DE2403056A1 - ADJUSTABLE DELAY LINE AND PROCEDURE FOR ITS OPERATION - Google Patents

Description

DIPL.-ING. KLAUS NEUBECKER

P at en * in ν / ξ It
4 Düsseldorf 1 · Schadowplatz 9 9 Λ Ω 3 GS β

43 801 Düsseldorf, Jan. 22, 1974

Westinghouse Electric Corporation,
Pittsburgh, Pennsylvania, USA

Adjustable delay line and method of operating it

This invention relates to signal delay lines and, more particularly, to a method and apparatus for selective Adjustment of the phase dispersion characteristics of a Meander line and to use the adjustable phase dispersion characteristic to suppress the second harmonic generated in amplifier chains.

Meander lines are known and are generally constructed in such a way that that the central ribbon conductor is made of a planar ribbon waveguide in a pattern which is several forms spaced apart, generally parallel, electrically interacting segments. the Meander line has a phase dispersion characteristic, which means that the total delay time, which a longitudinal The signal transmitted on this line is a non-linear function of the signal frequency.

If two signals in phase with different frequencies, for example a first and a second harmonic which are transmitted through such a meander line are located the two output signals of the line are no longer in phase.

409833/0709

The relative phase difference between the two output signals depends on the phase dispersion characteristic of the meander line at the frequencies of the supplied signals and is a puncture of the spatial structure of the meander line. Therefore, in order to change the phase dispersion characteristic of a meander line at a predetermined frequency, the spatial structure of the line can be changed. To achieve the desired phase dispersion properties of a meander line with different To obtain frequencies, the spatial structure of the meander line must be changed in a similar manner.

It can be useful to determine the phase dispersion properties, which a meander line in a signal with a fixed Frequency has to change or have a certain phase dispersion characteristic Maintain over a range of frequencies. For example, it can be useful to set the phase of a second harmonic to shift a certain amount with respect to the first harmonic and the fundamental wave to the second Suppress harmonics. In an application, for example the suppression of harmonics in a radar system, the Fundamental wave frequency must be variable within a predetermined frequency band, and accordingly the phase dispersion characteristic must necessarily the meander line be adjustable. The known signal delay devices with meander lines however do not have this property.

The main object of the invention is to provide a method and a device for changing the phase dispersion characteristic to create a delay line and to use this change to suppress the second harmonic.

In a variable delay line with a first member having a first electrical conductor having a plurality of has spaced-apart, electrically interacting phase dispersion segments along its length, this object is achieved according to the invention by a

409833/0709

second link, which covers at least a portion of the first link and has a Einrichtlang which with the first conductor is electrically connected and the electrical interaction between the segments of the first conductor accordingly the relative movement between the first and second links changed. .

According to the invention, a meander line with an optionally changeable physical or spatial structure is created. In particular, a first substrate is provided with an electrically conductive tape, which has a plurality of electrically having interacting segments or sections along a surface. A second substrate covers at least partially the tape of the first substrate. The second substrate contains an electrically conductive device which is connected to the tape of the first substrate and the electrical interaction between its segments accordingly the relative movement between the two substrates changed.

The device for changing the electrical interaction can preferably consist of another electrically conductive strip consist, having a plurality of electrically interacting segments or sections extending along the surface of the '' second substrate are arranged. The tape along the surface of the second substrate can preferably be substantially a mirror image of the tape along the surface of the first substrate so that the tapes are substantially the same Have extension and coincide in a position of the first substrate with respect to the second substrate.

When using the phase dispersion characteristic changeable meander line for the suppression of the power oscillating with the frequency of the second harmonic In power amplifier chains, an output signal from a signal source, for example a first power amplifier, an amplifier, for example a second power supply

AO 9 833/0709

stronger through a line with variable phase dispersion characteristics fed. The output signal from the signal source contains a fundamental component and one of the second harmonics corresponding frequency component, and the phase distribution characteristics of the delay line are adjusted, so that approximately a 180 phase shift is obtained between the fundamental wave and the twice frequency components will. The power generated by the second power amplifier and oscillating at twice the frequency of the fundamental wave is thus due to the phase-shifted signal frequency component with twice the frequency of the fundamental wave suppressed, which is fed to the amplifier from the signal source.

So it also becomes a means for suppressing the signal power created with twice the fundamental wave frequency, which is a signal source which is an electrical signal with a fundamental wave component and a second harmonic, and comprises a signal amplifier and is characterized in, that a delay line with a phase dispersion characteristic the electrical signal from the signal source Signal amplifier supplies and a device the phase dispersion characteristic the delay line changed so that about 180 phase shift between the fundamental and the second harmonic of the electrical signal fed to the signal amplifier is achieved.

