EP1570542B1 - Tunable high-frequency filter arrangement and method for the production thereof - Google Patents

Description

TECHNICAL AREA

The present invention relates to the field of high frequency engineering. It relates to a tunable high-frequency filter assembly according to the preamble of claim 1, and a method for their preparation.

Such a high-frequency filter arrangement is for example from the US-A-6,147,577 , or US-A-5 612 655 (STRONKS JOHN ET AL) March 18, 1997 (1997-03-18).

For example, a single tunable dielectric resonator in which the movable dielectric body is linearly movable in a recess of the dielectric resonator element in a vertical or horizontal direction is shown in FIG EP-A1-0 601 369 or from " PATENT ABSTRACTS OF JAPAN vol. 012, no. 158 (E-608), May 13, 1988 (1988-05-13 ) - & JP 62 271503 A (MURATA MFG CO LTD), November 25, 1987 (1987-11-25).

STATE OF THE ART

For the fast and flexible construction of wireless communication networks, especially in rough terrain without corresponding infrastructure, transportable radio links (LOS = Line of Sight) have proved successful in the frequency range of several GHz (eg 4.4 to 5 GHz, or 14.62 to 15.23 GHz). For the signal processing in the context of the transmitting and receiving devices of such microwave links appropriate filters, in particular bandpass filter, required that are not designed only for individual frequencies, but are automatically tuned and are characterized by the tuning range by consistently high grades.

In addition to the indispensable electrical and high-frequency properties such filters must also be inexpensive to produce, robust in construction, safe in use and space and weight-saving designed. In particular space (volume) and weight are essential factors for the mobility of the entire communication system.

For such filters, solutions have increasingly been proposed with a view to reducing the voids in the past, which as a tunable base element has a dielectric resonator element arranged in a cavity, which can be changed in its resonant configuration to tune the filter. Such a solution is for example in the aforementioned US-A-6,147,577 described. In this known solution, a first round dielectric disk ("ceramic puck") is arranged as a resonator in each of the cavities of the filter. A similar second round dielectric disc lies in parallel over the first and can be raised and lowered vertically by means of an electronically controlled motor drive relative to the first disc. The linear motion required for this is generated by a digital stepper motor whose rotary motion is converted into linear motion by an elaborate threaded rod mechanism.

On the one hand, it is comparatively difficult to achieve the comparatively high accuracy and reproducibility of the disc position required for a good tunability of the filter in the case of a linear movement of the displaceable disc. On the other hand, the adjustment mechanism required for the linear displacement requires a lot of space. How out Fig. 4 of the US-A-6,147,577 can be easily seen, about the cavities arranged motorized adjustment mechanism takes about 2/3 of the total volume of the filter. In addition, because of the displaceability of the upper disc in the vertical direction of the cavity must be designed from the outset comparatively high.

In the also mentioned above EP-A1-0 601 369 there is proposed a single tunable dielectric resonator in which an off-center (eccentric) recess is provided in the dielectric disc, which is fixed in a cavity, into which a dielectric body suitably shaped to the recess can more or less submerge. The tuning of the resonator via an adjustment of the immersion depth. For this purpose, the dielectric body via a rod-shaped holder In vertical ( Fig. 1 of the EP-A1-0 601 369 ) or horizontal ( Fig. 2 of the EP-A1-0 601 369 ) Are moved in a linear direction. About the achievable with this solution tuning behavior are no further details. Likewise, no mechanically designed adjusting mechanism is indicated, so that this proposal is rather attributable to the paper state of the art and its feasibility is more than questionable. In particular, the same disadvantages due to the linear shift can be expected in this proposed solution, as have already been discussed above.

PRESENTATION OF THE INVENTION

It is therefore an object of the invention to provide a tunable high-frequency filter assembly, which is inexpensive to manufacture, with good high-frequency properties by a particularly compact and robust Structure distinguished, and has a favorable Abstimmverhalten, and to provide a cost-effective and simple method for their preparation.

The object is solved by the entirety of the features of claims 1 and 27. The essence of the invention is to provide as a tunable filter module a cavity with a fixedly arranged dielectric resonator element, which has an eccentric recess in which a dielectric body is rotatably arranged. Due to the rotatable arrangement of the body in the recess, the dielectric resonator element can be made extremely compact. The rotational movement can be carried out with high precision, so that a high accuracy and reproducibility can be achieved in the vote.

A preferred embodiment of the inventive filter arrangement is characterized in that the dielectric resonator element has the shape of a flat, circular disk such that the dielectric body is rotatable about an axis of rotation which is perpendicular to the disk plane of the dielectric resonator element, the dielectric resonator element being a predetermined one Thickness, and that the dielectric body in the direction of the axis of rotation has a height which is substantially equal to the thickness of the dielectric resonator element.

As a particularly favorable in the tuning characteristics, a development of this embodiment has been found in which the recess in the dielectric resonator is a concentric to the axis of rotation circular cylindrical through hole, the dielectric body is fitted in its outer dimensions in the recess in the dielectric resonator element such that both only by narrow Air gaps are separated from each other, and the dielectric body in a first, perpendicular to the rotation axis direction by two parallel planar surfaces and in a second, perpendicular to the axis of rotation and the first direction direction is limited by two concentric to the axis of rotation cylinder jacket surfaces.

