DE1081084B - Delay line and method of making it - Google Patents

Description

The invention relates to delay lines whose delay depends on the frequency over linear over a wide frequency range, as well as processes for their manufacture.

The delay line described below is of the type that evenly distributes reactance values having. There are delay lines with evenly distributed reactance values in the usual embodiment of a hollow cylindrical outer conductor to which one Terminal of the signal source is connected, and from a cylindrical concentrically arranged therewith Inner conductor that is connected to the other terminal of the signal source. Modifying this In principle, the inner or outer or both conductors can be designed as tightly wound coils. The formation of the conductors as a coil has the consequence that the inductance of the members per unit of axial length and hence the time delay per unit length, which is proportional to the square root of the distributed Inductance (inductance per axial unit of length) is increased.

Magnetic materials are used in the present delay line. Magnetic Materials are known at. Delay lines with evenly distributed reactances used in various ways. It is known to have a magnetic core in the interior, as Introduce coil formed conductor to increase its distributed inductance. A magnetic one Core was also inserted between the outer and inner conductors. In this known arrangement the magnetic core increases the distributed inductance of the delay line when this has an outer conductor designed as a coil. The magnetic core must and will insulate usually chosen to reflect not only the line inductance but also the line capacitance increased by increasing the capacitance between the conductors. Since the time delay is proportional to the Is the square root of the distributed capacitance, the material should have a high dielectric constant.

The delay line according to the invention uses magnetic members, their magnetic properties are selected such that a novel delay characteristic is obtained, which in the is substantially linear over a wide range of frequencies.

A substantially linear phase shift over a wide band of the supplied frequencies is achieved by a known delay line with distributed reactances went out. A well-known way to have a frequency-independent delay over a wide

Delay line and procedure
for their manufacture

Applicant:

General Electric Company,
Schenectady, NY (V. St. A.)

Representative: Dr.-Ing. B. Johannesson, patent attorney,
Hanover, Göttinger Chaussee 76

Claimed priority:
V. St. v. America May 22, 1958

Harold William Katz, Camillus, NY (V. St A.),
has been named as the inventor

Generating a frequency band consists in the use of a complicated filter network. A well-known one Filter network consists of a multitude of parallel paths, each of which has a narrow frequency band lets through and gives it a given delay. When the pass frequency ranges the filter occupy successive stages of a broad frequency band and the time delays of the successive filters are appropriately chosen according to the frequencies, then a stepwise frequency-dependent phase shift is generated over a wide frequency band. This well-known possibility of achieving a linear phase shift over a wide frequency band, assumes the use of numerous filters and gain-compensating elements and generates no really linear characteristic as the delays increase in stages.

According to another known method, an all-pass is made up of concentrated switching elements.

uses, which is composed such that the desired linear phase shift as a function is achieved by the frequency. The coordination of this network is due to the large number of necessary settings very critical.

It is accordingly an object of the invention to provide a delay line with evenly distributed reactances to create a simple structure which has a linear phase frequency characteristic over a has a wide frequency band.

009 508/293

Known delay lines with distributed reactances are not individually capable of the to generate the required linearity over a wide frequency range. Generally these were Arrangements used to operate in the lower frequency range of the spectrum, in which their time delay is independent of the frequency. When these same arrangements operated at higher frequencies their losses increase due to skin effect, eddy currents, core losses and the like Causes very quickly, whereby these effects often completely mask the phase effects. Where the phase effects these delay lines could be determined at higher frequencies, it was found that the phase delay to a point whose frequency is at the upper limit frequency at normal Operation is constant and then drops very quickly with increasing frequency. After this the total time lag has decreased over a larger range, becomes the ratio of the decrease decreases in time delay with increasing frequency, and the total time delay asymptotically approaches a fixed value. The operation of such arrangements in the asymptotic realm is generally out of the question due to the sharp rise in losses and the small amount of Change in delay. The phase characteristic of such delay lines is initially concave directed downwards in the region of the reversal frequency and becomes concave upwards above this Area. The phase shift areas of the known arrangements where these are not due to the losses are therefore strongly non-linear, and most of the phase shift occurs in the lower part of the frequency range of a very narrow one Frequency spectrum.

The invention is intended to create a delay line with "evenly" distributed reactances which generates a linear phase shift in a wide frequency range and has low losses.

