US2549867A - Antenna system - Google Patents

Description

April 24, 1951 H. c. A. VAN DUUREN ANTENNA SYSTEM Filed Dec. 21, 1940 Patented Apr. 24, 1951 ANTENNA SYSTEM Hendrik C. A. van Duuren, Wassenaar, Netherlands Application December 21, 1940, Serial No. 371,176

In the Netherlands December 21, 1939 17 claims. 1

The present invention relates to a directional antenna, system for wireless reception comprising a plurality of rhombic antennae of similar form and similarly arranged, such as in horizontal end-to-end array. These antennae have lead-in connection from corresponding angular points of each rhomb, each constituting a lead-in point for the rhomb, and each rhomb has maximum effectiveness of reception in a vertical plane which extends symmetrically through the rhomb from the lead-in end to the opposite or terminating end. In this end-to-end array, the maximum eectiveness of reception lies in a direction which is the same for all rhombs, this direction extending at an angle to the horizontal and being a function of the length of the wave received. A Well known system of this general type is known as the MUSA system (abbreviated from Multiple Unit Steerable Antenna) which is described in the Bell System Technical Journal of 1937, pages 337 et seq. This MUSA system utilizes a number of rhombs arranged end-to-end in a row and connected to each other and to the receiver by the Way of phase rotators or phase Shifters which permit of the modiiication, within certain limits, of this angle of directivity in the vertical plane from which the combination of rhombs receives signals with maximum eiectiveness for a given wave length.

It is a requirement of this MUSA system, as will hereinafter appear, that each successive phase shifter shall shift the received current through an angle which, With respect to that of the first phase shifter, is greater by a factor which is a whole number.l This necessitates an expensive arrangement.

The directional characteristic of these multiple unit antennae systems having steerable directivity can be deduced or determined from one directional characteristic which depends only on the position of the individual antenna relatively to each other and to their interconnection (hereinafter referred to as the group directional characteristic) and also from the directional characteristic of a single rhomb (hereinafter referred to as the individual directional characteristic). The relative transmitting or receiving intensity in a certain direction is proportional to the product of the intensities of the above two directiona characteristics for the given direction.

For satisfactory reception from a given direction, the two directional characteristics for the direction concerned must have a sufficient intensity. The systems of the prior art have the operating disadvantage that, when the condition stated above for reception from a given direction l and at a given wave length is satisfied, the device cannot be used for a different Wave length at a given adjustment of the phase Shifters, because the single rhomb directional characteristic and the group directional characteristic, which have now both been modied, have as a rule such a different orientation that from no direction is suitable reception possible. The single rhomb directional characteristic cannot be modified by simple means. i

The group directional characteristic, however, can be varied by the introduction of differences in propagation time of which the values increase equally in the lead-in feeders of the individual rhombs, which variation may be attained by means of the phase shifters referred to above. These phase Shifters in such prior art systems must be adjusted in a different way for each wave length.

These prior art systems employing numerous t phase Shifters are rather expensive, and hence the problem arises of providing an antenna system which is suitable. for the reception of different wave lengths Without phase shifters or with a smaller number of phase Shifters, or with other means to be adjusted for each separate wave length.

In effecting the solution of that problem, it is necessary that the group directional characteristie and the individual rhomb directional characteristic shall have for each different wave length substantially the same orientation relatively to each other, which orientation inv itself will depend, of course, on the Wave length.

One of the features disclosed in the present invention is the provision of a system wherein two or more rhombic antennae are placed with their lead-in feeding points in such spaced relation, and are connected to the receiver by means of transmission lines having such dilerences in propagation time, that the angle of maximum sensitivity or effectiveness for each frequency in the aforesaid. vertical plane, Within at least an octave of frequencies, is equal, or almost equal, for both the group directional'characteristic and the individual rhomb directional characteristic.

With such a system,fthe directional properties or directional eifect cannot be controlled in the way that is possible when phase Shifters are utilized. However, this control of directional eect is possible when employing two or more of these systems with the systems interconnected over phase rotators or phase Shifters. Compared to the relatively small angle of directivity in transmitting or receiving intensity is of satisfactory strength (in which satisfactory strength may be defined, for example, as 50% of the maximum receiving power) are closer than with a device in which all rhombs are coupled over phase rotators.

If it should be necessary to have ,available a wider span or interval of steerable directivity, another series of rhombs differently dimensioned can be utilized for the next interval, and so on.

A"Asthese series'can be arranged in superposed relation over the same-space of ground, no further space is required to this end.