Preferably unwanted interference fields in the dielectric resonator element and in the metallic cavity are thereby suppressed, that the dielectric resonator element has a central through hole.

Furthermore, it is expedient if the dielectric resonator element and the dielectric body each consist of the same material.

A particularly simple and kompalder construction of the filter assembly as a whole is obtained if according to another embodiment, the at least one filter is housed in a preferably rectangular filter housing, the filter housing is constructed of a bottom plate and perpendicular to the bottom plate wall plates for the side walls and on the upper side is covered by a motor support plate lying parallel to the floor panel, the cavities of the filter are formed by in the filter housing retracted, perpendicular to the floor panel dividers, and are provided in the floor panel, in the wall panels and in the baffles mounting slots, by means of which Sheets inserted into each other and connected to each other, in particular soldered, are. The electromagnetic interaction of the cavities is achieved in a particularly simple manner, that in individual partitions at predetermined locations coupling openings, in particular coupling slots, are provided.

Another development of the invention is characterized in that a preferably circular opening is provided in the motor support plate above each of the cavities, through which the respective dielectric resonator element and the respective dielectric body are held in the cavity, that the dielectric resonator element and the Dielectric body are part of a cavity associated with the tuning unit, which is mounted on the motor support plate, and that the tuning unit each have a passing through the opening in the motor support plate, fixed support for the dielectric resonator, one through the opening in the motor support plate passing through, rotatably mounted support for the dielectric body, a motor, in particular a stepping motor, and a transmission unit, which transmits the rotational movement of the motor to the rotatably mounted support.

Particularly space-saving is the arrangement when, according to a preferred embodiment, the transmission unit is housed in a housing, the housing is mounted on the motor support plate, the motor is flanged to the housing, and the holder of the dielectric resonator is attached to the housing.

A particularly precise tuning is achieved in that the gear unit comprises a mounted in a preloaded precision bearing axis-shaped rotary member which is fixedly connected to the holder for the dielectric body, that the rotating element Within the gear unit via a fixedly seated on the rotary gear from a drive shaft is driven, which is connected to the motor and is connected via a worm with the gear in engagement, and that the rotary member for the elimination of play, preferably biased by a coil spring in the direction of rotation.

Space can be further saved by the fact that the gear is not formed as a full wheel, but circular segment. Such a segmental design with a segment angle of about 100 ° is sufficient to fully exploit the entire reasonable adjustment of about 90 ° of the dielectric body in the recess of the dielectric resonator.

A particularly secure tuning with high reproducibility is achieved in that, for controlling the rotation of the dielectric bodies in the eccentric recesses of the dielectric resonator bodies, a controller is provided which comprises a control block, a memory and an input unit that determine the initial position of the dielectric bodies in the high-frequency filter arrangement position sensor, in particular in the form of

Photocells, are provided, which are in communication with the control block, and that in the memory value tables are stored, which allocate a few selected frequencies of the high-frequency filter assembly, a corresponding angular position of the dielectric body.

A preferred embodiment of the inventive method is characterized in that the sheet metal parts are silvered and soldered together by means of a silver solder, that the sheet metal mounting auxiliary equipment, in particular in the form of coordinated crossing slots, mounting slots and mounting tabs that the sheet metal parts by means of assembly aids or the intersection slots, mounting slots and mounting tabs are initially loosely assembled to form the filter housing and the mated filter housing is mechanically stabilized by caulking the mounting tabs in the mounting slots, that at the joints between the assembled sheet metal parts silver solder, preferably in paste form, is applied, and that the mated Sheet metal parts, preferably in an oven, are heated to such an extent that the silver solder melts and flows into the joints.

The production is particularly simple and cost-effective if all sheet metal parts of a filter housing are cut out of a common, unversilvered metal sheet by means of a cutting process, preferably by means of laser cutting, such that the cut sheet metal parts are connected to the remaining region of the metal sheet only by a few narrow webs, that the metal sheet with the cut sheet metal parts is then silvered, that the sheet metal parts are removed after silvering from the metal sheet and then used to build the filter housing, in particular, the webs remain predominantly at the locations of the sheet metal parts, which in the finished filter housing outside the cavities lie.

Further embodiments emerge from the dependent claims.

BRIEF EXPLANATION OF THE FIGURES

Fig. 1

in einer perspektivischen Gesamtansicht das Filtergehäuse (die Filterbox) einer Hochfrequenz-Filteranordnung gemäss einem bevorzugten Ausführungsbeispiel der Erfindung für insgesamt drei nebeneinander angeordnete Filter, die jeweils vier im Quadrat angeordnete und untereinander gekoppelte Hohlräume umfassen (die Abstimmeinheiten mit den dielektrischen Resonatorelementen und verstellbaren dielektrischen Körpern sind der Übersichtlichkeit wegen weggelassen);

Fig. 2

das Filtergehäuse aus Fig. 1 in der Seitenansicht auf die Längsseite mit den Ein- und Ausgängen der drei Filter;

Fig. 3

das Filtergehäuse aus Fig. 1 in der Seitenansicht auf die Querseite;

Fig. 4

die perspektivische Ansicht eines Bleches, das als Wandblech für die Querseiten des Filtergehäuses nach Fig. 1 und als querliegendes Trennblech zwischen den drei Filtern verwendet wird;

