EP2374182B1 - Filter arrangement - Google Patents

Description

The invention relates to a filter assembly according to the preamble of claim 1.

In many fields of electrical engineering and in particular also in communications and mobile radio technology, filter arrangements and, in turn, notch filters are of great importance. Such blocking circuits may be known, e.g. be realized by a parallel connection of a coil and a capacitor in the form of a resonant circuit. The filter arrangements in question may consist, for example, of a high-pass filter (HP), a low-pass filter (TP) or a bandpass filter (BP), which are constructed, for example, from series and / or parallel circuits of L / C components.

Such filter arrangements or blocking-circle filters are frequently used in mobile radio technology for operating multiband antennas, for example in order to achieve a decoupling of approximately 50 dB between the frequency bands. For example, such filters can also be used for intersystem decoupling be used in multi-band antennas, since additional blocking filters are needed to achieve the aforementioned 50 dB decoupling between the frequency bands. In addition, a good adaptation (VSWR) and a low attenuation must be ensured in the pass band of the frequency band to be transmitted.

Finally, solutions are also known in addition, in which a transformation line and associated spur lines are designed as microstrip lines on a printed circuit board. Such solutions are for example from the pre-publication " Microstrip Filters for RF / Microwave Applications, Wiley Series in Microwave and Optical Engineering, by John Wiley & Sons, Inc., 2001, Jia-Sheng Hong and MJ Lancaster, Chapter 6, pp. 161-190 as well as out Chapter 5 "Lowpass and Bandpass Filters" of the same prior publication, namely from pages 109 to 121 to be known as known.

An extent comparable microstrip filter training is for example also from the VS MÖTTÖNEN ET AL .: "Subharmonic Waveguide Mixer AT 215 GHZ Utilizing Quasivertical Schottky Diodes", Microwave and Optical Technology Letters, Vol. 27, No. 2, Oct. 20, 2000 (2000-10-20), pages 94-97 , XP002589626 as known.

A corresponding RF filter arrangement is for example also from the US Pat. No. 6,278,341 B1 to be known as known. The filter is designed so that lead away from an RF inner conductor one or more stubs. The inner conductor is arranged at a distance to the outer conductor. The stub lines leading away from the inner conductor are arranged directly adjacent to an outer conductor section.

In other words, the stub line is arranged on one side of a substrate, wherein the substrate rests on a corresponding outer conductor surface, so that the stub directly interacts with the outer conductor.

It is also known, instead of the above-explained, directly cooperating with a separate outer conductor microstrip spur lines trap circuit filter using coaxial cables. In this case, one or more branch lines are branched off from a signal line transmitting an HF signal. For this purpose, for example, triple soldered connectors are arranged on the RF signal line, one of these solder joints serves as a branch point for the aforementioned spur line, which ends open, so idle. In the longitudinal direction of the RF signal line, a plurality of such stub lines can be arranged lying in an offset manner, which also extend towards one another, for example, between two triple solder connections and ends in each case freely. In addition, then also transformation routes can be provided.

Such filters using coaxial cables (also for the spur lines) are very sensitive to tolerances and can not be optimally tuned due to their design (using the discrete cable impedances and the solder joints).

Furthermore, for example, from the US 2,751,558 a high frequency filter has become known, which at a distance to a ground surface comprises an inner conductor which sits on a dielectric and thereby at a distance from the ground plane is held. In this inner conductor branch off spiral-shaped stub lines, which are formed on a dielectric material as a strip conductor and are thus arranged at a distance from the ground surface. The entire assembly is housed in a conductive housing. Thus, therefore, the inner conductor and the helical stub arranged in a common plane at a constant distance from the ground surface, said distance is predetermined by the mentioned dielectric layer.

Finally, it will be on the US 2 392 664 A directed. This prior publication describes an ultra high frequency filter with an inner conductor and an outer conductor, wherein the inner conductor is provided on a longitudinal section of the inner conductor of a pot completely surrounding the inner conductor. The inner conductor passes through the bottom of the pot, which is electrically-galvanically connected to the inner conductor. The cylindrical wall of the pot is located between the inner conductor and the outer conductor. In a modification, a plurality of such nested pots may be provided, with the result that the HF current passes through the pots so formed successively. The locking pots are thus arranged in series, ie their mode of action is serial.

A comparable with the above-mentioned prior art solution of a transmission path with a arranged in an outer conductor tube locking pot is for example from the US 3,872,412 known.

Object of the present invention is to provide a comparison with the prior art improved filter ago all a simpler and thus cheaper producible filter.

The object is achieved according to the features specified in claim 1. Advantageous embodiments of the invention are specified in the subclaims.

It must be said that it is very surprising that in the context of the invention a blocking filter, i. a barrier circuit filter is provided, which is very simple in construction, can be easily manufactured, while having the desired electrical properties. The filter according to the invention also has advantages insofar as it can easily be adapted to the blocking frequency, etc.