It can preferably also be provided that the phase dispersion characteristic a meander delay line is changed between predetermined limit values, the effective spatial arrangement of the meander line is changed non-destructively.

Furthermore, one application of the invention is a method for suppressing the signal power by twice that Fundamental frequency at which the phase dispersion

409833/0709

-5- 24-3056

Characteristic of a delay line that transmits a signal with a fundamental wave component and a second harmonic is fed, is changed such that a relative phase shift of about 180 ° between the fundamental wave and the second harmonic connected to the first conductor is reached.

The following is a preferred embodiment of the invention explained with reference to the drawing; it represent:

Fig. 1 is a perspective view of a known one

Meander line for phase dispersion;

FIG. 2A is a graph of the delay characteristics of FIG

dispersive and non-dispersive delay lines;

Figure 2B is a diagram of typical waveforms of a

Fundamental wave signal and a second harmonic of this signal to explain the transmission through dispersive and non-dispersive delay lines;

3 shows a block diagram of an arrangement for suppressing the signals with twice the fundamental wave frequency ;

Fig. 4 is an exploded perspective view of a meander line with a changeable Phase dispersion;

5A and 5B are cross-sectional views of the meander line according to FIG

4 in two selected positions;

Fig. 6 is a diagram from which the between the fundamental wave signal and its second harmonic

• ■ 409833/0709

introduced phase difference as a function of the physical properties of the meander line emerges with variable dispersion characteristics according to FIG. 4; and

7 is a diagram for explaining the changes

the wave resistance of the meander line according to FIG. 4 as a function of its physical Properties.

A meander line can typically be found in a microwave system can be used as a delay element or phase shifter. A typical meander line is shown in Fig. 1, and may include an electrically conductive tape 10 encased in a substrate 12 of microwave dielectric is, which is largely lossless. The substrate can be made of any dielectric material with a conductive exist outer layer, for example, it can be copper-coated polytetrafluoroethylene fiberglass. That conductive tape 10 may have connections for microwave conduction. The band 10 forms a zigzag pattern or a "Meander line" with several essentially parallel, electrically interrelated, spaced apart from one another or connected phase dispersion segments 16 between its ends 14. Each segment 16 has a length L, which is conventional Way is determined by the frequency for which the meander line is designed, and a bandwidth W together with one Gap S and a segment spacing D, which values essentially determine the dispersion properties of the meander line.

A meander line like that in Fig. 1 has a phase dispersion characteristic, i.e. that the delay or phase shift between the terminals 14 of the meander line is one is a non-linear function of the frequency of the input signal. This phase dispersion property of a meander line is one

409833/0709

Function of the physical structure of the meander line and the frequency of the supplied signal. For example, if the ratio the width W of the band IO is increased from zero to one at the distance D of the segments, the phase dispersion behavior changes from non-dispersive to resonance. Similarly, the phase dispersion of the meander line is reversed Ratio to the ratio of the bandwidth S to the distance D, i.e. as the ratio S to D decreases, the phase dispersion increases the meander line too.

The phase dispersion behavior of a meander line compared to a non-dispersive delay line is shown in FIG. 2A shown. 2A, there is a linear relationship between the frequency of an input signal, expressed as Angular frequency ω and the electrically effective length of a non-dispersive one Delay line expressed as relative phase 0 according to curve 18. It can be seen that with a non-dispersive delay line a signal with an angular frequency ej, and a signal with an angular frequency 2 «* /, be shifted in phase by the same relative amounts due to the linear delay properties a non-dispersive delay line at different frequencies.

This linear relationship is explained with reference to Fig. 2B, in which a first signal 20 with a fundamental wave frequency and a signal 22 with the second harmonic of the Fundamental frequency are shown. When these two signals are fed to a non-dispersive delay line, each signal is linearly delayed or shifted in phase, and the phase of the fundamental wave signal 20 with respect to the phase of the second harmonic 22 is preserved before and after the signal delay.

A dispersive delay line, on the other hand, results in a non-linear delay in signals with different frequencies.

409833/0709

sequences and leads to a curve 24 according to FIG. 2A. Therefore, if the same fundamental wave frequency 20 and the same second harmonic 22 are fed to a dispersive delay line with the dispersion behavior according to curve 24 in FIG. 2A, a relative phase shift A 0 is introduced between the output signals of the fundamental wave and the second harmonic. This relative phase shift is illustrated in Figure 2B.

