EP2920840B1 - Radio-frequency blocking filter - Google Patents

Description

The invention relates to a high-frequency cut filter in coaxial design according to the preamble of claim 1.

In radio systems, especially in the mobile sector, a common antenna is often used for transmit and receive signals. The transmit and receive signals each use different frequency ranges, and the antenna must be suitable for transmitting and receiving in both frequency ranges. For the separation of the transmit and receive signals, therefore, a suitable frequency filtering is required, with the one hand, the transmission signals from the transmitter to the antenna and on the other hand, the received signals are forwarded from the antenna to the receiver. For the division of the transmit and receive signals, high frequency filters in coaxial design are used today.

For example, a pair of high frequency filters may be used, both of which pass a particular frequency band (bandpass filter). Alternatively, a pair of high frequency filters may be used, both of which block a particular frequency band (bandstop filter). Further, a pair of high frequency filters may be used, of which a filter passes frequencies below a frequency between transmit and receive bands and blocks frequencies above that frequency (low pass filter) and blocks the other filter frequencies below a frequency between transmit and receive bands and passes frequencies thereabove (high pass filter). Other combinations of the just mentioned filter types are conceivable.

High-frequency filters are often constructed from coaxial resonators because they consist of milling or castings, making them easy to manufacture. In addition, these resonators ensure a high electrical quality and a relatively high temperature stability.

A high-frequency filter known from the prior art comprises an input terminal and an output terminal, which are galvanically connected to one another via a connecting line. Furthermore, the high-frequency filter comprises at least two coaxial resonators, which are each capacitively coupled to the connecting line, so that the resonators are also capacitively coupled to the input terminal and the output terminal. The coupling points of the resonators with the connecting line must have on the connecting line a distance of one quarter of the wavelength of the high-frequency filter to be filtered center frequency signal, so that the individual resonators are resonantly coupled to each other.

E-GSM signals used in mobile radio use the frequency range of 880-915 MHz for the so-called uplink and the frequency range of 925-960 MHz for the so-called downlink. Due to the omission of television programs transmitted analogously via satellites, the so-called "digital dividend" in the frequency range of 790-862 MHz is accessible to mobile radio. The frequency band of 791-821 MHz is used for the uplink, whereas the frequency band of 832-862 MHz is used for the downlink.

A high-frequency filter is for example from the US 4,276,525 known. This is a conventional bandpass filter in which capacitive coupling elements are provided, coming from an input up to an output at the level of the free ends of the inner conductors (which are designed as coaxial resonators). Therefore, in such bandpass filters, the signal transmission takes place directly via the resonators, ie the resonance frequencies are within the useful frequency range.

A similar prior art is also from the US Pat. No. 6,366,184 B1 refer to. Again, a high-frequency bandpass filter is described with a plurality of adjacent resonators, in which the individual resonators are coupled to each other via different additional coupling devices, for example in the form of coupling wires.

The same is true for the end of the US 4,268,809 previously known high frequency bandpass filters. Also there is a series of line members to form a capacitive transmission path across the resonators away.

A coaxial resonator is further example of the EP 0 576 273 A1 known. However, this is a different type of resonator differs from the aforementioned prior art filter assembly. The from the EP 0 576 273 A1 known type of filter comprises a dielectric block, which is longitudinally penetrated centrally by a hollow cylindrical space which is formed as a cylindrical hollow inner conductor tube.

A dielectric filter is also from the GB 2 234 399 A known.

Finally, even on a previously known high-frequency filter according to the WO 2006/029868 A1 which comprises a substrate of a dielectric material having a first and an opposite second side, wherein on the first side of the substrate at least one strip conductor is applied. The filter preferably comprises a plurality of resonators, which are electrically coupled to the at least one strip conductor. Spaced apart from the strip conductor, a ground surface is provided, wherein at least one resonator in the form of a coaxial resonator with an outer conductor pot and a rod-shaped inner conductor arranged coaxially in the outer conductor pot is galvanically connected to the ground surface.

In contrast to the bandpass filters mentioned above, so-called notch filters are also known which, when constructed in a coaxial design similar to the above-explained filters, usually comprise a plurality of coaxial resonators coupled together, with a signal line from one input adjacent to the internal conductors of these resonators goes to an exit. With blocking filters of this type, the smaller the blocking frequency, the longer the signal line between two adjacent resonators must be. One of the reasons for this is that the length of the signal line between two resonators is often supposed to be one quarter of the wavelength of the blocking frequency. For a signal with a frequency of 790 MHz, a quarter of this wavelength is 0.1 m. In a high-frequency filter, the distance between two inner conductors of two adjacent resonators is usually about 2 cm to 3 cm, so that the approximately 10 cm long connecting lines between adjacent resonators must be folded consuming. The production of a correspondingly constructed high-frequency filter is complicated and expensive.

The object of the present invention is, starting from the generic state of the art, to realize an improved and simpler high-frequency filter in the form of a high-frequency blocking filter which requires no complicated laying of a connecting line through the high-frequency blocking filter and can be realized in a space-saving and cost-effective manner.

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

As mentioned and as is known, a high-frequency notch filter is different from a high-frequency band-pass filter by its signal transmission path.