The barrier circuit filter according to the invention is characterized in that similar to the construction of a coaxial barrier circuit filter according to the prior art stub lines are used, which branch off from the RF signal-transmitting main, but these locking lines do not have their own outer conductor, so not as a separate coaxial or microstrip -Leitungen are constructed, but that the RF signal main line and the branching off branch lines in a common outer conductor, ie are arranged in a common outer conductor arrangement.

A favorable and space-saving arrangement of the filter according to the invention can be realized that the only one inner conductor structure having stubs more or less in their essential longitudinal extent are arranged parallel to the signal transmitting main RF line and are only connected via a short elbow electrically-galvanically connected to the main line. The entire arrangement can then be accommodated in an outer conductor tube with arbitrary outer conductor cross-sectional shapes, that is to say in a cylindrical outer conductor, in an outer conductor with an angular cross-section etc. Restrictions do not exist in this respect.

The impedance of the blocking filter can be infinitely easily adjusted. A change in the impedance can be easily realized by the distance of the realized only in the form of an inner conductor stub to the outer conductor is changed, which surrounds this stub and the RF main line together. The smaller this distance, the lower / lower the impedance (low impedance). The stub is preferably formed in the form of a sheet, i. in the form of a metal strip. The wider this strip becomes (more or less in parallel alignment with the outer conductor tube surrounding it), the lower / lower the impedance (lower resistance). By changing the above-mentioned distance between the stub line and the common outer conductor on the one hand or by increasing the width of the stub line, therefore, the impedance can be increased or decreased.

The solution according to the invention proposes at least two branch lines within the scope of the filter arrangement according to the invention. For a first sense would cause a frequency response that would be overcompensated by the subsequent transformation line. The measures provided for in the context of the invention follow However, the second spur line then compensates for the "overcompensated" frequency response caused by the transformation line. As a result, an optimal adaptation of the filter can be achieved.

Furthermore, the stub lines can also be realized in multiple stages, that is to say with different impedances. In other words, the stubs may transition from a wider portion to a narrower portion so that their width changes. This allows very large transmission bandwidths to be realized. The stop band is set with the number of stub lines (poles). Likewise, the stubs can be strengthened not only two or more stages to form different widths, but also have different diameters (material thicknesses).

Preferably, the width of the stub to the open end increases towards.

If the bandwidth to be blocked is to be increased, the number of spur lines may need to be increased. In other words, the number of poles must be increased accordingly depending on the bandwidth to be disabled. In this case, a plurality of stub lines in the longitudinal direction of the RF signal line can be arranged offset from one another, wherein the stubs can for example run towards each other, and are optionally offset in the circumferential direction of the signal main line to each other. As a result, a plurality of stub lines can be realized very space-saving. It can even from a common branch point are arranged from several stubs over circumferentially offset to the main signal line elbows that do not affect each other in fact.

Above all, the solution according to the invention also has great advantages insofar as particularly high RF powers can be transmitted. Because it can be used in the invention very thick inner conductor for the main signal line, which also leads to particularly low resistance values in the DC transmission. In contrast, the solution according to the prior art has often allowed only the use of comparatively thin inner conductor.

If necessary, a mechanical improvement and increase in stability can also be realized by placing electrical spacers, for example in the form of dielectric disks, on the signal main line (ie the transformation line), on the outer circumference of which the stub lines extending parallel to the main signal line rest. If required, dielectric spacers may also be placed on the stub lines, so that they can not contact the outer conductor itself during assembly with the outer conductor and / or also maintain the distance to the signal main or transformation line.