According to FIG. 2B, the fundamental wave 20 and the second harmonic 22 can be fed to a phase dispersion meander line according to FIG. 1 will. Assume that each segment 16 of the meander line according to FIG. 1 has the phase dispersion characteristic shown by curve 24 in FIG. 2A the output signals of the meander line have a relative phase shift NE0 (where N is the number of segments 16) determined by the phase relationship between the fundamental wave signal 20 and the non-linearly delayed second harmonic 26 is shown in broken lines in Fig. 2B.

It has been found that the non-linear dispersion behavior of a meander line in microwave amplifier circuits for the suppression of those generated in power amplifier chains that oscillate at twice the fundamental wave frequency Power is usable. According to FIG. 3, for example, a power amplifier 28 can have a relatively high high-frequency output power that has an undesirably high proportion of the second Has harmonics. In order to reduce the proportion of the second harmonic in the output signal, the output signal from Power amplifier 28 can be fed to amplifier 30 through a meander line 32, as will be explained below.

In operation, the phase relationship between the fundamental wave and the second harmonic of the power amplifier 28 is via the Phase dispersion behavior of the meander line 32 is set. If this phase relationship is set correctly, so that the second harmonic approximately 180 ° phase shift from

409833 / Ü7Q9

above the fundamental wave, the second can be in the output amplifier 30 generated harmonics essentially by the introduced, phase-shifted second harmonic of the Meander line 32 can be reduced. While it is generally required both the amplitude and the phase of the Controlling the applied second harmonic to achieve complete cancellation became a significant degradation of more than 10 dB with respect to the proportion of the second harmonic in the output amplifier 30, in which only the phase the applied harmonics has been changed.

The meander line 32 according to FIG. 3 can according to the preferred Embodiment of the invention according to FIGS. 4 and 5 constructed be. According to FIG. 4, the meander line 32 with variable phase dispersion characteristics can be a first substrate having a thickness A and an electrically conductive tape 36 which is embedded in a surface 35 of this tape. As can be seen from FIGS. 5A and 5B, this is electrically conductive Tape 36 preferably embedded in substrate 34 sufficiently so that the outer surface of tape 36 meets surface 35 of the Substrates 34 are aligned.

The band 36 is preferably designed in such a way that a plurality of spaced apart, essentially parallel, result in electrically interacting phase dispersion segments 36 'along its length. According to Figure 5A, the segments 36 · each have a width W and a separation distance S. The separation distance S as well as the width W define a distance D between corresponding edges of the segments 36 ', for example between the left and right edges of the segments 36 ".

A second substrate 38 includes an electrically conductive tape 40 that is embedded and aligned with a surface 37 and a device for changing the phase dispersion behavior of the segments 36 'can result in the first substrate 34

• 403833/0709

are bedded. The electrically conductive tape 40 is preferred as a mirror image of the strip 36 with a plurality of identically designed, electrically interacting phase dispersion segments 40 'formed along its length. When the surfaces 35 and 37 of the respective substrates 34 and 38 according to Adjacent to Fig. 5B, there are conductive strips 36 and 40 electrically in contact and result in an electrically continuous, essentially flat band. By moving one of the substrates 34 and 38 with respect to the other as shown in Fig. 5B, the ratio S / D can be changed so that the phase dispersion characteristics the meander line can be changed.

While the segments 40 'are preferably made from an electrically continuous tape 40, it can be seen that the portions of the tape 40' do not directly affect the S / D ratio when the substrates 34 and 38 are moved relative to one another. The segments 40 ^f therefore do not need to be electrically connected in order to achieve a change in the ratio S / D which is responsive to a movement and thus in the phase dispersion properties of the meander line. The illustrated embodiment is preferred, however, since losses due to sharp corners are minimized.

The substrates 34 and 38 can be made from a largely lossless microwave dielectric, for example from polytetrafluoroethylene fiber glass be made with copper plating. The conductive ribbons 36 and 40 can be any electrical highly conductive material, for example copper with a gold coating. Also the corners of the through the conductive strips 36 and 40 formed waveguide; ; to the Reduction of reflections should be rounded off.

4, the substrates 34 and 38 can be precisely slidably aligned with one another, so that the dispersion properties of the meander line through the slidable arrangement of one substrate over the other, for example the substrate 38

409833/0709

2A03056

can be changed in a support frame 42. The support frame 42 can be a relatively flat support plate 44 with a transversely extending Have flange 46 at one end and spacers 48 at each edge. The spacers 48 can with respect to the Thickness essentially corresponds to the thickness A of the substrate 38 and the substrate 38 slidably accommodate between them, a surface 50 of the substrate 38 adjoining the surface of the support plate 44.

