US2126295A - Antenna system - Google Patents

Description

Aug. 9,1938;

w. H. WARREN ANTENNA SYSTEM Filed Feb. 21, 1935 FIG.

TL V 7/7 1211 OTHER ANTENNAS FIG. 3

2 Sheets-Sheet 1 TL ,EZLI AZ/Mnw/m INVENTOR WH. WARREN ATTOB/VEV W. H. WARREN ANTENNA SYSTEM Filed Feb. 21, 1935 2 Sheets-She et 2 FIG. 4

COUPLING DEV/CE lNl/EN TOR 'W. H. WARREN ATTORNEY Patented Aug. 9, 1938 UNITED STATES PATENT ()FFICE ANTENNA SYSTEM Application February 21, 1935, Serial No. 7,501 In France April 25, 1934 15 Claims. (01. 250-11) The present invention relates to improvements in antenna systems, and more particularly in systems comprising a plurality of directional antennas or antenna arrays.

Heretofore, in long distance broadcasting of news and in certain transcontinental transmissions, it has been necessary to provide several directional systems directed in different directions, these systems being supplied simultaneously with energy modulated in the same manner at least for high frequency. Also each directional system has been ordinarily associated with a separate radio transmitter.

One object of this invention is to transmit or receive energy in several predetermined directions utilizing a single aerial system.

Another object of the present invention is to .transmit, efficiently, energy in several directions with a minimum amount of apparatus.

Still another object of this invention is to radiate a maximum amount of the energy supplied by a transmitter to a radiating system.

According to this invention a plurality of directional arrays, preferably aperiodic, is provided, each of the arrays serving to establish directive communications in different directions and said arrays being fed by a common high frequency feeding system on which one or several frequency bands may be transmitted. The several directional arrays are associated either in series or in parallel or in combined grouping, with the transmission system, the arrangement being preferably such that a predetermined quantity of energy is radiated by each antenna network.

The invention will be better understood by referring tothe attached drawings on which like reference characters denote elements of similar function, and on which:

Fig. 1 represents a directional antenna of the well-known diamond or rhombic type which .is disclosed in the application of E. Bruce, Serial No. 513,063, filed February 3, 1931;

Fig. 2 shows a series or tandem arrangement of two such rhombic antennas;

Fig. 3 shows a parallel arrangement of two rhombic antennas;

Fig. 4 shows a coupling arrangement which is suitable for transmitting two large bands of frequencies and for associating a rhombic antenna with a radio transmitter;

Fig. 5 shows the combination of a rhombic antenna and another antenna arranged to obtain a polarized radiation;

Fig. 6 shows an arrangement comprising a rhombic antenna and an inverted V of the type disclosed in Patent 1,899,410, E. Bruce, February 28, 1933;

Fig. '7 represents a tandem arrangement of V antennas.

It is well-known that one of the properties of the rhombic antenna is its faculty of functioning efficiently for a considerable band of frequencies. This property, however, cannot be entirely utilized when the antenna is rendered unidirectional by means of a reflector because a reflector which would be suitably placed for a "given frequency would not be suitably positioned for another frequency. In order to preserve the multi-frequency characteristic of the rhombic antenna and at the same time effect unilateral operation, the antenna is designed to have the same characteristic impedance as the feeding system and an absorbing line is connected to the distant end of the antenna, the characteristic impedance of the absorbing line being approximately equal to that of the antenna, whereby reflection of non-radiated energy is eliminated. In such an arrangement about half the total energy supplied to the feeding system and antenna is lost in the absorbing transmission line.

In accordance with this invention the energy feeding the absorbing line and otherwise lost is utilized to energize a second preferably directive antenna, this antenna being directed either in the same direction as the first antenna or in a dinerent direction. Alternately, this energy otherwise lost may before or after passage through a suitable rectifier system be employed for metering the power radiated.