Fig. 5

die perspektivische Ansicht eines Bleches, das im Filtergehäuse nach Fig. 1 als querliegendes Trennblech mit Kopplungsöffnung zwischen den vier Hohlräumen innerhalb jedes der drei Filter verwendet wird;

Fig. 6

die perspektivische Ansicht eines Bleches, das im Filtergehäuse nach Fig. 1 als in Längsrichtung laufendes Trennblech mit Kopplungsöffnungen zwischen den vorderen und hinteren Hohlräumen aller drei Filter verwendet wird;

Fig. 7

die perspektivische Ansicht des Bodenbleches des Filtergehäuses nach Fig. 1 mit einer Vielzahl von Montageschlitzen, in welche die Trennbleche und Wandbleche gemäss Fig. 2 bis 5 mit ihren Laschen einsteckbar sind und verlötet werden können;

Fig. 8

die perspektivische Ansicht einer Abstimmeinheit mit Motor, Getriebeeinheit, dielektrischem Resonatorelement und drehbarem dielektrischen Körper;

Fig. 9

die Abstimmeinheit aus Fig. 8 in der Ansicht von unten;

Fig. 10

einen Längsschnitt durch die Getriebeeinheit der Abstimmeinheit aus Fig. 8;

Fig. 11

die perspektivische Ansicht des kreissegmentförmigen Zahnrades aus der Getriebeeinheit nach Fig. 10;

Fig. 12

die perspektivische Ansicht des dielektrischen Resonatorelements der Abstimmeinheit nach Fig. 8;

Fig. 13

die perspektivische Ansicht des drehbaren dielektrischen Körpers der Abstimmeinheit nach Fig. 8;

Fig. 14

die prinzipielle Anordnung der Hohlräume eines Filters in einem Quadrat gemäss dem Ausführungsbeispiel der Fig. 1 und die Orientierung der zugehörigen dielektrischen Resonatorelemente und Körper innerhalb der Hohlräume im Bezug auf die Kopplungsschlitze;

Fig. 15

eine zu Fig. 14 alternative Anordnung der Hohlräume eines Filters in einer Reihe;

Fig. 16

das Prinzipschaitbild einer Steuerung der Hochfrequenz-Filteranordnung nach der Erfindung;

Fig. 17

die Anordnung und Ausbildung der Blechteile für ein Filtergehäuse nach Fig. 1 auf einer gemeinsamen Blechtafel;

Fig. 18

die Abhängigkeit der Filterfrequenz des Filters nach dem Ausführungsbeispiel vom Verdrehwinkel des dielektrischen Körpers 45;

Fig. 19

den gemessenen Frequenzverlauf der S-Parameter S11 (Reflektionskoeffizient am Eingang; Kurve B) und S21 (Transmissionskoeffizient in Vorwärtsrichtung; Kurve A) des Filters gemäss Ausführungsbeispiel bei der abgestimmten Frequenz von 4,7 GHz über einen Frequenzbereich von ± 15 MHz um die jeweilige Mittenfrequenz; und

Fig. 20

den gemessenen Frequenzverlauf des S-Parameters S21 des Filters gemäss Ausführungsbeispiel bei der abgestimmten Frequenz von 4,7 GHz über einen grösseren Frequenzbereich von ± 60 MHz um die jeweilige Mittenfrequenz.

The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. Show it

Fig. 1

in a perspective overall view of the filter housing (the filter box) of a high-frequency filter assembly according to a preferred embodiment of the invention for a total of three juxtaposed filters, each comprising four square arranged and mutually coupled cavities (which are tuning units with the dielectric resonator elements and adjustable dielectric bodies omitted for clarity);

Fig. 2

the filter housing off Fig. 1 in the side view on the long side with the inputs and outputs of the three filters;

Fig. 3

the filter housing off Fig. 1 in the side view on the transverse side;

Fig. 4

the perspective view of a sheet, as a wall plate for the transverse sides of the filter housing after Fig. 1 and used as a transverse divider between the three filters;

Fig. 5

the perspective view of a sheet, the filter housing after Fig. 1 is used as a transverse baffle with coupling opening between the four cavities within each of the three filters;

Fig. 6

the perspective view of a sheet, the filter housing after Fig. 1 as a longitudinally running partition plate with coupling openings is used between the front and rear cavities of all three filters;

Fig. 7

the perspective view of the bottom plate of the filter housing after Fig. 1 with a plurality of mounting slots, in which the dividers and wall panels according to Fig. 2 to 5 are plugged with their tabs and can be soldered;

Fig. 8

the perspective view of a tuning unit with motor, gear unit, dielectric resonator element and rotatable dielectric body;

Fig. 9

the voting unit off Fig. 8 in the view from below;

Fig. 10

a longitudinal section through the gear unit of the tuning unit Fig. 8 ;

Fig. 11

the perspective view of the circular segment gear from the gear unit after Fig. 10 ;

Fig. 12

the perspective view of the dielectric resonator element of the tuning after Fig. 8 ;

Fig. 13

the perspective view of the rotatable dielectric body of the tuning after Fig. 8 ;

Fig. 14

the basic arrangement of the cavities of a filter in a square according to the embodiment of Fig. 1 and the orientation of the associated dielectric resonator elements and bodies within the cavities with respect to the coupling slots;