In the case of a high-frequency bandpass filter, the signal transmission path takes place directly via the resonators. That is, the resonance frequencies are within the useful frequency range of the high-frequency filter. In other words, the resonators oscillate with those frequencies that are to be transmitted.

In contrast, high-frequency cutoff filters have a completely different signal transmission path. In the case of high-frequency blocking filters, the useful signal transmission takes place via a separately provided line, which usually runs continuously from an input to an output of the blocking filter according to the prior art. In addition, it is provided that this connecting line, also referred to below as a signal line, can be brought closer to the resonators, i. an approximation to the inner conductors of the capacitive resonators is capacitively coupled. In this case, the resonators thus oscillate at a frequency which is outside the transmission frequency range which is to be transmitted via the connecting line.

In particular, but at low frequencies, this requires a comparatively long connection line, with the result that the high-frequency filter must have a considerable size. This is where the invention starts.

In the context of the invention, it is proposed that the connecting or signal line which is continuous in the prior art in the case of a high-frequency blocking filter now has at least one or more galvanic separation points, which are designed as capacitive separation points in this line. These capacitive separation points are also capacitively coupled to individual resonators. As a result, a significant reduction in the size of corresponding high-frequency cut filter in coaxial design is possible. Because of the galvanic separation points in the form of the aforementioned coupling capacitance, a phase shift of the signal on the connecting line is made possible, which corresponds to the effect of a shortened continuous connecting line.

In other words, the invention thus comprises a signal line running through the high-frequency cutoff filter, which is provided with at least one or more galvanic separation points (corresponding to the number of resonators), wherein the resonators are arranged by means of one each at the separation point and with two free ends the connecting line connected coupling capacity are interconnected. It is therefore sometimes spoken of capacitive separation points.

The signal line thus comprises two galvanically separated line sections. In the equivalent circuit of the corresponding high-frequency filter, the input terminal and the output terminal are through the connected between the line sections coupling capacitance connected to each other.

The capacitive coupling of the respective resonators with the signal line and thus with the input terminal and the output terminal is realized in that the signal line in the region of the respective inner conductor of the respective resonators each having a further coupling surface.

In the prior art, corresponding high-frequency cutoff filters are built comparatively large. A large size of such a filter is also necessary to achieve a high quality and a high insertion loss per se. The distance between the individual domes, i. the adjacent inner conductor of two adjacent resonators have a certain order of magnitude, so that the here at the two adjacent domes passing signal lines have a corresponding size for generating a specific high frequency blocking frequency. At this point, the invention starts and creates a highly miniaturized solution.

Due to the connection of the at least two resonators by the coupling capacitance, the length of the signal line between the coupling points of the at least two resonators with the signal line, as mentioned, be shortened, since the coupling capacitance leads to a phase shift of the signal to be filtered, wherein the phase shift of the signal has the same effect as transmitting the signal to be filtered via a corresponding long connection line, ie a correspondingly long signal line.

The inventive compound of the resonators on the coupling capacitance, which is arranged at the separation point of the connecting line, thus not only reduces the length of the necessary signal line but the high-frequency cut filter according to the invention are made very compact and yet simple and therefore inexpensive.

In the high-frequency blocking filter according to the invention, the inner conductors preferably extend from the housing bottom perpendicularly in the direction of the housing cover.

Furthermore, in the high-frequency blocking filter according to the invention, the inner conductors are preferably designed as inner conductor tubes. This makes it possible that in the correspondingly formed cavity of the inner conductor tube, a tuning element can be introduced distance variable, so that the high-frequency filter is tuned.

Preferably, the connecting line comprises at least two line sections, which are galvanically separated from one another at the separation point of the connecting line. In this case, a first line section is galvanically connected to the input terminal and / or capacitively coupled and comprises a first coupling surface, and a second line section is galvanically connected to the output terminal and / or capacitively coupled and comprises a second coupling surface. The first coupling surface and the second coupling surface are at least one another partially opposite such that the first coupling surface and the second coupling surface form the coupling capacity.

A correspondingly constructed high-frequency filter is particularly simple in its construction. The coupling surfaces of the respective line sections may be aligned parallel to the longitudinal extent of the high-frequency filter and parallel to the height extent of the respective inner conductors of the resonators. This makes the geometry of a correspondingly constructed high-frequency filter particularly simple. The size of the respective coupling surfaces of the respective line sections can be easily adapted by simply replacing the corresponding line sections, wherein the line sections have at their respective ends adapted to the requirements large coupling surfaces.

Preferably, the line sections are offset parallel to each other and the first coupling surfaces and the second coupling surfaces arranged offset parallel to each other. As a result, the positioning of the respective coupling surfaces with each other is particularly easy. Furthermore, the distance of the coupling surfaces to each other is easily adjustable.

Preferably, a partition wall comprising a dielectric material is arranged between the first coupling surface and the second coupling surface.

In a correspondingly constructed high-frequency filter, the capacitance of a correspondingly formed coupling capacitance can be influenced by selecting the dielectric material.

Preferably, the high-frequency filter further comprises a holding and / or receiving device, which is supported on the inner conductor and / or fastened to the inner conductor and has two pocket-shaped receiving spaces, which are separated by a partition wall. In this case, the first coupling surface is arranged in a first receiving space of the holding and / or receiving device, and the second coupling surface is arranged in a second receiving space of the holding and / or receiving device.