In Vone preferred embodiment of the invention,

two series of rhombs are used, each series consisting of two groups of rhombs, there being a phase shifter between the two groups of each series. The groups of the first series each have `two rhombs, and the groups of the second series each have four rhombs. Such a combination permits of directive control between two angles, rthe sines of which are 1:2.8. This is amply sufficient, since a rhombic array according to the MUSA system is variable between two angles, Vthe vsines of whichare related as 1:2.45 withl the above power condition or requirement.

In this preferred embodimentof the present invention, four feeders arrive at the receiver, one from eachgroup of rhombs; These feeders are terminated at the receiver and are connected to the input of a high frequency amplifier. The outputs of two of these high frequencyr amplifiers, one associated 'with' one series of rhombs and the other associated with the other series of rhombs, are connected to phase Shifters, which may again be followed byk high frequency ampliers. The outputs of these devices are, insoiaras they are associated with groups of rhombs of the same series, paralleled on the input of a receiver arranged to rectify the signal. The receiver outputs, which'correspond in number to the number of series of rhombs, are paralleled onfthe low frequency output byv way of networks for correcting diiferences in propagation time. Since the various series of rhombs are adjusted to different angles, they receive rays which, having been emitted simultaneously, arrive with different retardations. It may be pointed out here that the Wide band characteristic mentioned at the end of the above-mentioned article of the Bell System Technical Journal on the MUSA system therein described relates exclusively to very narrow bands, as compared with an octave.

The invention will be exemplified below with reference to the accompanying drawing illustrating one preferred embodiment of the invention. In this drawing:

Figure 1 is a diagram representing the received voltage as a function of the angle of wave arrival for one rhomb and for combinations of rhombs; and

Figure 2 is a diagram schematically illustrating the antenna system, together with the connections with the receivers, etc.

' Referring rst to Figure 2, this gure illustrates two separate series of rhombic antennae,

one series being indicated by the rhombs designated l to 4 inclusive, and the other series being indicated by the rhombs designated 9 to I6 inclusive. In the first series, 1 4, the two rhombic antennae l and 2 constitute one group, and the other rhombic antennae 3 and 4 constitute a separate group. These two groups are connected in group arrangement by xed feeders 5 and 6 for the lirst group, and by xed feeders 1 and 3 for the second group, the points of juncture of the respective pairs of feeders being indicatedV at 50 and 5l. Each pair of feeders is connected to the left hand extremity of its respective rhomb. The right hand extremity of each rhomb is shown as being terminated by a terminating, resistance 55 which equals the characteristic antenna resistance.

The other series of eight rhombio antennae 9-l6 is likewise divided into two groups, one group consisting of the rhombs, 9, Il), Il and i2, and the other group consisting of the rhombs I3, I4, l5 and I6. The rst group of rhombs 9-I2 in this second series is provided with pairs of feeders l1, I8, i9 and 20, respectively, which have a point of juncture indicated at 25. The second group of rhombs lil-I6 in this second series also has pairs of feeders 2|, 22, 23 and 24 which have a point of juncture indicated at 26. The mutual or interspacing distances of the rhombs and the lengths of their connecting lines, both between the two groups of antennae and between the receivers and the junction points 5I and 26, must satisfy certain requirements in order that the combinations of rhombs shall have the same directional characteristic as a single rhomb with regard to dependence of the angle for maximum effectiveness of reception on a given frequency or wave length. In this regard, the dilerence of the distances from juncture point 5l and its companion juncture point 26 to the receiver, as compared to the distances from juncture point 5U and its companion juncture point 25 to the receiver, should be taken into account, and not these distances themselves. An effort has been made to indicate this in the drawingfby inclined lines. The above dependance of the angle on frequency is of such nature that, for a given antenna construction, at a certain wave length M, a given angle of arrival Ao will result in maximum effectiveness of reception. The relation between wave length A and the angle A for which the reception remains a maximum, may be stated for small angles to be approximately This formula is also valid for a series of rhombs if the distance of two of these is given by i M 2sin2 Aocos A0 and if the length of their connecting line equalsing line leads should be omitted.

The series of large rhombs I, 2, 3 and d is built in accordance with the above description and equations. Similarly, the lengths of the feeders 5 and 8 with their connection at junction point 553, and also the lengths of the feeders 'l and 3 with their connection at junction point E l are proportioned or chosen in accordance with the above conditions. The difference in length of the lines from point 5S to the receiver in comparison with the length of the lines from point 5i to the receiver is of such value that, according to the above formula, the immediate paralleling of the lines from points 56 and 5i to the receiver will establish for the series of rhombs l, 2, 3 and li a dependence in the above sense which is equal to that of a single rhomb.

