ES2608580T3 - HF-filter arrangement as well as method to vary an electromagnetic coupling resistance between two coaxial cavity resonators - Google Patents

Abstract

An HF-filter arrangement (1) with at least two capacitively coupled coaxial cavity resonators (2, 3), which are coupled through an electrically conductive common cavity wall (4) or through electrically connected cavity walls , respectively, in which a coupling window (5) is inserted in the common cavity wall (4) or in the electrically connected cavity walls, the window of which is completely enclosed by electrically conductive material (6) and in which a coupling means (7) of variable capacity is introduced, characterized in that the coupling means (7) comprise an electrically conductive rod element (8) with a rod axis (9) as well as two ends ( 10, 11) of the bar element, whose element is connected on both sides to be conductive of electricity through the ends (10, 11) of the bar element to the electrically conductive material (6) the coupling window (7) errs and because, electrically isolated from the bar element (8), at least two electrically connected tongue elements (12, 13) made of electrically conductive material and fixed to the bar element (8 ) are rotatably mounted around a rotation axis (19) that coincides with the bar element (9).

Description

HF-filter arrangement as well as method to vary an electromagnetic coupling resistance between two coaxial cavity resonators

Technical Field The invention relates to an HF filter arrangement with at least two capacitively coupled coaxial cavity resonators, coupled through a common electrically conductive cavity wall or through electrically connected cavity walls, respectively, in which A coupling window is inserted in the common cavity wall or in the electrically connected cavity walls, the window of which is completely enclosed by electrically conductive material and into which a coupling means of variable capacity is inserted. In addition, an HF filter is described which comprises a plurality of coaxial cavity resonators that are arranged in the form of a matrix along at least two rows and at least two columns, in which the coupling between the coaxial cavity resonators arranged in the direction of the row is inductively configured and the coupling of at least two adjacent coaxial cavity resonators in the form of a column is carried out capacitively. Finally, a method for varying an electromagnetic coupling resistance between two coaxial cavity resonators is described.

State of the art The transmitters or air systems for the emission of HF-signals, for example in the form of telecommunication, television or radio signals normally have band filters arranged between the transmission amplifier unit and the air system, in order to suppress interference signals that may be present in the output signal of the amplifier in the form of supplementary interference lines or secondary lines directly adjacent to the useful frequency range. This represents a special technical challenge, in particular because such interference lines or parts of interference signals in adjacent channels must be eliminated or suppressed due to the small frequency distance from the useful frequency range predefined by the respective transmission channel and its center frequency and channel bandwidth without a relevant negative impact, as far as possible, on the useful frequency range. In addition, the transmission of HF signals in certain frequency bands or frequency ranges is governed by normal binding, for example normal for the transmission of digital content, for example television, radio, multichannel sound signals, adherence to DVB standards, ATSC , etc.

In order to achieve the spectral properties required for useful signals with high HF power, band filters with coaxial cavity filters coupled with respect to HF are used, which are arranged such that cross-sectional or negative coupling (feedback) is provided between two nonconsecutive coaxial cavities (with respect to HF). Such a band filter composed of coaxial cavities is described in DE 199 16 605 C1. Due to the negative coupling (feedback) between nonconsecutive coaxial cavities, the flanks of the bandpass feature become steeper, so that the selectivity of the band filter is increased. With this arrangement, it is accepted that the bandpass characteristic of the filter in the area blocked at lower and higher frequencies comprises attenuation minima (the so-called CAUER characteristic), while the bandpass characteristic of band filters without negative feedback shows a progression of attenuation that grows monotonously (TSCHEBYSCHEFF features). With the multi-circular band filter with negative feedback according to DE 199 16 605 C1, the coaxial cavities that must be negatively coupled are arranged such that the coaxial cavities are mechanically adjacent and the negative feedback is configured as a loop that it is immersed in a coaxial cavity, which is connected through a groove formed in the partition between the two coaxial cavities adjacent to a pattern in the other coaxial cavity. The loop and the stamp conveniently form a uniform line section, in which the depth of immersion in the coaxial cavities and, therefore, the degree of negative feedback can be varied. The loop accuses inductive coupling, while the stamp causes a capacitive coupling. The transition from inductive coupling to capacitive coupling simultaneously causes a necessary phase rotation of 180 °. If, for example, the filter, in a manner known as such, is tuned to a lower center frequency and if the feedback of the respective coaxial cavities remains constant, the area of immersion of the loop in the coaxial cavity must be extended. This is done by expanding the depth of immersion in the section of the line. At the same time, the stamp in the other coaxial cavity that causes the capacitive coupling, also moves.

