US2375580A - Directive antenna - Google Patents

Description

May 8, 1945. H. o. PETERSON DIRECTIVE ANTENNA Filed June 25, 1942 INVENTOR HAROLD 0. PETERSON BY )Z/Ww TTORNEY May 8, 1.945 H. o. PETERSON 2,375,580

DIRECTIVE ANTENNA Filed June 25, 1942 2 Sheets-Shee' l 2 33 3l /Zf A m MCE/VEP l Fig. 7

/Z I X 7\ I @ECE/VER Fz'g-8 INVENToR HAROLD 0. PEERSo/V lATTORNEY `latenled May 8,1945

DIRECTIVE ANTENNA 4HaroldiO. PetersomRiverhead, N. Y., assigner to i Radio Corporation of America, a corporation of Delaware i `Applicanta June 25, i942, serial No. 448,341

leoiaims. (o1. 2504-11) i rlhe present invention relates to ldirective an` tennas and, more particularly, `to broad band directive antennaarray systems.

.,An object of the present invention isthe pro vision` of `a method 4of arranging two antennas to 'produce a unidirectional directivity pattern. `Another object of the present invention is to provide an antenna system giving a unilateral response over a broad band of frequencies.V

Still .another object is` the` provision of a uni-` laterally` directive antennasystem which is not critical as to frequency and which does ,not need readjustment when the operating frequency is changed. `In systems heretofore `used it has been possible to produce a unidirectional pattern but the effect has generally only occurred at` one particular frequency designed. i i r The foregoing objects are attained, in accordance withY the principlesof the present invern tion, by providing a plurality of antennas disfor which the system was placed along the line of signal travel. The` antennas `are connected through a transmission line to the receiver with phase reversing structure between the` antennas. The spacing between the antennas `and the `length of` transmission lineV are so related that signals `arriving from` the de-` sired direction combine` in additive relationship one wavelength. Thus the `desired unidirectional `effect mayreadily `be `obtained over `a frequency range of greater than 5 to 1;.` ,i f

Thevector diagrams shown in Figures` 2 and 3,

explaining the principle of operation of the an-` tenna of Figure 1, are for the sake `ofi convenience, drawn `for the condition wherethe distance between antennas l `and `8` is 90 electrical degrees or one quarter wavelength.` i

Figure 2 shows the condition for a signal jtrav elling in the direction from A to l2.` The signal `first reaches antenna `8 at location A inducing a voltage represented by a in Figure 2. 90 degrees later the wave frontreaches antennaB linducingavoltage b 90` degrees behind Athat in- This is represented by the coincidence of vectors Ia and b.

The voltage represented bythe addition of vectors a and b'f consequently is transwhile signalsfrom the opposite `direction com-,1

bine in` an opposing phase relationship 'thuslgiving `a directivity patternvvhichis"v substantially unidirectional in shape. i

The present invention will be `more fully, un-

derstood by` reference to theV following, `detailed description, which is accompanied by drawings in which Figure 1 illustrates diagrammatically one form of the present invention, while Figures., 2 and 3 are vector diagrams explanatory of the principle of operation of` thepresent invention,

` l WhileFigures 4 toi8, inclusive, diagrammatically illustrate modifications ofthe form of `the invention shown in Figure 1.` l i f In Figure 1 are shown two antennas landvat" .by box I I,.is connected to the end ofthe trans-` mission line nearest the source 2 of the desired signals.` Phase reversing structurel?. `isfinserted -mitted over transmission line TL to receiver Il.

In Figure ,3 isj shown the condition for `a sig- `nal travelling in the direction from location B to location A. The `wave frontfirst induces a voltage `in antenna 'l indicatedby vector b and i 90 degrees later, as indicated by angle ce, a voltagerepresentedby vector` a in the antenna 8. The voltage represented by vector o originally induced in antenna l at location B loses L90 degrees `in travelling along the transmission `line TL over the distance from B to Aas indicated by the angle pi and is identied by vector b. Another i 180 degrees of phase change, indicated bythe fat location A `when it arrives at thatv position and, therefore, the two cancel each other` and in the transmission` line between the points` of coupling of antennas 1 and 8. Antennas land 80` are spacedv along the line of travelof theidesired signal by a distance ranging from somewhat less than 30 electrical degrees to approximately 0150 electrical degrees, "3610 electrical 1 `degrees being i angle cr, is caused by thephase reverser R. Con- .sequently` the voltage, bff, `which was induced in antenna B, is exactly degrees outof phase with `the voltage a contributedby the antenna no signal is received l atfreceiver` il, If the Velocity of propogation along the ti'ansniissionline is substantially `equal to `that of light,1signals received in the `direction fromiB to A will always cancel eachother due to the reversal in the 4coul pling system within the range'of spacllgs I1have indicated, whereas the additive effect for signals travelling in the other direction, that lis,;from A to B will generally amount to anappreciable value depending, to some extent, upon the distance between locations A and B.

