DE2407668A1 - ARRANGEMENT FOR SEPARATING THE SIGNALS OF EACH CHANNEL OF A MULTI-CARRIER REMOTE INDICATING SYSTEM - Google Patents

Description

Description of the patent application

of The Post Office, 23 Howland Street, London, OP 0HQ /

England

concerning:

"Arrangement for separating the signals of each channel of a multiple carrier for running Id e sy s t era s"

The invention relates to an arrangement for separating the Signals of each channel of a multicarrier telecommunications system.

Remote system using hollow metallic Waveguides with a round cross section are known. Such systems have large usable bandwidths, which as a result The nature of traffic and the limitations of digital facilities must be broken down into many signal channels. Means must be provided at the receiving station to separate the individual channels from one another. the Separation is usually provided through the use of resonant cavity filters.

Dielectric waveguides, consisting of a body of any cross-sectional shape made of dielectric, surrounded by an infinite medium of different permissility

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versus that of the body can be used at frequencies similar to those for which hollow waveguides are used will. The body and the surrounding medium need not have uniform pennissility across the transverse plane, and the boundary between the two can be diffuse. Most aspects are dielectric Waveguides similar to hollow waveguides. However, there are some cases where the characteristics are more dielectric Waveguide the structure of a particular waveguide component very difficult compared to the corresponding element in hollow waveguides. Such a case is the broadband directional coupler, where the change in coupling coefficient with the frequency between two dielectric waveguides so great that the construction of a useful Component becomes impossible. Since this is so, new techniques are required to make the dielectric waveguide to use with all its advantages. It can be shown that the coupling coefficient characteristic determined Excludes components, but enables a completely new form of channel separation network.

The object of the invention is to provide a filter for dielectric waveguides that operates over a wide frequency band is working.

In accordance with the present invention, a dielectric waveguide filter comprises a dielectric medium in which two dielectric waveguide regions are completely immersed, each waveguide region having a length over which the area is so close to a length of the other area that the areas can exchange electromagnetic energy, which length sections should be referred to as coupled lengths,

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the coupled lengths being such that, in use, energy transmitted at a particular frequency into a waveguide region from one end of the coupled length thereof is substantially contained in the other region at the other end of the coupled lengths, the dimension of each waveguide region across its length is such that the ratio ^ g / λ- _{2 is of} the order (including both limits) of

0.95 JEl + -0.05

0.05 /! Ζ + 0.95

where Kg is the wavelength of the electromagnetic energy in the waveguide away from the coupled lengths, A> _{2 is} the wavelength in free space of a TEM wave of the same frequency as the electromagnetic energy, E ₁ and E _{2 are} the dielectric constants that part of each range of the maximum permittivity and mean dielectric constant of the medium, or the dielectric constants of that part of the ranges of minimum permittivity and mean dielectric constant of the medium.

In the case where the dielectric constants are not variable over the areas and the medium, according to the

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invention also provides a dielectric waveguide filter having two dielectric waveguides which are completely immersed in a dielectric medium such that they exchange electromagnetic energy and are located close to one another over a limited section of length (the coupled lengths) which are the lengths over which the Centroids of the dielectric constant of the cross-sections of the waveguides are at a distance from one another in such a way that the antisymmetric mode of the filter can be propagated during operation and the transverse dimensions of the waveguides are such that the ratio ^ - g / λ. is of the order of magnitude (including both limit values) of

0.95 / E ^ "+ 0.05 / Ej

0.05 ΓΈ7 + 0.95

where Kg is the wavelength of the signal in waveguides in sections distant from the coupled lengths, ^ _{2 is the} wavelength of a TEM wave of the same frequency in free space, E is the dielectric constant of the material of the waveguide and E _{2 is} the dielectric constant of the medium in which the waveguides are embedded or embedded.

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The ends of the coupled lengths can be characterized by increasing distance between the areas or the waveguides to a level at which the energy transfer ceases, or by placing an electrically conductive screen between the areas or waveguides.

The regions and waveguides and the dielectric medium can each be isotropic.

According to a further feature of the invention, the two dielectric waveguides are arranged on a conductive plane, and the combination of the waveguides and the conductive plane can be completely immersed in a dielectric medium.