In addition, a band filter with coaxial cavities T1, T2 negatively coupled, in which a common wall W of two coaxial cavities T1, T2 adjacent mechanically comprises a window F is known (see Figure 4b). A capacitive coupling element K, similar to a bridge, arranged symmetrically to the plane of the window, which is supported against an insulator I, is arranged in the window area, see Figure 4a. The coupling element K, in the plane of symmetry / window, comprises a bore that extends parallel to the inner conductors of the coaxial cavity resonators, in which through the insulator I a coupling pin KS is axially movable mounted , which is electrically isolated. When the coupling pin KS is in the non-inserted position, the capacitive coupling between the coaxial cavity resonators T1, T2 is at its maximum. When the coupling pin KS is inserted in the bore of the insulator I, it acts as a variable capacity against mass, that is, the capacitive coupling is reduced

effective between coaxial cavity resonators.

The drawback of such an arrangement is that a certain maximum power determined by the geometry of the coupling element similar to a bridge is always decoupled, whose part of the decoupled power, when the filter is tuned, is short-circuited, however, by a variable capacity towards mass.

Document DE 12 22 600 B has described a tunable filter arrangement consisting of at least two sections of resonant line coupled, where the coupling is varied transversely to the longitudinal axes of the resonator through a change in the radial extension of two parts of linearly movable pins in the resonant line sections.

Description of the Invention The requirement of the invention is to improve the capacitive transverse coupling between two coaxial cavity resonators, in particular as regards the possible variations of the coupling factor and the minimization of existing losses.

The requirement of the invention is met by an HF filter arrangement according to claim 1, an HF filter according to claims 10 and 11 as well as by a method for varying an electromagnetic coupling resistance according to claim 12.

The devices according to the solution and the features that further develop the method according to the solution in an advantageous manner are the subject of the dependent claims as well as the detailed description.

Claim 1 relates to a filter arrangement with at least two coaxial cavity resonators that are coupled through an electrically conductive cavity wall or, respectively, through electrically coupled cavity walls, in which a window of The coupling is inserted in the common cavity wall or in the electrically coupled cavity walls, the window being completely closed by electrically conductive material and into which a coupling means of varying capacity can be introduced.

An HF-filter arrangement according to the solution is characterized in that the coupling means comprise an electrically conductive rod element with a rod axis as well as two ends of the rod element, the element of which is connected on both sides to be electricity conductor through the ends of the bar element to the electricity conductor material that encloses the coupling window and because, electrically isolated from the bar element, at least two electrically connected tongue elements made of electricity conductive material and fixed to the bar element they are rotatably mounted around a rotation axis that coincides with the bar element.

It is essential for the invention that because the electrically conductive rod element is electrically connected to the surrounding material, the coupling window is divided into two smaller partial windows, in which an effective parasitic inductive coupling across the area of the Window can be substantially suppressed or compensated due to this partial window arrangement. As such, just a small addition of capacitive coupling is sufficient to compensate for an existing parasitic inductive coupling. Therefore, compared to known arrangements, a considerably more robust capacitive coupling between coaxial cavity resonators is possible.

Therefore, using the arrangement according to the invention, the size of the coupling factor can be varied over a large range, so that the filter characteristic of a bandpass filter is adjustable for many different radio broadcast standards, such like ATSC, DVB-T, ISDB-T. The coupling factor can be varied in this way between a minimum coupling, that is, a coupling factor = zero and a maximum coupling, in principle with 1/4 turn of the tongue elements around the axis of rotation. With minimal coupling, the tongue elements are approximately in a plane assignable to the window. Lingues develop an additional inductive umbrella effect because, in conjunction with the bar element, they divide the original window into four smaller windows.