Referring to the drawings the system of the prior art illustrated by Fig. 1 comprises a radiating transmitter RT feeding a rhombic antenna A by means of a transmission line TL of any suitable type, such as a coaxial line or a line comprising parallel wires. An absorbing transmission line 'ILa, is connected to the distant end of the antenna A. Assuming that the loss in the transmission line TL is negligible, 50% of the energy supplied by the radio transmitter RT is radiated by the antenna A while the remaining 50% is dissipated in the absorbing transmission line TLa, the loss in the terminating line TLa being approximately 3 decibels. Instead of dissipating 50% of the energy in the absorbing transmission line, this energy or a part thereof is, in accordance with this invention, employed to feed a second antenna, as illustrated by Fig. 2.

In Fig. 2, RT designates a radio transmitter, TL a transmission line of any suitable type and A a rhombic antenna whose far end is connected by transmission line TL to a second antenna A, at the distant end of which isplaced an absorbing transmission line 'I'La. A coupling device CD such as illustrated by Fig. 4 is included in the line TL. Arrows l and 2 indicate respectively the desired direction of operation for antennas A and A. In an actual case, the absorbing transmission line 11a was formed of two galvanized iron wires 480 meters long and having diameters of 2 to 3 millimeters. centimeters between centers. To secure the same attenuation with shorter lines the wires may be formed of certain suitable alloys. 7

In the system of Fig. 2, if the losses in the transmission lines TL are ignored, 50% of the power supplied by the radio transmitter RT is radiated by the transmitter A, 25% of the power is radiated by the transmitter A, assuming that the losses in the transmission line TL- are-negligible and 25% of the energy is dissipated in the absorbing transmission line 'I'La. It will thus clearly be seen that a portion of theenergy otherwise dissipated maybe advantageously employed to drive another antenna, this'antenna being'preferably provided with means for preventing reflection' losses. V

Fig. 3 illustrates'two rhombic antennas A and A connected in parallel. A radio transmitter RT feeds a transmission line TL of any suitable type, this line being terminated by branch lines TL and TL" which feed the antennas A and A in parallel. Antennas Aand A terminate, respectively, in absorbing transmission lines 'ILa and TLa.

The distribution of energy in the system of Fig. 3 is as follows: 25% of the energy supplied by radio transmitter RT is radiated by each of antennas A and A, and 25% is absorbed by each of the lines 'I'La and TLaLI Comparing the tandem arrangement of Fig. 2 to the parallel arrangement of Fig; 3 it will be seen that in the case of a tandem connection only a small loss is sustained since there is only one dissipating line. Other advantages of the tandem array over the parallel array are that a simple transmission system is employed and'the impedance in which the radio transmitter RT discharges is approximately the same whatever the number of antennas fed. It should be noted that in the case of the parallel system, special precautions must be taken to properly terminate line TL for efiicient operation over a band of frequencies. To insure this the two auxiliary transmission lines TL and TL" may be extended to the radio transmitter RT and connected in parallel at the output terminals of the power amplifying unit.

The tandem array of Fig. 2 permits the aperiodic' characteristicfaswell as the unidirectional property, of each antenna to be retained so that one antenna may be directed in a certain direction while another is directed in a different direction. Also a definite quantity of energy may be successively brought to the various antennas connected in tandem, a small part of this energy supplied finally arriving at the absorbing circuit whose function is to render the system electrically long and to prevent reflection losses. By aligning groups of these antennas at various points increased directional propagation may be realized in diiferent directions,

Expressed on a transmission basis, thefirst antenna. is equivalentin efficiency to a single isolated rhombic antenna of the same dimension and, in the case of a rhornbic antenna having They were spaced at.20v

sides four wave-lengths long, a gain of decibels over an ordinary dipole is realized. The gain of the second antenna will be, in view of the energy received by the system, 3 decibels less than that achieved by the first antenna, the gain being about 12 decibels over the dipole. Each successive antenna will approximately lose 3 decibels in efiiciency with respect to the preceding antenna. In the case of four antennas connected in tandem, the last antenna will still give about 6 decibels more than a dipole. Attenuators and other devices used in high frequency transmission circuits may be employed in the system for adjusting the amount of energy radiated by each antenna as desired. Thus, in the case of directional antennas directed in diverse directions the quantity of energy radiated by each antenna may be regulated in accordance with the distance to be covered by the various transmissions.

spirals arranged in parallel, these spirals taking up about the same space as the primary winding.