Fig. 15

one too Fig. 14 alternative arrangement of the cavities of a filter in a row;

Fig. 16

the Prinzipschaitbild a control of the high frequency filter assembly according to the invention;

Fig. 17

the arrangement and design of the sheet metal parts for a filter housing after Fig. 1 on a common metal sheet;

Fig. 18

the dependence of the filter frequency of the filter according to the embodiment of the angle of rotation of the dielectric body 45;

Fig. 19

the measured frequency response of the S-parameters S11 (reflection coefficient at the input, curve B) and S21 (transmission coefficient in the forward direction, curve A) of the filter according to the embodiment at the tuned frequency of 4.7 GHz over a frequency range of ± 15 MHz to the respective center frequency ; and

Fig. 20

the measured frequency response of the S parameter S21 of the filter according to the embodiment at the tuned frequency of 4.7 GHz over a larger frequency range of ± 60 MHz to the respective center frequency.

WAYS FOR CARRYING OUT THE INVENTION

The tunable high-frequency filter arrangement described below comprises a filter housing (10 Fig. 1 ) to which a plurality of tuner units (40 in Fig. 8 ) and with the motor support plate (13 in Fig. 1 ) are bolted. Filter housings and tuning units are explained separately. On the representation of a fully assembled filter arrangement has been omitted for reasons of simplicity.

This in Fig. 1 illustrated, rectangular filter housing (filter box) 10 is composed of a (overhead) thicker engine support plate 13 and a plurality of sheet metal parts, which form the bottom, side walls and (inner) partitions of the filter housing 10. The sheet metal parts include the in Fig. 7 individually illustrated floor panel 11, the transverse wall panels 12 and 20 (see also Fig. 4 ), the longitudinally extending wall panels 14 and 32 (FIG. Fig. 1 . 2 ), in the 4 and 5 individually shown transverse (inner) separating plates 15, .., 19, and in Fig. 6 individually shown, in the longitudinal direction (inner) separating plate 33. The sheet metal parts are for example made of a 1 mm thick, silver-plated steel sheet (material No. 1.4301). The motor support plate 13 is made of the same material and is also silvered, but has a thickness of for example 4 mm.

The production of sheet metal parts can according to Fig. 17 be carried out in a particularly simple and cost-effective manner that all sheet metal parts of a filter housing 10 from a common plate 69 suitable size in the in Fig. 17 be cut out as shown. The metal sheet 69 is initially unversilvered. By laser cutting or a comparable cutting technique, the contours of the required sheet metal parts 11, 12, 14, .., 20, 32 and 33 are first cut in the metal sheet 69, wherein the cut sheet metal parts with the remaining rest of the metal sheet 69 at different points by narrow webs stay connected. The webs are arranged predominantly on parts of the sheet metal parts, which lie outside the cavities 21,... 24 in the case of later filter housings 10. A missing silver layer at these points has no effect on the high-frequency properties of the cavities. After the cut metal sheet 69, the in Fig. 17 has shown shape, it is provided over the entire surface with a silver layer. In this way, the sheet metal parts are almost completely silvered. Only in the areas of the later separated webs missing such a silvering. However, since these are largely outside the cavities, there is no disadvantage.

The filter housing 10 is made of the individual sheet metal parts 11, 12, 14, .., 20; 32, 33 and the motor support plate 13 formed by soldering and pinning. The soldering is done by means of a suitable silver solder in an oven. The sheet metal parts 11, 12, 14, .., 20; 32, 33 are initially provisionally connected by nesting of mounting brackets and mounting slots provided, and by caulking the mounting tabs in the mounting slots formed sheet metal housing is mechanically stabilized. Only the wall panels 14, 32 on the longitudinal side of the filter housing 10 are pinned at the top with the end faces of the motor support plate 11. At the junctions of the sheet metal parts, the solder is applied in a suitable amount in the form of a solder paste and distributed so that the existing at the connection points column are securely closed during soldering. The thus prepared housing is then heated in an oven to the necessary temperature for soldering and - after the solder has melted and run in the joints - cooled again.

For nesting the sheet metal parts 11, 12, 14, .., 20; 32, 33, the bottom plate 11 and arranged on the longitudinal sides of the housing wall plates 14, 32 with a plurality of (partially crossing) mounting slots 39 are provided. The wall panels 12, 14, 20, and 32 and the partitions 15, .., 19 and 33 are provided at their lower edges with matching mounting tabs L1, with which they can be inserted through the mounting slots 39 of the bottom plate 11 and soldered. The transverse wall panels 12 and 20 and dividers 15, .., 19 additionally have at their side edges mounting tabs L2, with which they can be inserted and soldered through corresponding mounting slots in the longitudinal wall panels 14, 32. To unhindered crossing the transverse wall and dividers 12, 14, .., 20; 32 with the longitudinally extending partition plate 33 are in these sheet metal parts special crossing slots 34, 36, 37 and 38 ( Fig. 4-6 ) intended. The crossing takes place alternately on the top and bottom (old intersection slots 37, 38 in Fig. 6 ).

