EP1349232B1 - Microwave resonator - Google Patents

Abstract

Near an end face or edge, the conductive layer (3) includes penetrating bores (2). It covers both sides. It also covers inner surfaces of the bores, electrically-connecting the layers on both sides. The signal input (13) region of the substrate (12) borders an insulated region lying opposite another part of the layer (3).

Description

State of the art:

The invention relates to a microwave resonator according to the preamble of the main claim.

In the production of high-quality RF oscillators, that is, with low phase noise, resonators are required which also have a high quality. Such resonators must be characterized by low ohmic conduction losses, by low dielectric losses and by low radiation losses.

From the prior art multiple attempts are known to meet these conditions. Thus, in the literature source, DK Paul and P. Gardner, "Microwave Oscillator and Filters based on Microstrip Ring Resonator", IEEE MTT-S 1995, a ring resonator described high quality, but has the disadvantages that the coupling is problematic, and that spurious modes occur, which must be suppressed when a larger tuning range is needed. By such measures, the quality of the resonator decreases again.

Also known is a planar resonator consisting of a ceramic substrate, which is metallized on both sides and has circular recesses in both metallization surfaces. This resonator has a high quality, but has the disadvantage that for its mounting on both sides of the substrate, a larger volume of air must be present. This requires larger chambers for the resonator, which proves to be disadvantageous when the resonator is to be realized in "MIC" technique.

From JP 10303618 a rectangular resonator with three or four conductive layers is known. At the outer edge of the resonator bores are mounted, which form a rectangle. The insides of the holes are conductive coated.

From the Literature Source, Electronics Industry 4-1190: Dr. med. Gundolf Kuchler: Coaxial ceramic resonators for 400 MHz to 4.5 GHz, and from the source, FM Report 2/1989: Dr. med. J. Jirmann: Coaxial ceramic resonators, interesting components for the frequency range between 1 and 2.4 GHz, are known coaxial ceramic resonators, which depending on the frequency range and ceramic material have a quality between Q = 400 to Q = 800. Their disadvantages are that in this case extra components are required, and that the transition between IC and resonator is critical.

Also known from the literature source, Artech House: Kajfez / Guillon: Dielectric resonators, dielectric resonators _having a quality between Q = 1000 and Q = 10000 depending on the frequency range and resonator material at room temperature and in the fundamental mode TE _01δ . The disadvantage is that these resonators are relatively large, and that in this case a resonator chamber is required in which propagates the electric field. In addition, the resonator represents an additional component. And in the context of the use of this resonator, a post-processing (grinding) may be required. As further disadvantages, it has an above-average case and lid sensitivity (microphony), the electrical tuning bandwidth is very low due to the high quality, ie, only about 10 MHz, and the installation and adjustment of an oscillator equipped with this resonator is very complicated ,

Finally, E. Belohoubek, E. Denlinger, Loss Considerations for Microstrip Resonators, IEEE MTT, June 1975, and A. Gopinath, Maximum Q-Factor of Microstrip Resonators, IEEE MTT Feb. 1981, describe MIC stripline resonators An optimum configuration, ie conductor width and substrate thickness, can be realized for each frequency and for each substrate material The disadvantage of these known resonators consists in the relatively low quality of only Q = 50 to Q = 200.

An example of such a resonator is shown in FIGS. 1 and 2. It consists of a strip-shaped substrate 12, which is covered on both sides with a conductive layer 3, and which has holes 2 near the right end face. The inner surfaces of the holes 2 are also covered with the layer 3, so that the Layer 3 of the top 4 and the layer 3 of the bottom 5 are electrically connected together. In this case, the ohmic resistance of the layer 3 at the relatively short end, which is short-circuited via the holes 2, determines the large ohmic conduction losses and the rather large geometric dimensions of the left open end serving as the signal input 13, the large radiation losses of the known strip line resonator. Since the quality of the resonator depends on the size of the line losses and the radiation losses, this results in the relatively low quality of the known resonator.

The invention and its advantages:

In contrast, the microwave resonator according to the invention with the characterizing features of the main claim has the advantage of reduced ohmic line losses and reduced radiation losses, so that it has a very high quality and is well suited to be installed in RF oscillators with high quality.

The conductive layer, or the arrangement of the holes, has the shape of a circular disk whose top and bottom are covered with the layer, the holes are arranged on the edge of the circular disc. The thus minimized dimensions of the open end reduce the radiation losses of the microwave resonator, and its very wide spread short-circuited end significantly reduce its ohmic line losses, so that thereby the quality of the resonator according to the invention is greatly increased.