• es lässt sich im Rahmen der Erfindung eine besonders einfache Bauweise dadurch verwirklichen, dass die eine oder mehreren Stichleitungen in einem gemeinsamen Außenleiter angeordnet sind;
• bei mehreren Stichleitungen können diese ineinander verschachtelt, d.h. in Umfangsrichtung zur Signalhauptleitung versetzt zueinander angeordnet sein, wodurch nur ein sehr geringer Platzbedarf benötigt wird (dadurch lässt sich auch die Gesamtlänge des Sperrfilters minimieren);
• die Stichleitungen können in Umfangsrichtung versetzt zueinander so angeordnet werden, dass beispielsweise zwei Sichtleitungen in einem gleichen Abschnitt des Außenleiters eingebracht werden können;
• die erfindungsgemäße Sperrkreisfilteranordnung kann direkt in einen HF-Verbinder eingebaut werden (und zwar integrierbar);
• die Stichleitungen können aber müssen nicht voneinander durch getrennte bzw. eigene Außenleiter entkoppelt werden;
• die erfindungsgemäßen Sperrfilter erlauben eine hohe Sperrdämpfung, insbesondere für Mobilfunkbänder (30 dB). Ferner ist ein sehr gutes VSWR-Verhältnis realisierbar (von z.B. > 30 dB im Durchlassbereich), also ein sehr günstiges Stehwellenverhältnis (voltage standing wave ratio);
• durch den koaxialen Aufbau des Filters ist dieses sehr unempfindlich gegen Einstrahlung;
• keine Abstrahlung nach außen, da die Stichleitungen innerhalb des nach außen geschlossenen koaxialen Außenleiters angeordnet sind;
• die Dimensionen des Filters können auch durch Auffüllen des Leerraumes innerhalb des Außenleiters mit geeignetem Dielektrikum verringert werden;
• insgesamt ist dadurch eine sehr kompakte Bauform möglich;
• das Filter kann beispielsweise aus Spritzgussteil hergestellt werden, so dass die Herstellung mit geringsten Fertigungstoleranzen möglich ist;
• die Innenleiter-Stichleitungen können als Stanz-/Biegeteil ausgeführt sein, aus Rundmaterial oder Flachmaterial bestehen etc.;
• die Außenleiterbauformen können differieren, d.h. sie können im Querschnitt kreisförmig sein, quadratisch, U- oder rechteckförmig;
• durch entsprechende Gestaltung und Lageveränderung der Stichleitungen (beispielsweise Bildung von Endkapazitäten) lassen sich verschiedene Wellenwiderstände und sehr große Bandbreiten realisieren;
• die Stichleitungen können mehrstufig aufgebaut sein, das heißt über ihre Länge hinweg unterschiedliche Abschnitte mit verschiedenen Breiten aufweisen, wobei die Breite bevorzugt zu deren offenen Ende hin zunimmt; dadurch lässt sich eine besonders gute Breitbandigkeit realisieren;
• da kein Serien-Kondensator benötigt wird, ist das erfindungsgemäße Filter vor allem auch für die Übertragung von Gleichstrom- und von Datensignalen geeignet, z. B. Modem-Signale.

Finally, the use of such a dielectric also leads to a shortening factor for the stubs. In summary, the following advantages can thus be realized within the scope of the invention:

• It can be realized in the context of the invention, a particularly simple construction in that the one or more stubs are arranged in a common outer conductor;
• in the case of several stub lines, these can be interleaved, ie offset in the circumferential direction relative to the main signal line, whereby only a very small space requirement is required (this also minimizes the overall length of the notch filter);
• the stubs can be arranged offset in the circumferential direction to each other so that, for example, two visual lines can be introduced in a same section of the outer conductor;
• the blocking circuit filter arrangement according to the invention can be installed directly in an HF connector (and can be integrated);
• but the stubs must not be decoupled from each other by separate or own outer conductor;
• The blocking filters according to the invention allow a high stopband attenuation, in particular for mobile radio bands (30 dB). Furthermore, a very good VSWR ratio can be achieved (eg> 30 dB in the passband), ie a very favorable VSWR (voltage standing wave ratio);
• Due to the coaxial design of the filter, this is very insensitive to radiation;
• no radiation to the outside, since the stubs are arranged inside the coaxial outer conductor closed to the outside;
• the dimensions of the filter can also be reduced by filling the void space within the outer conductor with a suitable dielectric;
• Overall, this makes a very compact design possible;
• the filter can be made for example of injection molded part, so that the production with the lowest manufacturing tolerances is possible;
• the inner conductor stub lines can be designed as stamped / bent part, consist of round material or flat material, etc .;
• the outer conductor designs may differ, ie they may be circular in cross-section, square, U-shaped or rectangular;
• by appropriate design and change in position of the stubs (for example, formation of endcapacities) can be different impedance and very large bandwidths realize;
• The stubs can be constructed in multiple stages, that is, over their length have different sections with different widths, wherein the width preferably increases towards the open end; This makes it possible to realize a particularly good broadbandity;
• Since no series capacitor is required, the filter according to the invention is particularly suitable for the transmission of DC and data signals, z. B. modem signals.

Figur 1 :

ein erstes erfindungsgemäßen Ausführungsbeispiel in schematischer Axialschnittdarstellung;

Figur 1a :

ein zu Figur 1 abgewandeltes Ausführungsbeispiel mit Streifenleitungsabschnitten in Halbzylinder- oder Teilzylinderform;

Figur 2 :

eine räumliche Darstellung des Ausführungsbeispiels nach Figur 1 unter Weglassung des Außenleiters;

Figur 3a :

eine Axialschnittdarstellung durch das Ausführungsbeispiel nach den Figuren 1 und 2;

Figur 3b :

eine ausschnittsweise räumliche Darstellung bezüglich des Ausführungsbeispiels nach den Figuren 1 bis 3;