Instead of a single conductive level, two conductive levels can also be used.

The dielectric meijdum between the two waveguides may have a dielectric constant with a value different from that of the rest of the surrounding medium. In this case is the dielectric constant E », which appears in the range given above, that of the dielectric in which the waveguide is inserted and the material is immersed between them.

The invention relies on the fact that if two waveguides are uniformly coupled along their coupled lengths then when a waveguide is excited at one end of the coupled lengths, one between the waveguides Power transfer takes place. As the original excitation progresses along the coupled length it becomes increasing

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Share of the power taken over by the second waveguide, until the transfer occurs at a distance that is determined by a variable which is referred to here as the coupling coefficient is essentially complete. There are then conditions for the transfer of the service back to the original one Waveguides at a similar distance. In this way it can be said that the power between the two waveguides swings back and forth. The interval between points of substantially complete energy transition becomes only and determined solely by what is referred to here as the coupling coefficient Size provided that the waveguides are identical and the coupling is uniform along the coupled one Lengths is. In the dielectric waveguide, uniform coupling can be achieved by maintaining the Parallelism between the waveguides over their coupled lengths, and the coupling coefficient can be varied by Change in the distance between the waveguides.

The end of the coupled length can be designed so that it coincides with one of the points where the electromagnetic energy is essentially entirely in one of the Waveguide appears in which case the electromagnetic energy would emerge along that waveguide in which it would appear at the end of the coupled length, which is not necessarily the case is the waveguide that she entered. The coupled length can be the interval between the points substantially exceed total transfers of power, and indeed many times over, provided that the ratio between the two lengths is an integral multiple, the performance is essentially complete in that one or the other of the waveguides appear.

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It has been found that because the coupling coefficient is a function of frequency, the filter can be used to separate two carriers of different frequencies by choosing the coupled length and the coupling coefficient so that at the end of the coupled length there is a carrier in essentially entirely in one waveguide and the other carrier appears essentially entirely in the other waveguide. Signals derived by modulating the carriers would behave similarly except that they consist of a band of frequencies and, as a result, it is not entirely true that the entire band appears essentially entirely in a waveguide. The condition that a carrier introduced at the input leaves one of the outputs with almost no attenuation can be defined as j CIL = η -ζ, where C is the coupling coefficient that changes with frequency, L is the coupled length and η is the integer Multiples.

If η is an even number, the carrier leaves the waveguide that also had the inlet. If η is odd, the carrier leaves the waveguide which only forms the outlet. Energy in the _carrier,% which does not satisfy this condition is not found substantially completely in one of the waveguides at the end of the coupled length, but this condition can be fulfilled in general for any carrier that enters the filter by changing either the coupling coefficient or the coupled length, or both.

Additionally, the filter can be used to combine carriers on a single dielectric waveguide, by the coupled length and the coupling coefficient so

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be chosen that on the linde of the coupled length the carrier appear on the same waveguide.

Furthermore, the waveguides are able to relate to each waveguide by choosing a transverse resolution for each waveguide Length, as defined above, to guide a group of carriers, and the filter separates the band into a number of contituents Girders or channels. Alternatively, the filter can operate in reverse and combine carriers or channels.

A filter with one inlet and two outlets is called denotes a "coupled line filter". It forms an arrangement in which a number of equidistantly spaced Signal channels form the input, and a separation to be made so that alternating channels appear on each of the two outputs.

Embodiments of the invention can include more than two Use waveguide. The electromagnetic coupling between the waveguides is not limited to a single plane, so that a particular waveguide can be coupled to different waveguides at the same time, but can the characteristics of an arrangement with more than two waveguides are derived from the superimposed characteristics of the waveguides considered in pairs, provided that all combinations of two waveguides are taken into account will. Embodiments of the invention can use three, four, or more waveguides.

A channel separation filter using the "coupled line filter" is constructed as a series of units in cascade, each of which is designed to serve the

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It receives output from one of the vial conductors of the previous unit and performs the separation. D & iigeaass supplies uei a network, which is provided for the separation of acut i_.i decency lying channels, the ir see "Jinhsit four on each of its outputs. The second filter stage consists of two units, one of which is connected to an output of the first In this way there are now four output waveguides, each of which carries two of the original eight channels.The third stage operates in a similar manner using four units.

