JPH0758516A - Band pass filter using degenerate dielectric resonator - Google Patents

Abstract

PURPOSE:To form a small sized band pass filter offering a dual turning band characteristic by giving an unbalanced dielectric constant to a so-called degenerate dielectric resonator in which the same resonance frequency is provided to a single dielectric resonator and two resonance modes orthogonal to each other are included so as to differentiate the resonance frequency of the two resonance modes. CONSTITUTION:Orthogonal degenerate resonance modes shown in figures (b), (c) are mutually coupled by providing slots SL1, SL2 to orthogonal symmetrical faces S1, S2 as shown in figure (a) in an oblique direction at an angle of 45 deg., and a duel tuning band characteristic is realized by the even mode resonance whose resonance angular frequency is omegae and the odd mode resonance whose resonance angular frequency is omega0 as shown in figure (d) and the coupling coefficient is varied with the size of the slots.

Description

Detailed Description of the Invention

The present invention has a band pass filter exhibiting a so-called double tuning band characteristic due to mutual coupling of a plurality of resonance circuits, and in particular, is configured to be extremely compact by degenerately coupling the resonances of a plurality of modes generated in a small dielectric resonator. The present invention relates to a bandpass filter using a degenerate resonator.

[0002]

2. Description of the Related Art Even when a band pass filter exhibiting a double tuning band characteristic by mutual coupling of a plurality of resonance circuits is constructed by using a small dielectric resonator, conventionally, a dielectric block whose outer circumference is surrounded by a conductor wall is conventionally used. In this case, two single resonators each having a quarter-wave conductor at the center are capacitively coupled.

[0003]

Therefore, even a bandpass filter using a small-sized dielectric resonator has a problem that the conventional structure has a complicated structure and a large size. It is a conventional problem to realize a bandpass filter having an extremely small size and a simple structure by fully utilizing the advantages.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the related art and to take advantage of the use of a dielectric resonator, thereby exhibiting a bandpass having a double tuning band characteristic of an extremely small size and a simple structure. It is to provide a filter.

According to the present invention, a single dielectric resonator is provided with a dielectric constant imbalance in a so-called degenerate dielectric resonator including two resonance modes having the same resonance frequency and orthogonal to each other. The resonance frequencies of the resonance modes are different from each other, and the band pass filter exhibiting the double tuning band characteristic is extremely small in size.

That is, the bandpass filter using the degenerate dielectric resonator of the present invention comprises planes of symmetry (S ₁ , S ₂ or S ′ ₁ , S ′ ₂ ) which are orthogonal to each other and shares an orthogonal axis. And at least first and second orthogonal symmetry planes (S ₁ ,
S ₂ and S ′ ₁ , S ′ ₂ ) each having a cross-sectional shape symmetrical with respect to their orthogonal symmetry planes and located in the cutoff waveguide at a distance from the conductor tube wall. Providing an inhomogeneous dielectric constant region symmetrically parallel to the orthogonal axis on _one symmetry plane (S ′ ₁ or S ′ ₂ ) of the two orthogonal symmetry planes (S ′ ₁ , S ′ ₂ ). The second orthogonal symmetry plane (S ₁ , S ₂ ), which is asymmetric with respect to the first orthogonal symmetry plane (S ₁ , S ₂ ), and has an electric field and a magnetic field parallel to the _second orthogonal symmetry plane (S ' ₁ , S' ₂ ). So that the resonance frequencies of the degenerate resonance modes are different from each other and the first degenerate resonance modes having an electric field and a magnetic field parallel to the _first orthogonal symmetry planes (S ₁ , S ₂ ) respectively exhibit a complex resonance band characteristic. It was done.

[0007]

Therefore, according to the present invention, a bandpass filter having an extremely small size and a simple structure, which fully utilizes the advantages of the dielectric resonator, is provided by giving the degenerate dielectric resonator a simple structure change. Can be realized.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. First, hold the electromagnetic wave of the resonance frequency in the rectangular parallelepiped dielectric block.