Figur 4 :

eine Abwandlung zu den vorausgegangenen Ausführungsbeispielen in räumlicher Darstellung unter Weglassung der Außenleiteranordnung mit insgesamt drei in Längsrichtung des HF-Leiters versetzt abzweigenden Stichleitungen;

Figur 4a :

ein zu den Figuren 1 bis 1a abgewandeltes Ausführungsbeispiel im Axialschnitt, bei welchem sich die freien Enden zweier Stichleitungen im unterschiedlichen Radialabstand zueinander angeordnet überlappen;

Figur 5 :

eine entsprechende axiale Schnittdarstellung vergleichbar der axialen Schnittdarstellung nach Figur 1, wobei jedoch auf den Stichleitungen Abstandshalter aufgesetzt sind, um den Abstand zwischen den einzelnen Stichleitungen zur HF-Leitung zum einen bzw. zur Innenwandung des Außenleiters zum anderen zu beschränken bzw. einzuhalten;

Figur 6 :

ein weiteres Ausführungsbeispiel in schematisch auszugsweise axialer Schnittdarstellung, bei welchem die erfindungsgemäße Filteranordnung in einer Buchsenanordnung eingebaut bzw. integriert ist;

Figur 7 :

eine schematische Seitenansicht einer Stichleitung, die im gezeigten Ausführungsbeispiel in Längsrichtung der Stichleitung mit zumindest einem Stufenabsatz unter Ausbildung von zwei Streifenleitungsabschnitten mit unterschiedlicher Breite ausgebildet ist; und

Figur 8 :

ein zur Figur 2 abgewandeltes Ausführungsbeispiel mit gleich langen Stichleitungen.

Further advantages, details and features of the invention will become apparent hereinafter from the embodiments illustrated with reference to drawings. In detail:

FIG. 1:

a first embodiment of the invention in a schematic axial sectional view;

FIG. 1a

one too FIG. 1 modified embodiment with stripline sections in half-cylinder or partial cylinder shape;

FIG. 2:

a spatial representation of the embodiment according to FIG. 1 with the omission of the leader;

FIG. 3a:

an axial sectional view through the embodiment of the FIGS. 1 and 2 ;

FIG. 3b:

a partial spatial representation with respect to the embodiment of the FIGS. 1 to 3 ;

FIG. 4:

a modification of the previous embodiments in a spatial representation with omission of the outer conductor arrangement with a total of three offset in the longitudinal direction of the RF conductor branching stubs;

FIG. 4a

one to the Figures 1 to 1a modified embodiment in axial section, in which overlap the free ends of two stubs arranged at different radial distance from each other;

FIG. 5:

a corresponding axial sectional view comparable to the axial sectional view FIG. 1 However, where spacers are placed on the stubs to limit the distance between the individual stubs to the RF line to one or the inner wall of the outer conductor to the other or to comply;

FIG. 6:

a further embodiment in a schematic excerpts axial sectional view in which the filter assembly according to the invention is installed or integrated in a bushing arrangement;

FIG. 7:

a schematic side view of a stub, in the embodiment shown in the longitudinal direction of the stub with at least one stepped shoulder to form two stripline sections is formed with different widths; and

FIG. 8:

one to FIG. 2 modified embodiment with equal stub lines.

In FIG. 1 is an RF inner conductor 1 is shown, which may for example consist of a metallic, rod-shaped inner conductor.

In this case, the RF inner conductor 1 forms a high-impedance transformation line 1 ', which extends between two inner conductor sections 1 "offset in the longitudinal direction of the HF inner conductor 1. In the drawing, it can be seen that the high-resistance transformation line section 1' coincides a thinner cross-section is provided as the adjoining inner conductor section 1 ", which represent a 50 Ω system.

In the illustrated embodiment is - but this is not absolutely necessary - starting at the mutually facing transitions from the inner conductor section 1 "to the transformation line 1 'each stub 5, in the illustrated embodiment, a stub 5a and 5b electrically-galvanically connected, the extends over its greatest length more or less parallel to the RF inner conductor 1 and is connected via a connection angle 7 mechanically and electrically connected to the RF inner conductor 1.

In the embodiment shown, the length of the two branch lines 5a and 5b is chosen differently, whereby the number of mutually offset blocking poles is increased, whereby the bandwidth to be blocked is increased.

The length of the respective spur line is chosen so that, depending on the desired blocking effect, the open circuit is transformed into a short circuit at the respective connection point 7a, at which the spur line 5 is electrically connected to the RF inner conductor 1.

The electrical length of the transformation line 1 'is chosen such that the frequency response or frequency responses caused by the at least one stub or by the multiple stubs (for example 5a, 5b etc.) are compensated or overcompensated. With an overcompensated frequency response, the "next" spur line compensates.

