US2258407A

US2258407A - Wide band antenna

Info

Publication number: US2258407A
Application number: US221694A
Authority: US
Inventors: Philip S Carter
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1938-07-28
Filing date: 1938-07-28
Publication date: 1941-10-07
Anticipated expiration: 1958-10-07
Also published as: GB530406A

Description

oct. 7, 1941. l v P. s. CARTER 2,258,407

WIDE BAND ANTENNA Filed July 28.,l 1958 2 sheets-sheet 1 l ATTORNK Qct. 7, 1941.

' P.A s. CARTER 2,258,407

WIDE BAND ANTENNA Filed'July 28, 1958 2 sheets-sheet 2 INVEN TOR.

' PH/ m5. CARTER BY ATTORNEY.

Patented Oct. 7, 1941 Philip S. Carter, Port JeifersonN. Y., assigner to Radio Corporation of America,.a corporation of Delaware Application July 28, 1938, Serial No. `221,694

(Cl. Z50-33) s claims.

`The present invention relates to antennas and, more particularly, to antennas for use with wide band television transmissionand reception.

The primary object of the .present invention lsto Aprovide a highly directional antenna system which will have Van extremely wide frequency band when connected to a transmission line of ordinary impedance characteristics. words, an object isto provide an antenna which when directly connected to` a transmission line has `a flatimpedance versus frequency characteristic over a broad range as seen looking toward the antenna from theapparatus connected to the transmission line and which will be highly directional.

`Another object is to provide a directive antenna which will require noimpedancematching circuitbetween the antenna andthe transmission lincin'order to match the surge impedance of lthe transmission lineto the impedance of the antennal l i i i `AVtype directive antenna,.such as disclosed in my prior Patent #1,974,387 patented September 18, 1934, has ofitself a sufliciently broad tuning characteristic to give ysatisfactory transmission and reception over bands of frequenciessuch as used .in television, but it has been` found that when :this type of antenna is matched to a transmission line in'any of theknown ways the tuning characteristic may .be narrowed suiiiciently to makethe system too `narrowfor wide band tele vision.

This vdiiculty is overcome and the foregoing objects achieved in accordance with the present invention by providing a multiple `V antenna array, `the component elements of which; are arranged eiectively in parallel and by connecting the `ends of the V together and feeding the system'from the apex of one ofthe Vs. While the component elements of themultiple` V antenna are effectively in parallel in that all of .the elements radiate or receive inparallel, the wires i the elementmay be actually-connectedin series.

A better understanding of my invention willbe had `by referring to the following detaileddescription, which `is accompanied by drawings, wherein Figures 1, 1a, 2, 2a illustrate the `manner inrwhich the currents inthe individual wires of two'` forms. of antennae combine to affect the distribution of' the total current, which is shown in Figures 1b and `2h. Figure Billustrates a VVan- `ten-na to which the principles of the foregoing figures have been applied in accordance withv my invention, and Figures 4 and 5 illustrate the modifications of` myinventiont 'Thetheory underlying `the present'nvention will be given particularly .with reference to Figure 1, and is similartothatgiven in my co-pending application, Serial #155,385 filed July 24, 1937` (RCA'Docket #13,081). While l,the'theory is believed tobe an approximately correct explanation ofthe principles underlying the present invention, further investigation may lead to ysom'emodication of this theory. It is to be understood, of course, that the invention is independent of any theory .which maybe advanced to account yfor the results obtained.

Figure 1 shows in effect a double dipolecoml prising'two half wave length lconductorsAand B ofequal length, except forthe break inthecenter of conductor VB for connectionvto the transmissionline TL which extends toA a.` suitable transmitter or receiver (not shpwn) Conductors A and Barevery closely'spaced from one another, perhaps a distance of $600 of a wave` length and are electrically connected together at theirextreme ends. The currents flowing in the two conductors will be in the same direction in space although in opposite directions within the antenna'circuit due to phase reversal at theends.

The arrows indicate the direction of current. flow in the conductors. Consequently, the arrangement will `be almost kidentical in its radiation characteristic with that of a `single wire half wave dipole antenna.` With such close spacing the mutual impedance, that is, the couplingbetween V'the two conductors, is almost equal tothe impedance of one wire. Assuming the total currentin Figure 1 to be the-same as in a single wire dipole, then the current in eachof the wires A and -B will be` one-half `the total current and the power in both examples will be equal. The effective resistance of the antenna of Figure 1, however, will be quadrupled due to the current in each `of the wires A and B being one-halfof the total: current. vIt will thus be seen that the radiation resistance of the antenna shown in Figure :1 is equal tofour 'times the radiationresistance of a `single wire dipole Without the use of any speccial impedance matching circuit betweenl the antenna and the transmission line.

fFigure `1a illustrates'the current distribution in each'of the conductors A and B of the antenna of Figure 1, while Figure 1b illustrates the total current `of the antenna, of Figure l. Figure 2 illustrates another embodiment Athe Vlengths of the conductorsA andB are greater than` one-half a Wave-length. .In thiszparticular instancez'the; length 'oi eachconductor leg equal of the doubledipole arrangement of Figure 1 wherein quency range.

to an odd number of eighths of a wave length.