[Outer 1]An example using a mode dielectric resonator will be described.
, Having the same resonance frequency in a single resonator,
So-called degenerate type, in which two orthogonal resonance modes coexist
When a resonator is used, for example, the rectangular shape shown in FIG.
Similar to the body-shaped hollow cavity, similar to
It was placed in the conductor shield so as not to contact the conductor wall.
In the rectangular parallelepiped dielectric resonator, it is shown by the chain line
The electric field component in the cross section is shown in Fig. 1 (b) and (c).
As shown by the solid arrows,
There are two resonance modes that are parallel and orthogonal to each other
Is perpendicular to each electric field component
Resonance angular frequency ω₁And ω ₂Are equal and their common
Resonance angular frequency ω_rThen, ω₁= Ω₂= Ω_rAnd
The resonance mode corresponding to the sum and difference of the two resonance modes.
1D, the even mode shown in FIG.
The odd mode shown in (e) is entered, and as shown in FIGS. 1 (b) and (c).
Fig. 1 shows the double tuning band characteristics in which the two resonance modes shown in Fig. 1 are combined.
Using only a single dielectric resonator of the shape shown in (a)
Can be realized.

In the present invention, the dielectric resonator is subjected to the process of coupling the two degenerate resonance modes of the dielectric resonator to each other. In the illustrated embodiment, as shown in FIG. A pair of opposite corners of a rectangular cross section,
That is, the upper right corner UR and the lower left corner LL are cut off to form a sectional shape. The resulting even-mode resonance angular frequency ω _e is ω _e <ω _r , and a resonance electric field and a resonance magnetic field in the directions shown in FIG.
The resonance angular frequency of the odd mode is ω _O > ω _r , as shown in FIG.
A resonance electric field and a resonance magnetic field in the directions shown in (h) are generated.

That is, FIGS. 1 (b) and 1 (c) respectively.
If you simply add the indicated resonance modes,
At the same resonance angular frequency ω_rAs shown in Fig. 1 (d)
The electromagnetic field distribution is shown in Fig. 1 (b) and (c).
The electromagnetic field distribution of the difference between the resonance modes shown in Fig. 1 (e)
The same resonance angular frequency ω_rTona
It On the other hand, as shown in FIG.
The corners UR and LL are cut off to form a cross-section
When the above two resonance modes are coupled to each other,
In the electromagnetic field distribution of even mode resonance shown in (g),
The distance of the strongest electric field indicated by the solid line is the corner cutoff.
It becomes shorter by dropping, and the equivalent capacitance of the equivalent resonant circuit increases.
The even mode resonance angular frequency ω_eIs ω
_e<Ω_rAnd the odd mode shown in Fig. 1 (h)
In the electromagnetic field distribution of the vibration, the strongest magnetic field shown by the dotted line
The distance of the open part is shortened by cutting off the corner,
This will reduce the equivalent inductance of the equivalent resonant circuit.
The odd mode resonance angular frequency ω _OIs ω_O> Ω_rTona
It

As described above, the fact that the resonant angular frequency changes due to a slight deformation of the dielectric block in the dielectric resonator can be explained by the perturbation theory and can be calculated. You can

Now, in the dielectric resonator having the structure shown in FIG. 1 (f), an opening or a pair of terminals 1, 1'to be coupled to the electromagnetic wave of the resonance mode shown in FIG. 1 (b) and FIG. 1 (c). By providing an opening or a pair of terminals 2, 2'which are coupled to electromagnetic waves of the resonance mode shown in Fig. 2, an example of the structure shown in Fig. 2 (a) is obtained, and its equivalent circuit is shown in Fig. 2 (b) or (c). As shown.