The foregoing also applies to the series of eight rhombs 9 9 inclusive, making up the two groups of rhombs s-E and i3-i$, respectively.

The lines coming from the points 51B, 5i, 25 and 26 are led to the receivers through tubes 2, 28, 29 and 3@ and arrive at input transformers 35, 36, Si and 38.

The rhomb dimensions may be calculated according to the methods given in the article by Bruce appearing in Proceedings oi the Institute of Radio Engineers of January 1935, starting on page 24, and more particularly according to the Alignment Design Method appearing on page 3G.

Referring to the values tb and Z appearing at rhomb i in Figure 2, we have, according to the above method:

yb and the side Z may be chosen in accordance with the formulae 0.371 2M (1-a2) Sinz A0 If a is chosen smaller than 2, the maximum will, in comparison to Bruces method, remain in this Reduced project, practically in the same place. If a=\/2, the rhombs will become so much smaller that the adjacent angular points of subsequent rhombs of each series may be suspended on the same mast. Of course, the length may also be calculated according to Bruce, and the system will then consist of rhombs in which every succeeding rhomb somewhat overlaps the previous one. From the point of View of operation there is no objection to this, but more poles will be required.

At the receiver shown at the left hand side of Figure 2, the transformers 35, 3S, 3l and 38 lead to the high frequency ampliers 3|, 32, 33 and 36. It will be noted that the ampliers 3l and 33 have phase rotators 39 and @il interposed in their outputs. Beyond these phase rotators, the outputs of the two ampliiers of each series are connected together in parallel relation, as indicated at lil and 42, respectively. Interposed in these parallel connections il and 42 are receivers d3 and "Ll which rectify the signals. In the output circuit of one of these receivers is connected a retardation or delaying network-l5 for correcting diierences in propagation time. Beyond this retardation network 135, the outputs of the two receivers are paralleled t0 the common output 46 leading to a conventional translation device.

The two series of rhombic antennae i-i and S-l 6, respectively, may be continuously in simultaneous operation.

Cil

It has been found possible with the system des scribed to control angles of arrival in a sector between 8 and 20 from the horizontal.

The choice of a denite angle within this sector is effected by means of the phaserotators 39 and 0, the action of which will be explained in connection with Figure 1.

This Figure 1 shows some characteristics of rhombic antennae and combinations of rhombs. On the horizontal axis, the proportion of sin A:sin Am has been kset out, the value of Am giving the angle for which the rhomb or combination of rhombs supplies maximum current to the receiver. The ordinates in this Figure 1 are currents. It should be observed that actually the diagram should be constructed as a function of the angle. However, it has been found that the plot; ting of the characteristics as a function of the independent variable chosen gives a curve which, with a considerable degree of exactness, is valid for any value of am when this value is less than approximately 30, as will be the case in practical operation. The maxima of the different curves have been taken as equal. Curve a is for a single rhomb, b for two rhombs, c for four rhombs and d for eight rhombs. If the rhombs are all of equal size, the maximum of curve d would be eight times as high as that of curve a; the scale is thus eight times as small for curve d.

rihe curves given are validfor an adjustment of the phase rotators in which the latter do not bring about a phase rotation. Let us now see how the curve of the 8-fo1d series varies with displacement of the phase rotator 40. From such description, the action of the other phase rotator (is will then be easily understood.

The '-fcid series consists of two groups of four rhombs, according to which characteristic c should be used. Ii phase rotator it is varied, the currents of the two curves c will no longer be in phase in the maximum, but the currents of both groups are mutually in phase for an angle, which is different from that of the original maximum, it will be clear that the point of maximum reception for the series of 8 rhombs will be displaced. It has been found that this displacement may be continued until the current value has been reduced to about IAA/2, without undue increase of the secondary maxima or side loops, which are not shown in the iigure.

in operation, the maximum of each series of rhombs will be so adjusted that it yields maximum reception, in connection with the direction from which the rays arrive. Therefore, the receiving station should preferably be provided with apparatus permitting of the measurement of the signal strength behind each series of rhombs separately.

If receiving conditions are particularly unfavorable, the combination of receptions of the two series of rhombs on the output 'it may be dispensed with, i. e., one of the series of rhombs may remain entirely unused. Transformers 35 and 3'! and the associated transformers 36 and 3S may also be paralleled when one of the series of rhombs is put out of action, because no strong dependable signals may be received thereon. It may be that when using such a circuit connection the introduction of intermediate amplication becomes desirable. With such circuit, the two phase rota-tors 3s and d will be in connection with a single series, and consequently two rays or waves from the reception range of that series are susceptible of isolation and of being fed to the receivers 43 and 44.

l L 2 sin2 A@ cos A0 and leads connecting said spaced rhombs with Vthe receiver having lengths substantially represented by l lo N,

2 sur Aff 2 in which 0=wave length and A0=angle of arrival above a horizontal plane for which maximum reception is obtained with the given wave length and antenna construction, whereby with a given frequency change in a given range of frequencies the directional characteristic for the group of rhombs is oriented to a new angle of maximum effectiveness which is substantially equal to the angle of maximum eiiectiveness established for a single rhomb with the same frequency change.

