.

In witness whereof, I hereunto subscribe my name this 15th day of January A. D., 1924.

HAROLD XV. NICHOLS.

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