Through the longitudinal separating plate 33 and the transverse separating plates 15, .., 19 are in the filter housing 10 a total of 3 x 4 = 12 similar cavities each with a square base area (A1, .., A4 in Fig. 7 ), of which in Fig. 1 four associated by way of example with reference numerals 21, .., 24 are designated. The four arranged in a square, belonging together cavities 21, .., 24 form a filter F3. In the filter housing 10 of Fig. 1 In addition to the filter F3, two further, similar filters F2 and F1 are housed, which also each comprise four cavities arranged in a square. Each of the filters F1, F2 and F3 has according to Fig. 2 an associated input 26, 28, 30 and output 27, 29, 31.

The four cavities of each of the filters F1, F2 and F3 are coupled to each other with high frequency. This is done by suitably arranged, elongated coupling slots 35 in the transverse separating plates 15, 17 and 19 (FIG. Fig. 5 ) and in the longitudinal separating plate 33 (FIG. Fig. 6 ). The coupling slots 35 are positioned in the present example so that they lie in the middle of the wall of the adjacent cavity or in the vertical center plane of the cavities to be coupled. The importance of this position for the coupling properties will be discussed in more detail. The transverse separating plates 16 and 18, which separate the filters F1, F2 and F3 with each other, are naturally not equipped with coupling openings.

In the center of each of the cavities 21, .., 24 formed in the filter housing 10 is a circular disk-shaped dielectric resonator element 44 (FIG. Fig. 12 ), which determines the overall high-frequency and transmission characteristics of the individual cavity and the respective filter significantly. The dielectric resonator element 44 is part of a compact tuning unit 40 (FIG. Fig. 8-10 ). The tuning unit 40 is screwed from above onto the stable engine support plate 13 and protrudes with a fixed support 46 (FIG. Fig. 10 ), at the end of which the dielectric resonator element 44 is fastened, by a cavity (circular) opening 25 (FIG. Fig. 1 ) into the underlying cavity.

The dielectric resonator element 44 has a central circular through-hole 58 and an eccentrically arranged circular recess 59 (FIG. Fig. 12 ). In the eccentric recess 59 is a dielectric body 45 (FIG. Fig. 13 ) of equal thickness about an axis of rotation 60 rotatably mounted, which is perpendicular to the disc plane of the dielectric resonator 44. The recess 59 is formed as a concentric with the axis of rotation 60 circular cylindrical through hole. The dielectric body 45 is fitted in its outer dimensions in the recess 59 such that both are separated from each other only by narrow air gaps. For this purpose, the dielectric body 45 is in a first, perpendicular to the axis of rotation 60 direction by two parallel planar surfaces 61, 62 and in a second, the axis of rotation 60 and the first direction perpendicular direction by two concentric to the axis of rotation 60 cylinder jacket surfaces 63, 64th limited (see Fig. 13 ; the body 45 inserted in the recess is in Fig. 9 visible).

The dielectric body 45 is preferably made of the same dielectric material as the dielectric resonator element 44. It is attached to the end of a rotatably mounted support 47 and can be rotated about the axis of rotation 60 relative to the dielectric resonator element 44 by means of the mechanism housed in the tuning unit 40. The rotation of the resonant frequency of the resonator element and thus the center frequency of the filter can be changed.

The tuning unit 40 ( Fig. 8-10 ) consists essentially of a gear unit 42 and a laterally flanged to the gear unit 42 motor 41, which drives the rotatable support 47 via the gear unit 42. The motor 41 is preferably a stepper motor. According to Fig. 10 The transmission unit 42 comprises a housing 43, on the underside of which the holder 46 for the stationary dielectric resonator element 44 is fastened. In a through hole passing through the bottom of the housing 43, an axis-shaped rotary element 49 is rotatably mounted by means of a precision bearing 48, which rotates with the rotatable Holder 47 is firmly connected. As a precision bearing 48, for example, a special, provided with two ball bearings, preload bearing is used, which is used in hard disk memories of PCs. Such bearings are, for example, under the name "RO Bearing" (after the inventor R ikuro O bara) by the Japanese company Minebea Co, Ltd. available. Their principle is among others in the US-A-5,556,209 described. The precision bearing 48 helps to achieve a positioning accuracy of the dielectric body 45 in the range of a few microns, which is necessary for a precise tuning of the filter F1, F2 and F3.

On the rotary member 49 is a circular sector-shaped gear 51 according to Fig. 11 attached. Since the full tuning range of in Fig. 9 shown configuration of dielectric resonator 44 and dielectric body 45 by a rotation of the body by 90 ° from the in Fig. 9 imaged position can be overlined for the gear 51, a sector angle of 100 ° more than sufficient. By forming the gear 51 in the form of a circular sector, the gear unit 42 and thus the tuning unit 40 can be built extremely compact.

With the gear 51, the worm meshes with a drive shaft 55 which is perpendicular to the axis of rotation 60 and which is connected directly to the motor 41. Thus, the engagement between the worm and the gear 51 is carried out without play, the rotary member is biased by means of a housing 43 mounted on the coil spring 50 in the direction of rotation. For controlling the drive unit 40, two light barriers 52 and 53 are provided in the gear unit 42. The first photocell 52 scans (in Fig. 10 not shown) rod-shaped marking element which sits in a corresponding mounting hole 56, 57 of the gear 51 ( Fig. 11 ) and the end points of the swivel range are marked. The second light barrier 53 scans a position sensor disk 54 which is seated on the drive shaft 55 and provided with a radial slot. The interaction of the two light barriers allows the initial or zero position of the toothed wheel 51 and thus the initial position of the dielectric body 45 to be determined precisely.