By providing a correspondingly constructed holding and / or receiving device, the attachment of the respective line sections to the inner conductor is particularly simple. Furthermore, the arrangement of the respective line sections and consequently the respective coupling surfaces to each other by the holding and / or receiving device is particularly simple, since the corresponding coupling surfaces must be easily inserted into the space provided receiving spaces or receiving pockets of the holding and / or receiving device. The holding and / or receiving device can either be easily supported on the respective inner conductors of the resonators. Furthermore, it is also possible that the holding and / or receiving device is connected, for example, by a bond with the inner conductors or attached thereto.

The respective second coupling surfaces of the line sections are preferably arranged opposite the respective inner conductors, so that the respective resonators are capacitively coupled to the respective line sections. Between the respective second coupling surfaces and the respective inner conductors while a support wall of the holding and / or receiving device is arranged.

By a corresponding arrangement of the respective second coupling surfaces of the line sections, the capacitive coupling of the resonators with the respective line sections is achieved in a structurally particularly simple manner. Furthermore, by selecting the material of the support wall, which is arranged between the inner conductors and the second coupling surfaces, the capacitive coupling between the coupling surfaces and the inner conductors can be adjusted.

Preferably, the high-frequency filter further comprises a further connection. This additional connection can also be referred to as the send / receive connection. The further connection is arranged between the input connection and the output connection and is galvanically connected to the connection line. In this case, the further connection between coupling points of the resonators is arranged with the connecting line.

By a corresponding structure of the high-frequency filter, this can form a duplex switch in a corresponding embodiment of the resonators. In this case, the input terminal may be provided for a transmitter, whereas the output terminal may be provided for a receiver. The further connection or the transmission / reception connection can then be connected to an antenna which is provided and designed for the transmission and reception of signals.

Preferably, at least two resonators are capacitively coupled to the connection line between the further connection and the input connection. Furthermore, at least two resonators are also capacitively coupled to the connecting line between the further connection and the output connection.

By means of a corresponding design of the high-frequency blocking filter, it can have a high attenuation over a wide frequency range, so that a wider frequency range can be blocked by the correspondingly constructed high-frequency blocking filter.

The high-frequency cutoff filter according to the invention preferably operates in the range between 790 MHz to 862 MHz and / or in the range between 880 MHz to 960 MHz and / or in the range of the 1800 MHz mobile frequency and / or the 2000 MHz mobile frequency.

Figur 1:

eine räumliche Darstellung eines erfindungsgemäßen Hochfrequenz-Sperrfilters mit abmontiertem Gehäusedeckel;

Figur 2:

eine Draufsicht des in Figur 1 dargestellten Hochfrequenz-Sperrfilters;

Figur 3:

eine Seitenansicht des in den Figuren 1 und 2 dargestellten Hochfrequenz-Sperrfilters, das entlang der Schnittebene P-P aus Figur 2 aufgeschnitten ist;

Figur 4a:

eine Seitenansicht des in den Figuren 1 bis 3 dargestellten Hochfrequenz-Sperrfilters, das entlang der Schnittebene P1-P1 aus Figur 2 aufgeschnitten;

Figur 4b:

ein Vergrößerung des in Figur 4a umrandeten Bereichs des Hochfrequenz-Sperrfilters;

Figur 5:

eine räumliche Darstellung des erfindungsgemäßen Hochfrequenz-Sperrfilters mit einem Eingangsanschluss, einem Ausgangsanschluss und einem Sende-/Empfangsanschluss;

Figur 6:

den in Figur 5 dargestellten Hochfrequenz-Sperrfilter ohne Halte- und/oder Aufnahmeeinrichtungen;

Figur 7:

eine Seitenansicht entlang eines Längsschnitts des in den Figuren 5 und 6 dargestellten Hochfrequenz-Sperrfilters;

Figur 8:

eine Draufsicht auf das in den Figuren 5 bis 7 dargestellte Hochfrequenz-Sperrfilter;

Figur 9:

ein Ersatzschaltbild eines erfindungsgemäßen Hochfrequenz-Sperrfilters mit lediglich zwei gekoppelten Resonatoren; und

Figur 10:

ein Ersatzschaltbild des in den Figuren 1 bis 8 dargestellten Hochfrequenz-Sperrfilters.

The invention will be explained in more detail with reference to drawings. In detail:

FIG. 1:

a spatial representation of a high-frequency blocking filter according to the invention with dismantled housing cover;

FIG. 2:

a top view of the in FIG. 1 shown high-frequency cutoff filter;

FIG. 3:

a side view of the in the FIGS. 1 and 2 shown high-frequency blocking filter, along the cutting plane PP off FIG. 2 is cut open;

FIG. 4a

a side view of the in the FIGS. 1 to 3 shown high-frequency cut filter, along the cutting plane P1-P1 off FIG. 2 cut;

FIG. 4b:

an enlargement of the in FIG. 4a rimmed area of the high frequency cutoff filter;

FIG. 5:

a spatial representation of the radio frequency rejection filter according to the invention with an input terminal, an output terminal and a transmission / reception port;

FIG. 6:

the in FIG. 5 shown high-frequency cut filter without holding and / or recording devices;

FIG. 7:

a side view along a longitudinal section of the in the FIGS. 5 and 6 shown high-frequency cutoff filter;

FIG. 8:

a plan view of that in the FIGS. 5 to 7 illustrated high frequency rejection filters;

FIG. 9:

an equivalent circuit diagram of a high-frequency cutoff filter according to the invention with only two coupled resonators; and

FIG. 10:

an equivalent circuit diagram in the FIGS. 1 to 8 shown high-frequency blocking filter.

