EP0901692B1 - Method of tuning planar superconductive filters - Google Patents

Description

State of the art

The invention is based on a method for tuning of planar superconducting filters according to the genus of independent claim.

EP 05 22 515 A1 describes a method, a planar one superconducting filter with a single resonator too upset, known. The planar filter to be tuned consists of a substrate with a Superconductor layer on the underside, which as Ground line serves. On the top is also made of superconducting material, a microstructure, which has a conductor for capacitive coupling of the High frequency signal, a resonator, and a line for capacitive decoupling of the signal includes. The resonator is an approximately circular planar microstructure, the lateral dimensions determine its resonance properties. It also determines the effective dielectric function around the resonator its resonance properties. The Imaginary part of the effective dielectric function the filter losses, their real part affects the location of the Resonance frequency. The filter is in one Housing, in the lid at least one with a thread provided through hole is provided. This will turned a screw so that the screw head itself located outside the housing, and the threaded end of the Screw in the electrical field in the filter reproducing microwave or millimeter wave immersed. To minimize the loss, the application of a superconducting platelets with approximately the same diameter like the thread of the screw on the screw tip suggested.

In a filter with multiple resonators, one affects First approximation of a screw located over a resonator its resonance frequency. A screw, which in the Space between two adjacent resonators immerses, primarily affects the coupling between these two resonators. The one in EP 05 22 515 A1 individual resonator is proposed tuning method suitable for the production of filters with very low Losses, however, is the tuning of more complex filters with a larger number of resonators due to the large number of degrees of freedom, extremely time consuming. This is known to the person skilled in the art.

Furthermore, from WO 94/28592, in particular FIG. 12, is a planar bandpass filter High-temperature superconductor base in microstrip technology known. There is one on a carrier substrate Superconductor layer on the underside, which as Ground line serves. On the top is also made of superconducting material, a microstructure, which has a conductor for capacitive coupling of the Radio frequency signal, several resonators, and a line for capacitive decoupling of the signal. The Resonator is a strip conductor of approximately rectangular shape, the lateral dimensions of its resonance properties determine. In WO 94/28591 there is the carrier substrate from a layer structure, which at least one ferroelectric or antiferroelectric layer includes. By applying a voltage to it ferroelectric or antiferroelectric layer can whose dielectric function is changed significantly, and thus also the dielectric function of the environment of the planar filter. Thus, the resonance characteristic can also of the filter can be changed, but only integrally, that means, in approximately the same way for everyone Resonators that form the filter. With goes along with this process an increase in losses.

From US-A-4-849-722 it is known for a planar Band filter a conductive shield body made of two parts to be provided, the one part relative to the other part can be moved.

Advantages of the invention

The method according to the invention with the characterizing features of the independent claim has the advantage that the tuning is significantly less complex and still allows to produce filters with low losses, whereby, due to the less time involved in the tuning, the manufacturing costs of a fully matched filter are significant turn out to be lower, since the time required for the coordination represents a significant part of the manufacturing costs, it being particularly advantageous to provide a displaceable wall on the housing, since this means that all resonance frequencies of all resonators are shifted evenly and only a minor adjustment effort is required for less Screws for coupling the individual resonators is necessary, with a double-walled housing wall with a lowerable inner cover, the housing can be easily sealed and with mi Piezotranslators also fine-tune the operating temperature
(usually 77 Kelvin) and, if necessary, also in the refrigerant bath. Another advantage is that, due to the electrical control of the resonance shift, this method is compatible with electrical control loops.

By those listed in the dependent claims Measures are advantageous training and Improvements to what is stated in the independent claim Procedure possible.

It, the housing cover on the Inside with a conductive plate one exactly defined thickness, since this method already with mounting the filter a roughly pre-adjusted filter supplies. Another advantage is that Production of a suitable set of plates, which are very are inexpensive to manufacture, using a set of filters produced slightly different resonance frequencies can be without different To produce superconductor microstructures for which a incomparably more expensive set of different masks would be necessary.