As already mentioned above, in each of the filters F1,..., F3, the four cavities 21,..., 24 with the dielectric resonator elements 44 and bodies 45 placed therein are arranged in a square. In Fig. 14 this is shown again with reference to the exemplary filter F3. The RF energy is coupled into the first cavity 21, propagates via the coupling slots 35 via the adjacent cavities 22, 23 and 24 and is decoupled at the last cavity 24 again. The coupling slots 35 are in the vertical center planes or in the middle of the partitions of the cavities 21, .., 24th The dielectric resonator elements 44 are rotated with their eccentric recesses 59 out of the vertical center plane of the coupling slot 35 closest to the recess by a predetermined angle, which in the example is about 57 °. By this particular configuration of recess and coupling slot, a high-frequency behavior of the filter is achieved, in which the coupling factor decreases with increasing frequency when the dielectric body 45 is turned to the nearest coupling slot. An additional degree of freedom results from the possibility of an additional coupling between the first cavity 21 and the last cavity 24, as shown in FIG Fig. 14 is indicated by the S-shaped coupling element.

Another configuration of a filter F ', with which - apart from the cross-coupling - the same effect can be achieved, is the linear arrangement of the rows of cavities 21, .., 24 according to Fig. 15 , Here, too, the coupling slots 35 are arranged centrally and the dielectric resonator elements 44 with their recesses are rotated out of the median plane by approximately 60 °.

For the tuning of the filter arrangement by means of the tuning units 40, a control is provided, as in Fig. 16 is reproduced in a highly simplified block diagram. The controller 65 comprises a control block 66 which comprises, for example, a suitable microprocessor and a number of power outputs corresponding to the number of motors 41. The control block 66 controls the stepper motors 41 via the power outputs. It is activated externally via an input unit 68. The control block 66 operates with a memory (EPROM) 67 are stored in the value tables, which assigns a certain number of steps of the stepper motors 41 to some selected frequency values of the filter. Intermediate values are generated by interpolation. The control block 66 also receives signals from the two light barriers 52, 53 per tuning unit 40. If a specific frequency for the filter (s) is to be set (at start-up), first the dielectric bodies 45 are returned to their initial position. Reaching the starting position is signaled by corresponding signals of the two light barriers 52, 53. From the starting position, the stepper motors 41 are then advanced by as many steps as correspond to the table value taken from the memory 67 or a value for the desired frequency determined by interpolation. The motors 41 of a filter can all be switched substantially simultaneously or following a specific algorithm.

If the high-frequency filter assembly with the filter housing 10 according to the embodiment ( Fig. 1 4), ie, a tunable frequency range of about 4.4 GHz to 5 GHz, the housing (without the tuner units) has a footprint of about 66 mm x 186 mm and a height of about 30 mm. Each of the cavities has a base (A1, .., A4 in Fig. 7 ) of 28 mm x 28 mm and a height of 20 mm. The dielectric resonator element 44 has a thickness of about 6 mm, an outer diameter of about 15 mm and an inner diameter of about 6.5 mm. The diameter of the eccentric recess 59 is about 6 mm, the width of the dielectric body 45 between the parallel vertical boundary surfaces about 3 mm. The tuning unit 40 protrudes only about 24 mm beyond the surface of the engine support plate 13.

• Fig. 18 zeigt die Abhängigkeit der abstimmbaren Filterfrequenz von dem Drehwinkel des dielektrischen Körpers 45 in der exzentrischen Aussparung 59 des dielektrischen Resonatorelements 44. Der Bereich des Drehwinkels geht von 0° bis 90°. Bei 0° liegt der dielektrische Körper 45 mit seinen geraden Seiten tangential zum dielektrischen Resonatorelement 44.

For a filter arrangement designed in this way, characteristic curves result, as shown in FIGS Fig. 18 to 20 are reproduced:

• Fig. 18 shows the dependence of the tunable filter frequency on the angle of rotation of the dielectric body 45 in the eccentric recess 59 of the dielectric Resonator element 44. The range of the rotation angle is from 0 ° to 90 °. At 0 °, the dielectric body 45 lies with its straight sides tangential to the dielectric resonator element 44.

in Fig. 19 are the measured curves for several S-parameters of the filters according to the embodiment, namely the reflection coefficient at the input, S11 (curve B), and the transmission coefficient in the forward direction, S21 (curve A), as a function of the frequency at a set center frequency of 4, 7 GHz. The frequency range is ± 15 MHz around the respective center frequency. The plot is logarithmic. The scale in the vertical direction is 0.5 dB per division for S21 and 5 dB per division for S11.

In Fig. 20 For example, the measured curve for S21 is plotted for 4.7 GHz over an extended frequency range of ± 60 MHz around the respective center frequency. The plot is logarithmic. The scale in the vertical direction is here 10 dB per division.

Overall, with the invention results in a tunable high-frequency filter assembly that can be easily and inexpensively build, can be tuned very accurately and reproducibly over a wide frequency range, is extremely compact and is characterized by very good high-frequency characteristics. In particular, several similar filters can be accommodated with little additional effort in a common filter housing.