In the description that follows, the same reference numerals designate the same components or the same features that a description made with respect to a figure with respect to a component also applies to the other figures, whereby a repetitive description is avoided.

The following is with reference to the FIGS. 1 to 10 an inventive high-frequency filter 1 described in coaxial design. This high-frequency filter 1 is hereinafter referred to above all as high-frequency blocking filter 1, since it is a blocking filter. It comprises an outer conductor housing with a housing bottom 11 and a housing cover 11 which is at a distance from the housing bottom 11 and arranged opposite to it, and which is only in the housing cover 11 FIG. 7 is shown. The outer conductor housing in this case comprises the so-called resonator interior 10a. In the remaining figures, the high frequency blocking filter is shown with the housing cover 12 removed. Between the housing bottom 11 and the housing cover 12, a housing wall 13 is provided circumferentially. That in the FIGS. 1 to 8 shown high-frequency cutoff filter 1 comprises six resonators 10, which are separated from each other by partitions 14.

The six resonators 10 each comprise an inner conductor 16, wherein the inner conductors 16 are each electrically connected to the housing bottom 11 and extend perpendicularly from the housing bottom 11 in the direction of the housing cover 12. The outer conductor housing may be formed integrally with the inner conductors 16, for example as a milling, turning or casting.

How out FIG. 1 and 4a and FIG. 4b shows, the respective inner conductors 16 end in each case at a distance in front of Housing cover 12. Alternatively, the respective inner conductor 16 may extend to the housing cover 12, which then have to be electrically isolated from the housing cover 12 by an insulating layer.

From the FIGS. 5 to 8 It can be seen that the high-frequency cutoff filter 1 comprises an input terminal 20, an output terminal 30 and a further terminal 40 in the form of a transmitting / receiving terminal 40. This transmitting and receiving port thus has a dual function as the output and input port. The input terminal 20, the output terminal 30 and the transmitting / receiving terminal 40 are coupled to each other via a (continuous) connection line 50, that is connected, which is also referred to below as the signal line 50. Via this signal line corresponding high-frequency signals are transmitted in the passband, whereby the so-called passband is ultimately defined or defined. In this case, the so-called high-frequency blocking frequency is also generated by the resonators, that is to say that band-stop filter in whose frequency range a signal transmission can not take place. At this time, the transmission / reception port 40 is disposed between the input port 20 and the output port 30. How out FIG. 7 can be seen, the input terminal 20, the output terminal 30 and the transmitting / receiving port 40 are each formed as a coaxial connection, wherein the respective outer conductor to the outer conductor housing and the respective inner conductor to the connecting line 50 are electrically connected.

In the illustrated barrier filter, the resonators are usually not directly coupled, but only about the signal line 50. In this case, the individual resonators are each preferably in the correct phase, for example coupled capacitively. In an optimal arrangement, it is then possible to detune or change the individual Sperrpolfrequenzen a respective resonator without affecting the remaining Sperrpole (resonators).

For example, from the drawings from the FIGS. 5, 6 . 7, 8 . 9 or 10 2, the signal line 50 passes from the one end of the input terminal 20 closer to the high-frequency notch filter 1 to the output terminal 30 adjacent the opposite end of the notch filter 1, passing through all the resonators 10, ie through all the resonator interiors 10a. For this purpose, recesses or openings 14a are formed in the partition walls 40 separating the individual resonators from one another in the area and at the height of the connecting line, through which the connecting line 50 extends (electrically isolated from the partitions 40).

In the illustrated embodiment, the connecting line 50 on three galvanic separation points, the four line sections 51, 52, 53, 54 of the connecting line 50 from each other electrically. Here, in each case one - which will be discussed in detail below - capacitive separation point 60 'is formed. The line section 51 comprises a first coupling surface 51.1 facing the output connection 30 and a second coupling surface 51.2 facing the input connection 20. The line section 52 comprises a first coupling surface 52.1 facing the output connection 30 and a second coupling surface facing the input connection 20 52.2. The line section 53 comprises a first coupling 53.1 facing the outlet connection 30 and a second coupling surface 53.2 facing the inlet connection 20. The line section 54 in turn comprises three second coupling surfaces 54.2.

The respective first coupling surfaces 51.1, 52.1, 53.1 and second coupling surfaces 51.2, 52.2, 53.2 and 54.2 run parallel to a longitudinal extent of the outer conductor housing of the high-frequency blocking filter 1. In particular from the Figures 2 and 8th It can be seen that the line sections 51, 52, 53, 54 are parallel to one another and offset relative to one another such that the first coupling surface 51.1 of the line section 51 faces the second coupling surface 52.2 of the line section 52. Because the first coupling surface 51.1 faces the second coupling surface 52.2, these two coupling surfaces form a capacitive separation point 60 'in the form of a first coupling capacitance 60, which is arranged at this capacitive separation point between the two line sections 51 and 52, and which are shown in FIGS the leftmost two resonators 10 capacitively interconnects.