Finally, the invention provides for several filters same design in a housing with a stepped cover to accommodate, because in this way a very inexpensive Filter bank for frequency division multiplex applications can be obtained can.

drawing

Figur 1 die perspektivische Ansicht eines Filters in einem aufgeschnittenen Gehäuse, welches mit einem höhenverstellbaren Deckel versehen ist,

Figur 2 eine Transmissionskurve eines erfindungsgemäßen Filters,

Figur 3 ein Filter eingebaut in ein Gehäuse, welches einen vom Deckel absenkbaren Innendeckel aufweist,

Figur 4 einen Filter, welcher in ein Gehäuse eingebaut ist, welches einen mittels Piezotranslatoren gegenüber dem Deckel absenkbaren Innendeckel aufweist,

Figur 5 einen Filter, eingebaut in ein Gehäuse, welches mit Platten auf der Deckelinnenseite versehen ist und

Figur 6 eine Filterbank, auf deren Gehäusedeckel eine gestufte Platte angebracht ist.

Embodiments of the invention are shown in the drawing and explained in more detail in the following description. Show it

1 shows the perspective view of a filter in a cut-open housing which is provided with a height-adjustable cover,

FIG. 2 shows a transmission curve of a filter according to the invention,

FIG. 3 shows a filter installed in a housing, which has an inner cover that can be lowered from the cover,

FIG. 4 shows a filter which is installed in a housing and which has an inner cover which can be lowered relative to the cover by means of piezo translators,

Figure 5 shows a filter installed in a housing which is provided with plates on the inside of the lid and

Figure 6 is a filter bank, on the housing cover a stepped plate is attached.

Description of the invention

Figure 1 shows a planar filter in Microstrip construction in one housing. The planar Filter consists of a dielectric substrate (1), which on the bottom with a superconductor, preferably a high temperature superconductor coated is. This layer forms the ground line (2). On the Top of the dielectric substrate (1) is one Microstructure, also made of superconducting material, applied, consisting of an input line (3), Resonators (4,5,6) and an output line (7). This planar superconducting filter is made into a housing consisting of a base plate (10), a housing wall (11) and a Cover (12) installed. The cover (12) is by means of two Screws (13, 14) attached to the housing wall (11). in the The following text also includes the terms housing wall or Wall as a collective term for cover, base plate and wall used. In the lid (12), vertically above the line (30) is a coupling screw (20), the threaded end in the inside of the case protrudes. Line (30) runs between the Resonators (5,6); Sectional drawings in the following Figures give cuts along a plane, which this Line includes and perpendicular to the surface of the substrate (1) runs, again.

An incoming millimeter or microwave is over the Input conductor (3) to the series of resonators (4,5,6) coupled. The filtered signal is capacitive coupled output conductor (7) are available. At the in 1 is a planar filter Bandpass filter, in which only microwaves or Millimeter waves (in the following also with the collective term High frequency waves) with a frequency which corresponds to the natural frequency of the resonators (4,5,6), between input conductor (3) and output conductor (7) be transmitted. Through appropriate structuring other filter types can also be implemented, in particular Band-stop filter, low-pass filter or high-pass filter which also applied the method according to the invention can be. The cover (12) is by means of the screws (13,14) attached to the housing wall (11). Furthermore these screws (13, 14) are used to adjust the height of the Cover used. This is done by loosening the Screws (13, 14) and hold the cover (12) up by one lock nut (15) placed on the screws (13, 14). The lock nut placed on screw (14) is removed from Cover (12) hidden in Figure 1. By lowering the lid (12) the resonance frequencies of all resonators (4,5,6) and thus the transmission band of the filter to higher Frequencies shifted, lifting the lid works opposite. The characteristic of such a filter, but with seven resonators, for two different ones Layers of the cover are shown in Figure 2.

The coupling between the individual resonators determines the spectral fine structure within the transmission band. An example of this very weak spectral fine structure is marked with an arrow in FIG. This Coupling is influenced by the coupling screw (20). The Threaded end of the coupling screw dips into both electric field of the resonator (5) as well as in that electric field of the resonator (6) and thus serves as double capacitive coupling between the resonators (5) and (6). A more developed coupling, which is here selected embodiment of a further turned Corresponds to the screw, smoothes the fine structure within the Transmission bands. With stronger coupling, this will also be the case Transmission belt spread, so that the fine adjustment Target has bandwidth and fine spectral structure of the filter to adapt to the intended use at the same time. This Fine adjustment of the spectral transmission characteristics is generally after fixing the spectral position of the entire transmission belt through the lowerable Cover to be made.