LIST OF REFERENCE NUMBERS

10 Filter housing (filter box) 11 floor panel 12.20 Wall plate (transverse) 13 Motorträgerplatte 14.32 Wall plate (longitudinal) 15, .., 19 Divider (cross) 21, .., 24 cavity 25 Opening (circular) 26,28,30 Input (filter F1, F2, F3) 27,29,31 Output (filter F1, F2, F3) 33 Separating plate (longitudinal) 34,36,37,38 crossing slot 39 mounting slot 35 coupling slot 40 tuning 41 Motor (stepper motor) 42 gear unit 43 Housing (gear unit) 44 dielectric resonator element (fixed) 45 dielectric body (movable) 46 Bracket (half-shell-shaped) 47 Bracket (rotatable) 48 precision bearings 49 rotating member 50 spiral spring 51 Gear (circular segment) 52.53 photocell 54 Position sensor disk 55 Drive shaft (with worm) 56.57 Mounting hole (locating pin) 58 central through-hole 59 eccentric recess 60 axis of rotation 61, .., 64 boundary surface 65 control 66 control block 67 Memory (EPROM) 68 input unit 69 metal sheet A1, .., A4 area F, F1, F2, F3 Filter (bandpass filter) K1, K2 Curve L1, L2 mounting tab

Claims (26)