Due to the capacitive type of the coupling according to the solution, a greater distance of the coupling means, that is, the tongue elements and the rod element, can be made from the resonators, which leads to higher dielectric strength. Therefore, the HF filter arrangement can be constructed to accommodate higher powers than in the case of known comparable filter arrangements.

In a preferred embodiment, the bar element divides the coupling window into two essentially symmetrical window areas, that is, the bar element blocks the center of the original coupling window, as a result of which they can be realized Very small coupling factors.

In a preferred embodiment, the HF-filter arrangement is characterized in that the rod element is

arranged to be rotatable about the axis of rotation within the coupling window and the at least two tongue elements are fixed in a non-rotational manner to the bar element. A tongue support of electrically conductive material, on which the tongue elements are arranged, is particularly suitable for this purpose. The tongue support comprises a drill, and the electrically conductive rod element projects through this drill. The bar element is electrically insulated with respect to the tongue holder or the tongue elements by which an insulator is introduced, preferably preferably concentrically surrounding (with respect to the axis of rotation) the bar element at least partially in the area of the tongue holder.

The interstices between the tongue elements and the coupling window do not necessarily have to be parallel at all costs, that is, the tongue elements could be inclined, for example, in a radial direction with respect to the axis of rotation.

However, it is especially preferred if the tongue elements are bar-shaped and extend parallel and equidistant from the axis of rotation. Preferably, the tongue elements are arranged diametrically opposite to the bar element. Instead of a diametrical arrangement, a slightly offset arrangement is also feasible, that is, that an angle formed by the imaginary radial connection lines, respectively, between a tongue element and the bar element, is not 180 °, but which deviates from it, preferably within a range of angles of α  15 ° from the 180 ° position and the bar element intersects with a background defined by the bar element and the other tongue element, in a angle α, which means α  15º.

In general terms, the interstices between the tongue elements and the coupling window do not have to be parallel at all costs, that is, the tongue elements could be inclined radially with respect to the axis of rotation.

Similarly, the shape of the rod element, the tongue elements and the tongue holder can be of any random shape. With respect to the rod element and the tongue elements, its cross-sectional shape may vary, in principle, for example, they may be round, square, oval, symmetrical, asymmetric, made of hollow or solid material, and its shape of the Cross section in axial direction can also vary, for example it can be spherical or notched, stable or unstable. All the elements of the coupling means, that is to say, the elements of tongue, bar element, support of tongue, are preferably treated on the surface, that is, for example, can comprise a highly conductive surface consisting, for example of silver, copper, gold, etc. in order to optimize its effectiveness.

With a particular embodiment, the rod element is aligned in parallel with the longitudinal extension of its inner conductor of at least one of the at least two resonators4 of coaxial quality.

In addition, it is preferred to enclose the at least two coaxial cavity resonators at least partially, preferably completely in a housing, the conductive housing being electrical and configuring the rod element such that it can be rotated directly or indirectly from the outside of the housing with the help of a means of action. It is especially preferred if the tongue elements are rotatably mounted around the axis of rotation within a range of rotational angles of at least 80 °, preferably at least 90 °, especially preferably 180 °. It is especially preferred to provide a locking means for blocking the rotation angle adjustment to secure the actuation means, with which the rotation angle of the tongue elements is adjusted, against an inadvertent adjustment.

The filter arrangement according to the solution is advantageously characterized by its structural compactness, particularly because the complete coupling means, which include actuation and fixing, can be integrated within the minimum construction space of the filter arrangement. In particular, control elements that project up to varying degrees are not necessary depending on the degree of coupling in the environment of the filter housing, as is the case with known comparable filter arrangements. Furthermore, the actuation of the coupling means is possible from two opposite sides of the filter housing, provided that the actuation means extend to the outside on both sides, while the transverse couplings known from the prior art they can be activated normally from one side of the filter housing.