In Figure 4 I have shown another arrangement of antennas based on the same principle as Figure l. In this case, the antennas 'I and 8 are coupled to the transmission line through coupling condenser I3, whilebalancing condensers III are connected between the transmission line and articial lines I5. Condensers I4, together with the artificial lines I5, are so arranged as to `balance the reactancefof the antenna loading of the other side of the line. The artificial line sections I5 may have an electrical length equivalent to the electrical length of antennas 'I and 8 and include resistance components such as to perectly match the impedances of antennas 1 and 8. In some cases it may not be necessary to actually use articial line sections I5 but the condensers I4 may be directly connected to ground. In this figure I .have shown `the transmission line TL as being terminated by a damping resistance yI2 having a-value equal to the surge impedance of v erallyused frequency. The wave antennas and 26 are coupled to transmission line TL through coupling transformers 29 and 30. The damping resistance 22 is connected across the short end of the transmission line'for the same purpose as damping resistance I2 in Figure 4.

The system of the present invention may also, asshown in rFigure 6, be applied to balanced antenna systems. In Figure 6 the balanced antennas consist of doublets 3|, 32 and 33, 34.

The wave antennas are several While they are indicated in perspective as .beinghorizontally arranged they may, of course, for vertically polarized waves, be vertically arranged. Except for the dil-ference in types of antennas shown, the operation of the modification of Fig` ure 6 is the same as that-of Figure 1.

Furthermore, the system of the present invention may be applied to a pair of V antennas 3l, v

38 of Figure 7 and, as before, the antennas connected to a transmission line TL having a phase reversing arrangement R -between the two an-v tennas.

Similarly, as shown in Figure 8, the system may be applied toa pair of rhombic antennas 41 and 48.

While the system of the present invention has been described particularly with reference to receiving antennas it may, of course, be equally well applied to transmitting antennas. Furthermore, a combination of two antennas set up according to the principles heretofore described may be duplicated by another group of similar antennas displaced from the rst group and the two groups in turn combined according to the principles above set forth,

While I have shown and particularly described' several embodiments of my invention, it is to be distinctly understood that myinvention is not limited thereto but that modications within the scope of my invention may be made.

I claim: v

1. A unilaterally directive antenna system in- 'cluding transducer equipment, a transmission line extending from said equipment along a line away from the direction of maximum response, a plurality of antennas located at spaced points along said line and coupled to said transmission line, and phase reversing means in said transmission line between said antennas, thedistance between said antennas'and thev length of transmission line therebetween being so related that said system has a maximum response to signals of said4 transmission line toward said transducer I equipment.

3. A unilaterally directive antenna system Aincluding transducer equipment, a transmission line extending from said equipment along a line away fromthe direction of maximum response, a plurality of antennas' located at spaced points along said line and coupled to said transmission line, and phase reversing means in said transmission line between said antennas, the distance between said antennas and the length of trans-y mission line therebetween being between 30 and electrical degrees. l

4. A unilaterally directive antenna system including transducer equipment, a transmission line extending from said equipment along a line away from the direction of maximum response, a pair of antennas located at spaced points along said line and coupled'to said transmission line, and phase reversing means in Said transmission line between said antennas, the distance between said antennas and the length of transmission line therebetween being between 30 and 150 electrica degrees. v

5. A system, as set forth in claim 4, wherein said transmission line is terminated at its other vend by a resistor having a resistance equal to the surge impedance of said line.

6. A system, as set forth in claim 4,' wherein each of said antennas is a long wire antennahaving its free end in the direction of maximum response.

7. A system, as set forth in claim 4, wherein each of said antennas isa long wire antenna having its free end in the Vdirection ofv maximumresponse, each of said free ends being connected 10. A system', as set forth in claimv 4:,V wherein each of said antennas is a V antenna.

11. A system, as setiforth in claim 4, wherein each of said antennas is a rhombic antenna having its end remote from its coupling yto said transmission line directed in the direction lof maximum response. Y

12. A unilaterally directive antenna system including transducer equipment, a transmission line extending from said equipment along a line away from the direction of maximum response, a plurality of antennas located at spaced points along said line and coupled to said transmission line, and phase reversing means in said transmission line between said antennas, the distance between and Iphase reversing means in said transmission line between said antennas, the distance between said antennas and the length of transmission line therebetween being or the order of a quarter wavelength.

14. A system, as `set forth in claim 12, wherein said transmission line is terminated at its other end by a resistorhaving a resistance equal to the surge impedance of said line.

15. A system, as set forth in claim 12, wherein each of` said antennas is a long wire antenna having its free end in the direction of maximum response.

16. A system, as set forthin` claim 12, wherein each of said antennas isa long wire antenna f having its free end in the direction ofmaximum response, each of said free ends being connected to ground through a resistor having a resistance equal to the characteristic impedance of said antenna.

HAROLD O. EEfI'ERSON.

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