JPH04292001A - Dielectric coaxial resonator - Google Patents

Abstract

PURPOSE:To improve Q0 of a dielectric coaxial resonator adopted for a filter and an oscillator, etc., and also, to standardize parts while keeping high Q0. CONSTITUTION:A through hole 26 is formed at the central axis of a dielectric block 25, and an inner conductive film 27 is formed on the inner peripheral surface of said through hole 26, and simultaneously, an external conductive film 28 is formed on the outer surface of the above-mentioned dielectric block 25 excepting the open side end surface 25a, to form the dielectric coaxial resonators R1 to R8. Then, the above-mentioned dielectric block 25 is formed into the form of a square pole, and simultaneously the ratio a/b of the inner diameter (a) of the above-mentioned through hole 26 to the outer dimension (b) of said dielectric block 25 is made within a range of 0.2 to 0.43.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to dielectric coaxial resonators used in filters, oscillators, etc., and specifically, the Q0 of the coaxial resonator can be improved, and the inner diameter in particular can be standardized while ensuring a high Q0. Regarding the structure that made it possible.

0002

2. Description of the Related Art For example, as a λ/4 dielectric coaxial resonator, there is conventionally a structure shown in FIG. This dielectric coaxial resonator 40 has a circular through hole 42 formed in the axis of a cylindrical dielectric block 41, an inner conductive film 43 formed on the inner peripheral surface of the through hole 42, and block 4
It has a structure in which an outer conductive film 44 is formed on the outer surface except for the open side end surface 41a of 1. When determining Q0 of such a dielectric coaxial resonator 40, conventionally both conductive films 43 are
, 44 resistance value (for example, electrode thickness, electrode material, frequency, etc.), the ratio of the diametrical cross-sectional area of the dielectric block 41 to the resonator length L, and the diametrical cross-section of the dielectric block 41 The shape and material of the dielectric block 41 (tan δ
), etc. are selected.

0003

By the way, the dielectric coaxial resonator 40 is required to have an improved Q0 due to its intended use. However, in the conventional dielectric coaxial resonator 40, there is a limit to the improvement of Q0 by each of the above-mentioned selection methods, so there is a problem that the above-mentioned request cannot be met at present. In addition, in the conventional coaxial resonator 40 described above, in order to obtain a high Q0, the dielectric block 4
Since the ratio of the outer diameter b of 1 and the inner diameter a of the through hole 42 is defined within a narrow range, even if the outer diameter b changes slightly, the inner diameter a must also be changed, resulting in standardization of the inner diameter. In other words, there is a problem in that it is difficult to standardize the parts inserted into the inner conductor.

The present invention has been made in view of the above-mentioned conventional situation, and an object of the present invention is to provide a dielectric coaxial resonator that can meet the above-mentioned demands by improving Q0 and also allows standardization of components.

[0005]

[Means for Solving the Problems] Accordingly, the present invention provides a method for forming a through hole in the axis of a dielectric block, and for forming an inner circumferential surface of the through hole and an outer surface portion of the dielectric block other than the open end surface. In a dielectric coaxial resonator formed with an inner conductive film and an outer conductive film, the dielectric block is a column with a substantially square cross section, and the side length b of the dielectric block and the through hole are It is characterized by having an a/b ratio of 0.2 to 0.43 with respect to the inner diameter a.

[0006] Here, the reason why the above configuration is adopted in the present invention will be explained. The reason why the above dielectric block is made into a substantially square columnar body is that the dimensions of the resonator length L, outer diameter b, and inner diameter a are the same for the cylindrical and square columnar types, as shown in FIGS. 7 and 8. This is because it has been found that Q0 is higher for the square prism type than for the conventional cylinder type. The inventors of the present invention have focused on the fact that Q0 is related to the cross-sectional shape of the dielectric block, and for example, Q0 in a λ/4 dielectric coaxial resonator is Q0 = L/δ・(1/1+L/2b・F) (δ is the thickness of the inner conductive film and the outer conductive film). Here, F is a parameter that depends only on the cross-sectional shape of the dielectric block, and is expressed by Formula 1.

[0007]

[Math 1]

Here, H is the magnetic field of the short-circuit surface, S is the cross-sectional area, m
is the outer circumference length. For example, a=2.6mm, b=4.0
mm, L=8.0mm, the cylindrical type has F=5.
8.F=5.0 for the rectangular prism type, and when compared with Q0, the rectangular prism type is about 13% higher. Also,
The reason why the a/b ratio is set to 0.2 to 0.43 is that within this range, a reduction of about 5% with respect to the maximum Q0 is sufficient. This was obtained through experiments, and as shown in Figure 4, the relationship between the a/b ratio and Q0 is that the larger this ratio is, the higher Q0 becomes, reaching a maximum at about 3.0. It has a parabolic characteristic in that when it is increased, Q0 decreases again. Here Q0 is max
(When the above ratio is 3.0) If it is about 5% lower than before, it is practically usable, and from this point of view, the above a.
/b ratio may be set within the range of 0.2 to 0.43. Therefore, for example, if the inner diameter a is 2 mm, 0.2≦2.0/b≦0.43, so
The outer diameter b may be 4.65 to 10.0 mm, that is, even if the outer diameter b is about twice as large, the inner diameter a may be the same.