2. A directional antenna system as claimed in claim l characterized by the fact that there is a plurality of groups of rhombic antennae in end-to-end array, said groups being arranged in series relation and each group having the interconnections therebetween as set forth in claim 1, each two groups of said series having an individual phase rotator for interconnecting the output paths of the antennae of its associated two groups.

3. In a directional antenna system, the combination of a series of relatively large rhombic antennae in end-to-end array, a series of re1- atively smaller rhombic antennae in end-to-end array, one of said series being in superposed 'relation to the other, and translating means having common connection with both series of antennae.

4. In a directional antenna system the combination of a series of relatively large rhombic antennae in end-to-end array, a series of relatively smaller rhombic antennae in end-to-end array, each series comprising a plurality of groups of antennae, one of said series being in superposed relation to the other, phase shifting means connected between groups in one of said series, and translating means having common connection with both series of antennae.

5. In a directional antenna system the combination of a series of relatively large rhombic antennae in end-to-end array, a series of relatively smaller rhombic antennae in end-to-end array, each series comprising a plurality of groups, each group comprising at least two rhombic antennae, one of said series being in superposed relation to the other so that both series of relatively large antennae and relatively smaller antennae can be carried by the same supporting poles, independently operable phase Shifters connected between groups in said two series, and translating means jointly controlling or controlled by both series of antennae.

6. In a multiple unit steerable antenna system.

the combination of a iirst series of rhombic antennae of relatively large size, a second series of rhombic antennae of relatively smaller size, each of said series comprising at least two groups, a phase rotator between the groups of said first series, a phase rotator between the groups of said second series, and translation means connected to both series of antennae.

'7. In a multiple unit steerable antenna system, the combination of a first series of rhombic antennae of relatively large size, a second series of rhombic antennae of relatively smaller size, each of said series comprising at least two groups, a phase rotator between the groups of said irst series, a phase rotator between the groups of said second series, one of said series being in superposed relation to the other, and a common output circuit connected to both series of antennae.

8. In a multiple unit steerable antenna of the class described, the combination of a first series of rhombic antennae each of relatively large size, a second series of rhombic antennae each of relatively small size, each of said series comprising a plurality of groups, each group comprising at least two antennae, there being at least twice as many antennae in each group of said second series as there are in each group of said first series, amplifiers foreach of said groups, phase rotators connected only between groups in each series, and a translation device connected in joint control relation with both series ofv antennae.

9. In a multiple unit steerable antenna of the class described, the combination of a first series of rhombic antennae each of relatively large size, a second series of rhombic antennae each of relatively small size, each of said series comprising a plurality of groups, each group comprising at least two antennae, there being at least twice as many antennae in each group of said second series as there are in each group of said first series, high frequency amplifiers for each oi' said groups, phase rotators connected only between groups in each series, said phase rotators being mutually independent, receivers for each of said series, one of said series of rhombic antennae being in predetermined physical relationship to the other series of rhombic antennae, and a common output circuit `ointly connected with both series of antennae.

10. In a multiple unit steerable antenna of the class described, the combination of a rst series of rhombic antennae each of relatively large size, a second series of rhombic antennae each of relatively small size, each of said series comprising a plurality of groups, each group comprising at least two antennae, there being at least twice as many antennae in each group of said second series as there are in each group of said rst series, one of said series being in superposed relation to the other, high frequency amplifiers for each of said groups, phase rotators connected only between groups in each series, said phase rotators being mutually independent, receivers for each of said series, a retardation network in the output of one of said yreceivers for correcting differences in propagation time, and a common output circuit on which the outputs from said receivers are paralleled.

l1. In a multiple unit steerable antenna of the class described, the combination of a iirst series of rhombic antennae each of relatively large size, a second series of rhombic antennae each of relatively small size, each of said series comprising a plurality of groups, each group comprising at least two antennae, there being at least twice as many antennae .in each group of said second series as they are in each group of said rst series, ampliers for each of said groups, phase rotators connected-only between groups 'in each series, said phase rotators being mutually independent, receivers for each of said series for rectifying the signals, and a common output circuit on which the signals rom said receivers are paralleled.