At one end of the substrate 38, a laterally extending Flange 52 can be provided, and threaded bores 54 and 56 can be introduced through the flange sections 46 and 52 will. An adjustable threaded screw 58, e.g. one in opposite directions at opposite ends A screwed-in machine screw can be screwed into the threaded bores 54 and 56 and precise movement of the Secure the substrate 38 along the channel formed by the spacer elements 48 in accordance with the rotation of the screw 58. The substrate 34 can then be attached to the support frame 42 in a conventional manner so that it is relative to the support frame is fixed. For example, threaded bores 60 can be made in the spacer elements 48 and the correspondingly arranged openings 62 can be provided through the substrate 34. The substrate 34 can thereby be screwed to the spacer element 48 so that the surfaces 35 and 37 of the substrates 34 and 34 are slidably engaged.

During operation, the substrates 34 and 38 of the meander line can originally have an adjustable dispersion behavior according to FIG be aligned so that the bands 36 and 40 extend in substantially the same manner in width as shown in FIG. 5A. For the sake of simplicity, it is assumed that the meander line is used to determine the content of the second harmonic of an amplified signal, as described with reference to FIG. 3. An amplified microwave signal can be used for this purpose from a first power amplifier via the

409833/0709

Meander line according to FIG. 4 supplied and the resulting Output signal are fed to a second power amplifier. The output signal of the second power amplifier can monitored for the content of signal components of the second harmonic and the relative position of the substrate 34 and 38 can be adjusted by means of the adjusting screw 58.

When the adjustment screw 58 is rotated, the substrates 34 and 38 and the electrically interacting segments become 36 'and 40' moved relative to each other, reducing the ratio S / D and thus the phase dispersion properties of the meander line can be changed. According to FIG. 6, the phase delay of the fundamental wave versus the second harmonic for each electrically interacting segment of the Meander line can be changed non-linearly over a relatively wide range by changing the ratio S / D.

According to FIG. 6, the phase difference Δ 0 changes for different ratios of the substrate thickness 2A to the connected segment spacing D in a decreasing sense with an increase in the ratio S / D. Therefore, with a ratio 2A / D = 2.0 (curve 66), the phase difference A 0 for each interacting segment of the meander line can be varied between approximately 35 ° and by changing the ratio S / D between 0.5 and 0.01 is changed. Similarly, curves 68 and 68 show the changed phase dispersion properties at 2A / D ratios of 1 and 0.5.

A phase difference of 180 between the fundamental and the added second harmonic signals usually gives one maximum cancellation of the second harmonic. Therefore, a meander line with the properties according to curve 66 in FIG three electrically interacting segments are produced, so that a change in the phase difference over one Area between 105 ° and 270 °, i.e. three times the size 2A / D is obtained for a meander line section. The S / D ratio

409833/0709

can then be changed within this range by adjusting screw 58 and achieving a total phase shift of 180 ° between the fundamental and the first harmonic. In the meander line with the properties indicated by curve 66, this ratio S / D is approximately 0.15, since this ratio has a phase difference A0 of approximately 60
brings with it.

0 of about 60 for three interacting segments

The practically usable range over which the ratio S / D can be changed is determined by the change in the wave resistance determined, which is accepted in the special application of the meander line with variable phase dispersion can be. If the ratio S / D is changed, the wave resistance of the meander line also changes and can lead to a lead to an inadmissible loss of performance if the mismatch becomes too large due to the change in the S / D ratio.

In FIG. 7, the change in the characteristic impedance Z _{Q of} a meander line with variable phase dispersion as a function of the ratio S / D for ratios 2A / D is 2.0 (curve 72). 1.0 (curve 74) and 0.5 (curve 76) are shown. 7 shows the product of the characteristic impedance Z _Q times the square root of the relative dielectric constant (Tr of the substrate material as a function of the ratio S / D. With a ratio of 2A / D β 2.0 (curve 72) the product of the characteristic impedance and the relative dielectric constant vary between about 46 ohms for an S / D ratio of 0.01 to about 46 ohms for an S / D ratio of 0.01 to about 130 ohms for an S / D ratio of 0.5 the meander line explained for example in connection with FIG. 6, which is set to a ratio S / D of 0.15, the product of the characteristic impedance and the relative dielectric constant is approximately 80 ohms.