' This antenna system will give a higher impedance ence of sine wave current distribution throughout the conductors.

Figure 3 illustrates the application of the principles heretofore set forth with regard tol Figure 2 to a V type antenna with which a directional characteristic is obtained. The directional characteristic as determined by the included-angle between the legs of the V follows the principles set forth in my prior Patent #1,974,387, issued September 18, 1934.

A V type antenna, as shown in Figure 3, and having single Wire legs, each equal in length to an. odd number of eighths of the length of the operating wave, has a radiation resistance of approximately 200 ohms, but by the transformation action heretofore explained and obtained from folding the wires, as shown in Figure 3, the radiation resistance'is increased to the vicinity ofg400`ohms. l

Figure 4 illustrates an arrangement similar to Figure 3, except that the length of each of the conductors from the center point to the extreme end in `this modification is an integral number of half wave lengths, as shown in the figure by the term 11k/2. must be provided in the center of conductor A since, if conductor Afwere a continuous wire the currents in the twoconductors would be equal and opposite and the radiation resistance would be negligibly small.

In Figure 5 I have shown a further modification of my invention which is desirable for use where it is necessary to have anA antenna which issubstantially aperiodicover a very wide fre- The length of the conductors is lthe same as in the arrangement of Figure 4. In this case a resistance is placedat-the apex of the folded wires. If the resistance is given a value equal to the average surge impedance of the V antenna, the antenna will be substantially aperiodicr over a very wide band of frequencies. In this modification we have a case of two travelling waves on adjacent conductors combining their` radiation effect to obtain the equivalent of agsingle standing wave. The antenna of this figure is bi-directional along the axis of the V in spite of the travelling wave on the wires.

In the foregoing examples it has been assumed that the conductors of the multiple V antennae are all of the same diameter. This does not have to be the casejhowever, and, if desired, the conductors may have different diameters, particularly in cases where it is desired to depart above or below, from an even transformation ratio. When conductors of different diameters are employed inthe antenna systems of the invention 'it will be 'found that the conductor of larger diameter'will carry lthe larger current. The difference in the amount of current carried `bytheconductors results in a different transformation ratio from the case where the conduc- In this modification a break antenna system, the transformation ratio will be larger than the ratio for an antenna having conductors of the same diameter and, by the same token, if the conductor of the antenna which is directly fed by the transmission line has the larger diameter than the other conductors of the antenna system, the transformation ratio will be less than that of a single antenna system wherein the conductors are all of the same diameter.

While I have particularly shown and described several forms of my invention, it is to be understood that my invention is not limited to the forms illustrated and described but modifications may be made within the scope of my invention.

I claim: Y

1. A directional antenna comprising a pair of linear conductors, said conductors being disposed at an angle other than 180 with respect to each other in a single plane, a transmission line connected to the adjacent ends of said conductors, a second pair of conductors similar and parallel to said first pairv of conductors and so closely spaced therefrom that the mutual impedance between said conductors is substantially equal to the impedance` of vone of said conductors, means for connecting the corresponding remote ends of said first pair of conductors to the remote ends of said second pair'of conductors so that corresponding conductors of each pair are effectively energized that radio frequency energy from said transmission line in a series relationship, each of said conductors being of a length including at. least one-half the length ofthe operating wave, whereby there is minimized the existence of reflected waves on said transmission line which might disturb the radiation characteristicsof said antenna conductors.

2; A directional antenna comprising a pair of linear conductors', said conductorsbeing disposed at an angle other than 180 with respect to each other in a single horizontal plane, a transmission line connected to theadjacentends of said conductors, a secondr pair of conductors similar and parallel to vsaid first pair of conductors and so closely spaced therefrom that the mutual impedance between. saidY conductors is substantially equal to theY impedance of one of said conductors, means for connectingthe remote ends of said rst pair of conductors to the corresponding remote ends of said second pair of conductors so that corresponding conductors of each pair are effectively energizedthat radio frequency energy from said transmissionline in a series relationship, each of (said conductors being of a length including at least one-half the length of the operating wave, whereby there is minimized the existence of reflected waves on said transmission line which might disturb the radiation characteristics of said antenna conductors.