For example, a first spur line would cause a frequency response that would be overcompensated by the subsequent transformation line. The adjoining second stub line then compensates for the "overcompensated" frequency response caused by the transformation line. This makes it possible to achieve optimum adaptation of the filter.

The lengths of the transformation lines and the impedance of the transformation line are thereby selected for optimal frequency compensation. As a result, a particularly good VWSR ratio can be achieved overall.

The peculiarity of the invention lies in the fact that not only the RF signal line 1, so the Transformation line 1 ', but also the one or more stubs 5 and 5a, 5b, etc. are housed in a common outer conductor assembly 11. In other words, therefore, the stubs do not have any further outer conductor arrangements 11 assigned to them separately. Here is the in FIG. 1 the tubular outer conductor arrangement shown in axial section as the inner conductor 1 "separated by an insulator or by a dielectric from the inner conductor, which in FIG. 1 but not further shown.

As can be seen from the spatial representation according to FIG. 2 and above all from the axial cross-sectional view according to FIG. 3a or the spatial partial representation according to FIG. 3b results, the stubs 5 are not formed of round material (although this is possible), but preferably from a flat material, similar to an electrically conductive metal strip. The metal strip of the stub 5 extends with its leg 7 'in a length of preferably over 60%, in particular more than 70%, 80% or more than 90% more or less parallel to the RF signal-transmitting inner conductor arrangement 1 and is only about a short to the inner conductor 1 radially extending leg 7 "connected to the RF inner conductor 1 and mechanically anchored and held.

As already mentioned, the stub lines 5, ie in particular the legs 7 'can also be formed from round material, for example also with an almost semicircular cross section. This would open up the possibility that in a same section of the transformation line 1 'at least two in the same direction or in opposite directions running stubs with the transformation line 1 'can be arranged running in the center. The outwardly bow-shaped convex legs 7 'would then preferably be coaxial with the outer conductor or outer conductor tube to lie. It is so far on FIG. 1a in derogation to FIG. 1 a leg 7 'of the stub 5 extending from the connection point 7a or the radial limb 7 "and extending in the illustrated embodiment along the transformation conductor 1' adjacent to the free end comprises a stub portion 105a having a significantly greater width, this stub portion 105a with its stub larger width B is designed semi-cylindrical, and that coaxial with the inner or transformation conductor 1, 1 ' FIG. 1a The bottom stub is similarly designed so that both stubs overlap without the semicircular stripline portions 105a being able to touch. In this embodiment, the stripline sections 105a could also be less than semicircular in cross-section or even be provided with a more than 180 °, part-circular stripline section.

Likewise, the stubs in total or at least the free-ending leg 7 'may be cylindrical and arranged with lateral offset to the transformation line 1 within the outer conductor.

In principle, it would also be conceivable that the leg 7 'running parallel to the inner conductor 1 in the drawings can also be arranged at an angle to the axial extent of the HF inner conductor 1, in such a way that this leg 7' is at an angle α to the axial extent of the inner conductor 1 is arranged running. This is in FIG. 2 only indicated by dashed lines for a leg 107. In other words, it is thereby possible that the stub 5 and in particular the free-ending legs 7 'have different distances to the outer conductor 11 or to the inner conductor arrangement 1 over the length of the stub lines. In this case, the arrangement need not be oriented in a continuous angle α to the axial extent of the inner conductor 1, but it may also step-like subdivisions or sections may be provided in which portions of the leg 7 'of the respective stub 5 have different distances to the inner conductor or the outer conductor ,

From the axial section according to FIG. 3 is also to be taken in this embodiment, a common tubular outer conductor assembly 11, which may consist of an electrically conductive metal tube. It can also be seen that between the metallstreifenförmingen leg 7 'or the stub 5 (in its parallel section to the RF inner conductor) and the inner wall 11' of the tubular outer conductor assembly 11, a distance 13 is formed, in which a dielectric 19 is inserted. In the illustrated embodiment according to FIG. 3 can even be seen that the strip-shaped in the axial direction of the entire arrangement extending portion 7 'of the stub 5 is slightly convex in cross-section, so in its cutout coaxial with the hollow cylindrical in the embodiment shown outer conductor arrangement comes to rest. By the width B of the metal strip-shaped leg 7 'of the stub 5 and the distance 13 between the strip-shaped stub section and the outer conductor arrangement can be the impedance set differently. The impedance decreases as the width B becomes larger. The impedance also decreases as the distance 13 becomes smaller. Thus, even with a larger width B of a stub 5 by increasing the distance to the outer conductor tube, the impedance can in turn be increased in opposite directions. Thus, the impedance can be set steplessly different. This also offers great advantages in the context of the invention, since the tolerances with respect to the impedance should be kept as accurately as possible. A slight adjustment is easily possible here in the context of the invention by changing the position of the axially extending stub section. As can also be seen from the drawing, the thickness D across the width B (which is measured transversely to the longitudinal direction of the stub 5) can be significantly smaller than the width B. The thickness can easily be less than 50%, 40%, 30% , 20% or even less than 10% or 5% based on the width of the extending in the axial longitudinal direction leg portion 7 'of the associated stub 5. However, the thickness can also be made much larger, but this has no significant effect on the electrical effect.

