US2366195A - Antenna array - Google Patents

Description

Jan; 2, 1945; -A. e. KANDOIAN 2,356,195

ANTENNA ARRAY Fil ed Nov. 23, 1942 2 Sheets-Sheet 1 DEV/C E INVENTOR. HEM/G G- KHNDO/fi/V ATTORNEY Patented Jan. 2, 1945 ANTENNA Armig' G-..Kandoiai1; New York, N. Y assignor to- Federal Telephone and Radio Corporation, Newark, N. J a corporation. of Delaware Application November 23; 1942, Serial No. deems l s Claimsi (01. 250-911 This invention relates. to antenna arrays an I re particularly" to a simplified array of loo j antennae. l Antenna loops have been proposed in which the loop is made of two wires" each equal to one-half j wavelength, the Ioopbeing fed at one. end and the twowiresat theiar' end of the loop being left open. ci'rcuited. such a loop produces a radiation ance with my invention; I provide a series of such patternin'ah directions.therearound. In accordloops serially connected one to another so that they willali be energized. in phase coincidence.

I at the crossing oints and are open ended at the farend. The lengths of conductors lii, M between each ofthecrossing points are madeequal to /2 where x is the operating wavelength. Thus each loop acts as a phase changer for the succeeding loop and substantially uniform distribution of standing wave energy is produced in the loops. Accordingly, if the array. I2 is made relatively short, each loop may be con sidered as producing an individual radiation pattern as shown by curve 33 in Fig. 3 while the combined arraywill produce a sharp radiation Since each of the loops is equivalentto a half wavelength transmission line, each loop acts as aphase change: for the succeeding loop so that all the loops in the array will. be energizedin phase coincidence.

It is a principal object of'my invention to provide a simplified arrayofloopsenergizedin phase coincidence.

It is" afurther object of my invention to rovide an array or series" connected loops in which theienergy distribution maybe different from loop to cop.

A better understanding of my invention. ofthe objects and features thereof may be hadloy referonce from the particular descri tion thereofmade pattern such as shown bycurve 44 in Fig. 4. The radiation patterns are substantially symmetrical with relation to the composer radiation, said sources being schematically illustrated by the points 3 and] of Figs. 3 and4 respectively.

The particular shape of the loops is not material to my invention and as shown in Fig; 2 they may be made in a square formation. The loops generally shown at 22 in Fig. 2 maybe used as withrefereiice to the accompanying drawing in I which; I

Fi Iis an illustration. of a loop array in accordance with my invention: t Fig. 2 is a modified loop array" in accordance with myinvention: i

Fig: 3 illustrates the radiation pattern oi a singlel'oop element: a

Fig: 4 illustrates the radiation diagram ofajii Fig. 5 is a loop array in which the succeeding 1 Fig. dis a still fiii'thermodifled form of loop. array in accordance with my invention.

In Fig. 1, l0 represents a translating device which may be either a. transmitter or receiver. Transmission line I I serves to connect translating device ID with aseries of loop antennae indicated generally at l2. These loops are made up by two conductors. l3 and I 4 arranged substantially in the same plane and crossing each other to form an array of similar shaped co-planar loops. Conductors l3 and M are insulated from one another an array place of the loops [2 of Fig; 1., n-wm be noted thatwiththe dimensions chosen, the currents in each loop will traverse the loop in l thesame direction as indicated by the arrows in Fig; '2. Likewise; because of the cross ov'ers at t the junction point between loops, there is prd'-' duced a phase reversal" so that this eliective cophasal energization of all the loops is produced.

[It is not necessary to have the complete net-- work radiating as shown in Figs. 1 and." 2. In-

stead, when desired, only a portion of each halfwave distribution may be used as a radiator. In such a case, the loop would be inade up near the current maximum region of each half-wave as shown Fig. '7. The remainder of the network would be used as a feeder, causing no radiation.

. The spacing d. between the radiating loops would then be made any desired value up to a maximum of one-half wavelength.