Characterized in that the mentioned line sections 51, 52, 53, 54 not only to each other but also parallel to the longitudinal extension of the outer conductor housing, ie parallel to the long housing walls 13 and thereby the individual line sections 51, 52, 53, 54 in the region of the capacitive separation points are offset parallel to each other to form a small coupling distance, resulting in an arrangement as based on FIG. 8 is shown in plan view. In other words, it is added the first in FIG. 8 left-lying resonators the distance between each line section between the in FIG. 8 underlying lateral housing wall 3 and a subsequent capacitive separation point 60 'by the thickness of the coupling distance greater. At the same time a distance between the corresponding line section to the in FIG. 8 upper side housing wall 13 smaller by the same amount. But since the coupling distances between the individual line sections and the respective inner conductor 16 remain the same (should be the same), is off FIG. 8 It can also be seen that the inner conductor from the first to the fourth resonator in different relative position between the two parallel housing walls 13 extending in the longitudinal direction. In this case, the inner conductors perform the same lateral offset, with which the successive line sections are arranged with respect to each other in question, caused by the coupling section lateral offset.

The first coupling surface 52.1 of the line section 52 faces the second coupling surface 53.2 of the line section 53 in such a way that the first coupling surface 52.1 and the second coupling surface 53.2 form a further coupling capacitance 60 capacitively interconnecting the second and third resonators 10 counted in the figures from the left coupled.

Furthermore, the first coupling surface 53.1 of the line section 53 of the second coupling surface 54.2 of the line section 54 is arranged opposite, so that the first coupling surface 53.1 and the second coupling surface 54.2 form a further coupling capacitance 60 which corresponds to the on the left of counted third and fourth resonators 10 capacitively coupled with each other.

The fourth, fifth and sixth resonators 10 counted from the left in the figures are not coupled to one another via separate coupling capacitances 60, but the individual resonators 10 are coupled to one another only via the line section 54.

The line sections 51, 52, 53, 54 each have second coupling surfaces 51.2, 52.2, 53.2, 54.2, which are arranged opposite the respective inner conductors 16 of the resonators 10, so that the respective resonators 10 or the inner conductor 16 with the corresponding line sections 51 , 52, 53, 54 are capacitively coupled, namely via the so-called capacitive internal conductor or resonator coupling 65.

It can be seen from the figures that the high-frequency blocking filter 1 according to the invention comprises a number of holding and / or receiving devices 70 corresponding to the number of resonators 10. The positioning of the holding and / or receiving devices 70 with respect to the respective inner conductors 16 of the resonators 10 is exemplary in the FIGS. 4a and 4b shown. The holding and / or receiving device 70 comprises a support wall 74, by means of which the holding and / or receiving device 70 is in direct contact with the inner conductor 16, or which is arranged at a small distance from the inner conductor 16 spaced. It can also be seen that the corresponding line sections 51, 52, 53, 54 and the respective associated coupling surfaces 51.2, 52.2, 53.2, 54.2 of the signal line 50 in the lateral distance are arranged to the respective inner conductors 16 of the resonators 10. Since the corresponding line sections 51, 52, 53, 54 are designed strip-shaped, ie transverse to the longitudinal direction of the lines have a more or less rectangular cross-section (ie at least two parallel side surfaces 50, which are aligned in the embodiment shown also parallel to the inner conductors), be formed by the correspondingly dimensioned cooperating coupling surfaces on the galvanic separation points without additional measures. That is, the line sections form at the galvanic separation points, the so-called capacitive separation points 60 'with the respectively associated end portions of the line sections, which form the coupling surfaces of a coupling capacitance formed thereby. The mentioned holding and / or receiving device 70 is supported on the upper free end 16 a of the inner conductor 16 and / or fixed to the inner conductor 16. The attachment of the holding and / or receiving device 70 to the inner conductor 16 may be realized, for example by gluing.

From the figures it can be seen that the holding and / or receiving device 70 has two receiving spaces 72, 73, which are separated from one another by a partition wall 71. The first coupling surface 52.1 of the line section 52 is arranged in a first receiving space 72 of the holding and / or receiving device 70, whereas the second coupling surface 53.2 of the line section 53 is arranged in a second receiving space 73 of the holding and / or receiving device 70.

Thus, the line sections 51, 52, 53, 54 are each arranged in the region of the upper free ends 16 a of the corresponding inner conductor 16. It can be seen from the drawings that extend the line sections with their parallel to the inner conductor height sections then also from the upper free end 16a of the inner conductor 16, starting over a certain vertical distance parallel to the inner conductor 16 down toward housing bottom 11, but preferably only in a range of not more than 10% or 20% or up to 30% of the axial length of the inner conductor 16. In this height range relative to the inner conductor 16 and the aforementioned recesses or openings 14a are then formed at the partitions 14, about which Connecting line at the same height or at the same distance from the housing cover 12 and the housing bottom runs.

The holding and / or receiving device 70 is preferably made of a dielectric material, in particular a plastic. After attaching the respective holding and / or receiving devices 70 to the respective inner conductors 16, the respective line sections 51, 52, 53, 54 with demounted housing cover 12 from above into the corresponding receiving spaces 72, 73, which are formed as receiving pockets, are pushed. Thereby, the positioning of the line sections 51, 52, 53, 54 to each other and to the inner conductors 16 in a very simple manner possible, so that the desired resonance properties of the respective resonators 10 and thus the filter characteristics of the high-frequency blocking filter 1 are always relatively easily achieved because the positions of the line sections through the holding and / or receiving device 70 are determined.