In the case of a delay line with evenly distributed reactances from one to one magnetic core wound coil-shaped conductor connected to a second core made of magnetic Material is surrounded, there is, according to the invention, the permeability of the outer core is greater than that Inner core permeability.

It is useful here, the coil-shaped conductor, which is wound so that it is a cylindrical Takes shape to be provided closely adjacent to a second conductor that is concentric to the first is arranged and consists of a plurality of axially extending conductive elements, wherein the two conductors are arranged between an inner and an outer core so that they are between have a very small air gap.

The small spacing of the conductors between the cores causes an increase in the distributed capacitance the delay line and thus the delay time per unit of length. The usage of the inner and outer cores increases the distributed inductance of the conductor wound as a coil and thus also the time delay per unit length of the delay line. By using an outer core, which has a higher permeability than the inner core, takes the operating frequency range of the delay line increases noticeably and becomes more linear over a wider frequency band than it was possible with the known delay lines. With this arrangement the linearization is on largest when the gap between the cores is reduced to a minimum.

An exemplary embodiment of the invention will be explained in more detail below with reference to FIGS will.

Fig. 1 shows a section through the longitudinal axis of a delay line according to the invention.

Fig. 2 shows a section of the delay line according to the invention perpendicular to the longitudinal axis.

3 shows a schematic representation of the use of the delay line according to the invention in a circuit, and

4 shows a graph of the improved broadband properties of an inventive Delay line.

1 and 2, 10 is an exemplary embodiment of a delay line according to the invention designated. The delay line 10 is designed in such a way that it covers part of the high-frequency spectrum works essentially linearly below 10 MHz. The delay line 10 consists of one Pair of conductors 11 and 12, which in the space between a tubular core 13 of magnetic Material and a cylindrical core 14 arranged centrically for this purpose, also made of magnetic Material, are arranged. The entire arrangement is located in an insulating housing 15 and is provided with suitable connection terminals 16, 17 and 18.

The head elements consist of a coil shape coiled conductor 11, which is outside, but in little Distance from the inner conductor 12 is arranged, which consists of a plurality of conductive elements. The conductors 11 and 12 are carried by the inner core 14 and fill the space between the inner core 14 and the outer core 13.

The inner conductor 12 is applied directly to the surface of the inner core 14; it consists of many small insulated wires, which are attached to the core 14, close together and in extend in the axial direction over the entire length of the surface of the core 14. For these wires you can z. B. Use wire with a thin enamel insulation, the thickness of which is of the order of 0.075 mm. These wires are (in the illustration of FIG. 1) at the left end of the delay line 10 electrically interconnected and connected to terminal 17. That the elements of the Conductor 12 are only connected to one another at the end near the terminal 17, has the purpose of eddy currents to avoid. In an embodiment similar to that just described, in which the inner core has a diameter of 3 mm, e.g. B. the inner conductor consist of 150 conductive elements. These elements reduce the eddy current losses to one at frequencies below 5 MHz Minimum.

The inner conductor 12 can also consist of thin conductive strips or documents with the help of a known technique can be applied to the surface of the inner core 14. By using this conductive members a slightly smoother conductive surface is achieved, but with the application of these elements on the core there is the difficulty of accommodating an equally large number of conductive elements, like when insulated wires are used. The effect achieved depends of course on the highest operating frequency; with eight eggs

5 6

For example, attenuation of the size 2: 1 becomes very important if you have a large frequency band of 1.5 db / cm at 2.4 MHz. Because the broad wants to achieve.

The magnitude of the eddy current losses at the higher fre- At the present time are ferrite material sequences limits the operating range, the Ken, which the specified permeabilities and the

Subdivision of the inner conductor 12 along the circumference 5 do not have the required low losses

the higher the higher the upper limit frequency always available. Therefore, according to a

lies. Formation of the invention two suitable magnetic

The outer conductor 11 consists of one suggested on the materials for the cores 13 and 14,

inner conductor 12 arranged conductive, tightly The tubular outer core 13 can be made of the following

wound coil. The delay lines of the moving components consist of:

sought type, which at frequencies below mole percent

10 MHz can be used, the conductor 11 consists of Fe O 48

For example, made of wire that is enamelled and insulated. NK) ³ '''' · «· · · ^

winds is that there are 200 turns for 1 cm. £ nO '* "27 *

The part of the conductor designed as a coil 11- 15 VO .......... r -

extends over a substantial part of the inner ^{2 ε}

Core 14 and ends with two or three core diameters These materials are ground in a ball mill.

before the end of the inner core. The ends of the grind, dried and fired in an air atmosphere.