Based on FIG. 4 schematically shows that, for example, in the longitudinal direction of the transformation line 1 'offset terminal points 7a each staggered in the circumferential direction lying several stub lines 5a to 5c, with two stubs 5a, 5c not opposite to each other extending as in the embodiment according to FIGS. 1 and 2 are aligned. Here, two, three or more stub lines (possibly also in different lengths for different design of the band-stop filter) can easily be provided. Deviating from this, however, the rather radially oriented legs 7 "producing the connection to the transformation line 1 'can also have a different length, ie have a different radial height to the inner conductor 1. The adjoining legs 7' of the stub 5 thus have a different distance from each other Inner or outer conductor 1, 11. This also allows two or more stub lines 5 can be arranged with their free-ending legs 7 'in a same section of the route, and not necessarily have to be offset in the circumferential direction to the inner conductor the same side of the inner conductor or only slightly offset lying in the circumferential direction, since the free-ended leg portions 7 'due to the different ending height of the first leg 7 "do not touch, but in the radial direction to the inner conductor 1, 1' offset. This variant with partial overlapping of the stripline legs 7 'is in FIG. 4a played.

Especially with this arrangement as well as in the examples according to FIG. 4 It can be seen that the freely ending legs 7 'of the stub can be arranged to extend in the same direction or in opposite directions. As a result, the stubs, in particular the free-ending legs 7 ', completely or partially cover (couple). The overlap can also be realized only partially over different angles of the legs 7 "by the freely ending legs 7 'of the individual stub lines in the circumferential direction around the inner conductor 1 are at least partially offset (thus only a partial overlap of the free-ending leg 7' realized).

As FIG. 4 also shows, the stub lines 5 in the longitudinal direction of the inner conductor 1, 1 'can also be arranged one after another, regardless of whether the freely ending leg 7' of this stub 5 point in the same direction or are arranged in opposite directions on the inner conductor 1.

Notwithstanding the embodiment according to Figure 1 to 4 It would also be possible, for example, for two or for example 3 stub lines 5a, 5b and 5c, which are of different lengths, to be connected to the transformation line at a common connection point 7a only offset in the circumferential direction, all three with their open end in a common direction or may be partially aligned in different directions.

Based on FIG. 5 (The principle of the embodiment according to the axial sectional view according to FIG. 1 It is shown that, for example, one or more spacers 17, which consist of an electrically nonconductive dielectric, are arranged in the region of the stub lines on the RF inner conductor 1 forming the HF signal line and its longitudinal direction. The outer circumference of these spacers 7 then serves as a stop surface for the possibly axially adjacent stub lines 5, 5a, 5b, etc., ie the legs 7 '.

Likewise, however, as in FIG. 5 is additionally shown - alternatively or additionally also on the stub line sections 7 'electrically non-conductive dielectric spacers 19 may be arranged, whereby a certain distance from the surrounding outer conductor tube 11th can be complied with. These dielectric spacers 19 can also be arranged and / or fixed on the inside of the outer conductor tube 11 in order to obtain the stub line sections 7 'at a predetermined distance from the outer conductor tube 11.

In addition, the entire interior or large parts of the interior can be filled within the outer conductor arrangement with a dielectric, which can be realized by changing the dielectric constant due to the dielectric used a so-called. Shortening factor for the length of the stubs 5.

Such a blocking-circle filter arrangement or the arrangement of such a band-stop filter can be realized on any coaxial RF link.

The invention has great advantages, but especially if the filter is installed directly in a socket or socket arrangement (connector). This is for example based on FIG. 6 shown schematically.

In all the embodiments shown, the great advantage of the invention is that z. B. a corresponding barrier filter through the one or more stub lines (open ends) easily made and then only has to be introduced into a common outer conductor arrangement, which surrounds the signal line, for example in the form of a transformation line and the one or more stubs together. Despite this arrangement, no detrimental alternation of the function of the spur lines is recognizable.

Based on FIG. 6 is now a modification in axial sectional view shown insofar as the solution according to the invention with a socket 100 (coaxial connector) firmly connected or is designed to be handled together.

According to FIG. 6 It can be seen that here the filter assembly is constructed so that the tubular outer conductor 11 merges into the female outer conductor 111 and the RF inner conductor 1 in the female inner conductor 101. The socket inner conductor 101 is in the embodiment shown not plug-shaped (which would also be possible) but designed bush-shaped and has at its insertion end a plurality of circumferentially longitudinal slots through separate contact fingers.