It can be seen from the figures that the respective second coupling surfaces 51.2, 52.2, 53.2 and 54.2 are arranged opposite the respective inner conductors 16. As a result, the resonators 10 (and / or the inner conductors 16) are capacitively coupled to the respective line sections 51, 52, 53, 54 (capacitive inner conductor and / or resonator coupling 65). Between the second coupling surfaces 51.2, 52.2, 53.2, 54.2 and the respective inner conductors 16 is one, the upper end 16a of an inner conductor 16 (adjacent to the housing cover 12) partially overlapping support wall 74 (FIG. FIG. 4b ) of a corresponding holding and / or receiving device 70. Since the support wall 74 is made of a dielectric material, the capacitive coupling 65 (ie, the so-called capacitive inner conductor coupling 65, which is sometimes called capacitive resonator coupling 65) of the respective second coupling surface 51.2, 52.2, 53.2, 54.2 with the Inner conductors 16 influenced by the material selection of the support wall 74.

It can be seen from the overall construction that the mutual coupling of the resonators 10 used in the notch filter is not effected by a direct coupling between the resonators, but only via the signal line 50. Therefore, no otherwise conventional coupling window or coupling diaphragms are provided between the individual resonators. The coupling of the resonators via the signal line 50 is preferably carried out in each case in the correct phase, for example by the capacitive coupling. With optimal arrangement then the individual Sperrpolfrequenzen detuned or changed without affecting the remaining locking poles. In other words, therefore, the explained inventive construction of the high-frequency cut filter usually includes a plurality of coaxial resonators 10, wherein adjacent and z. B. capacitive coupled to the inner conductor 10 of these resonators, the signal line 50 between two terminals 20, 30, 40 extends.

The resonators 10 of the in FIGS. 1 to 8 shown high-frequency blocking filter 1 are formed such that the high-frequency cut filter 1 is a duplex switch 1. FIG. 10 shows an equivalent circuit diagram of the in FIGS. 1 to 8 shown high frequency blocking filter 1. The transmitting / receiving port 40 is connectable to an antenna, not shown in the figures. Via the antenna, not shown, output signals can both be sent and received signals can be received. To the input terminal 20, a transmitter not shown in the figures can be connected, and to the output terminal 30, a receiver not shown in the figures can be connected.

E-GSM signals used in mobile radio use the frequency range from 880 to 915 MHz for the so-called uplink and the frequency range from 925 to 960 MHz for the so-called downlink. Thus, in this example, the transmitter operates in the frequency range 880-915 MHz. The duplexer 1 is then designed such that the three resonators 10 between the input terminal 20 and the transmitting / receiving terminal 40 are designed in their size and their geometry such that these three coupled resonators 10 signals in the frequency domain from 880 to 915 MHz, but strongly attenuate signals in the frequency range of 925 to 960 MHz. The three resonators 10 between the output terminal 30 and the transmitting / receiving terminal 40 in turn are designed in size and geometry such that these signals in the frequency range of 925 to 960 MHz pass, whereas signals in the frequency range from 880 to 915 MHz strongly attenuated, So be locked.

Consequently, a signal introduced from the transmitter into the duplex switch 1 via the input terminal 20 is forwarded to the transmitting / receiving terminal 40, whereas this signal is attenuated by the three resonators 10 between the transmitting / receiving terminal 40 and the output terminal 30, so that the signal does not reach the output terminal 30. The signal fed from the transmitter into the duplexer 1 is emitted via the antenna (not shown), but does not pass via the output terminal 30 to the receiver (not shown) of the high-frequency blocking filter 1 thus formed. In other words, this means that a passband or passband is longitudinal the signal line 50 is provided, via which, for example, received by an antenna received signals or received by the antenna high-frequency band transmitted from the transmitting / receiving port 40 to the output terminal 30 to a receiver, not shown, whereas a corresponding high frequency frequency band with respect to the transmission mode from an input terminal 20 to the transmitting-receiving terminal 40 and transmitted to an unspecified antenna shown there is supplied, so what about the corresponding signals in the transmission mode can be transmitted. As a result, the receiving branch is separated from the transmitting branch by the corresponding high-frequency blocking bands or blocking regions, so that over-coupling is avoided.

Signals received by the antenna in the range of 925 to 960 MHz are fed to the duplex switch 1 via the transmission / reception port 40. These signals are forwarded via the three resonators 10 between the transmit / receive port 40 and the output port 30 to the receiver. However, these signals are so much attenuated by the three resonators between the transmit / receive port 40 and the input port 20 that they do not pass through the input port 20 to the transmitter.

In the example, the transmitter operates in the frequency range 880-915 MHz. The spacing of the coupling points of adjacent resonators to the connecting line 50 must be a distance of λ / 4 of the center frequency of this frequency band. The three resonators 10 facing the output terminal 30, which are arranged between the transmitting / receiving terminal 40 and the output terminal 30, have a passband of 925 to 960 MHz, so that the distance between the coupling point of adjacent resonators 10 to the connecting line 50 is smaller, so that the connecting lines or the corresponding line sections between the respective resonators can be made shorter than in the case of the three resonators 10 facing the transmitter.

