JPH03124102A - Dielectric filter - Google Patents

Abstract

PURPOSE:To add an adjustment function of a coupling degree to a dielectric filter itself and to miniaturize a mount board by providing a magnetic field coupling pattern while being widened up to a side face of a dielectric plate. CONSTITUTION:The width of an input/output coupling pattern 5 with a prescribed length and width coupled magnetically with a resonator 4 at both ends of a bonding face is widened up to a side face of a dielectric plate with a prescribed interval from a pattern of the said resonator in parallel, one end is in continuity with a face 3, the other end is led from the side face and prolonged up to an end of an opposite face of the bonding face to form a conduction pattern 51 and the ground face 3 of the opposite face and the side face is shaped off by the space of the pattern 51. The degree of coupling is adjusted by making the width of the coupling pattern 5 exposed to the side face of the dielectric plate 22 thin through the shaping off of the conductor layer little by little so as to obtain the optimum characteristic.

Description

[Detailed Description of the Invention] [Summary] Regarding the triplate type dielectric filter, the purpose is to provide a dielectric filter in which a coupling adjustment function is added to the dielectric filter itself. A triplate type dielectric in which the body plates are brought into close contact with each other, the outer surface is used as the grounding surface of the conductive layer, and a pattern of the conductive layer is placed on the contact surface to form a TEM mode resonator and an input/output magnetic field coupling pattern. The magnetic field coupling pattern is configured to extend in width to a side surface of a dielectric plate.

[Industrial application field]

The present invention relates to a triplate dielectric filter.

In recent years, wireless communication has made remarkable progress in the mobile communication field due to miniaturization and improved performance.

For example, car phones, mobile phones, or home wireless phones are rapidly becoming popular.

Dielectric filters used in the 800 MHz band and quasi-microwave band of these mobile radios have been significantly miniaturized as dielectric materials have higher dielectric constants.

On the other hand, the higher the dielectric constant, the wider the variation in the permittivity during the manufacturing of the dielectric (this means that when a filter is manufactured, variations in characteristics, including variations in resonance frequency, cannot be ignored. It is necessary to adjust according to

[Conventional technology]

FIG. 2(a) shows a configuration diagram of a conventional tri-plate type dielectric filter, and FIG. 2(b) shows a perspective view from A.

As shown in FIG. 2(a), the dielectric filter 15 is a triplate type dielectric filter 15 in which two rectangular parallelepiped dielectric plates 25 and 26 made of a high dielectric constant ceramic material and having the same external shape are adhered together with an adhesive.

The entire outer surface of the dielectric plate 25, except for the adhesive surface, is metallized and provided with a conductive layer to form a ground surface 35.

The dielectric plate 26 is provided with a ground plane 35 in substantially the same manner as the dielectric plate 25, and furthermore, a conductor pattern of a predetermined length x width for two 72M mode resonators 45 is provided on the adhesive surface at one end. An input/output coupling pattern 55 having a predetermined length x width is connected to the ground surface 35, and the other end is provided as an open end 46, and one end is connected to the ground surface 35. The other end is drawn out to the side to form a connection pattern 56.

In this dielectric filter 15, an input connected to the connection pattern 56 from an external circuit is applied to the coupling pattern 55,
A 72M mode resonator 45 is excited by magnetic coupling, and the frequency that resonates with the length of that pattern excites the next resonator 45, and that resonant frequency is further selected to excite another similarly magnetically coupled resonator 45. Connecting pattern 55 to connecting pattern 56
The output is led to an external circuit via the filter, and the filter characteristics are obtained.

However, variations in the dielectric constant of the dielectric plates 25 and 26,
Due to manufacturing errors in the length and width of the conductor patterns of the resonator 45 and the coupling pattern 55, the desired filter characteristics generally cannot be obtained.

If the resonance frequency of each resonator 45 varies and the degree of coupling between the input and output coupling pattern 55 and the resonator 45 is strong,
The sharpness of the filter characteristic decreases, and if it is weak, it becomes too sharp and the bandwidth becomes narrow.

Therefore, the adjustment of the input/output coupling degree is originally the coupling pattern 5.
This can be done by changing the dimensions of 5, but in this case, since this is on the adhesive surface, the adhesive must be peeled off and adjusted, which is impractical, and the external circuit part (not shown) that is connected to the outside. ) was adjusted by providing an impedance matching section at a predetermined position.

(Problems to be Solved by the Invention) However, (1) Since the input/output coupling degree adjustment section is provided in the connected external circuit, the completion test cannot be performed with the filter alone, and cannot be performed unless it is connected to the external circuit.

(2) Since the adjustment section is provided in the external circuit, miniaturization of the external circuit is hindered accordingly.

There were problems such as.

SUMMARY OF THE INVENTION In view of these problems, an object of the present invention is to provide a dielectric filter in which a coupling degree adjustment function is added to the dielectric filter itself.

(Means for Solving the Problems) The above problem is solved by assembling two dielectric plates 21 and 22 of the same shape in close contact with each other, and using the outer surface as the grounding surface 3 of the conductive layer, as shown in FIG. A triplate type dielectric filter 1 has a conductive layer pattern disposed on a dielectric plate to form a 72M mode resonator 4 and an input/output magnetic field coupling pattern 5. 2
This problem is solved by the dielectric filter of the present invention, which is provided with a wide width extending to the side surface of L22.