As shown in FIG. 2 (a), the above-mentioned opening 1,1'O ₁ is formed in the dielectric resonator D in which the opposite corners of the square section of the [outer 1] mode are cut off to couple the degenerate modes. And the equivalent circuit of the configuration example in which the openings ₂ and 2'O ₂ are provided so as to be orthogonal to each other as shown by arrows, in the case of the combination in the direction of the arrows shown, ω _e <ω _r , ω _O > ω _Since it is _r , the equivalent double-tuned circuit of inductive coupling as shown in FIG. 2B is obtained, and the degenerate coupling coefficient k between both modes is

[Equation 1] Becomes

If the directions of the electric fields of the openings ₂ and 2'O ₂ in the configuration example shown in FIG. 2 (a) are reversed, the relative relationship between the even mode excitation and the odd mode excitation becomes opposite. Two
An equivalent double-tuned circuit with capacitive coupling is obtained as shown in (c).

The rectangular dielectric block has been described above.
As can be seen from the principle of the basic configuration, the degenerate type invitation of the present invention.
In bandpass filters using electric resonators,
First, as the structure of the dielectric block that constitutes the resonator,
Two planes of symmetry S orthogonal to each other₁, S ₂Have and their symmetry
Surface S₁, S₂The resonance modes corresponding to
The resonant frequencies of both degenerate and degenerate resonance modes are equal.
New things are necessary.

As the degenerate dual mode dielectric resonators orthogonal to each other, in addition to the [outer 1] mode rectangular dielectric resonator shown in FIG. 1A, a circular one as shown in FIG. 3A. Similar to the hollow cavity resonator of

[Outside 2] There is a circular dielectric resonator of a mode, and although it is not a resonator, it also has two symmetrical planes orthogonal to each other, and as a dielectric waveguide for propagating both degenerate modes orthogonal to each other,
There is a cross-shaped dielectric waveguide as shown in FIG.

In the circular dielectric resonator shown in FIG. 3 (a), conductor screw posts SP in a direction oblique to each other at an angle of 45 degrees are inserted in two orthogonal planes of symmetry to couple the degenerate modes to each other. In the cross-shaped waveguide shown in FIG. 3B, the two opposite corner angles UR of the cross-shaped dielectric D,
The degenerate two modes can be coupled to each other by providing a protrusion on the LL as shown by a dotted line and deforming it.

In the above description, the degenerate resonator using the small dielectric resonator is described from the beginning in accordance with the object of the present invention to provide a bandpass filter having an extremely small double tuning band characteristic. Although an example of the structure of the inventive bandpass filter has been described, in principle, even when considering a degenerate resonance mode for a hollow cavity resonator, there are planes of symmetry that are orthogonal to each other, and the two planes of symmetry orthogonal to each other It can be considered that the corresponding resonance modes are orthogonal to each other.
In that case, since the portion of the conductor wall forming the cavity resonator is a magnetic wall on the surface of the dielectric block forming the dielectric resonator, the circumference of the cross section of the cavity resonator is increased by about λ _g / 4. Later corresponding to the permittivity ε _r

[Outside 3] Consider a dielectric resonator having a cross-section with a geometry that is only reduced.

Therefore, a dielectric resonator corresponding to the circular resonator shown in FIG. 3 (a) formed by a hollow cavity resonator is

[Outside 4] As shown in FIG. 4A, the slot S is formed in a direction oblique to the orthogonal symmetry planes S ₁ and S ₂ at an angle of 45 degrees.
By inserting L ₁ and SL ₂ , as shown in FIGS.
The orthogonal degenerate resonance modes shown in and are coupled to each other, and
As shown in (d), double-tuning band characteristics can be realized by the even mode resonance of the resonance angular frequency ω _e and the odd mode resonance of the resonance angular frequency ω _O , and the coupling coefficient changes depending on the size of the slot. be able to.

Next, FIG. 5 shows the measurement results of the pass band characteristics obtained by coupling of the degenerate resonance mode in the prototype of the band pass filter using the circular dielectric resonator shown in FIG. The pass band characteristic shown in the figure is that of a circular dielectric block having a diameter of 10 mm, a thickness of 1 mm and a dielectric constant of 40.
It is measured with respect to a band-pass filter prototyped with slots for degenerate resonance mode coupling as shown in (a), and the required double tuning band characteristic is clearly obtained.

