US2350747A - Aerial system for radio beacons - Google Patents

Description

June 6, 1944. P. P. GAMl-:T 2,350,747

AERIAL SYSTEM FOR RADIO BEAQONS Filed May 9, 1942 Patented June 6, 1944 AERIAL SYSTEM FOR RADIO BEACON S Pierre Paul Garnet, Paris, France; vested in the Alien Property Custodian Y Application May 9, 1942, Serial No. 442,374

In France May 29, 1941 Y (ci. .25o-11) 2 Claims.

This invention relates to improvements in aerial systems for radio beacons.

It relates more particularly to an aerial system for radio beacons which provides foreflecting in a novel manner a well known method of radio direction finding.

In the known aerial systems for radio beacons it is necessary that the distance between the three aerials providing for the transmission of the radio-electric fwaves in la preferential direction shall be equal to a quarter of the wave length, which offers the disadvantage of requiring a cumbersome device which can be mounted only with difculty on a rotating plate for obtaining a rotating beam.

Furthermore, these systems require the use of at least three aerials.

The present invention has for its object to remedy these disadvantages and to provide a device with two aerials which are set very close together, the said device permitting to obtain a radiation in a preferential direction and in a given range of frequencies.

On the other hand, if it is desired to obtain a circular pattern of radiated beam, the known aerial systems for radio beacons necessitate a fourth aerial, which still further increases the space required by the system and its cost.

Another object of the present invention is also to do away with this disadvantage by providing an aerial system for radio beacons which necessitates no special additional aerial for the circular radiating beam.

An improved aerial system for radio beacons permitting to attain the above mentioned objects possesses the characteristic features which appear from the following description and especially from the appended claims.

Systems made according to the invention are shown diagrammatically in the appended drawing, in which:

Figures 1 and 2 are radiation diagrams of the systems;

Figures 3 and 4 are circuit diagrams of the system;

Figure 5 is a View of a system for obtaining a rotating radiation pattern by rotating the antennas on a rotating plate, and

Fig. 6 shows an arrangement for selectively obtaining a desired one of a variety of radiation patterns.

The diagram of Figure 3 comprises an aerial I which is supplied directly by the transmitting station 3 by means of a transmission line II.

An aerial 2 is supplied by the same transmitting station 3 by means of the transmission line and of a phase shifting unit 5 so that the supply voltage of this aerial is shifted in phase by a certain value with respect to that of the other aerial I.

'I'he operation of the device is identical to that of the device which is generally used for obtaining the radiation pattern transmitted in a preferential direction and in which a system of two aerials is used which are spaced from one another by a quarter of a wave length, this spacing effecting the difference of course giving the phase shifting which is necessary for the operation of the system and permitting to obtain the radiation diagrams of Figures 1 and 2.

'I'his phase shifting obtained by a difference of course is effected, in the device according to the present invention, through a phase shifting circuit which permits by adjusting the phase in a convenient manner to set the aerials at any distance from each other. Thus a radiation diagram with a radiation pattern shown by the cardioid 6 is obtained, the axis of the aerials being at 1.

This device permits to easily set up all the relations which are necessary for the operation of apparatus such as rotating radio beacons or beaconing devices for a, channel. namely:

(1) Reversing of the direction of radiation;

(2) Obtaining a rotating radiation beam;

(3) Obtaining a circular radiation pattern.

Referring to Fig. 4, the desired direction of the radiation is obtained by reversing the supply connections of the aerials I and 2.

The aerial I is then supplied through the medium of the phase shifting circuit 5 and the aerial 2 is supplied directly. For carrying out this operation one may provide a reversing switch 8 which effects the changes of connections which are necessary for directing the radiating beam sometimes in one direction and sometimes in the other, by reversing the supply connections of the two aerials.

For obtaining a rotating directional radiation beam the aerials are mounted on a plate I0 revolving about an axis II, and are connected to the transmitter in convenient manner.

The rotation of this plate I0 eiects the rotation of the directional radiating beam.

This system offers the advantage that it can be mounted on a plate of small dimensions since the aerials can be very close to each other contrary to the known systems where the distance between both aerials must be equal to a quarter of a wave length.

A circular radiating beam is obtained by feeding the aerials I and 2 in phase.

Such an arrangement is shown in Fig. 6, which' shows a modification of the arrangement of Fig.

`direct to the transmitter, and the other aerial to the phase shifter, in either combination desired. The switchv I8 is arranged ,andl wired to provide the third operating position.l When the Y transmitter 3 is connected directly to both aerial I and aerial 2 without passing through the phase shifter 5 at all, the aerials are fed in phase, a nd.

there is produced a circular radiation pattern.

In Fig. 6, the aerials I, 2, the transmitter 3, the transmission line 4, and the phase shifter-5, correspond to the similar elements of Figli, and the rotating table I0 carrying aerials I and 2 correspondsto rotatingA table I0 OtLFig. 5. AIn the three-position switch I8, the blade terminals I9 and 20 are respectively connectedto aerials Iand 2.` The outside contact terminals 2! and 24 are connected. together and to phase shifter 5. yThe inner contact terminals 22 and 23 are connected together and through transmission line :d directly to transmitter 3. In its extreme right position the switch IB connects transmitter 3 directly to aerial I, and connects through phase shifter `5 to aerial 2, while in the extreme left positionA of switch yI8 the connections to the aerials! and 2 are reversed.` In its middle position, switch I8 connects both aerials I andV 2 in phase directly Ato transmitter 3 through transmission line 4.v .l Y

With respect to theA known systems this de- Y vice offersv the advantage that it requires n0 pattern.

special "aerial vfor obtaining a circular radiation pair of aerials mounted Very close together relative to a quarter wavek length, a source of highifreq'uency oscillations, a rst transmission line` connected to a rst'one ofsaid aerials, a

Y Y second transmission line connected to a second one of said'aerials, ra phase shifting impedance Since these aerials Iavnd 12 are set ata small K distance from each other, they form -a unit whichV is equivalent to a single aerial equallyin all directions.

and thus .radiate n unit, and selective connecting means forv selectively connecting either the both of said trans-V mission lines to said source without passing through said phase shifting unit, or Vconnecting either one of said transmission lines to said source through said phase shifting unit Vand,

at the same time connecting the other one of saidtransmission lines directly to said source .v

Without passing l through said phase n shifting 2. In .an aeria system for radio vbeaconsVa pair of. aerials, va rotatable plate, saidgaerials being mounted on said plate very close together relativeto a quarterfwave length, a source Yof high-frequency oscillations, ai'lrst transmission line connected to a first onevof said aerials, a secondtransmission line connected toa second one of said aerials, a phase shiftingimped-ance unit, and selective :connecting means for selectively connecting either the both ofV said transmission lines to said source without passing through saidphase shifting unit, orV connecting either one of said transmission lines -to said source through said phase shifting unit and at the same time 1connecting the other one 'of said transmission linesldirectly tosaid source with- Vout passing through saidfphase shifting unit.v

andat all times maintaining both of said aerials energized from'said source. l

A. ripiani: PAUL GAMET.

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