12. In a multiple unit steerable antenna or the class described, the combination of a iirst series of rhombic antennae each of relatively large size, a second series of rhombic antennae each of relatively small size, each or said series cornprising a plurality of groups, each group comprising at least two antennae, there being at least twice as many antennae in each group of said second series as there are in each group of said first series, amplifiers for each of said groups, phase rotators connected between groups in each series, receivers for each of said series for rectifying the signals, a retardation network in the output of one of said receivers for correcting diferences in propagation time, and a common output circuit on which the signals from said receivers are paralleled.

13. In a multiple unit steerable antennae system, the combination of a series or" individual rhombic antennae units arranged in end on array, said series comprising a plurality of groups, each group comprising two or more of said individual rhombic units, and connecting leads extending from the feeding points of said rhombic units for connection with translation apparatus, the distances between feeding points of the units being substantially equal to:

i t 2 sin2 A0 cos A@ and the lengths of said connecting leads being substantially equal to:

1 )o t ST Acta (in which ko=wavelength and Ao=angle of wave arrival above a horizontal plane for which maximum reception is obtained with the given wave length and antenna construction.)

14. In a multiple unit steerable antenna of the class described, the combination of a series of individual rhombic antennae arranged in endto-end array and each having a terminating resistance at one end of each rhomb and a pair of connecting leads extending from the other end, said series comprisin at least two groups, each group comprising at least two individual antennae, a separate amplifier for each group connected jointly with the connecting leads from the two or more antennae of that group, the spacing distances between connecting lead ends of the two or more antennae in each group being substantially equal to i t 2 sin2 A0 cos A0 and the lengths of the connecting leads extending therefrom, being substantially equal to a single rhomb, the directional"characteristic for the group of rhombs is oriented with a' given frequency change to a new angle of maximum eiectiveness which is equal to the angle or" maximum eectiveness established for a single rhomb with said given frequency change, detector means receiving the output of said amplifiers, phase shifting means operatively interposed between one of said amplifiers and said detector means, and an output circuit leading from said detector means. l

15. In a multiple unit steerable antenna of the class described, the combination of a series of individual rhornbic antennae arranged in endto-end array `and each having a pair of connecting leads extending from one end, said series comprising atleast twoA groups, each group comprising at least two lindividual antennae, a separate amplifier for each group connected jointly with the connecting leads from the two or more antennae of that group, the spacing distances between corresponding points of the two or more antennae in each group being substantially equal to i t 2 sin2 A0 cos A0 and the lengths of the connecting leads extending from said latter antennae, being substantially equal to in which M=wave length, and A0=the angle of wave arrival above a horizontal plane, for which maximum reception is obtained with the given wave length, whereby a sharper directional characteristic is attained and the angle of maximum effectiveness in the vertical plane, for a substantial range of frequencies is substantially the same for said group of antennae as for the individual antenna, output means receiving the output from said amplifiers, and phase shifting means interposed between one of said ampliers and said output means.

1S. In an antenna system of the class described, the combination of a rst series of relatively large rhombic antennae arranged in an end on array, a second series of relatively smaller rhombic antennae in an end on array, the difference in size being operative to provide a wider range of wave lengths over which said system is adjustably responsive each of said series comprising a plurality of groups to provide a sharper directional characteristic, each of said groups comprising at least two individual antennae, there being a larger number of individual antennae in each group of said second series than there are in each group of said rst series, leads extending from each individual antenna, and translation means having common connection with both said iirst and said second series of antennae through said leads, said antennae being arranged in a predetermined relative spaced relation and said leads being constructed of different lengths and arranged to eiiect with said predetermined antenna spacing, an angle of maximum electiveness in the vertical plane for each frequency, which over a substantial range of frequencies is substantially the same for the group in each series as for the individual rhomb in that series. i

17. In an antenna system of the class described, the combination of a first series of relatively large rhombic antennae arranged in an 1l end on array, a second series of relatively smaller rhombic antennae in an end on array, each of said series comprising a plurality of groups, each of said groups comprising at least two individual antennae, there being a larger number of individual antennae in each group of said second series than there are in each group of said first series, a rst receiver for said first series, a phase shifter interposed between one of the groups of said rst series and said rst receiver, a second receiver for said second series, a phase shifter interposed between one of the groups of said second series and said second receiver, a common output circuit for receiving the output from both of said receivers, and a retardation network interposed between one of said receivers and said common output circuit.

HENDRIK C. A. VAN DUUREN.

12 REFERENCES CITED The following references are of record in the file of this Ipatent:

UNITED STATES PATENTS

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