DE2244724A1 - CONTROL DEVICE FOR AN ANTENNA LINE FOR GENERATING ELECTRONICALLY SWIVELING RADIATION DIAGRAMS - Google Patents

Description

Dipl. Phys. Leo Thul

Patent attorney J 2 LL 7 9 L

Stuttgart 3ο

Short street 8

YES. Chick -2

INTEENATICMAL STAEDAED ELECTEIC COEPOEATION, EEV YOEK

Control device for an antenna line to generate electronically pivotable radiation diagram ^

The invention relates to a control device for an antenna array for generating an electronically pivotable one- or two-dimensional transmit or receive radiation diagram, in particular in such wireless connections where fixed frequencies are transmitted or received.

Antennas whose radiation pattern can be pivoted electronically are known. The beam swivel takes place in that the individual radiators of the antenna preferably have an antenna line progressive bubbles of the RF energy are fed, the base value of the phase changing linearly.

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Such antennas are in Chapter 11, Page 11-1 of the "Radar Handbook by Merrill J. Skolnik, Mc G-raw Hill, 197 ° described "in detail".

However, the known electronically controllable antennas still have some disadvantages:

1. For example, it is very difficult to design an antenna with which a swivel angle of more than ± 45 ° perpendicular to the antenna axis can be achieved.

2. The gain increases with large antennas

roughly proportional to the number of

4 emitters, for example 1o

Radiators are required to achieve 43 db directivity.

The first disadvantage is that either 4 or 5 rows of antennas are necessary if a hemisphere is to be completely coated. The second disadvantage requires a large number of phase shifters if a beam swiveling in two directions is required is. The further difficulty arises that there are phase discontinuities in digital phase shifters appear.

These phase discontinuities can be interpreted as a second antenna that emits incorrectly and whose radiation diagram the desired radiation

—3—

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diagram bothers. Assuming that the effective excitation of the error aperture is equal to half the error of the Phase step, then you get the table

Phase step in radians approximate error in the side lobes

άί 0 db (two main lobes)

Λ / 2 -8.3 db

Jl / 4-13-3 db

oT / 8 -19.3 db

The sidelobe error can add up to the normal sidelobe values in terms of voltage.

It can be seen from this that a considerable number of phase steps are required if one can obtain useful sidelobe values wants to achieve at all pivot angles. Take an additive phase shifter with JT / 4 Steps, then you need 4-bit to switch (22.5 °, 45 °, 9o ° and 18o °). For a non-adding Phase shifters, on the other hand, require 15 bits. This number is to be multiplied by the number of emitters, because the control of each radiator in one coordinate is independent of the control in the other coordinate he follows. The logic becomes simpler if one carries out a matrix-type control, but with an additional row or column phase shifter is required.

With radar antennas, beam swiveling can be simplified when using frequency scanning. Included

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the frequency is changed to accommodate the required phase shifts at taps on a delay line and a frequency is therefore assigned to each beam position. Such Radar antennas are generally only swiveled electronically in one dimension. In the other Dimension is swiveled mechanically. However, a grid-shaped beam swiveling can also be used obtained by taking orthogonal delay lines and the frequency change in a plane by one Magnitude more sensitive and the successive second, third, etc. main lobes of the fast pivoting plane used as the actual main lobe. The scanning is, however, between consecutive lines discontinuously. Each usable frequency is based on a point assigned to one of the grid lines. Such an arrangement is useful in radar technology, if the exact frequency is not important, as the oscillator of the receiver follows the transmission frequency. This technique However, it cannot be used directly for satellite connections where the frequencies are in fixed in both directions.

It is the object of the invention to provide a simplified control device for an antenna array or a Specify antenna matrix in which the beam swiveling is caused by progressive phase changes of the individual radiators radiated RF energy takes place, in which, however, the phase changes due to changes in a Control frequency are caused.

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This task is with a one-dimensional pivotable Transmission radiation diagram achieved in that the two sidebands, one fixed and one variable Frequency are formed, that one of the two sidebands to a delay line with taps whose spacing corresponds to the radiator spacing, given that the signals taken from each tap individually along with the other sideband be given to one mixer each, the outputs of which are connected to the radiators of the antenna array, such that the emitters double the reading frequency, each phase shifted by the required angle is emitted, the phase change from Depends on the value of the variable frequency.

According to a further development of the invention, this can Control device also for generating a one-dimensional electronically pivotable reception radiation diagram use.