Conductor 11 are connected to the input terminal 16 and the temperature is steady for 6 hours up to

Output terminal 18 connected. At this 20 it is about 1200 ° C increased. The maximum temperature will be

Place emphasizes that the simplicity of the illustration is then held for 4 hours, after which time the oven

for the sake of the conductors 11 and 12 to a greater extent - switched off and the cooling relatively quickly

are shown as the other links. In which is taken.

In practice, the wires that make up the members 11 and the material that makes up the inner core 14

12 form, a much smaller diameter 25 can consist of the following components:

than terminals 16, 17 and 18. The intermediate mole percent

space between the inner core 13 and the outer p _e q 49 g

Core 14 is also shown enlarged. The tat- NK) ³ ". ··. ···· ^^

the neuter thickness of the gap lies in the ZnO 171

Order of magnitude of 0.125 mm if for the ladder 30 VO '''* O ¹ S

wires the indicated wire is used · ² °

The cores 13 and 14 form the magnetic part. These components are made in a ball mill.

of the delay line 10. The inner core can be ground, dried and fired in an air atmosphere.

z. B. 3 to 13 mm in diameter, while the temperature increases to 500 ° C per hour

the total length increased by the total amount of 35 1150 ° C. The connection will take about 20 minutes

desired delay is determined. Which was kept at this temperature for a long time and then im

For the sake of increased production, it is generally cooled down very quickly in the oven.

desires to keep the length of the delay line. Both of the aforementioned materials have intrinsic values below 50 cm. If the inner core extends half of a frequency range that extends up to 10 ¹ MHz 3 mm in diameter, the usual length is 40, high permeabilities at a relatively low 20 to 30 cm. Losses on. It should be noted that other magnetic

The outer core 13 can be the same length as the table connections in particular applications inner core 14 or can find the connection use, provided that they have the with the conductive elements of the inner conductor 12 to the required permeability ratios and low facilitate, at the end of the delay line, 45 losses in the operating frequency range. There to which the terminal 17 is connected, both properties are significantly different from those provided be shortened. The outside diameter of the tubing will depend on the application of the delay lines, shaped core 13 can be somewhat less than the double can bepelte many known magnetic materials Diameter of the inner core, especially when used at lower Freweder the magnetic resistance nor the linear 5 ° sequences can be used. The above-mentioned intrinsic properties the delay line and connections are reduced as examples only will. It is important, however, that named. The members 11, 12, 13 and 14, which the the inner diameter of the tubular member is an integral part of the delay line

13 is not significantly larger than the outer diameter, a diameter of the inner core 14 is inserted into an insulating housing 15 so that it is pushed between the 55. In the illustration according to FIG. 1, only a very small air gap remains on the left core. In the end of the delay line 10, the two \ ^r erzögerungsleitungen be of the type considered is a terminals 16 and 17 insulated from each other by the distance of less than 0.25 mm is desired. Cap 19 of the sleeve 15 held. As mentioned above,

For the sake of the linearity of the characteristic, the terminal 16 is wound as a coil

Delay line, the outer core must be connected to a 60 conductor, which forms the outer coil 11,

have higher permeability than the inner core. The clamp 17 is secured by means of a flexible metal

There are materials for this, their permeability in connection with each of the conductive members, which

Range from 400 to 500. When the inner core forms the inner conductor 12, connected. The clamps

has a permeability of 80 to 100, a per- 16 and 17 will thus form the entrance of the delay

Meability ratio of about 5: 1 achieved. In general management. The output terminal 18 is through the

What is common is a ratio of 10: 1, held by the theoretically insulating cap 20 of the sleeve 15 and is

From a table point of view, it is optimal. The larger one is connected to the coil 11 at its inner end.