The primary windings P1 and P2 are connected to the transmission line TL through coupling condensers C1 and C2. In Fig. 4 a terminal of each primary winding is connected to ground since one of the conductorsof the transmission line TL is'connected to ground.

The transformers T1 and T2 transmit different frequency bands. In' a particular installation transformer T1 was designed to transmit frequencies included between 4,500 kilocycles per second and 12,000 'kilocycles per second, and transformer T2 to transmit the frequency band extending from 12,000 kilocycles per second to approximately 21,000 kilocycles per second. The attenuation was substantially constant for frequencies between 9,000 and 14,000 kilocycles per second. It may be added that in constructing the antenna care must be taken to avoid any irregularity, which would destroy the uniform character of the characteristic impedance. For example, the insulators should be small and the wires should be of uniform dimensions and unassociated with conducting members such as the metal fixtures. The invention may be employed in various arrays and systems as, for example, the systems illustrated by Figs. 5, 6 and 7. Referring particularly to Fig. 5, the transmission line TL" feeds through transformer T a transmission line TL which terminates in a transmitting antenna A of any type. This arrangement insures the use of energy which would otherwise be lost and which can be radiated by a directional or nondirectional antenna. The phases of the currents of A and A may be adjusted to obtain elliptically polarized waves. 7

In Fig. 6 the antenna A is a directive V antenna array comprising a plurality of V antenna elements V1, V2, V3, V4, connected to the auxiliary transmission line TL. The V antennas V1, V2,

V3, Vi are terminated, respectively, at their far ends by suitable resistances R1, R2, R3 and R4,

point of horizontal half wave-length counter poises. Obviously, the absorption resistances terminating the V antennas may be replaced by radiating elements. The direction of maximum propagation in a horizontal plane of the rhombic antenna and of the V antenna array coincide, as indicated by arrows 3 and 4.

Fig. 7 illustrates a tandem arrangement of two V antenna arrays. In the system of this figure the radio transmitter RT feeds a transmission line TL to which are connected at points spaced a half wave-length V antennas V1, V2, V3 and Vi constituting an array. The far ends of these V antennas are connected to another transmission line TL at points spaced a half wave-length. Transmission line TL, which may be of any length, supplies an array similar to that which has just been described and comprising V antennas V1, V2, V3 and V4. The far ends of these V antennas are terminated in absorbing resistances connected to ground or to counterpoises such as those illustrated by Fig. 6. Between the two groups of antennas A and A, Fig. '7, impedance networks may be provided, such as filters, for causing the antenna A to radiate different frequencies from those of the antenna A. The major directive lobes of the antennas A and A may be similarly or differently directed.

It may be desirable to radiate different quantities of energy in specified directions, utilizing arrays connected in tandem or parallel. In the tandem arrangement the desired division between the power radiated in the several directions may be easily controlled within certain limits by properly orienting the different arrays since, as already pointed out, the successive arrays radiate gradually diminishing amounts of energy. In the parallel arrangement, the energy is divided according to the law of shunted circuits and equal amounts of energy may be radiated in the specified directions. It is clear that, in accordance with this invention, a single radiating system may be used for multi-channel and multi-directional operation, whereby for example, communication may be realized between a single transmitter and a certain number of receiving stations, any one of which may be adapted to receive one or more of the frequencies transmitted by the central radio transmitting station.

Although the invention has been described in connection with certain specific embodiments, it is to be understood that it is not to be limited to such embodiments. Obviously, different tandem or parallel arrangements, or combinations of such arrangements, arranged either for transmitting or receiving, may be satisfactorily employed without exceeding the scope of the invention.