In addition, on the basis of the capacitive type of the coupling described above between two coaxial cavity resonators, an HF filter can be formed comprising a plurality of coaxial cavity resonators coupled to each other, which are arranged in the form of a matrix along of at least two rows and at least two columns, in which the coupling between two coaxial cavity resonators arranged in the direction of the row is inductively configured. As a prerequisite, coaxial cavity resonators arranged in rows are coupled with an HF-handle. For a two-row serial HF-coupling that extends in parallel, merely two coaxial cavity resonators that are placed opposite each other at the end of the row along a column are also coupled with respect to HF . Coaxial cavity resonators arranged in series in a U-shape are coupled to each other in this way with respect to HF.

In other aspects, all coaxial cavity resonators in a U-shaped arrangement that are placed column-to-column enters are not coupled with respect to HF.

The HF filter is characterized in that at least one pair of coaxial cavity resonators arranged in the direction of the column are configured as an HF filter arrangement according to one of claims 1 to 9, wherein the two resonators of coaxial cavity adjacent to each other through a common wall in the direction of the column have a window arrangement in them, in which the bar element is provided with the tongue elements rotatably fixed thereto, in order of several without stepping the coupling capacity and, therefore, the coupling resistance between the two coaxial cavity resonances arranged in the direction of the column. It goes without saying that the variablely adjustable coupling capacity can also be modified when the filter is used in accordance with the variants described above.

Especially preferred is an arrangement consisting of at least six coaxial cavity resonators, which are arranged in two rows. The coupling of the HF-signal to be filtered into the first coaxial cavity resonator is carried out in the direction of the row, preferably by induction. The main propagation path extends in the direction of the row through the coaxial cavity resonators 1 to 3, then in the direction of the column through the coupling of the coaxial cavity resonators 3 and 4 and then again in row direction (but this time in the reverse direction) through coaxial cavity resonators 4 to 6 that are arranged in the second row. A filtered HF-signal can be decoupled in the direction of the row from the coaxial cavity resonator 6. The transverse coupling between the coaxial cavity resonators 2 and 5 that with respect to HF are not adjacent to each other is performed in accordance with the HF filter arrangement of the invention.

A second HF filter according to the solution comprises a plurality of coaxial cavity resonators coupled to each other, which are arranged in the form of a matrix along at least two rows and at least two columns, in which the coupling between At least two coaxial cavity resonators arranged in the direction of the column is configured in an inductive manner. It is characterized in that the coupling, respectively, between two coaxial cavity resonators arranged in the direction of the row is capacitively configured and that the two coaxial cavity resonators as an HF filter arrangement are configured according to one of claims 1 to 9.

The operation and function of the HF-filter described above are based on a method according to the solution to vary the resistance of the electromagnetic coupling between two resonators of the coaxial cavity, which uses the structural specifications of an HF-filter arrangement according to claims 1 to 3. To continuously vary the capacitive coupling resistance between two coaxial cavity resonators, the tongue elements, which together with the rod element define a plane of the fingers, move from a first position, in which the tongue elements are in or within an area of a plane of the coupling window assignable to the coupling window, to a second position exclusively by rotation around the axis of rotation, in which the plane of the tongues assignable to The tongue elements form an angle a with the plane of the coupling window.

It is worth noting that by rotating the plane of the fingers to the first position, in which the plane of the fingers forms an angle a with the plane of the coupling window from 0º  to  10º, a minimum of the coupling resistance, preferably a zero coupling resistance, and which by rotating the plane of the fingers to the second position, in which the plane of the fingers forms an angle α with the plane of the coupling window of 85 °  to  95º, preferably a = 90º, a maximum of the capacitive coupling resistance can be adjusted.

Modes of realization of the invention

Figure 1 shows a coupling window with a coupling means configured in accordance with

the solution.

Figures 2 a-c show sequential views of a coupling means in different positions

Rotary inside a coupling window.

Figure 3 shows an HF filter with six HF-coupled coaxial cavities and

Figure 4 shows a known coupling arrangement using a coupling window between

two coaxial cavity resonators arranged adjacent.