[0009]

[Operation] According to the dielectric coaxial resonator according to the present invention, since the dielectric block is made into a square columnar body, Q0
can be improved and meet the above requirements. Furthermore, in the present invention, the ratio between the outer diameter b of the dielectric block and the inner diameter a of the through hole is a/b.
Since the ratio is set to 0.2 to 0.43, the inner diameter can be the same even if the outer diameter differs by about twice while maintaining a high Q0. Therefore, the inner diameter can be standardized, and in other words, the parts inserted into the inner conductor can be standardized. can be achieved.

0010

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings. 1 to 3 are diagrams for explaining a dielectric coaxial resonator according to an embodiment of the present invention. In this embodiment, a case where the present invention is applied to a dielectric coaxial resonator constituting the transmission and reception filters of an antenna duplexer will be explained as an example. In the figure, 1 is an antenna duplexer, in which an RX side (reception side) filter 1a and a TX side (transmission side) filter 1b are arranged in parallel inside a case body 2, and a case cover 3 is placed on the case body 2. It is configured by installing. A coupling board 4 is disposed on each of the above-mentioned RX side filter 1a and TX side filter 1b, and a TX side transmission line 5,
And the RX side transmission line 6 is patterned. An ANT terminal 8 is connected to the connection between both transmission lines 5 and 6, and the outer end of the TX side transmission line 5 and the RX
The outer ends of the side transmission lines 6 are connected to TX terminals 7 and R, respectively.
X terminal 9 is connected. Incidentally, reference numeral 19 denotes a mounting hole of the bonding board 4, into which the projection 2a of the case body 2 is inserted and fixed. Further, 22 is a ground electrode, and the ground electrode 22 is connected to the connecting piece 2b of the case body 2.

Further, a capacitor mounting portion 10 and a coil mounting hole 20 are formed in the TX side transmission line 5, and one electrode of the chip capacitors C8 to C11 is connected to each of the capacitor mounting portions 10. has been done. The coupling terminals 16 to 18 of the TX filter 1b are connected to the other electrodes of the capacitors C8 to C11. Further, one ends of the coils L1 and L2 are connected to the other electrode of the capacitor C8, and the other ends of both the coils L1 and L2 are inserted and connected to the coil attachment hole 20. Further, coils L3 and L4 are inserted and connected to the coil mounting holes 20 between the capacitors C9 to C11, thereby forming a band rejection filter.

The RX side transmission line 6 of the coupling board 4 includes:
Slits S1 to S6 are formed to divide the transmission line 6 into a plurality of parts. Chip capacitors C1 to C6 are inserted into each of the slits S1 to S6 in a half-filled state, and both electrodes of each of the capacitors C1 to C6 are connected to the transmission line 6. In addition, each of the above capacitors C1, C3, C
4 and C6 are connected to respective coupling terminals 11, 12, 14, and 15 of the RX side filter 1a, respectively. Further, one electrode of a chip capacitor C7 is connected to the capacitor mounting portion 21 formed approximately at the center of the RX side transmission line 6, and the other electrode is connected to the RX side filter 1a.
A coupling terminal 13 is connected thereto. This constitutes a bandpass filter.

The RX side filter 1a is composed of five dielectric coaxial resonators R1 to R5, and the TX side filter 1b is composed of three dielectric coaxial resonators R6 to R5.
8. Each of these coaxial resonators R1 to R8
As shown in FIGS. 1 and 2, a circular through hole 26 is formed in the axis of the dielectric block 25, an inner conductive film 27 is formed on the inner peripheral surface of the through hole 26, and the dielectric block An outer conductive film 28 is formed on the outer surface of the conductor 25 except for the open end surface 25a. Each coaxial resonator R on the RX side above
The side surfaces of the coaxial resonators R6 to R8 on the TX side are in contact with each other, and the lower surfaces are connected to the bottom surface of the case body 2 by soldering. Further, the case cover 3 is in contact with the upper surface of each of the coaxial resonators R1 to R8, and the coaxial resonators R1 to R8 are connected and fixed by solder filled in solder holes 3a formed in the case cover 3. Note that 3b is an adjustment opening for adjusting the inductance and resonance frequency of the coil.