I In case it is desired to increase the physical spacing between successive radiating. loops: to greater than one half wavelength the method shown in Fig; Smay be used; where the. electrical length between corresponding" points of succes sivc loops is made 360 degrees. In this casea cross-over in the feeder between successive loops is not required and the physical spacing between loops may be made any value up to one wavelength.

In the arrangement of Figs. '7 and 8, the physical spacing may be adjusted without changing the size of the loops by displacing the portions of the transmission line between successive loops without altering the spacing of the line con- It should be understood that if the array is made very long, there will be an appreciable travelling wave component in addition to the normal standing wave component of the open ended loops. This will serve to produce a modification of the directive pattern of the loops but in some cases may be considered desirable. V

It is often desirable to'energize the antenna units of an array in phase coincidence but with different amounts of power-in the successive antenna units as for example in the case of a binomial expansion array. In accordance with my invention, this may'readily be done by merely altering the impedance of the loops so that the impedance thereof increases from the one end to the other of a series connected loop array.

3 In Fig. 5 one system for producingthis effect is illustrated. In this figure, transmission line 50 serves to connect the antenna array to any desired-translating device. From line 50, branch lines 5| 52 serve to supply the energy to antenna ,arrays'indicated by antenna units 53, 54 and 55; and units 56, 5'! and 58. Units 53 and 56 are made of relatively large conductors and thus will have relatively low impedance. The succeeding loop pairs 54, 51 and 55, 58 are madeof successively smaller diameter conductors to produce thehigher impedance of these loops. The radiation resistance of all 1oops,.however, remains substantially the same. Thus the current is distributed in a decreasing fashion from the center outward and the radiation from the outer loops is less than that from the loops nearer the translating device. A transposition 59 is'provided in .line 52 so that all of the units of both arrays may be energized co-phasally.

In Fig. 6 is shown another way of achievin energy distribution in an antenna array by varyingthe radiation resistance of the antenna units. Thus in this array units 63B6, 64-61, and

. 65-B8 decrease in area in the order given and thus have a decreasing radiation resistance in the same order. The power radiated is proportional to the radiation resistance. Accordingly, this an ray will likewise produce a variation and distribu tion of current in the antenna units.

It should be understood that any desired distribution may be achieved merely by properly relating the impedance of one antenna unit to the succeedingone. This 'may be accomplished in other ways than in the examples given.

While I have described above the principles of my invention in connection with specific apparatus, and particular modifications thereof, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of my invention as set forth in the objects of my invention 'and the accompanying claims.

What is claimed is:

1. An array of substantially co-planar loop antennae comprising a two conductor line the conductors of which are normally spaced a predetermined distance apart at a feeding point, said conductors being spread apart to form loops at predetermined intervals so spaced thatloops have the center part of the conductors thereof in the transmission line is transposed at half-wavelength intervals so that .all successive current maxima are in phase on the same side of said line,

whereby said loops are arranged at each elec-. trical half-wave intervals along said line, the conductors forming the sides of each loop. being a half-wavelength long, and said transpositions being at current nodal points, whereby: everyportion of said transmission line beyond the feeding point is utilized for radiation. 4. An array of substantially co-planar loop tennae comprising a pair of conductors, said con- 4 ductors alternatelydiverging and converging substantially in a common plane whereby they cross each other atregularly repeated intervals effecat the operating frequency, and means for coupling a translating unit to one end of said pair of conductors whereby the efiective instantaneous current flow is in the same direction aroundeach.

of said loops.

5. An antenna array according to claim:

wherein said conductors have different diameters increasing toward the connection point of said translating device to render the successive loops.

spaced from said translating device higher inimpedance than the preceding loop. r

6. An antenna array according to claim 4,

wherein said co-planar loops are made successively to enclose smaller areas to render the successive lo'ops spaced from saidtranslating device lower in radiation resistance than the preceding loop.

'7. An antenna array according to claim l; wherein adjacent co-planar loops are constructed so as to have different radiation resistances.

8. An antenna array according to claim 4; wherein adjacentco-planar loops areconstructed soa s to have different impedances. I

, ARMIG G. KAN'DOIAN.

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