3. A directional antenna comprising a pair of linear conductors, said conductors being disposed at an angle. other than 180 with respect to each other and being located in a single horizontal plane' there being 'ai predetermined relation :be-

tween the lengths ofthe conductors and theV in- Y pairof conductors similar and parallel to said first pair of conductors and closely spaced therefroml in the same horizontal plane, the spacingV being such' that the mutual impedance between Y said conductors .is substantially` equal to the impedance ofV one of saidconductors', means for connecting the remote ends of "said first pair of conductors to the corresponding remote ends of said second pair of conductors so that corresponding conductors of each pair are eiectively energized that radio frequency energy` from said transmission line in a series relationship, each of said pair of conductors being of a length including at least one-half the length of the operating wave, whereby there is minimized the existence of reflected waves on said transmission line which might disturb the radiation characteristics of said antenna conductors.

4. A directional antenna comprising a pair of linear conductors, said conductors being disposed at an angle other than 180 with respect to each other in a single plane, a transmission line connected to the adjacent ends of said pair of conductors, a second pair of conductors similar and parallel to said rst pair of conductors and so closely spaced therefrom that the mutual impedance between said conductors is substantially equal to the impedance of one of said conductors, means for connecting the remote ends of said rst pair of conductors to the corresponding remote ends of said second pair of conductors, the adjacent ends of said second pair of conductors being connected together so that corresponding conductors of each pair are electively energized that radio frequency energy from said transmission line in a series relationship, each of said conductors having a length equal to an odd multiple of an eighth of the length of the operating wave, whereby there is minimized the existence of reected waves on said transmission line which might disturb the radiation characteristics of said antenna conductors.

5. A directional antenna comprising a pair of linear conductors, said conductors being disposed at anangle other than 180 with respect to each other in a single horizontal plane, a transmission line connected to the adjacent ends of said pair of conductors, a second pair of conductors similar and parallel to said rst pair of conductors and so closely spaced therefrom that the mutual impedance between said conductors is substantially equal to the impedance of one of l.

said conductors, means for connecting the remote ends of said rst pair of conductors to the corresponding remote ends of said second pair of conductors so that corresponding conductors of each pair are eiectively energized that radio frequency energy from said transmission line in a series relationship, the adjacent ends of said second pair of conductors being connected together, each of said conductors having a length equal to an odd multiple of an eighth of the length of the operating wave, whereby `there is minimized the existence of reected waves on said transmission line which might disturb the radiation characteristics of said antenna conductors.

6. A directional antenna comprising a pair of linear conductors, said conductors being disposed at an angle other than 180 with respect to each other in a single horizontal plane, a transmission line connected to the adjacent ends of said pair of conductors, a second pair of conductors similar and parallel to said rst pair of conductors and closely spaced therefrom in the same horizontal plane, the spacing being such that the mutual impedance between said conductors is substantially equal to the impedance of one of said conductors, means for connecting the remote ends of said first pair of conductors to the corresponding remote ends of said second pair of conductors so that corresponding conductors of each pair are effectively energized that radio frequency energy from said transmission line in a series relationship, the adjacent ends of said second pair of conductors being connected together, each of said conductors having a length equal to an odd multiple of an eighth of the length of the operating wave,` whereby there is minimized the existence of reected waves on said transmission line which might disturb the radiation characteristics of said antenna conductors.

7. A directional antenna comprising a pair of linear conductors, said conductors being disposed at an angle other than 180 with respect to each other and being located in a single horizontal plane, there being a predetermined relation between t'he lengths of the conductors and the included angle, a transmission line connected to the adjacent ends of said pair of conductors, a second pair of conductors similar and parallel to said first pair of conductors and closely spaced therefrom in the same horizontal plane, the spacing being such that the mutual impedance between said conductors is substantally equal to theimpedance of one of said conductors, means for connecting the remote ends of said rst pair of conductors to the corresponding remote ends of said second pair of conductors so that corresponding conductors of each pair are effectively energized that radio frequency energy from said transmission line in a series relationship, each of said conductors having a length equal to onehalf the length of the operating wave, whereby there is minimized the existence of reiiected waves on said transmission line which might disturb the radiation characteristics of said antenna conductors.

8. A directional antenna comprising a pair of linear conductors, said conductors being disposed at an angle other than 180 with respect to each other and being located in a single horizontal plane, there being a predetermined relation between the lengths of the conductors and the included angle, a ltransmission line connected to the adjacent ends of said pair of conductors, a second pair of conductors similar and parallel to said rst pair of conductors and closely spaced therefrom in the same horizontal plane, the spacing being such that the mutual impedance between said conductors is substantially equal to the impedance of one of said conductors, means for connecting the remote ends of said irst pair of conductors to the corresponding remote ends of said second pair of conductors so `that corresponding conductors of each pair are PHILIP S. CARTER.