Assume that a typical substrate material has a relative

409833/0709

Has a dielectric constant of about three, so is the wave impedance of the meander line at a ratio 2A / D of 2.0 about 46 ohms at a ratio S / D of 0.15, and the The second harmonic is shifted by 180 ° in phase with respect to the resulting fundamental wave. In a circuit application in which the characteristic impedance is within certain must be kept within acceptable limits, for example 50 ohms + 5 ohms, this value of 46 ohms is within the acceptable Limits on the S / D ratio of 0.15 and allows adjustment on either side of the S / D ratio of 0.15.

From the preceding description it can be seen that the meander line with variable phase dispersion is continuous changeable dispersion behavior within the desired limits while essentially keeping the characteristic impedance of the line within an acceptable range is held.

The explained technique of variable phase dispersion can be used to create harmonics in microwave systems cancel, and this technique can be used in other systems that use phasers or devices need variable time delay of the signals.

Claims i

409833/0709

Claims (16)

Claims Adjustable delay line with a first element, which has a first electrical conductor which electrically interacts with a plurality of spaced apart electrical conductors has standing phase dispersion segments along its length, characterized in that a second member (38) overlapping at least a portion of the first member (34) and means (54; 56; 58) has, which is electrically in contact with the first conductor and the electrical interaction between the Segments (36 ') of the first conductor (36) corresponding to relative movement between the first and second links changed. 2. delay line according to claim 1, characterized in that the electrical Interaction changing device has a second electrical conductor (40) with several electrically interacting phase dispersion elements (40 *), which overlap the first member (34), the segments (36 *) of the first associated with the segments of the second conductor Cover the conductor and be in electrical contact with it. 3. delay line according to claim 1 or 2, characterized characterized in that each of the electrically interacting segments (36 ') of the first conductor (36) has a width W and a separation distance S and the device which changes the electrical interaction (54; 56; 58) the ratio of the distance S to the distance S + W according to the relative movement of the first and second link changed. 409833/0709 4. delay line according to one of the preceding claims, characterized in that with the first Conductor first and second terminals are connected. 5. Delay line according to one of the preceding claims, characterized in that the first and second conductors (36; 40) are each flat and through first and second members (34; 38) are carried in slidable contact with one another. 6 .. delay line according to one of the preceding claims, characterized in that the first and second member substrates (34; 38). 7. Delay line according to one of the preceding claims, characterized in that the first and second links have straps (36; 40). 8. Delay line in an arrangement for suppressing the second harmonic signal power component with a signal source that provides an electrical signal with a fundamental wave component and a component of the second Emits harmonics, and a signal amplifier, characterized in that a delay line (32) transmits the electrical signal from the signal source to the signal amplifier with phase dispersion behavior and means changing the phase dispersion behavior of the delay line so that a relative phase shift of about 180 ° between the fundamental wave and the second harmonic of the electrical, the signal amplifier supplied signal is obtained. 9. Arrangement for suppressing the second harmonic signal power component according to claim 8, wherein the means for changing the phase dispersion characteristic the delay line characterized 409833/0709 is that a device (54; 56; 58) the effective physical Arrangement changes. 10. The arrangement for suppressing the second harmonic signal power component according to claim 9, wherein the delay line is characterized in that a plurality of spaced apart, electrically interacting segments (36 '; 4O ¹ ) are provided and the device (54; 56; 58) to change the effective physical arrangement of the delay line (32) an electrically conductive device in sliding contact with the interacting segments for Having changing the electrical interaction between the segments. 11. Arrangement for suppressing a second harmonic signal power component according to claim 10, characterized in that the electrically conductive device and the interacting segments in the are essentially designed as mirror images of each other. 12. Method of optionally changing phase dispersion properties a meander delay line within predetermined limits, characterized in that that the electrically effective physical structure of the meander line is changed in a non-destructive manner. 13. The method according to claim 12, characterized in that the electrically effective physical The structure of the meander line (32) is changed by sliding contact of a first conductor (36) of the meander line with a second conductor (40) and by spatial displacement of one of the conductors to the other. 14. Method for suppressing the second harmonic signal • 409833/0709 performance component, characterized that the phase dispersion properties of a delay line (32) are changed, which a signal with a Fundamental wave and a second harmonic is fed, so that a relative phase shift of about 180 between the fundamental wave and the second harmonic frequency component is achieved at the end of the delay line will. 15. The method according to claim 14, characterized in that the relative phase shift is sampled between the fundamental wave and the second harmonic frequency components at the end of the delay line and the phase dispersion characteristic of the delay line corresponding to the sampled relative Phase shift is changed so that the relative phase shift of about 180 is achieved. 16. The method according to claim 13 or 14, characterized in that the phase dispersion characteristic is changed by changing the effective physical structure of the meander line. 409833/0709 Empty space