What is claimed is:

1. In a radio system, a transmitter, a plurality of directive antennas, said transmitter being connected directly to one antenna and only through said antenna to the remaining antenna or antennas, and said antennas being oriented for efiective operation in different directions.

2. In a radio system, a transmitter, a plurality of unilateral antennas connected in tandem and to said transmitter, said antennas being oriented for propagating energy in different horizontal directions.

3. In a radio system, a transmitter, a plurality of, rhombic antennas connected in tandem, the first of which is connected to said transmitter and the last of which is terminated in its characteristic impedance.

4. In a radio system, a transmitter, a plurality of rhombic antennas arranged in tandem, the first antenna being connected to said transmitter and the last being terminated in its characteristic impedance, said last antenna and the intermediateantennas each having an impedance equal to the characteristic impedance of the preceding antenna.

5. In a radio system, a transmitter, a plurality of similar rhombic antennas connected in tandem, the first of which is connected to said transmitter and the last of which is terminated in its characteristic impedance, at least two of the antennas being oriented for propagation in different horizontal directions.

6. In a radio system, a transmitter, a rhombic antenna connected thereto, each side element of said antenna being a half wave-length longer than the projection of said element on the path of maximum wave propagation, substantially, a second antenna having an impedance equal to the characteristic impedance of said first antenna, said second antenna being connected to said first antenna.

7. A radio system, a transmitter, a rhombic antenna connected thereto, each side element of said antenna being a half wave-length longer than the projection of said element on the path of maximum wave propagation, substantially, a second antenna connected thereto and oriented to radiate waves polarized differently from the waves radiated by said rhombic antenna.

8. In a radio system, a rhombic antenna connected to a V antenna, said V antenna constituting a means for rendering the rhombic antenna unilateral.

9. In a radio system, a transmitter, an antenna array connected thereto and comprising a unidirectional antenna oriented for maximum radiation in a given direction, a second array connected to said first array and comprising unidirectional antennas oriented for maximum radiation in a single given direction, the frequencies of operation for said arrays being different.

10. In a radio system, a transmitter, a plurality of antenna arrays each comprising V antennas, each element of said V antennas being approximately a half wave-length longer than the projection of said element on the path of maximum propagation, said first antenna array being connected to said transmitter and. second array being connected to said first array.

11. In a radio system, a transmitter, a plurality of antenna arrays each comprising V antennas, each element of said V antennas being approximately a half wave-length longer than the projection of said element on the path of maximum propagation, said arrays being connected. in tandem and each positioned for operation in a desired direction, and said transmitter being connected to the V antennas constituting one of the end arrays.

12. In a radio system, a first antenna system, a second antenna system, a translation device connected through the first system to the second system, said second system constituting means for rendering the first system uni-directional.

13. In a radio system, a first antenna comprising a pair of V-shaped elements having their directions of maximum radiant action superimposed, a second antenna, a translation device connected through the first antenna to the second antenna, said second antenna having an input impedance equal to the characteristic impedance of the first antenna.

14. In a radio system, a first antenna arranged for operation over one frequency band, a second antenna system arranged for operation over another frequency band, a translation device connected through the first system to the second system, said second system having an input impedance suitable for rendering the first system unidirectional, an impedance connected to the second system for rendering said system unidirectional, and coupling means included between 15 said device and said antennas, said coupling means comprising a transformer for passing one and a transformer for passing the other of said bands with the same attenuation.

15. In a radio system, a plurality of directive antenna systems each oriented for operation in a desired direction and each comprising a pair of V-shaped antenna elements, each element comprising two conductors, a translation device, said device being connected between and in series with the V-shaped elements of each antenna system, the conductors of each system having their directions of maximum radiant action superimposed and aligned with the desired direction of action for the system.

WILLIAM H. WARREN.

Images