According to another development, the control device for an antenna matrix for generating a ' two-dimensional electronically pivotable transmission radiation diagram suitable, with a second delay · * ·. lines are connected that have as many taps as the matrix has rows,. , ... '.

This last-mentioned control device allows sieii according to Another development of the invention for generating a σ electronically pivotable in two dimensions Use the received radiation diagram.

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This control device has the advantage that they, for example for location systems and for radar systems is usable. It does not require long-term stability of the control frequency.

The invention will now be explained in more detail with reference to the figures, for example. Show it:

1A shows a control device for one-dimensional beam pivoting,

1B shows the frequency spectrum of the control frequency generator depending on the azimuth swivel angle,

2A shows a control device for two-dimensional ©. Beam swivel and

2B shows the dependence of the control frequency and elevation ßchwenkwink · !,

In Fig. 1A, the control device for electronic Beam pivoting mainly for a transmission

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Radiation diagram shown. By analogous reversal of the arrangement and use of parts 12, 13 -> 14 and 15, a control device for a received radiation diagram results.

The frequency f of a fixed frequency generator 1 is mixed with the frequency f of a control oscillator 2 in a mixer 3. Their output signals, which appear on lines 1o and 11, are the upper sideband f ^ + f ^ and the lower sideband f -f _o . The frequency of the control oscillator 2 is variable in the frequency range of Iy, -f. The lower sideband f -f arrives at a delay line 6 with

O S

Taps A, B, C etc. The spacing of the taps on the delay line are the same and they straighten mainly according to the distance between the radiators 5 · At the taps A, B, C etc. the Delay line 6 enters the lower sideband f -f

out of phase on. The phase shift results the end:

p »IT tab")

Phase shift between A and B = ψ * = ——r— - (1)

• -DD 'Ad

in radians

worm:

(AB) = d = distance between points AB in meters and

χ Α meter (2)

OS O

In equation. (2) ^; .is c ^ the speed of propagation in the delay line.

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The taps of the delay line 6 are with mixer stages 4- connected, in which the phase-shifted lower sideband f - f each individually with the

O S

upper sideband f_ + f "is mixed. Since the delay

O S

line 6 via the periodic taps A, B, C etc. _{supplies the lower sideband f Q} -f with successive, in the example linear phase shifts, the same phase relationship is present at the outputs of the mixing stages 4-, since, as is known, phases are not changed during mixing . By mixing the upper sideband f + f with the phase-shifted signals at the outputs A, B, C of the delay line 6, the control frequency f drops out, so that the N outputs of the mixing stages 4- all have the same frequency, namely twice the fixed frequency f _Q , but the phases are retained. The output signals of the mixing stages 4 are connected to radiators 5, which thus each emit the same frequency but each phase shifted by a certain angle. If f is changed, only the beam is swiveled, but the emitted one. Frequency does not change. The filters that are sometimes required to screen out the appropriate sideband are not shown.

The arrangement of individual radiators 5 can, for example be an antenna line in which all radiators are arranged along a straight line and in which the Radiation diagram is created perpendicular to the straight line. The radiators 5 can either be monopoles or dipoles, which are arranged and fed in such a way that the desired radiation pattern is obtained. The delay line 6 is known. You need about 100 emitters 5

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and the same number of mixing stages 4 to one beam width of 1 to achieve.

In the arrangement of the ITIG, 1A can be "for example, with the beam steering at O, that is, perpendicular to the axis of the antenna line start. In this case, the driving frequency f is chosen so that is an integer wavelength J \ based d on the distances, that is AB, BC, etc. If the control frequency f is increased, the beam swivels from the specified formal position (O ⁰ ) to the right up to an angle Oi = 45 ° - It is advantageous to interrupt the beam swivel at + 45 °, which uses a sweep to angles ^ 45. This is desirable because the beam is generally irregular and no longer sharply focused at beam angles ^> 45. In addition, if the angle is increased above 45 °, a second main lobe occurs, the 90 ° to the left of the first main lobe, but if there are two main lobes, the advantage of electronic beam swiveling with a sharply focused main lobe is no longer available ^ If one does not measure took to suppress the first 'main' club.