To shorten the line sections 51, 52 and 53, the coupling capacitances described above are between them 60 arranged. These coupling capacitances 60 cause a phase shift of the signal. The sum of this phase shift with the phase shift corresponding to the transit time of the signal via the line sections 51, 52, 53 corresponds to the phase shift of an electrical line with a length of, for example, λ / 4 of the center frequency signal.

The line section 54, which couples the three resonators 10 between the transmit / receive port 40 and the output port 30, has no corresponding coupling capacitances 60, since the distance between the coupling point of two adjacent resonators 10 to the line section 54 is smaller, so that no coupling capacity 60 must be used for effective extension of the line section 54. From the FIGS. 1 . 3 and 5 to 7 However, it can be seen that the line section 54 is not straight but meander-shaped, so that the distances of the coupling points of two adjacent resonators 10 are just λ / 4 for center frequency signals in the band from 925 to 960 MHz.

From the Figures 2 and 8th it can be seen that the respective inner conductors 16 of the resonators 10 to the housing wall 13 each have different distances. On the one hand, this is due to the fact that, as a result, the individual line sections 51, 52, 53, 54 can be realized geometrically particularly simply by straight lines or plates. On the other hand, this is due to the fact that the respective resonators should have different resonance frequencies which differ from one another, so that a corresponding wide (in the frequency width) stopband can be achieved.

FIG. 9 shows an equivalent circuit diagram of a high-frequency cutoff filter according to the invention with a continuous signal line 50 (and the switched in the continuous signal line 50 coupling capacitor 60), which has only two resonators 10 which are capacitively connected to each other via a coupling capacitance 60. A corresponding high-frequency blocking filter 1 or a corresponding duplexer 1 has narrower blocking regions for the uplink and downlink, since only one resonator 10 is provided for the uplink and the downlink. The remaining functioning of the in FIG. 9 However, shown high-frequency cut filter 1 is identical to the operation of the reference to the FIGS. 1 to 8 and 10 described high-frequency blocking filter. 1

From the above description, it is apparent that in the described high-frequency cutoff filter the useful signal transmission via the connecting line 50 from one input to one output, wherein in the context of the invention, the connecting line additionally by approaching the resonators 10, ie to the inner conductor 16 capacitively coupled with these. By provided in the context of the connection line galvanic separation points in the form of capacitive separation points a de facto shortening of the entire length of the connecting line 50 is realized, whereby the high-frequency cut filter builds comparatively small, even at low high frequencies. Without the mentioned capacitive separation points, the line length would be between two Resonators 10 are about λ / 2. In the context of the invention, this line is significantly shorter.

In the case of the illustrated blocking filter, the desired blocking poles, which are located outside the transmission frequency range, then arise in the case of phase-correct coupling. In this case, the in-phase Sperrpolkopplung can be adjusted by an optimized combination between the individual cable lengths between the capacitive separation points and the size of the capacitance at the separation points themselves.

Claims (19)

1. Radio-frequency blocking filter of a coaxial construction, the radio-frequency blocking filter having the following features:

   - the radio-frequency blocking filter (1) comprises an external conductor housing, having a housing base (11) and a housing cover (12) arranged at a distance from and opposing the housing base (11), between which a housing wall (13) is provided peripherally;

   - the radio-frequency blocking filter (1) comprises at least two resonators (10), which each comprise an internal conductor (16);

   - the internal conductors (16) are each galvanically connected to the housing base (11) and extend from the housing base (11) towards the housing cover (12);

   - the internal conductors (16) each end at a distance from the housing cover (12) and/or are galvanically separated from the housing cover (12),

   - the radio-frequency blocking filter (1) comprises an input terminal (20, 40) and an output terminal (30, 40), the signal line (50) being galvanically connected or capacitively coupled to the input terminal (20, 40) on the one hand and to the output terminal (30, 40) on the other hand,

   characterised by the following features:

   - the signal line (50) extends through the resonators (10) of the radio-frequency blocking filter (1) past the respective internal conductor (16) so as to form a capacitive internal conductor coupling and/or resonator coupling (65) in each case,

   - the signal line (50) comprises at least one galvanic separation point in the form of a capacitive separation point (60'),

   - the capacitive separation point (60') is at a distance from and capacitively coupled to the internal conductors (16),

   - the resonators (10) or internal conductors (16) are each capacitively coupled to the signal line (50),

   - the radio-frequency blocking filter (1) further comprises a holding and/or receiving device (70), which is braced on the internal conductor (16) and/or fixed to the internal conductor (16), and two receiving spaces (72, 73), which are separated from one another by a partition wall (71); and