The functions of the inputs and outputs of the arrangement can be interchanged to create such an arrangement for the coordination of a number of signal channels a.a oondesnde of a Fernuieldesystei-as.

A range of carriers, which are introduced at the input of a coupled line filter "v / ir-Ί, can be separated into zv / ei subgroups, depending on 0.0 η even or odd for each carrier, provided that they are all the condition that η is a positive integer for the same coupled L'anjQ . This presupposes that the frequencies of the carriers have a certain relationship to the change in the Kopplanj coefficient ia with the frequency. Since ri is odd, they are transmitted to the iQ.-conductor without an input, while the carriers that meet the condition η even-numbered remain on the multi-conductor that formed the input. Each of the two subgroups can be further separated by additional units that work in a similar way, ura four smaller groups too

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ORIQJNAL INSPECTED

IO

produce which each do not exceed a quarter of the number of porters from the original group. This procedure can be repeated as often as necessary so each carrier is on a certain wavelength alone appears, with which: aan a complete separation of the original Group in their carrier! Component en achieved. One recognises, that the coupling described can have the characteristics of a cyclic filter over a large bandwidth, and a series of such arrangements can be used as a duct separation net zwerk.

It has been found that the change in the coupling coefficient rait makes the frequency essentially linear can be over a wide bandwidth by adjusting the spacing of the waveguides. In addition, it has been shown that small changes in distance only minimal changes in the rate of change in the coupling coefficient with frequency but mainly cause a uniform change across the bandwidth across the array. These relationships allow the construction of a sewer separation network, which is particularly useful for a multi-carrier fernineldesystein with equally spaced signal channels where the coupled length for all units in each Stage is the same and exactly half the coupled length for all units relative to the immediately preceding one Stage is provided. However, the spacing between the waveguides of each unit need not be the same.

A coupled line filter with dielectric waveguides with isotropic waveguides, dia into an isotropic one Are immersed in the medium, as well as a duct separator, on

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builds from a cascade of coupled line filters, whereby the Channel separation network is particularly suitable for a multiple carrierf ernineldesysteiu with equally spaced signal channels are described below with reference to the attached Drawings are explained in more detail as an exemplary embodiment.

Fig. 1 shows a coupled line filter with dielectric waveguides,

Fig. 2 shows the cross-sections of the isotropic waveguides that are used,

Fig. 3 shows a channel separation network of eight Outputs,

Fig. 4 shows the structure of a coupled line filter,

Fig. 5 shows the structure of part of a Kanaltrennet zes,

Fig. 6 shows the change in the coupling coefficient depending on the frequency,

1, 8 and 9 show the theoretical frequency response of the sub-channel separation network according to FIGS. 5, and

Figures 10, 11, and 12 show the measured outputs from various outputs of the network according to FIG. 5 to confirm the theoretical results.

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Ιί

Referring to Fig. 1, a coupled region 3 is formed over a coupled length L where a dielectric waveguide 2 is arranged parallel to a dielectric waveguide 5, while the distance between the centroids the cross-sections of the waveguides are denoted by d.

The distance d between the centroids is chosen so that the antisyiranetric mode propagates along the waveguide will.

An input 1 is provided on the waveguide 2, while two outputs PORT 1, PORT 2 are provided on the waveguides 2 or 5 are formed. The coupled area is defined by an increasing distance between the waveguides. The exchange of electromagnetic energy is then essentially limited to the coupled length.

Fig. 2 shows the cross section of the isotropic waveguides used in the embodiment. In the case of rectangular waveguides as used here, the distance d between the centroids of the cross-sections of the waveguides is related to the distance js between the facing sides of the waveguides, so that parameters which depend on d are equally dependent on j depend. This also applies to a number of symmetrical cross-sections which are suitable for dielectric waveguides. In Fig. 6, which shows the relationship between the coupling coefficient and the frequency, the distance s is used instead of the distance d.

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The dimensions a and b have such values that the ratio ^ gA _{2 is of} ^the order of magnitude (including both limit values)

0.95 [T ₁ + 0.05 / ~ Ej

0.05 / E ₁ + 0.95

where E, and E _{2 are} the dielectric constants of the dielectric material from which the two waveguides are constructed and of the dielectric material in which the waveguides are completely immersed, which in this case is air, where \ g and ^ _{2 are} both defined above became.