As is clear from the above description, according to the present invention, a bandpass filter exhibiting double tuning band characteristics is provided.
Originally, only a single dielectric resonator suitable for obtaining a small resonator is used, and a bandpass filter that exhibits extremely small double-tuning band characteristics by degenerately coupling two resonance modes of adjacent resonance frequencies with a simple configuration is easy. It is possible to achieve a particularly remarkable effect that can be realized.

[Brief description of drawings]

FIG. 1A is a perspective view showing a schematic configuration of an [external 1] mode resonator, and FIGS. 1B and 1C are cross-sectional views showing electric field distributions of two resonance modes orthogonal to each other.
(D) and (e) are cross-sectional views respectively showing electromagnetic field distributions corresponding to the sum and difference of the two resonance modes, and (f) is configured to couple the two resonance modes to each other [outer 1] is a perspective view showing a schematic configuration of a mode resonator, and (g) and (h) are cross-sectional views showing electromagnetic field distributions of even-mode resonance and odd-mode resonance in which the two resonance modes are coupled to each other. .

2A is a perspective view showing a configuration example in which an input / output opening is provided in the resonator shown in FIG. 1F, and FIGS. 2B and 2C are inductance coupling and capacitance of the configuration example. It is a circuit diagram which respectively shows the equivalent circuit by coupling.

FIG. 3 (a) is a cross sectional view of a cylindrical resonator in which two degenerate resonance modes are coupled to each other, and FIG. 3 (b) is perpendicular to a cross waveguide in which two degenerate two transmission modes are coupled to each other. It is a perspective view which shows two electric field distributions, respectively.

FIG. 4A is a perspective view showing a schematic configuration of a circular dielectric resonator in which two degenerate resonance modes are coupled to each other,
(B) And (c) is sectional drawing which shows the electric field distribution of the degenerate 2 resonance mode in the circular dielectric resonator, respectively, and (d) is the degenerate coupling 2 in the circular dielectric resonator.
It is sectional drawing which shows the electric field distribution of a resonance mode.

5 is a characteristic curve diagram showing pass band characteristics of a prototype band pass filter using the circular dielectric resonator shown in FIG. 4 (a).

Claims (4)

[Claims] 1. A has two symmetry plane (S ₁ and S ₂₎ which are orthogonal to each other, each of said plane of symmetry (S ₁ and S
₂ ) has the same cross section, and the symmetry plane (S ₁
And S ₂ degenerate dielectric resonator is even mode or odd mode for) in (D), the plane of symmetry (S ₁ and S ₂₎ plane forming an angle of 45 degrees respectively with respect to (S _'1 ) by changing a part of the dielectric constant of the dielectric resonator on the plane (S even mode or odd mode with respect to other plane orthogonal to _'1) and the plane (S' ₁₎ (S _'2) A new dielectric resonator (D ') having a different resonance frequency is arranged in a cutoff waveguide having a metal wall around the dielectric resonator so that the dielectric resonator does not come into contact with the cutoff waveguide.
An input aperture for coupling with an electric field or a magnetic field parallel to one of the symmetry planes (S ₁ ) is provided at one end of the cutoff waveguide, and the other symmetry plane (S ₂ ) is provided at the other end of the cutoff waveguide. )
A bandpass filter using a degenerate dielectric resonator, characterized in that it is configured by providing an output aperture that is coupled to an electric field or magnetic field parallel to the. 'As a means for changing a part of the dielectric constant ₍₁ on, the plane (S wherein said plane S)' be deformed partially slotted or bulge of the dielectric surface overlying ₁₎ A bandpass filter using the degenerate dielectric resonator according to claim 1. 'As a means for changing a part of the dielectric constant ₍₁ on, the plane (S wherein the plane S)' Claim 1, characterized by forming a hollow hole in the dielectric in ₁₎ on A bandpass filter using the degenerate dielectric resonator according to claim 1. 4. A bandpass filter using a degenerate dielectric resonator according to claim 1, wherein a plurality of the dielectric resonators are cascaded in the cutoff waveguide.