[Function] In other words, it is magnetic field coupling, and most of the characteristics are determined by providing a predetermined coupling interval between the coupling pattern 5 and the pattern of the resonator 4, but furthermore, the lower the impedance of the coupling pattern 5, the stronger it is. Focusing on the fact that a bond can be obtained, that is, the wider the bonding pattern 5 is, the lower the impedance, so the width of the bonding pattern 5 provided on both sides of the bonding surface is increased from the bonding surface toward the side surface. As a result, the impedance of the coupling pattern 5 is lowered, and a strong coupling can be obtained.

Therefore, the impedance of the coupling pattern 5 can be lowered by designing a slightly stronger coupling in consideration of various variations, and gradually removing and narrowing the widened part on the outer surface of the coupling pattern 5 by cutting or the like. , adjusted to the optimal degree of connectivity.

In this way, it is possible to provide a dielectric filter in which a coupling degree adjustment function is added to the dielectric filter itself.

〔Example〕

The present invention will be specifically described below with reference to embodiments shown in the drawings. The same reference numerals indicate the same objects throughout the figures. Figure 1 (
FIG. 1A shows a configuration diagram of an embodiment of the present invention, and FIG. 1B shows an enlarged perspective view of section A in the same figure.

This example is applied to a dielectric filter used in the 800 M) Iz band of mobile radio, and as shown in Fig. 1(a), two rectangular parallelepiped dielectric plates of the same external shape made of high dielectric constant ceramic material are used. This is a top-rate dielectric filter 1 in which 2L22 is adhered with an adhesive.

The entire outer surface of the dielectric plate 21, except for the adhesive surface, is metallized and provided with a conductive layer to form the ground surface 3.

The dielectric plate 22 is provided with a ground plane 3 in substantially the same manner as the dielectric plate 21, and furthermore, a conductor pattern of a predetermined length and width for two TEM mode resonators 4 is provided on the adhesive surface at one end. An input/output coupling pattern 5 having a predetermined length and width is provided at both ends of the bonding surface to connect the resonator 4 with a magnetic field. The width is expanded to the side surface of the dielectric Fi22 at a predetermined parallel interval to the pattern 4, one end is electrically connected to the ground surface 35, and the other end is drawn out from the side surface and extends to the end of the surface opposite the bonding surface. A connection pattern 51 is formed, except for the ground plane 3 on the opposing surface and the side surface.

This dielectric filter 1 is mounted on a wiring board (not shown), the microstrip line of the wiring board and the connection pattern 51 are connected with a connection copper foil, and input from an external circuit is applied to the connection pattern 5. A resonator 4 in TEM mode is excited by magnetic coupling, and the frequency that resonates with the length of that pattern excites the next resonator 4, and that resonant frequency is further selected to excite another resonator 4 that is similarly magnetically coupled. Output is led from the coupling pattern 5 to an external circuit via the connection pattern 51, and filter characteristics are obtained.

However, due to variations in the dielectric constant of the dielectric plates 21 and 22, manufacturing errors in the length, width, spacing, etc. of the conductor patterns of the resonator 4 and the coupling pattern 5, the desired filter characteristics cannot generally be obtained.

Therefore, in order to adjust the degree of coupling, the coupling pattern 5 exposed on the side surface of the dielectric plate 22 is
By scraping away the conductor layer little by little and narrowing the width, the optimum characteristics are adjusted.

Therefore, since the degree of coupling is adjusted in the direction of weakening, the coupling interval between each resonator 4 and the coupling pattern 5 is set in advance to be narrower than the optimum dimension.

The above embodiment shows one example, and the number of resonators 4 and the resonance frequency of each are determined by the filter characteristics, and are not limited to those of the above embodiment.

In addition, in order to adjust the degree of coupling, the sides of the dielectric plate 22 are widened,
In contrast to cutting off the exposed portion of the bonding pattern 5 to make it thinner, there is also a method of arranging a plurality of narrow width patterns in parallel to the basic portion and adjusting them in the amplification direction by soldering. In this case, contrary to the above embodiment, since the impedance is adjusted in an increasing direction, the coupling interval may be set to be a little apart.

Although this embodiment is for mobile radio use in the 800M11Z band, the applicable frequency band is not limited to this.

〔Effect of the invention〕

As described above, according to the present invention, a dielectric filter can be replaced with a coupling degree adjustment function added to the dielectric filter itself, and the structure is easy to adjust as a single unit, the mounting board can be downsized, and it is easy to manufacture and economical. The effects are significant.

4

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and FIG. 2 shows an example of a conventional triplate dielectric filter. In the figure, 1.15 is the dielectric filter, 3.35 is the ground plane, and 4
．． 45 is a resonator, 5 and 55 are coupling patterns,
21.22.25.26 are dielectric plates, 41.46 is an open end, and 51.56 is a connection pattern. Part A: A comical example of the present invention. Figure 1.

Claims (1)

[Claims] Two dielectric plates (21) (22) of the same outline are brought into close contact,
The outer surface is the ground plane of the conductive layer (3), and the conductive layer pattern is arranged on the contact surface to form a TEM mode resonator (4) and an input/output magnetic field coupling pattern (5). 1. A plate-type dielectric filter (1), characterized in that the magnetic field coupling pattern (5) is provided with the magnetic field coupling pattern (5) extended to the side surfaces of the dielectric plates (21, 22).