The female inner conductor 101 is held by an insulator (dielectric) 91 as known to the outer conductor 111 at a distance thereto while avoiding a galvanic contact.

On the opposite side of the inner conductor and the outer conductor can pass directly into a cable connection, which is not shown in detail. Likewise, however, a corresponding contact plug or a corresponding contact socket or contact plug (coaxial connector) can also be provided on the opposite side.

In the exemplary embodiment shown, it may be, for example, a standard socket according to the standard DIN 7-16 (IEC 60 169-4). The basic structure is also feasible for all other socket or plug assemblies with female or male inner conductor or female or male outer conductor. Finally, the embodiment according to FIG. 7 Reference is made, in which a stub 5 is shown in a schematic plan view. It may be, for example, the transverse view of in FIG. 6 act below lying drawn stubs.

It can be seen that the stub line 5, for example, starting from its connection point 7a has a first stub line section 105a, which then merges via a subsequent stage 106 in a comparatively wider stub section 105b. In other words, the width B of the stub line 5 is greater towards the free end than in the first stub line section 105a, which is closer to the connection point 7 'to the RF inner conductor 1 or to the transformation line 1'.

If required, a plurality of such gradations 106 may also be provided, that is to say not only a graduation with two stub sections 105a, 105b in different widths but, for example, with three strip lines of different widths or even more.

The stub lines can thus be configured in multiple stages, ie with different widths (the extension in the width direction being preferably symmetrical on both sides to the longitudinal direction of the inner conductor.) In addition, the diameters and thicknesses can be different Implement filter arrangement, which have advantages in many frequency ranges, especially in many frequency ranges, as used in mobile communications, for example in the range of 694 MHz to 960 MHz or, for example, in the field from 1710 MHz to 2700 MHz. Restrictions on certain frequency ranges, however, do not exist.

In conclusion, referring to FIG. 8 in deviation to FIG. 2 In principle, of course, the individual branch lines, in particular if two or more branch lines are provided, can basically also be of the same length, wherein the effective length parallel to the transformation line 1 'can correspond to the length of the parallel running section of the respective branch lines.

Claims (23)

1. Coaxial filter arrangement having the following features:

   - comprising an HF inner conductor (1) having a transformation line (1') which extends between two inner-conductor portions (1") which are offset from one another in the longitudinal direction of the HF inner conductor (1),

   - comprising a tubular outer-conductor arrangement (11) which has a round or square cross section, inside which the HF inner conductor (1) is arranged coaxially with the transformation line (1'),

   - comprising at least two stub lines (5; 5a, 5b, 5c) which are electrically/galvanically connected to the transformation line (1') at a connection point (7a), for which purpose the stub lines (5; 5a, 5b, 5c) are mechanically and electrically connected to the transformation line (1')

   - the at least two stub lines (5; 5a, 5b, 5c) are in the form of electrically conductive metal strips, the metal strips having a length, a width (B) and a thickness (D), and the width (B) transverse to the longitudinal extension of the metal strips is greater than the thickness (D) thereof,

   - the transformation line (1') and the at least two additional stub lines (5; 5a, 5b, 5c), which each have merely an inner-conductor structure, are arranged in the same outer-conductor arrangement (11), and