Embodiments of the invention, commercial applicability Figure 1 shows a cutout from the wall of common cavity 4 between two capacitively coupled resonators (not shown) with the coupling window 5, in which the coupling means 7 are arranged. Coupling window 5 is surrounded by electrically conductive material, in which, for example, three sides of the window are limited by the electrically conductive material of the common cavity wall 4, and the fourth electrical conductor limit of the window The coupling element is formed, for example, by a removable cover element 4 'of the HF-filter arrangement, with which the coaxial cavity resonators are closed in a vertical plane to the inner conductors. The cover element is therefore part of the housing.

The coupling means 7 comprise an electrically conductive bar element 8 with a bar axis 9 and two ends of the bar element 10, 11, which is connected to be an electrical conductor, through the ends 10, 11 of the element of bar, with the electrically conductive material surrounding the coupling window 7. At least two electrically connected tongue elements 12, 13 made of electrically conductive material are fixed to the bar element 8, which are insulated with respect to the element of bar

8. For this purpose, a tongue support 14 is provided, which connects the tongue elements 12, 13 in an electrically conductive manner. An insulator is provided between the tongue support 14 and the bar element 8, which ultimately ensures the electrical insulation 12, 13 and the bar element 8.

The tongue elements 12, 13 are non-rotationally connected to the rod element 8 through the tongue holder 14 and the insulated and, therefore, are rotatably mounted around a rotation axis 19 coinciding with the bar axis 9.

Figures 2a-c each show a cross-sectional view of two resonators of coaxial cavity T1, T2 inside a housing G with an intermediate cavity wall 4. Coaxial cavities T1, T2 each comprise some inner conductors 21, 22, extending axially vertically to the plane of the drawing. The coupling window 5, in which the coupling means 7 are arranged, can be recognized in the common cavity wall 4. In this view, the alignment of the rod element 8 parallel to the inner conductors 21, 22 can be recognized , also the insulator 15 concentrically surrounds the bar element 8 in the area of the tongue holder 14. The tongue elements 12, 13 are aligned here in parallel and symmetrically to the bar element 8.

Each of Figures 2a-c shows the coupling means 7 in different positions with respect to a plane of the window 16 defined by the wall of the cavity 4.

The position of the coupling means 7 shown in Figure 2a causes minimum capacitive coupling (zero coupling) between the coaxial cavity resonators T1, T2. In this case, the coupling means 7 are adjusted to rotate about the axis of rotation, such that the plane of the fingers 16 forms a small angle at, typically at  10 °, preferably near 0 °, with the plane of window. This leads to compensation of a parasitic inductive coupling through the coupling window 5 itself, which includes a smaller capacitive coupling, which is caused by the coupling element rotated slightly out of the plane of the window.

Figure 2b shows a rotation position of the coupling means 7, in which the plane of the tongue 17 forms a random angle between 90 ° and 0 ° with the plane of the window 16.

The maximum capacitive coupling between the two coaxial resonators T1, T2 is achieved in the rotational position in Figure 2c, in which the plane of the fingers 17 forms an angle a of 90 ° with the plane of the fingers 16 and in which The distance of the tongue elements from the respective inner conductors 21, 22 of the coaxial cavity resonators T1, T2 is minimal.

Figure 3 shows an HF filter consisting of six resonators of coaxial cavity T1 to T6, which are arranged in two rows Z1, Z2. The main path H with respect to HF is formed by the sequence of coaxial cavity resonators numbered in ascending order, as shown by the arrows. The coupling on the main path H is inductive. In addition, provision is made for an inventive capacitive transverse coupling QK between coaxial cavities T2 and T5, that is, along two coaxial cavity resonators in column SP, whose transverse coupling is performed using a coupling means mounted in a manner Rotary set according to the solution, preferably a coupling means with bar and tongue elements illustrated in Figures 1 and 2.