If you can achieve a continuous beam swivel with a further increase in the control frequency f wants without the two main lobes occurring, then it is necessary to set the control oscillator 2 so to interpret that its output signal at the

sequence is interrupted, which corresponds to 45 «Die

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However, the interruption must be very short. Or different Expressed when the main lobe reaches the angle of + 45 °, the continuous frequency range becomes Cut out a short piece of f so that in the meantime the first main lobe disappeared and the second main lobe appears at a pivot angle of -45. Now f continues

steadily increased, then the second main lobe swings from -45 ° via O ⁰ to + 4-5 °. At this point in time, f is again briefly interrupted. It should be noted that the bandwidth of the interruption corresponds to approximately half the beam width.

It is also possible to lay out the line in such a way that the main lobe disappears at a swivel angle of + 45 °. In in this case the periodic interruptions of the control frequency f shown in Fig. 1B are not mandatory. It is also pointed out that the interruptions or discontinuities of the control frequency f are not drawn to scale in FIG. 1B and in FIG. 2B Figures are only used to show the presence of these breaks.

The control oscillator 2 has a frequency range of f ^ ¹ ^ f ₀ % f ". The control can be designed so that the output signal of the control oscillator 2 begins with the frequency f ^ uirl the frequency changes continuously up to the frequency f and then immediately switches back to the frequency f ,, and increases again continuously from there, and so on

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Control can, however, also be carried out in such a way that when the end frequency is reached, the direction is reversed and the frequency slowly decreases until it reaches £ " again. In the latter case, it is possible to to choose the frequency range from f- ^ to f smaller.

The long-term stability of the control oscillator 2 is insignificant, since the frequency f stands out in the invention and only 2f is emitted.

In general, the individual radiators have the same mutual spacing. However, one can also use the technique of Apply the unfilled aperture, taking the lengths of the delay line between the taps must be proportional to the distance between the radiators.

To better understand the electronic. Beam pivoting through variable phase shifts is based on the book "Antennas and Transmission Lines" by John A. Kuecken, Howard ¥. Sams & Company, 1969, referenced.

When controlling a received radiation diagram xcLrd modified the arrangement of FIG. 1A so that the delay line 6 by means of a switch SW is connected to a line 12 which leads to one input of a mixer 13. The other The input signal of the mixer 13 is the control frequency f. The output signal of the mixer 13 leads to the ZF part and is usually processed there. In this operating mode, the incoming

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Signal frequency 2f received by the radiators 5. The received signal is processed in the mixer 4 so that the lower sideband in each case f -f according to the following relationship

stands:

^2f o - ^(f o ^{+ f} s ^} = ^f o - ^f s

the upper sideband f + f passing from mixer 3 to mixer 4-.

The lower sideband f_-f_ at the output of the delay line 6 is then mixed with the control frequency f in the mixer 13, so that the Output signal f results. In this case, this signal f is the intermediate frequency.

A control device for two-dimensional electronic beam swiveling is shown in FIGS. 2A and 2B a transmission radiation diagram and a reception radiation diagram are shown, as well as the dependency of the elevation swivel angle from the frequency of the Control oscillator 2. In FIGS. 2, the same reference numerals are used for the same parts as in FIG Fig. 1 is used. The control of the transmission radiation diagram is described below. the The reception radiation diagram is controlled in accordance with the description for FIG. 1.

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The arrangement according to the I ¹ Ig. 2A differs from the arrangement according to the Pig. 1A through further delay lines 16, 16 ', 16''etc. which are connected to the taps A, B, G of the delay line 6. These second delay lines themselves again have taps Aa, Ab, Ac ... Ba, Bb etc. as indicated at 17. The taps are in turn connected to mixing stages 18, the energy taken from the taps likewise being mixed with the upper sideband f _. + F_. The radiators 19, 19 _'5 19'', etc., however, are arranged in matrix form in rows and columns so that appropriate rows and columns of mixing stages 18, · 18', 18 * ', etc., are required.

In FIG. 1A, Ή taps A, B, C of one delay line 6 are required, as a result of which signals with the frequency 2f and the phase shifts o, \ | T, 2ij ", 3> /? ..UfN occur 2A, however, with the aid of the H "second delay lines 16, 16 ', 16", which are connected to the taps of the delay line 6, signals with the frequency 2f and the phases o, "UTA + IjTa, Ί1ΛΑ, + 2 y "a ,. etc. in the first row or column, and with the phases

ζ B + „7a, JB + 2 Ja etc. in the second line and with the phases \ J Ή + \ * J η, " U / U + 2 ./η etc. in the ΰ-th line.