A second exemplary embodiment according to the invention is shown in Figure 3 shown. Figure 3 shows a section through a filter in a housing along a cutting line (30) (see Figure 1). Like or components with the same function as in FIG provided with the same reference number. On the bottom (2) of a dielectric substrate (1) superconducting layer (2), which acts as a ground conductor. The resonators of the filter are outside of the Section plane and are therefore not visible in Figure 3. The Filter is in a housing, with base plate (10) and Housing wall (11), the structural design of which ensures secure fixation of the filter element, built-in. However, those skilled in the art are also alternative Attachment methods such. B. gluing, screwing, Brackets etc., obviously. Furthermore, the housing a lid (12), which has holes (50, 52, 53) is provided. Inside the housing, parallel to the lid (12), there is the inner cover (40), which one with the bore (50) has aligned bore (51), which is threaded. On the cover (40) two threaded bolts (41, 42) are attached, through the holes (52, 53) in the cover (12) to the outside protrude, as well as a seal (45) which the inner cover (40) seals against the housing wall. On the threaded bolt (41,42) nuts (44,45) are screwed on. On the Springs (16) are glued on the outside of the cover, such that that its resilient end is the end of the threaded bolt (41,42) touches and an axial force on this towards the Filters exercises. Through the threaded hole (51) is one Coupling screw (20) screwed in. On the housing walls (11) securing lugs (15) are provided.

The nuts on the threaded bolts (41, 42) (44,45) serve together with those on the threaded bolts pressing springs (16) for setting and fixing a Distance between the inner cover (40) and the cover (12). By loosening the lock nuts (44, 45) the inner cover is removed (40) lowered by the spring pressure and thus the frequency of the filter's transmission band increased. The Locking lugs (15) protect the superconducting Microstructure on top of the substrate Damage caused by a mistakenly detached Inner cover (40). It is through the coupling screw (20) possible the coupling between the individual resonators, and thus the spectral fine structure within the Transmission bands to influence. The seal (45) and the fact that the hole (51) is threaded cause a relatively tight housing. Still like it u. U. be appropriate, the hole (50) instead of the hole (51) with a thread to adjust the coupling screw (20) provided the coupling between resonators and the Separate frequency detuning of the resonators. Likewise another screw mechanism for height adjustment of the Inner cover (40) conceivable as the one shown here. In particular, there are also high-precision ones with low ones Installation dimensions waiting to be integrated in the cover Missions imaginable.

An electrically controllable method, the inner cover lowering to tune the filter is further on Embodiment shown in Figure 4. Again located one on a dielectric substrate (1) planar filter, of which in the illustrated Sectional drawing of the superconducting ground conductor only (2) is visible in a housing, which consists of a Base plate (10), a housing wall (11) and a cover (12) exists. Filters and housings are along the same Section line cut open like the device in FIG. 3. Identical or functionally identical components as in the previous figures have been given the same reference numerals Mistake. There are two on the inside of the cover (12) Piezotranslators (60) attached, which in turn with the Inner cover (40) are connected. Inner cover (40) and cover (12) have two coaxial bores (51, 50), one of which the bore (51) is threaded and the Bore (50) with an electrically insulating Guide bushing (61) is provided. In the hole (51) there is a coupling screw (20).

The raising and lowering of the inner cover, which the Filter characteristics in the same way as in the previous one Influenced example, happens in this example by Applying a voltage to the piezotranslator (s) (60). In the present embodiment, the Coupling screw (20) on the inner cover and not on the outer cover attached. An obvious solution for creating one Voltage at the piezo translator (60) is therefore one Tension between cover (12) and coupling screw (20) to create. There is also the possibility of Power supply to the piezotranslators (60) by means of to loosen two conductor wires; in this case there is also the possibility of the coupling screw (20) in the cover (12) instead of anchoring in the intermediate cover (40) to make the adjustment the spectral position of the transmission band on the one hand, and to separate its spectral form largely. One possible application of this exemplary embodiment of the Invention disclosed herein is the electrical controlled tuning of the filter with a control and Combine control loop, for example To compensate for drift phenomena.