[0014] Then, each of the dielectric coaxial resonators R1 to R
The dielectric block 25 of No. 8 is a columnar body with a square cross section, and the a/b ratio between the side length b of the dielectric block 25 and the inner diameter a of the through hole 26 is within the range of 0.2 to 0.43. is set to .

Next, the effects of this embodiment will be explained. According to this embodiment, the dielectric coaxial resonators R1 to R8 constituting the RX side filter 1a and the TX side filter 1b of the antenna duplexer 1 are made into square columnar bodies, so compared to the conventional cylindrical coaxial resonators. Although the dimensions are the same, Q0 can be improved and insertion loss can be reduced. In addition, in this embodiment, the a/b ratio between the outer diameter b of the dielectric block 25 and the inner diameter a of the through hole 26 is set to 0.2 to 0.43, so the inner diameter a is set within a range where a high Q0 can be maintained. This makes it possible to standardize the connection terminals 11 to 18 that are press-fitted into the through holes 26. Furthermore, it is possible to provide coaxial resonators R1 to R8 that have low input impedance and are not easily influenced by the surroundings. This generally applies to a above
By reducing the /b ratio, the input impedance can also be reduced, so the impedance can also be reduced within a range where a high Q0 can be maintained. In addition, in this embodiment, the coaxial resonators R1 to R8 are brought into direct contact with each other, and
Since each of the resonators R1 to R8 is directly connected to the case body 2 and the case cover 3 by soldering, the number of parts can be reduced and costs can be reduced, and the antenna duplexer 1 as a whole can be downsized. This is because when conventional cylindrical coaxial resonators are placed inside a case, they are connected with an earth spring interposed between the resonators and between the resonator and the case, which reduces the number of parts. There was a problem of increasing the size of the device as well.

Note that in the above embodiment, the dielectric block 2
Although the explanation has been given using an example in which the five through holes 26 have the same diameter, the structure of the dielectric coaxial resonator according to the present invention is not limited to this. 5 and 6 show a modification of the above embodiment. This dielectric coaxial resonator 30 includes through holes 32 having different inner diameters in a dielectric block 31 made of a square columnar body.
a, 32b are formed in a step shape, and both through holes 32a, 32b are formed in a stepped manner.
An inner conductive film 33 is formed on the inner peripheral surface of the dielectric block 31, and an outer conductive film 34 is formed on each side surface of the dielectric block 31 except for the open end surface 31a. This coaxial resonator 3
0, the dielectric block 31 is formed into a square column shape, and the a/b ratio between the side length b of the block 31 and the inner diameter a of the through hole 32a is set to 0.2 to 0.43. , substantially the same effects as in the above embodiment can be obtained.

[0017]

As described above, according to the dielectric coaxial resonator of the present invention, the dielectric block is formed into a square column shape, and the side length b of the dielectric block and the inner diameter a of the through hole are Since the a/b ratio was set to 0.2 to 0.43, Q0
This has the effect of improving the quality of the product, as well as standardizing parts while maintaining a high Q0.

[Brief explanation of the drawing]

FIG. 1 is a perspective view for explaining a dielectric coaxial resonator according to an embodiment of the present invention.

FIG. 2 is a sectional view of the dielectric coaxial resonator of the above embodiment.

FIG. 3 is an exploded perspective view showing an antenna duplexer employing the dielectric coaxial resonator of the above embodiment.

FIG. 4: a/b ratio and Q0 for explaining the configuration of the present invention
FIG.

FIG. 5 is a perspective view showing a dielectric coaxial resonator according to a modification of the above embodiment.

FIG. 6 is a cross-sectional view of the dielectric coaxial resonator.

FIG. 7 is a perspective view showing a conventional dielectric coaxial resonator.

FIG. 8 is a perspective view of a dielectric coaxial resonator for explaining the process of establishing the present invention.

[Explanation of symbols]

25, 31 Dielectric block 25a, 31a Open end face 26, 32a Through hole 27, 33 Inner conductive film 28, 345 Outer conductive film R1 to R8, 30 Dielectric coaxial resonator a Inner diameter b of through hole Side of dielectric block length

Claims (1)

[Claims] 1. A through hole is formed in the axis of the dielectric block, an inner conductive film is formed on the inner peripheral surface of the through hole, and
In the dielectric coaxial resonator in which an outer conductive film is formed on the outer surface of the dielectric block except for the open end surface, the dielectric block is a columnar body with a substantially square cross section, and the side length of the dielectric block is a/b between sab and the inner diameter a of the above-mentioned through hole
A dielectric coaxial resonator characterized in that the ratio is 0.2 to 0.43.