We; In the arrangement according to FIG. 1A, the lengths AB, HG etc. and A ₃ A ^ ₅ A- ^ A ₀ etc. between the taps on the delay lines are proportional to the distances

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22U724

the radiator in each row or column and now also proportionally to the distances between the rows. Figures 1B and 2B together show the mode of operation of the arrangement according to the invention according to FIG. 2A. If the frequency f is between ί. _{If Λ} and f are changed, then the highly collimated beam swings in the azimuth direction from left to right, as described above. As soon as a swivel angle of +45 is reached, the control frequency f, which reaches mixer 3, is interrupted within a narrow frequency range, as described above. As a result of this, the beam pivoting in the elevation plane, as shown in FIG. 2B, is also interrupted. Fig. 2B shows that the elevation increases continuously when an azimuth angle of -45 ° to + 45 ° is swept, the elevation in the next pivoting process begins at a slightly larger angle than it would have started, even if the frequency f not been interrupted

were. It should be noted that the distance Z in FIG. 2B, which corresponds to the interruption of the elevation by switching off the frequency f corresponds to in the

Elevation is much smaller than the width of a club. Thus, it can be seen that when f the elevation continuously increases linearly, although the periodic interruptions: occur.

As mentioned above, it is the object of the invention, according to the arrangement according to Fig. 2, the beam electronically in two planes namely vertically and horizontally

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sway. Another object "is to provide a way of making the beam swiveling in one plane, in the example in the horizontal plane an order of magnitude more sensitive than in the other plane. For this purpose, it is provided that the beam in the horizontal plane is much faster This is achieved by appropriately choosing the ratio of the lengths d and d ¹ between the taps on the first delay line 6 and the taps on the delay lines 16, 16 ', 16 ¹ ', etc. Im Example, the length AB is significantly greater than

the length A A selected. In this way he will. a υ

is enough that the pivot in the horizontal plane takes place very quickly, while the pivot in the Elevation level is much slower. This measure results in that one with a single Electronically very quickly run through the frequency range over a fairly large area of space raster scanned.

Both the first delay line 6 and the second delay lines 16, 16 ', 16' ' etc. satisfy the laws of equations (1) and (2). As mentioned, the arrangement delivers after 3? 2A a fast beam swivel from left to right and a slow beam swivel in the vertical direction. It should be noted that the phase shift of interest each element is general:

-ti / _g = > γ- kyr (radians)

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where K is an even number. In other words, the beam position is repeated every 2 3 [of the phase shift. 'Jum 2j ' jumps between successive grid lines, causing discontinuities in the frequency spectrum. In order to avoid this, one can take suitable measures, for example using a strongly bundled radiator.

In the arrangement according to FIGS. 1A and 2A, the output signals of the mixer 3? namely the upper one Sideband f + f on mixer 4 (or 18) and the lower sideband f -f on the delay line 6. It is of course also possible to reverse this assignment. So you can the upper sideband f_ + f on the delay line 6 and the lower sideband f -f on the mixer

ο s

Give 4 or 18. The mode of operation is then the same as described above.

4 claims
2 sheets of drawings

309812/090

Claims (3)

YES. Chicks -2 '- 17 - Claims Control device for an antenna line for generating an electronically pivotable one- or two-dimensional transmission or reception radiation diagram, especially "for those wireless connections in which fixed frequencies are transmitted or received, characterized in that the two sidebands of a fixed and a variable frequency are formed that one of the two sidebands on a delay line with taps, the spacing of which corresponds to the radiator spacing, is given that the signals picked up from each tap are given individually together with the other sideband to a mixer, the outputs of which are connected to the radiators of the antenna array, in such a way that the emitters emit twice the fixed frequency, each phase shifted by the required angle, the phase change depending on the value of the variable frequency. YES. Kuecken -2 - 18 - 2. Control device for generating a Electronically pivotable one-dimensional reception radiation diagram with a corresponding reversal of the function of the device according to Claim 1, characterized in that the input of the delay line, at which the lower sideband can be removed, is connected to one input of a mixer, at the other input of which the variable frequency is present, so that the fixed frequency can be removed at the output of the mixer stage. 3. Control device according to claim 1 for an _e antenna matrix for generating a two-dimensional, electronically pivotable transmission radiation diagram, characterized in that second delay lines are connected to each tap of the first delay line, each of which has as many taps as the matrix has rows. Control device for generating a two-dimensional electronically pivotable reception radiation diagram, characterized by the combination of the devices according to Claims 2 and 3. 309812 / 09-03 Blank page