The sectional drawing in Figure 5 shows another preferred embodiment. The cut is along the executed cutting line shown in Figure 1; same or functionally identical components as in the previous Figures are given the same reference numerals. Again is a filter consisting of a ground wire (2) applied on a dielectric substrate (1), and a resonator not visible in FIG Housing, consisting of base plate (10), housing wall (11) and cover (12) installed. A coupling screw (20) is in a threaded hole (50) is screwed in. On the inside of the Cover (12), a conductive plate (70) is attached.

In this exemplary embodiment, the selection of spectral location of the filter band by selecting a plate (70) with the appropriate thickness and its placement on the Inside of the cover (12). Again, that can Coupling screw (20) for influencing the spectral Fine structure of the filter belt can be used. The The change in the spectral position of the transmission band is after the assembly of the housing is no longer possible without it The case can be opened again, however, this way pre-vote with very simple means, which then only with the help of the coupling screws (20) Detail needs to be corrected. It is also possible to use a set of selected plates (70) from the same Superconductor microstructure to make a set of filters whose transmission characteristics are exactly in one defined way.

Figure 6 shows the cross section through a filter bank, in which are four identical planar filters (80), made with identical masks on identical Substrates, starting from identical superconductor layers on both sides. The housing consists of a Base plate (10), a housing wall (11) and a cover (12). On the inside of the cover (12) is one Step plate (72) attached.

Due to the different distances between the planar Filters (80) and the surface of the Step plate (72) is the spectral location of the Transmission frequencies through the individual planar filters realized channels easily detuned from each other without the change spectral fine structure. That way, with very simple means and bypassing the manufacture multi-channel filter bank can be built. If necessary and / or desired, this can also be done Realization example additional screws for Fine tuning will be provided.

In the previous embodiments, the Housing cover representative of other housing components, which are sufficiently close to the planar filter, so that it is with the electric field which is through the Filter structure propagating high frequency wave interact, used. Possible variations of the Invention is one or more side walls and / or the floor slidable in the above sense shape. It also seems conceivable to use the coupling screws (20) and the sliding lid on different surfaces to implement, for example the coupling screws (20) a side wall coaxial to the line shown in Figure 1 (30), and which are parallel to the substrate (1) trending, the surface (that is, the surface with the Resonators) facing housing surface as displaceable Form lid in the above sense.

In the above embodiments, coupling bolts were used (20), which is in the half-space between two resonators protruded to use, if in addition to the displacement of the Transmission bands through the sliding housing wall the fine structure of the transmission belt can be changed should. But it is also conceivable, in addition to the lowerable Housing cover, one or more tuning screws in the To provide field space over a single resonator. It is then possible to go through the entire transmission belt integrally Moving the housing wall to move, and additionally, for example by shifting the resonance of a single resonator, the filter narrowband or to design broadband.

Claims (4)

1. Method for tuning planar filters (80) for millimetric waves or microwaves having a number of resonators (4, 5, 6), with the filter being arranged in a housing and with a conductive element (40; 72), which is located sufficiently close to the filter that said filter can interact with the electric field of the millimetric waves or microwaves, is shifted relative to the filter, with the conductive element extending over a number of resonators, characterized in that the planar filter is superconducting, in that that part of a double-walled housing wall which faces the resonators is shifted relative to the filter, and in that the shift is produced by piezoelectric translators (60).
2. Method according to Claim 1, characterized in that at least one further housing wall is shifted.
3. Method according to Claim 1, characterized in that a conductive plate with the thickness required for the desired tuning is fitted to at least one inner wall of the housing.
4. Filter bank comprising at least two planar filters (80) having a number of resonators for millimetric waves or microwaves, installed in a housing, with a conductive element, which is in the form of a stepped plate (72) being fitted on the inside of the cover, in a sufficiently close position that the surface of the stepped plate which extends over a number of resonators and faces the filters can interact with the electric field of the millimetric waves or microwaves, with the conductive element having the capability to be shifted relative to the filters, characterized in that the planar filters are superconducting, in that that part of a double-walled housing wall which faces the resonators can be shifted relative to the filter, and in that the shift is produced by piezoelectric translators.

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