   - the first coupling face (51.1, 52.1, 53.1) is arranged in a first receiving space (72) of the holding and/or receiving device (70), and the second coupling face (51.2, 52.2, 53.2, 54.2) is arranged in a second receiving space (73) of the holding and/or receiving device (70).
2. Radio-frequency blocking filter according to claim 1, characterised in that the at least one capacitive separation point (60') is provided in the signal line (50) at a lateral distance from the internal conductor (16), preferably in the region in front of the upper end (16a) of the internal conductor (16).
3. Radio-frequency blocking filter according to either claim 1 or claim 2, characterised in that, at the capacitive separation point (60'), the galvanically separated signal line (50) in each case comprises a first coupling face (51.1, 52.1, 53.1) and a second coupling face (52.2, 53.2, 54.2), whereby the two galvanically separated portions of the signal line (50) are capacitively interconnected.
4. Radio-frequency blocking filter according to any of claims 1 to 3, characterised in that the signal line (50) is configured to be strip-shaped, having a rectangular cross section with respect to the direction of extension.
5. Radio-frequency blocking filter according to any of claims 1 to 4, characterised in that the internal conductors (16) are each formed as internal conductor tubes (16).
6. Radio-frequency blocking filter according to any of the preceding claims, characterised by the following features:

   - the signal line (50) comprises at least two line portions (51, 52, 53, 54) which are galvanically separated from one another at the capacitive separation point (60') of the signal line (50);

   - a first line portion (51, 52, 53) is galvanically connected and/or capacitively coupled to the input terminal (20, 40) and comprises a first coupling face (51.1, 52.1, 53.1);

   - a second line portion (52, 53, 54) is galvanically connected and/or capacitively coupled to the output terminal (30, 40) and comprises a second coupling face (52.2, 53.2, 54.2); and

   - the first coupling face (51.1, 52.1, 53.1) and the second coupling face (52.2, 53.2, 54.2) of the capacitive separation point (60') oppose one another at least in part, in such a way that the first coupling face (51.1, 52.1, 53.1) and the second coupling face (52.2, 53.2, 54.2) form a coupling capacitor (60).
7. Radio-frequency blocking filter according to claim 6, characterised in that the line portions (51, 52, 53, 54) are arranged in parallel and so as to be mutually offset and the first coupling faces (51.1, 52.1, 53.1) and the second coupling faces (52.2, 53.2, 54.2) are arranged in parallel and so as to be mutually offset.
8. Radio-frequency blocking filter according to either claim 6 or claim 7, characterised in that a partition wall (71) comprising a dielectric material is arranged between the first coupling face (51.1, 52.1, 53.1) and the second coupling face (52.2, 53.2, 54.2).
9. Radio-frequency blocking filter according to claim 8, characterised by the following features:

   - the respective second coupling faces (51.2, 52.2, 53.2, 54.2) are arranged opposing the respective internal conductors (16), in such a way that the respective internal conductors (16) and/or resonators (10) are capacitively coupled to the respective line portions (51, 52, 53, 54) so as to form a capacitive internal conductor coupling and/or resonator coupling (65), and

   - a supporting wall (74) of the holding and/or receiving device (70) is arranged between the respective second coupling faces (51.2, 52.2, 53.2, 54.2) and the respective internal conductors.
10. Radio-frequency blocking filter according to any of the preceding claims, characterised in that the resonators (10) are of different sizes.
11. Radio-frequency blocking filter according to any of the preceding claims, characterised in that at least some internal conductors (16) of the respective resonators (10) are at different distances from the housing wall (13).
12. Radio-frequency blocking filter according to any of the preceding claims, characterised in that the line portions (52, 53, 54) of the signal line (50) are orientated in parallel with the housing walls (13) extending in the longitudinal direction, and in that at least two line portions (52, 53, 54) in series are arranged with a lateral offset from one another so as to form a coupling distance in the region of the capacitive separation point (60'), and in that the internal conductors (16) which are coupled in this way are arranged so as to be offset from one another by a corresponding lateral offset with respect to the housing walls (13).
13. Radio-frequency blocking filter according to any of the preceding claims, characterised in that the housing cover (12) is in the form of a circuit board, of which the inside of the resonator is metal-coated.
14. Radio-frequency blocking filter according to any of the preceding claims, characterised in that the external conductor housing is formed integrally with the internal conductors (16), in particular as a milled, turned or cast part.
15. Radio-frequency blocking filter according to any of the preceding claims, characterised in that the external conductor housing and/or the internal conductor (16) consist of plastics material, the respective inner surfaces being metal-coated.
16. Radio-frequency blocking filter according to any of the preceding claims, characterised by the following features:

    - the radio-frequency blocking filter (1) further comprises a further terminal (40);

    - the further terminal (40) is arranged between the input terminal (20) and the output terminal (30) and is galvanically connected to the signal line (50); and

    - the further terminal (40) is arranged together with the signal line (50) between coupling points of the internal conductors (16) or resonators (10).
17. Radio-frequency according to claim 16, characterised in that the resonators (10) are configured and coupled in such a way that a duplex filter is formed.
18. Radio-frequency blocking filter according to either claim 16 or claim 17, characterised by the following features:

    - at least two resonators (10) are capacitively coupled to the signal line (50) between the further terminal (40) and the input terminal (20); and

    - at least two resonators (10) are capacitively coupled to the signal line (50) between the further terminal (40) and the output terminal (30).
19. Radio-frequency blocking filter according to any of the preceding claims, characterised in that the radio-frequency blocking filter (1) operates with the blocking range and pass-band range thereof between 790 MHz and 862 MHz and/or in the range between 880 MHz and 960 MHz and/or in the range of the 1800 MHz mobile radio frequency and/or the 2000 MHz mobile radio frequency.

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