The circular disc has as a signal input from a central region radially outwardly directed coupling tongue with the length L, which is laterally spaced over a gap with the width S of the circular disc. This results in the possibility of setting the tuning bandwidth over the gap width S and the coupling of the microwave resonator over the length L.

The gap between coupling tongue and circular disk is formed kreissektor shaped. This extensive enlargement of the gap width results in a particularly broadband version of the microwave resonator according to the invention.

According to a further advantageous embodiment of the invention, the microwave resonator has more than one coupling tongue. This allows the coupling of one of the number of coupling tongues corresponding number of lines and components.

According to a further advantageous embodiment of the invention, the substrate consists of low-loss dielectric material, which material in ceramic form has excellent insulation properties.

According to a further advantageous embodiment of the invention, the substrate consists of alumina, sapphire, quartz glass, Teflon or the like.

According to a further advantageous embodiment of the invention, the layer consists of highly conductive metal, so that it is particularly well suited for the present purpose.

According to a further advantageous embodiment of the invention, the layer consists of gold, silver, copper, aluminum, superconductor or the like. This material has a high electrical conductivity and is very resistant to corrosion, making it particularly suitable for the present purpose.

Further advantages and advantageous embodiments of the invention are the following description, the drawings and claims removed.

Drawings:

Fig. 1

Resonator aus einem streifenförmigen Substrat, das beidseitig mit einer leitfähigen Schicht belegt ist,

Fig. 2

Resonator gemäß Fig. 1

Fig. 3

einen Kreisresonator in Draufsicht,

Fig. 4

den Kreisresonator gemäß Fig. 3 im Schnitt entlang der Linie IV-IV,

Fig. 5

einen Kreisresonator in Draufsicht mit einer separaten Ankopplungszunge und

Fig. 6

einen Kreisresonator in Draufsicht mit einer separaten Ankopplungszunge und einem Spalt zwischen Ankopplungszunge und Kreisresonator in Form eines Kreissektors.

An embodiment of the invention is shown in the figure 6 and will be described in more detail below. Show it

Fig. 1

Resonator of a strip-shaped substrate which is covered on both sides with a conductive layer,

Fig. 2

Resonator according to FIG. 1

Fig. 3

a circular resonator in plan view,

Fig. 4

the circular resonator of FIG. 3 in section along the line IV-IV,

Fig. 5

a circular resonator in plan view with a separate coupling tongue and

Fig. 6

a circular resonator in plan view with a separate coupling tongue and a gap between Coupling tongue and circular resonator in the form of a circular sector.

Description of the embodiments:

An example of such a resonator is shown in FIGS. 1 and 2. It consists of a strip-shaped substrate 12, which is covered on both sides with a conductive layer 3, and which has holes 2 near the right end face. The inner surfaces of the holes 2 are also covered with the layer 3, so that the layer 3 of the top 4 and the layer 3 of the bottom 5 are electrically connected to each other. In this case, the ohmic resistance of the layer 3 at the relatively short end, which is short-circuited via the holes 2, determines the large ohmic conduction losses and the rather large geometric dimensions of the left open end serving as the signal input 13, the large radiation losses of the known strip line resonator. Since the quality of the resonator depends on the size of the line losses and the radiation losses, this results in the relatively low quality of the known resonator.

FIG. 3 shows a microwave resonator designed as a circular resonator 1, which has the shape of a circular disk in plan view. The radius of the circular disk is ¼ of the length of the electromagnetic resonant in the circular resonator 1 Wave. FIG. 4 shows a section which is not to scale through the circular resonator 1 along the line IV-IV in FIG.

The circular resonator 1 consists of a disk of aluminum oxide (Al ₂ O ₃ ), ie, of a well electrically insulating substrate 12, which disc has at its edge through holes 2 and, as in particular. Figure 4 shows, coated on both sides with a layer 3 is made of a highly conductive and non-corrosive material, which is particularly well suited to gold. The inner surfaces of the bores 2 are also covered with the conductive layer 3, so that the layers 3 located on the upper side 4 and the lower side 5 are thereby short-circuited. In the middle, the layer 3 of the top 4 has a round opening 6, which is used as a signal input 13.