Ratios lead to a little improved line A delay line according to the invention, whose

arity. As can be seen from the inner core ζ. B. has a diameter of 3 mm,

ven results, a permeability ratio is greater than 70 with an inner conductor consisting of eight strips,

7 8

a coil-shaped outer conductor made tightly so that the air gaps between the cores wound as much as possible! Wire and an inner core whose are small. In the event that a permeability-relative permeability is approximately 100 and a ratio of 4: 1 is used, the lower outer core, the relative permeability of which is 314 is a cut-off frequency in the range of a normalized F, has z. B. a linear frequency characteristic 5 quenz OrDt ₀ /) 0.1, where D is the diameter of the coil-shaped wound conductor in a frequency range from 400 to 240OkHz in centimeters, T ₀

a linearity of +2 ¹ ZzVo , where the group- the time delay of coaxial length, extrapolated to

delay approximately 0.3 μβεΰ / αη axial length being the zero frequency, and / is the operating frequency.

wearing. The attenuation at the upper limit frequency if larger permeability ratios are used

2400 kHz is approximately 1.5 db / cm. An increase in io or higher linearities are required,

the number of elements of the inner conductor in which it may be desirable to operate at something Embodiment reduced to sixteen, the higher starting frequencies to begin than z. B. at

Losses at 2400 kHz to less than 0.6 db / cm. the normalized frequency 0.2.

The phase delay as a function of the The different delay of the frequencies

Frequency is shown in FIG. 4 by curve 24. 15 in delay lines that go from one to one

You can see that this curve is still a non-coil wound conductor and a ground connection

linearity at the first reversal point and at a branch ladder can result in a reduction in the

Point in the range of a normalized frequency of series inductance of the outer conductor when the

0.6. This final kink will be attributed to the frequency applied. The Ver-

Air gap between the inner and outer 20 divided inductance of the delay line is allocated

Core causes, apart from the conductors, a factor that determines the maximum time delay

was approximately 0.012 mm. of the delay line, whereby the maximum

It is also possible to operate a line at a higher times time delay proportional to the square root than the above frequency, e.g. B. is in from this inductance. The reduction in the range from 2.5 to 7.5 MHz, which is the case with the inductance, is due to the fact that the dimensions given above lie just above the field at various points on the second delay point of the maximum curve. Such a line can have slightly different phases. This line was built, which consists of more than 100 internal conductors, with the result that the coupling inductance between conductors existed in order to reduce the eddy current losses to a contiguous turn and minimum, and at which the 3 ° thus also the distributed inductance of the coil. In the air gap between the inner and outer conductors, 0.01 cm, the area in which, with a usual delay, the diameter of the inner core, the phase delay being constant, was 0.3 mm. It has been shown that this line will have a group delay of 0.4 μ5ε ^ αη in which the wavelength of the signal is significantly greater than the number of turns which are inductively generated with the lower limit frequency and which are coupled to the upper 35 of a given winding.
Cutoff frequency of 7.5 MHz approximately an attenuation if, however, the operating frequency was down to one of 0.9 db. The change in the delay value is increased at which the factor π Dx _o f was 0.5 μβεΰ / αη in the specified frequency range reaches the value 0.1, then the distributed inductance is at a linearity of ± 2V2%. vity is significantly reduced, and the time lag

The curves 25, 26 and 27 mathematically show the 4 ° of the line decreases with frequency. The critilinearizing effect, as it is determined by increasing the value nDr _o f, depends, as mentioned above, on the ratio of the permeabilities of the outer core permeabilities of the magnetic material inside to the inner core in steps of 2: 1, 5: 1 and 10: 1 it is targeted on the delay line or the magnetic material. For comparison, curve 23 shows the rials surrounding the delay line and characteristics of a delay line in which 45 depends on their ratio. This theoretical explanation does not use an outer core. In general, in practice, it has been observed that a ratio of the permeabilities of more than 10: 1 only slightly improves the mathematical expressions that the operation of the delay brings about even more confusing. Describe what is important for the linear course of the lines; the unavoidable air 5 ° are also much more complicated characteristics.

split between inner and outer core, which is another factor of significant interest the achievement of the mathematically expected cha- the arrangement of the ladder with the least possible abracteristics prevent and a small kink in the stand. Such an arrangement increases the distributed Cause phase curve. In applications, in terms of capacity, very important. Often there is also a whichever this kink is portable, a fairly large ferrite tube can be inserted between the two conductors Part of the frequency spectrum can be used. by a decrease in the distributed capacity For more critical applications, as considered here and an increase in the distributed inductance, is the area of use is generally called, provided that the ground conductor in on the area below and above this point- first case is slotted so that there is no shielding tes limited. (In curve 24 of FIG. 4, 60 occurs. The distributed capacitance can be used in the inventive The kink at approximately 0.6 of the normalized arrangement according to the invention is also increased in frequency by removing the space between the lines

The lower cutoff frequency of the inventive tern with a fat high dielectric constant

The delay line is well above the fill, which also facilitates the construction

usual operating limits of known delay 65 is.