The operation of a channel separation network will now be explained with reference to FIG. Eight input signals, which are in channels f1 to f8, are fed to input 1 of the network. This input is provided by the first stage of coupled line filters, consisting of waveguides 2, 5. The signals reach the coupled area 3 and propagate in the direction of the outputs PORT 1, PORT 2 of the coupled line filter of the first stage, the signals f2 _f f4, f6, f8 now appear on the waveguide 5, while the signals fl, f3, f5 and f7 remain on the waveguide '2. The waveguide 5 now provides the input to a coupled line filter serving as the second stage, and the waveguide 7 forms the other waveguide of this stage.

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At the end of this coupled line filter are the Signals f2, f6 transferred to the waveguide 7 while the signals f4, f8 remain on the waveguide 5. The signals f2, f6 are now separated by the coupled line filter, consisting of waveguides 7 and 9, while f4, f8 are separated from the waveguides 5 and 10 by the coupled line filter. In the same way, the Signals fl, f3, f5, f.7 separated by the coupled line filter, each consisting of waveguides 2 and 8, waveguides 8 and 11 and waveguides 12 and 2, see above that at the end you get a signal on a mill conductor. In this way, fl appears on PORT 6, f2 on PORT 13, f3 to PORT 7, f4 to PORT 12, £ 5 to PORT 5, f6 to PORT 14, £ 7 at PORT 8 and f8 at PORT 11.

The manner in which the separation takes place can be explained with reference to Figs. 7, 8 and 9, which can refer to the frequency response characteristics of the coupled line filters. The frequency response curves of Fig. 7 can be derived from the coupled line filter according to FIG. 1. Assuming that a coupled Line filter suitable for use at frequencies between 30 GHz and 40 GHZ is used, and that the signals that are present at input 1 of the coupled line filter are at frequencies that correspond to the 0 dB loss 7, then the frequencies appear according to the solid curve according to FIG. 7 in response 1, and the Frequencies on the dashed curve of Figure 7 appear at PORT 2. This is the situation at the end of the first Level of the coupled line filter is present, from which the

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Channel separation network according to Fig. 3 is constructed. The effect the second stage, also designed as a coupled line filter, is shown in FIG. 8, and the effect the third stage coupler of FIG. 9.

The frequency characteristics are chosen so that they differ from stage to stage by progressively increasing the coupled length of the successive stage of the coupled Line filter halved and the distances as required changes. Accordingly, the coupled length of the waveguide 11 with the waveguide 8 is half that which is coupled Length of the waveguide 2 with the waveguide 8, and this in turn is half the coupled length of the waveguide 2 with the waveguide 5.

The coupled length of the waveguide 7 and the l & Llenleiters 5 is the same as the coupled length of the waveguide 8 and the waveguide 2. ¹ The coupled length of waveguide 9 and waveguide 7, the coupled length of waveguide 5 and waveguide 10, and the coupled length of waveguide 2 and waveguide 12 are all equal to the coupled length between waveguide 8 and waveguide 11.

The coupled length and the distance between the waveguides 2 and 5 are chosen so that the energy at frequency fl is completely transferred from one waveguide to the other N times, where -κ is an integer and the energy at frequency f-8 Is transmitted N-7 times.

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te

The distance between waveguide 8 and waveguide 2 is the same as that between waveguide 2 and waveguide 5, the distance between waveguide 12 and waveguide 2 is the same as the distance between waveguide 2 and waveguide 5. The distance between waveguide 11 and waveguide 8 differs slightly from the others in order to achieve optimal coordination. The distance between the waveguides IO and 5 is the same as the distance between waveguides 7 and 5, but this distance is different somewhat of that between waveguides 2 and 3. The spacing between waveguides 9 and 7 is somewhat different from that between waveguides 7 and 5 and is unrelated to any other distance.

Small changes in the spacing are required in order to operate the coupled line filter on the group of frequencies to vote. The tuning is effected in the structure according to FIGS. 4 and 5 by compressing the expanded Polystyrene blocks in the appropriate direction to decrease the spacing between the waveguides as needed.