Claims (13)

1.- An HF-filter arrangement (1) with at least two capacitively coaxial cavity resonators (2, 3), which are coupled through an electrically conductive common cavity wall (4) or through walls of electrically connected cavity, respectively, in which a coupling window (5) is inserted in the common cavity wall (4) or in the electrically connected cavity walls, the window of which is completely enclosed by electrically conductive material (6) and into which a coupling means (7) of variable adjustable capacity, characterized in that the coupling means (7) comprise an electrically conductive bar element (8) with a bar axis (9) as well as two ends (10, 11) of the bar element, whose element is connected on both sides to be conductive of electricity through the ends (10, 11) of the bar element to the electrically conductive material (6) that encloses the coupling window (7) and why, electrically isolated from the bar element (8), at least two electrically connected tongue elements (12, 13) made of electrically conductive material and fixed to the bar element (8) are rotatably mounted around an axis of rotation (19) that matches the bar element (9). 2. An HF-filter arrangement according to claim 1, characterized in that the rod element (8) is rotatably arranged around the axis of rotation (19) within the coupling window (5) and the at least two tongues (12, 13) are fixed non-rotationally to the rod element (8). 3. An HF-filter arrangement according to claim 1 or 2, characterized in that the tongue elements (12, 13) are configured in the form of a bar and arranged in parallel as well as equidistant from the axis of rotation (19) . 4. The HF filter arrangement according to any one of claims 1 to 3, characterized in that the tongue elements (12, 13) are arranged diametrically opposite to the bar element (8). 5. The HF filter arrangement according to any one of claims 1 to 3, characterized in that the elements (12, 13) are arranged diametrically opposite to the bar element, because a tongue element and the bar element they describe a foreground and why the other tongue element and the bar element describe a background, and why the first and second planes intersect at an angle α, in which α  15 °. 6. The HF filter arrangement according to claim 1 or 2, characterized in that the tongue elements (12, 13) are configured as bars and are arranged diametrically opposite to the bar element, and because the tongue elements they are arranged inclined in the radial direction relative to the axis of rotation. 7. The HF filter arrangement according to any one of claims 1 to 6, characterized in that the rod element (8) is aligned parallel to the longitudinal extension of an inner conductor (20, 21) of at least one of the at least two cavity resonators (1, 2). 8. The HF filter arrangement according to claim 2, characterized in that the at least two cavity resonators (1, 2) are surrounded, at least partially, by a housing (G) and that the rod element (8) It can be turned directly or indirectly from the outside of the housing (22). 9. The HF filter arrangement according to claims 1 to 8, characterized in that the tongue elements (12, 13) can be rotated around the axis of rotation (19) within a range of rotation angle α of at least 80 °, preferably at least 90 ° and particularly preferably at least 180 °. 10. An HF filter comprising a plurality of cavity resonators (1, 2), which are coupled to each other and which are arranged in a matrix-shaped manner along at least two rows and at least two columns, wherein the coupling between two cavity resonators arranged in the direction of the rows is configured to be inductive, characterized in that at least one pair of cavity resonators arranged in the direction of the columns is configured as an HF filter arrangement of according to any one of claims 1 to 9. 11. An HF filter comprising a plurality of cavity resonators, which are coupled to each other and which are arranged in a matrix-shaped manner along at least two rows and at least two columns, in which the coupling between two cavity resonators arranged in the direction of the rows is configured to be inductive, characterized in that the coupling, respectively, between two cavity resonators arranged in the direction of the rows is configured to be capacitive, and why the two cavity resonators are configured as an HF filter arrangement according to any one of claims 1 to 9. 12. A method for varying an intensity of the electromagnetic coupling between two cavity resonators that are configured in the course of an HF filter arrangement according to claims 1 to 9 and are coupled to each other, in which the tongue elements , which describe a tongue plane together with the element of bar, are transferred, exclusively by continuous rotation around the axis of rotation, from a first position, in which the tongue elements are located in or in the region of a plane of coupling window, which is assignable to the coupling window , to a second position, in which the plane of the tongue, assignable to the elements of the tongue, forms an angle α with the plane of the coupling window. The method according to claim 12, characterized in that turning the plane of the fingers to the first position, in which the plane of the fingers forms an angle α of 0 °  α  10 ° with the plane of the coupling window, a minimum coupling intensity is adjusted, preferably no coupling intensity, and by turning to the second position, in which the plane of the tongues forms an angle α of 85 °  α  95 °, preferably α = 90º with the plane of the coupling window, a maximum intensity of 10 capacitive coupling.