1. High-frequency filter arrangement having at least one filter (F1, F2, F3) which comprises a plurality of hollow spaces (21, ...24) which are connected to each other in a high-frequency manner and in each of which a dielectric resonator element (44) is fixedly arranged, and in each of which there is provided a dielectric member (45) which, in order to tune the frequency of the filter (F1, F2, F3), can be adjusted in terms of its position relative to the dielectric resonator element (44), characterised in that the dielectric resonator element (44) is in the form of a planar, circular disc which has a central circular through-hole (58), in that this annular resonator element has an eccentric circular recess (59) which is in the form of a circular-cylindrical through-hole, in that the axis (60) of this recess is located perpendicularly on the disc plane of the dielectric resonator element, in that the dielectric member (45) is arranged in this eccentric recess (59) of the dielectric resonator element (44) so as to be rotatable about an axis of rotation (60) which is located perpendicularly on the disc plane of the dielectric resonator element (44), and in that the dielectric member (45) is delimited in a first direction which is perpendicular relative to the axis of rotation (60) by two parallel, planar faces (61, 62) and in a second direction which is perpendicular relative to the axis of rotation (60) and to the first direction by two cylindrical outer faces (63, 64) which are concentric relative to the axis of rotation (60).
2. High-frequency filter arrangement according to claim 1, characterised in that the dielectric resonator element (44) has a predetermined thickness and in that the dielectric member (45) has, in the direction of the axis of rotation, a height which is substantially equal to the thickness of the dielectric resonator element (44).
3. High-frequency filter arrangement according to claim 2, characterised in that the dielectric member (45) is adapted in terms of its outer dimensions to the recess (59) in the dielectric resonator element (44) so that both are separated from each other only by narrow air gaps.
4. High-frequency filter arrangement according to any one of claims 1 to 3, characterised in that the dielectric resonator element (44) and the dielectric member (45) each comprise the same material.
5. High-frequency filter arrangement according to any one of claims 1 to 4, characterised in that the at least one filter (F1, F2, F3) is/are received in a preferably rectangular filter housing (10), in that the filter housing (10) is constructed from a metal bottom sheet (11) and metal wall sheets (12, 14, 20, 32) for the side walls that are located perpendicularly on the metal bottom sheet (11) and is covered at the upper side by a motor carrier plate (13) which is parallel with the metal bottom sheet (11), and in that the hollow spaces (21, ...24) of the filter (F1, F2, F3) are formed by metal separation sheets (15, ...19; 33) which are retracted into the filter housing (10) and which are located perpendicularly on the metal bottom sheet (11).
6. High-frequency filter arrangement according to claim 5, characterised in that there are provided in the metal bottom sheet (11), in the metal wall sheets (12, 14, 20, 32) and in the metal separation sheets (15, ...19; 33) assembly slots (34, 36, ...39), by means of which the metal sheets are introduced one in the other and connected, in particular soldered, to each other.
7. High-frequency filter arrangement according to claim 5 or claim 6, characterised in that coupling openings, in particular coupling slots (35), are provided in individual metal separation sheets (15, ...19; 33) at predetermined locations.
8. High-frequency filter arrangement according to any one of claims 5 to 7, characterised in that there is provided in the motor carrier plate (13) above each of the hollow spaces (21, ...24) a preferably circular opening (25), through which the dielectric resonator element (44) and the dielectric member (45) are retained in the hollow space.
9. High-frequency filter arrangement according to claim 8, characterised in that the dielectric resonator element (44) and the dielectric member (45) are part of a tuning unit (40) which is associated with the hollow space and which is secured on the motor carrier plate (13).
10. High-frequency filter arrangement according to claim 9, characterised in that the tuning unit (40) comprises a fixed retention member (46), which extends through the opening (25) in the motor carrier plate (13), for the dielectric resonator element (44), a rotatably supported retention member (47) which extends through the opening (25) in the motor carrier plate (13), for the dielectric member (45), a motor (41) and a gear unit (42) which transmits the rotational movement of the motor (41) to the rotatably supported retention member (47).
11. High-frequency filter arrangement according to claim 10, characterised in that the motor (41) is a stepping motor.
12. High-frequency filter arrangement according to either claim 10 or claim 11, characterised in that the gear unit (42) is received in a housing (43), in that the housing (43) is secured on the motor carrier plate (13), in that the motor (41) is flange-mounted on the housing (43) and in that the retention member (46) of the dielectric resonator element (44) is secured to the housing (43).
13. High-frequency filter arrangement according to claim 12, characterised in that the gear unit (42) comprises an axle-like rotary element (49) which is supported in a pretensioned precision bearing (48) and which is securely connected to the retention member (47) for the dielectric member (45), and in that the rotary element (49) is driven by a drive shaft (55) inside the gear unit (42) via a toothed wheel (51) which is securely located on the rotary element (49), which drive shaft (55) is connected to the motor (41) and is in engagement with the toothed wheel via a screw.
14. High-frequency filter arrangement according to claim 13, characterised in that the rotary element (49) is pretensioned in the direction of rotation in order to eliminate play, preferably by a helical spring (50).
15. High-frequency filter arrangement according to either claim 13 or claim 14, characterised in that the toothed wheel (51) is constructed in the manner of circle segments.
16. High-frequency filter arrangement according to any one of claims 1 to 15, characterised in that each of the filters (F1, F2, F3) comprises four hollow spaces (21, ...24) having dielectric resonator elements (44) arranged therein and rotatable dielectric members (45).
17. High-frequency filter arrangement according to claim 16, characterised in that the four hollow spaces (21, ...24) are arranged so as to adjoin each other in a square.
18. High-frequency filter arrangement according to claim 16, characterised in that a plurality of filters (F1, F2, F3) each having four hollow spaces (21, ...24) are received beside each other in a common filter housing (10).
19. High-frequency filter arrangement according to any one of claims 1 to 18, characterised in that the hollow spaces (21, ...24) are connected by coupling slots (35) which are each arranged in a vertical centre plane of the hollow spaces to be connected, and in that the eccentric recesses (59) are arranged in the dielectric resonator elements (44) so as to be rotated about the axis of the dielectric resonator element (44) out of the vertical centre plane through a predetermined angle, preferably approximately 57°.
20. High-frequency filter arrangement according to any one of claims 1 to 19, characterised in that a control unit (65) which comprises a control block (66), a store (67) and an input unit (68) is provided in order to control the rotation of the dielectric members (45) in the eccentric recesses (59) of the dielectric resonator members (44).
21. High-frequency filter arrangement according to claim 20, characterised in that position transmitters, in particular in the form of photoelectric barriers (52, 53), which are connected to the control block are provided in order to determine the start position of the dielectric members (45) in the high-frequency filter arrangement.
22. High-frequency filter arrangement according to either claim 20 or 21, characterised in that there are stored in the store (67) value tables which associate a corresponding angular position of the dielectric members (45) with the small number of selected frequencies of the high-frequency filter arrangement.
23. Method for producing a high-frequency filter arrangement according to any one of claims 1 to 22, characterised in that a plurality of planar sheet metal members (11, 12, 14, ... 20, 32, 33) are connected to form a filter housing (10) in order to construct the hollow spaces (21, ...24).
24. Method according to claim 23, characterised in that the sheet metal members (11, 12, 14, ... 20, 32, 33) are silver-plated and soldered to each other by means of silver filler.
25. Method according to claim 24, characterised in that the sheet metal members (11, 12, 14, ... 20, 32, 33) have auxiliary assembly means, in particular in the form of mutually corresponding intersecting slots (34, 36, ... 38), assembly slots (39) and assembly lugs (L1, L2), in that the sheet metal members (11, 12, 14, ... 20, 32, 33) are initially loosely assembled by means of the auxiliary assembly means or the intersecting slots (34, 36, ... 38), assembly slots (39) and assembly lugs (L1, L2) so as to form the filter housing (10) and the assembled filter housing is mechanically stabilised by means of caulking of the assembly lugs (L1, L2) in the assembly slots (39), in that silver filler, preferably in paste form, is applied to the connection locations between the assembled sheet metal members (11, 12, 14, ... 20, 32, 33), and in that the assembled sheet metal members (11, 12, 14, ... 20, 32, 33) are heated, preferably in an oven, to such an extent that the silver filler melts and flows into the connection locations.
26. Method according to any one of claims 23 to 25, characterised in that all the sheet metal members (11, 12, 14, ... 20, 32, 33) of a filter housing (10) are cut from a common non-silver-plated metal sheet (69) by means of a cutting method, preferably by means of laser cutting, in such a manner that the cut-out sheet metal members (11, 12, 14, ... 20, 32, 33) are still connected to the remaining region of the metal sheet (69) only by means of a small number of narrow webs, in that the metal panel (69) having the cut-out sheet metal members (11, 12, 14, ... 20, 32, 33) is subsequently silver-plated, in that the sheet metal members (11, 12, 14, ... 20, 32, 33) are disengaged from the metal sheet (69) after the silver-plating operation and are subsequently used to construct the filter housing (10).

Images