Waveguides of substantially round, elliptical or rectangular cross-section can be used in the construction described a coupled line filter can be used. The waveguides can be connected by a path the same material instead of being physically separated. Alternatively, the waveguides can be supported through a pipe, the rods being formed as internal ribs on opposite ends of diameters of the pipe are.

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- j »- ■

Figures 4 _f 5 show details of a Äusführungsform. The arrangement shows a coupled line filter with expanded polystyrene elements to support the dielectric waveguides.

According to FIG. 4, identical rectangular waveguides 2, 5 are supported in such a way that they are parallel to one another, the smaller axes of the cross-sections being coincident. Expanded polystyrene blocks 13 fill the space between the waveguides and are also in contact with the outer sides of the same _{e in} such a way that the waveguides are completely enclosed "The distance between the waveguides is given by the expanded polystyrene blocks between them." Animal pressure on the assembly in the appropriate direction to fine-tune the filter. In a modified Äusführungsfom the dielectric material filling the space between the waveguides can have a dielectric constant t, which differs from that of the material that contacts the outer surfaces.

Figure "5 shows esin three-stage filter network using the structure according to Fig. Explained 4« As the dielectric waveguide 2 _R 5, 8 and 12 embedded in expanded Paiystyren 13 _r wherein the waveguides are parallel and the minor axes of their cross-sections are coincident. Electromagnetic energy is injected into and extracted from the waveguides by conventional transducers 14 so as to create a connection between the rectangular waveguides and dielectric waveguides. Electrical

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IV

Magnetic energy is introduced at input 1 and propagates towards output PORT 6 of waveguide 2, with energy that passes to waveguide 5 appearing at PORT 2 _f energy that passes to waveguide 8 appears at PORT 4 and energy which transitions to waveguide 12 appears at PORT 5.

Although the embodiments thus far described disclose coupled line filters with sharp transitions of the dielectric constant ^ seen across the cross-section, the invention is also applicable to structures in which this transition is more gradual. For example, a coupled line filter can be built in which each Transition is divided into different stages. In addition, the assembly can be treated in such a way that this Levels are smoothed into a gradual transition. A drawn glass structure can be used for use at optical frequencies can be applied in several layers.

A coupled line filter can be constructed from a body of dielectric material that treats wfcd by ion plating, selective polymerisation or others Methods such that there is a change in the dielectric constant across the cross section according to Ä-Maintaining the symmetrical and antisymmetrical mode of the coupled Leitujjfngsfliter.

For example, a one-piece dielectric body · with a dielectric constant that increases continuously Changes across the cross-section of the body can be generated, for example, by selective polymerisation. Certain Monomers and low order polymers polymerize when irradiated rait, for example, ultra-violetteai light, where the

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-M-

Degree of polymerization that is achieved is a function the intensity of the irradiation and the duration of the exposure. If such irradiation on a focal point within a body of a monomer or a low order polymeric material, then the grade of the polymerization that is induced within the body will be the highest in focus. By moving the body an elongated area of increased polymerization can be achieved during irradiation. The rate at which the degree of polymerisation with the distance from the focal point changes is a function of the aperture of the optical system used to focus the exposure. If the source is fixed, a sector-shaped area will be created in which the degree of polymerization is at its highest center and at the same rate along any radius within of the sector drops, while outside the sector the degree of polymerization remains at the original value. A wider sector can be created by rotating or vibrating the radiation source and the optical system at the focal point. The source and the optical systems are preferably designed to generate a line focus Dielectric constant is higher in the area of higher polymerization. Alternatively, a substantially parallel beam can be used for the irradiation, for example a laser beam, selective polymerization being produced by rotating or vibrating the source about the point in the cross-section the body on which the highest degree of polymerization is desired.

When applying the formulas that determine the limit values for the ratio λg / x ₂ in the case of a filter in which the dielectric constant changes over the cross section,

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is the value of E, to be used, the maximum or minimum value, that is, the value representing the constants of electricity that part of the waveguide with maximum or minimum dielectric constant. The required The value for E- is the value of the mean dielectric constant of the medium.