   - at least one of the two stub lines (5; 5a, 5b, 5c), which branch off from the transformation line (1') and are formed in the manner of a metal strip, has a portion (7') which is more than 60 % of the total length of the relevant stub line (5; 5a, 5b, 5c), said portion (7') extending parallel to the HF inner conductor (1) or at an angle (α) of less than 10° relative to the HF inner conductor (1).
2. Filter arrangement according to claim 1, characterised in that the portion (7') of the stub line (5; 5a, 5b, 5c) which extends substantially parallel or at an angle α of less than 10° or 5° relative to the HF inner conductor (1) is more than 70 %, more particularly more than 80 % and more than 90 % or 95 % of the total length of the relevant stub line (5; 5a, 5b, 5c).
3. Filter arrangement according to either claim 1 or claim 2, characterised in that the portion (7') extends at an angle (α) of less than 10° relative to the HF inner conductor (1) or has stepped portions which are arranged in parallel at difference distances from the outer conductor (11) and/or at a different distance from the inner conductor (1).
4. Filter arrangement according to any of claims 1, 2 or 3, characterised in that the portion (7') of the at least one stub line (5; 5a, 5b, 5c) is mechanically and electrically connected to the HF inner conductor (1) by a connection bracket (7) at the connection point (7a).
5. Filter arrangement according to any of claims 1 to 4, characterised in that the portion (7') of the stub line (5) which extends substantially parallel to the HF inner conductor (1) is arranged at least approximately parallel to the inner wall (11') of the outer-conductor arrangement (11).
6. Filter arrangement according to any of claims 1 to 5, characterised in that the strip-shaped portion (7') of the stub line (5) has a convex cross section, and is thus arranged coaxially with the hollow cylindrical outer-conductor arrangement (11).
7. Filter arrangement according to claim 6, characterised in that the stub line (5) or at least the portion (7') of the stub line (5) which has a free end has an arcuate cross section transverse to the longitudinal extension, with a convex curvature pointing towards the outer-conductor arrangement (11), and is therefore configured to be maximally semi-cylindrical in the width direction, so that preferably two stub lines (5) which are offset from the inner conductor (1) by 180° are preferably arranged coaxially with the inner conductor (1).
8. Filter arrangement according to any of claims 1 to 7, characterised in that the impedance of the filter arrangement can be adjusted and/or preselected differently by changing the distance (13) between the substantially axially extending portion (7') of the stub line (5; 5a, 5b) and the inner wall (11') of the outer-conductor arrangement (11) and/or by changing the width (B).
9. Filter arrangement according to any of claims 1 to 8, characterised in that a dielectric spacer (17, 19) is attached to the HF inner conductor (1) and/or to the at least one stub line (5; 5a, 5b, 5c), by means of which spacer the distance between the portion of the stub lines (5; 5a, 5b, 5c) extending substantially parallel to the HF inner conductor (1) and the HF inner conductor is restricted and/or fixed.
10. Filter arrangement according to any of claims 1 to 9, characterised in that a dielectric spacer (19) is provided on or attached to the substantially axially extending portion (7') of the stub line (5; 5a, 5b, 5c) and/or the inner wall (11') of the outer conductor arrangement (11), by means of which spacer the distance (13) between the substantially axially extending portion of the stub line (5; 5a, 5b, 5c) and the inner wall (11') of the outer conductor arrangement (11) is restricted and/or fixed.
11. Filter arrangement according to any of claims 1 to 10, characterised in that the length of the stub line (5) is measured such that the filter arrangement generates a cut-off pole having a predetermined frequency.
12. Filter arrangement according to any of claims 1 to 11, characterised in that the space inside the outer-conductor arrangement (11) is filled in full or in part with a dielectric, with the exception of the HF inner conductor (1) and the at least one stub line (5; 5a, 5b, 5c).
13. Filter arrangement according to any of claims 1 to 12, characterised in that a plurality of stub lines (5) are provided.
14. Filter arrangement according to claim 13, characterised in that a plurality of stub lines (5; 5a, 5b, 5c) are arranged offset from one another in the peripheral direction in such a way that they overlap one another at least in part of the length of the HF inner conductor (1).
15. Filter arrangement according to either claim 13 or claim 14, characterised in that the plurality of stub lines (5; 5a, 5b, 5c) are mechanically and electrically held at the same height as the HF inner conductor (1) at a common connection point (7') and/or are offset from one another in the longitudinal direction of the HF inner conductor (1).
16. Filter arrangement according to any of claims 13 to 15, characterised in that the free ends of the plurality of stub lines (5; 5a, 5b, 5c) are oriented to extend in the same axial direction or in opposite directions to one another.
17. Filter arrangement according to any of claims 1 to 16, characterised in that the plurality of stub lines (5; 5a, 5b, 5c) have different lengths in order to achieve a different number of cut-off poles and thus a different bandwidth of the cut-off effect.
18. Filter arrangement according to any of claims 1 to 17, characterised in that the stub line (5; 5a, 5b, 5c) has a plurality of steps over the length thereof and comprises at least two portions, namely a stub-line portion (105a) and an additional stub-line portion (105b), which have different widths.
19. Filter arrangement according to claim 18, characterised in that the stub-line portions (105a, 105b) having different widths increase in width from the connection point (7a) towards the free end of a stub line (5).
20. Filter arrangement according to any of claims 1 to 19, characterised in that the branch (7") proceeding from the connection point (7a) of the inner conductor (1) with respect to at least two provided inner conductors (5) have different heights and/or end at different radial distances from the inner conductor (1), so that the portions (7') of the stub line (5) which are adjacent thereto and have a free end are preferably arranged to overlap one another in part.
21. Filter arrangement according to any of claims 1 to 19, characterised in that at least two stub lines (5) are provided, the portions of which (7') that have a free end are arranged to cover one another at least in part.
22. Filter arrangement according to any of claims 1 to 21, characterised in that at least two stub lines (5; 5a, 5b, 5c) are provided which are arranged offset from one another in the axial direction of the inner conductor (1) at least in part of the length thereof in a common section of the inner conductor (1).
23. Filter arrangement according to any of claims 1 to 22, characterised in that the filter is installed in a socket.

Images