The circular resonator 1 shown in FIGS. 3 and 4 can be operated up to a frequency of 20 GHz. The shape of the circular resonator 1 causes its resistive conduction losses and its radiation losses are very low, so that it has a quality of Q = 700. This has the particular advantage that even an oscillator equipped with the circular resonator 1 according to the invention has a high quality, that is, a low phase noise. In this case, the coupling of the electrical oscillator components takes place via the signal input 13 in that they are plated through in the middle of the upper side 4 through the opening 6 and through the aluminum oxide substrate.

FIG. 5 shows an example of a circular resonator 7, which has a coupling tongue 8 as signal input 13 with the length L instead of a central opening 6 on one side.

Their purpose is to electrically connect oscillator components to the circular resonator 7. The circular resonator 7 also consists of an aluminum oxide disc, which is coated on both sides with gold. Both sides of the gold layer have the shape shown in FIG. This embodiment of a circular resonator has a quality of Q = 700. It is now possible to adjust the coupling of the resonator 7 by a variation of the length L of the coupling tongue. If a gap 9 of the width S is left on both sides of the coupling tongue 8 between the latter and the circular resonator 7, it is possible to set the tuning bandwidth of the circular resonator 7 over the gap width S.

From this follows a configuration of a circular resonator 10 shown in FIG. 6, the structure of which is identical except for the circular sector-shaped gap 11 with that of the circular resonator 7 according to FIG. 5. In this case, the sides of the gap 11 enclose an angle of such a size that the circular resonator 10 has a tuning bandwidth of up to 15%.

In the embodiment of the circular resonator 10 according to the invention, it is now possible to couple oscillator components capacitively, that is to say via a capacitor or via a line which is separated by a coupling slot, on the upper side or the lower side of the aluminum oxide substrate.

For tuning, a varactor diode can be coupled by means of another line. This diode can be arranged both outside and inside the structure of the circular resonator.

In this case, the present invention has the particular advantage of being able to be realized in "MIC" technology, wherein the width S of the gap 9 or the opening angle of the circular sector-shaped gap 11 can be varied as desired. The circular resonator 7 or 10 may be provided for coupling multiple lines with more than one coupling tongue 8, in which case the width S of the gap 9 and the size of the opening angle of the circular sector-shaped gap 11 of the number of coupling tongues 8 and the desired Abstimmbandbreite of the circular resonator 7 or 10 according to the invention depends.

Another advantage is that the circular resonator according to the invention is very insensitive to such influences of the environment that trigger the effect of the microphones. This is effected by the fact that the electromagnetic fields are almost completely enclosed between the upper side 4 and the lower side 5 of the highly conductive layer 3, and that the layers 3 located on the upper side 4 and on the lower side 5 are electrically connected to one another via the bores 2.

LIST OF REFERENCE NUMBERS

1

Kreisresonator

2

drilling

3

conductive layer

4

top

5

bottom

6

opening

7

Kreisresonator

8th

coupling tongue

9

gap

10

Kreisresonator

11

gap

12

substratum

13

signal input

Claims (6)

1. A microwave resonator comprising a plate-shaped, electrically insulating substrate (12),

   - which is coated on both sides with an electrically conductive coating (3),

   - which has holes (2) close to a face of the conductive coating (3),

   - wherein the coating (3) covers the inner surfaces of the holes (2) and thereby creates an electrical connection between the coatings (3) applied to both sides of the substrate (12), and

   - wherein that area of the substrate (12) in which the edge of part of the coating (3) lies opposite another part of the coating (3), insulated by the substrate, can be used as a signal input (13),

   - wherein that area of the substrate (12) acting as a signal input (13) is smaller in size than the face of the substrate (12) containing the holes (2),
   characterised in that

   - the conductive coating (3) and configuration of the holes (2) is in the form of a circular disc,

   - the holes (2) are arranged along the edge of the circular disc; and

   - the upper conductive coating of the circular disc as a signal input (13) has a coupling guide (8) of length L directed radially outward from its central area, which is laterally spaced above gap (9) from the upper conductive coating of the circular disc;

   - each slit (11) is shaped as a circular segment.
2. The microwave resonator according to claim 1, characterised by more than one coupling guide (8).
3. The microwave resonator according to one of the preceding claims, characterised in that the substrate (12) is made from low-loss dielectric material.
4. The microwave resonator according to claim 3, characterised in that the substrate (12) is made from aluminium oxide, sapphire, quartz glass, Teflon or the like.
5. The microwave resonator according to one of the preceding claims, characterised in that the coating (3) is made from a conductive material.
6. The microwave resonator according to claim 5, characterised in that the coating (3) is made from gold, silver, copper, aluminium, a superconductor or the like.

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