It will be understood that while the waveguides may be identical, they are not uniform in cross-section need to be about the coupled lengths. The distance over the coupled lengths may decrease from the ends the coupled lengths up to the center thereof, at which point the distance is a maximum or a minimum may have, or may progressively change from one end of the coupled length to the other. The bandwidth of a filter using one of the mentioned configurations, it is somewhat limited compared with the other embodiments of the filter, as explained above.

- patent claims -

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Claims (15)

Claims IJ Dielectric waveguide filter, characterized by a dielectric medium in which two waveguide regions are completely immersed, each of which has a length section in which both are spaced from one another sufficiently small for the exchange of electromagnetic energy (hereinafter referred to as "coupled length"), which are coupled Lengths are dimensioned such that energy fed into a waveguide region from one end of its coupled length at a certain frequency is essentially contained in the other waveguide region at the other end of the coupled length, the dimensions of each waveguide region being chosen across its length so that the ratio Xg / X ₂ in the range (including both limits) of 0.95 \ f E ₁ + 0.05 \ J E ₂ up to 0.05 n / E ₁ + 0.95 s / E ₂ where λ g is the wavelength of the electromagnetic energy in the waveguides outside the coupled lengths, X _{2 is} the wavelength in free space of a wave of the same frequency in the TEM mode as the electromagnetic energy, E ₁ and E _{2 is} the dielectric constant of that part of the Waveguide regions of maximum dielectric constant or the mean dielectric constant of the medium - or the dielectric constant of that part of the waveguide regions of minimum dielectric constant 409835/0786 or the mean dielectric constant of the medium. 2. Dielectric waveguide filter according to claim 1, characterized in that the dielectric constants of the waveguide regions are not variable. 3. Dielectric waveguide filter according to claim 2, characterized in that the waveguide regions with one another are connected by an intermediate piece made of the same material. 4. Dielectric waveguide filter according to claim 1, characterized in that the dielectric constants of the waveguide areas and the medium are not variable, that the coupled length is the length over which the centrifugal dielectric constant of the cross-sections of the waveguides have such a distance from each other that in operation of the anti-symmetric mode of the filter is fortpflangzbar that the transverse dimensions of the waveguides are chosen so that the ratio Xg / λ, i ⁿ the range äem 0.95 \ ΓΈ ^ + 0.05 \ Z ~ iJ and 0.05 v / E ₁ + 0.95 \ / ^ ^E 1 ^E 2 where X g is the wavelength of the signal in the waveguides in those sections distant from the coupled length, X "is the wavelength of a TEM wave of the same frequency in free space, E _{1 is} the dielectric constant of the material of the waveguide and E _{2 is} the Is the dielectric constant of the medium in which the waveguides are immersed. 409835/0786 5. Filter according to one of the preceding claims, characterized characterized in that the ends of the coupled lengths are defined by increasing the spacing of the waveguide regions to a size at which the energy transfer breaks off » 6. Filter according to one of the preceding claims, characterized characterized in that the coupled length is limited by an embedded between the two waveguide regions electrically conductive screen. 7. Filter according to one of claims 4, 5 or 6, characterized in that the waveguide regions and the dielectric Medium are isotropic. 8. Filter according to one of the preceding claims, characterized in that it consists of a plurality of individual Filter elements is constructed. 9. Filter according to one of claims 2 to 8, characterized in that that the waveguides are supported by at least one conductive plane and this combination is complete immersed in a dielectric medium. 10. Filter according to claim 9, characterized by two conductive ones Levels. 11. Filter according to one of claims 2 to 10, characterized in that that the waveguides have a substantially rectangular cross-sectional shape. 12. Filter according to one of claims 2 to 10, characterized in that that the waveguides have a substantially round cross-sectional shape. 4098 35/0786 13. Filter according to one of claims 2 to 10, characterized in that that the waveguides have a substantially elliptical cross-sectional shape. 14. Filter according to one of claims 3, 11, 12 or 13, characterized characterized in that the waveguides are interconnected by a section of material of the same dielectric constant how the waveguides themselves are connected. 15. Filter according to one of claims 11, 12 or 13, characterized in that the waveguide is supported by a tube are, wherein the waveguides are designed as inner ribs on opposite sides of the pipe diameter. 409835/0786