lines, which are generally operated in such a way, The use of the delay according to the invention

that there are no phase shifts in the connection lines in a circuit is shown in FIG.

which result in frequencies. In general, this is the case. Here input terminals 16 and 17 are the

lower limit by the core permeabilities and the delay line 10 with a high frequency source

Permeability ratios are determined assuming 70 21 connected while output terminal 18 is on

9 10

a consumer 22 is switched on. The terminal 17, 3rd delay line according to claim 1 or 2, a terminal of the source 21 and a terminal of the Ver, characterized in that the coil-shaped user 22 are connected to each other and a second conductor, be grounded closely adjacent to conductors. Since the wave resistance of the deceleration is composed of several lines extending in the axial direction in the operating frequency range differently and connected to one another at the end, it is generally desirable that conductive elements be provided.
consumer 22 and in more critical cases also the source 4. delay line after one of the An-21 are provided with a matching network, Proverbs 1 to 3, which is dimensioned such that which is dimensioned such that the wave resistance is greater than the size π DxJ 0.1, where D is the level of the delay line in the operating frequency ¹⁰ diameter of the area formed by the first conductor is always adapted. The wave resistance of the deten coil, T ₀ the phase shift per length delay line, falls in the area of linear phase unit at the frequency zero and / the limit delay linearly and is proportional to the frequency.

Delay Time. As matching networks with a 5th delay line after one of the

Such a frequency characteristic can in itself be * 5 Proverbs 1 to 4, characterized in that the

known circuits are used. Ratio of the inner diameter of the outer

In a practical application of the invention, the core can be the outer diameter of the inner core

the source z. B. provide a pulse train whose carrier ^is largely the value approaches 1,

frequency with the middle of the linear range of the ⁶ · delay line after one or more

Delay line matches. The rise time ^{ao rere11} of claims 1 to 5, characterized by

the pulse should then not overshoot the rise time that the magnetic material for the

increase, which approximates with the bandwidth of the linear outer core (13) of constituents

range of the filter, d. H. consists of the following composition:

management example 0.5 ^ isec, in which the linear mole percent
The range of the delay line is 2 MHz wide. ^a 5

The delay lines described can lsrV) ³ '94- ^

are connected in cascade to the ^Phasenver-: r '

Increase shift effect. Where a multitude of ⁿ ^ r. _

Elements are connected in cascade, 2 5 »

Stronger elements with suitable frequency characteristics 3 °

be provided to the passage gain (or 7th method of making the magnetic

Attenuation). Materials for the outer core of the deceleration

While in the above-described execution line according to claim 6, characterized

examples of the ground conductor inside the coil-shaped draws that the material is ground, dried

wound conductor is also the reverse 35 and fired in an air atmosphere, the

Training possible in which the ground conductor is kept at constant temperature for 6 hours up to 1200 ° C

the surface of the conductor wound into a coil is increased, the maximum temperature is 4 hours

lies. This embodiment is kept the same good and then a relatively fast cooling

Have properties as described above.

Arrangement. The base plate can also be set to 4 ° 8.Delay line after one or more

attached to the outer surface of the outer core of claims 1 to 5, characterized

be, also the linearizing effect of the draws that the magnetic material for the

outer core is preserved. This arrangement approximates the inner core (14) from components

generally leads to somewhat lower phases - the following composition consists of:

shifts between the frequencies because the ⁴⁵ Mit

distributed capacity compared to the described ° ^ T ^ ¹

Arrangement is slightly lower. il ^ ² ir ³ tnr

NlO ΟΔ, Ό

Claims (2)

Claims:? I ⁿ ^ I ' _c 50 V ₂ U ₅ 0.0 ! .Delay line, consisting of an on a magnetic core wound coil- 9. Method of manufacturing the magnetic migen conductor, with a second core of material for the inner core of the retardation magnet Material is surrounded, characterized by a conduit according to claim 8, characterized in that indicates that the permeability of the outer 55 that the material is ground, dried and put into Core is greater than the permeability of the inner air atmosphere is fired, the Tempe core. temperature per hour increased by 500 ° C to 1150 ° C 2. delay line according to claim 1, there is, the maximum temperature about 20 ¹ minutes characterized in that the ratio of per- long and then a relatively fast cooling meabilities between 2: 1 and 10: 1. ⁶ ° development is carried out. 1 sheet of drawings © 009 508/293 4.60