JPH03150905A - Dielectric filter - Google Patents

Abstract

PURPOSE:To attain compactness, high reliability and low cost for the dielectric filter by ensuring a plane in common to each resonator on an upper face of a dielectric base, forming an input output pattern and a polarized pattern on the plane and providing a resonator for countermeasuring a 3rd harmonic wave. CONSTITUTION:Input output pattern 24, 25 and a polarized pattern 26 (as required) made of a metallized conductor layer 22 are formed on the upper face of a dielectric base 10 by utilizing a space in common to each resonator formed by terminating resonance slots 11-15 and coupling slots 16-19 on the way. Moreover, a rejection filter for countermeasuring a 3rd harmonic wave comprising resonator slots 20, 21 for countermeasuring a 3rd harmonic wave is formed on the same dielectric base 10. Thus, the dielectric filter with rejection filter which is compact, highly reliable and of low cost is constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dielectric filter used in a transmitting/receiving (alul) path of, for example, a car telephone.

[Conventional technology]

For example, dielectric filters are used as filters in transmitting/receiving circuits in mobile radio communications such as car telephones and multi-channel medium access radios, as well as in microwave multiplex radio communications. As this kind of dielectric filter,
In a dielectric filter in which a strip conductor and a ground conductor are integrally formed with a conductive film closely adhered to a dielectric substrate, in order to easily adjust the degree of coupling between resonators and the resonant frequency, as shown in Fig. 6. , a plurality of resonator grooves 41, 42, 43 are provided on a dielectric substrate 40 having a conductive layer (matte patterned portion) 49 at ground potential on each side and bottom surface, and each resonator groove has one end (short circuit). one end) is electrically connected to the four conductive layers, and the other end (
Strip conductor 44.45.46 with open end)
It has already been proposed to form strip conductors so that their open ends are in the same direction, and to connect the open ends of these strip conductors via capacitors 47° and 48 (Japanese Patent Laid-Open No. 161801/1983). Public bulletin).

In this known dielectric filter, each resonator groove 41
, 42.43, one stage of resonator is constructed, and the interstage coupling is provided between the open ends of the strip conductors.
7.48. The terminal as a dielectric filter can be provided by leading out a tab from the strip conductor 44 in its longitudinal direction, or by using a tab (lead wire) not shown in the strip 50 formed on the dielectric substrate 40 at right angles to the resonator groove.
This is done by connecting.

In this type of dielectric filter, as illustrated by the attenuation curve Q1 in FIG. 4, the center frequency f.

There is also a relatively large “second wave” at the frequency 3f, which is three times
There is a problem that ``mountains'' tend to appear. In order to avoid this, conventionally, as shown in Fig. 5, a rejection filter having characteristics that cancels out the "second peak" that occurs at the triple frequency 3f has been connected. There is.

[Problem to be solved by the invention]

However, this rejection filter is provided in conjunction with a separate component from the dielectric substrate, which is not preferable in terms of reliability and cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable and low-cost dielectric filter having a deflection filter means for dealing with third harmonic waves.

[Means to solve the problem]

In order to achieve the above object, the present invention provides main resonator grooves and coupling grooves alternately along the longitudinal direction on the upper surface of the dielectric substrate.
The short-circuited end is formed almost perpendicularly to the longitudinal direction so that one end, which is a short-circuited end, penetrates one side of the dielectric substrate, and the other end, which is an open end, does not reach the other side of the dielectric substrate. A third harmonic resonator groove having a length of approximately 1/3 of the main resonator groove is formed at at least one end of the dielectric substrate, and the side and back surfaces of the dielectric substrate and each resonator groove are electrically connected to each other by metallization. A matching conductive layer is applied to the other side of the upper surface of the dielectric substrate, one end facing the open end of the main resonator groove which becomes the input/output end of the main resonator groove, and the other end facing the third harmonic wave. The dielectric filter has an input/output pattern formed of a conductive layer facing the open end of the resonator groove and connected to the input/output terminal.

[For production]

In the above dielectric filter, on the top surface of the dielectric substrate,
By forming the main resonator groove and the coupling groove so that one end, which is a short-circuited end, penetrates one side of the dielectric substrate, and the other end, which is an open end, does not reach the other side of the dielectric substrate, A common plane for each resonator is secured on the top surface of the dielectric substrate, an input/output pattern and a polarized pattern are formed as necessary on that plane, and third harmonic countermeasures are further capacitance-coupled via the pattern. Since the resonators are provided on the same dielectric substrate, it is possible to construct a compact, highly reliable, and low-cost dielectric filter.

〔Example〕

FIG. 1 shows an embodiment of a dielectric filter according to the present invention. In this dielectric filter, main resonator grooves 11, 12, 13 running in the width direction of the dielectric substrate 10 are provided.
．． 14 and 15 are arranged in parallel along the longitudinal direction, and coupling grooves 16.17 and 18.19 are arranged between adjacent main resonator grooves.

Further, at the ends of the first and fifth main resonator grooves 11.15, there is provided a third harmonic countermeasure resonance which functions as a rejection filter and has a length of about 1/3 of the main resonator grooves 11 to 15. A groove 20.21 is provided. Each resonator groove is set on the same side of the dielectric substrate 10, that is, the short-circuited ends, which will be described later, are placed on the same side of the substrate. Dielectric substrate 10
A conductive layer 22 made of metallization is formed on the bottom and side surfaces, the main resonator grooves 11, 12, 13, 14° 15, and the third harmonic countermeasure resonator grooves 20, 21, respectively, as shown by the matte pattern. The bottom and side surfaces of the dielectric substrate 10 and the lid 23 placed thereon are connected to each other and are used at ground potential.

Main resonator grooves 11 to 15 and third harmonic countermeasure resonator groove 20.
21 and the coupling grooves 16 to 19 each have one end penetrating the side surface of the dielectric substrate 10 to form a short-circuited end, and the other end terminating halfway to the side surface to form an open end.

With the above configuration, the main resonator grooves 11, 12, 13°, 14.
A resonator is constructed for every 15, and these are coupled via coupling grooves 16, 17, 18, 19 to constitute a dielectric filter, and a resonator groove 20, 21 for third harmonic countermeasure is formed.
A rejection filter for third harmonics is configured.

Utilizing the space common to each resonator created by terminating each resonator groove and coupling groove midway, input/output patterns 24 and 25 made of a conductive layer formed by metallization are formed on the upper surface of the dielectric substrate 10. A polarized pattern 26 is formed as required. Input/output pattern 2
One end of 4.25 is opposite to the open end of the first and fifth main J (oscillator groove 11. -1 direction and a terminal pin 27 provided through the dielectric substrate 10.
．． 28. Terminal pin 27.28
As shown in FIG. 2, the portion through which the dielectric substrate 10 penetrates is configured as a non-conductive portion 29 in which no conductive layer is provided on the back surface of the dielectric substrate 10.

Terminal pins 27 , 28 are therefore insulated from conductive layer 22 . Both ends of the polarized pattern 26 are
In this example, the second and fourth main resonator grooves 12.1
Therefore, the capacitive part is connected between the second and fourth main resonators.

According to the above configuration, the input/output patterns 24 and 25 formed on the dielectric substrate 10 and the main resonator groove 1 facing thereto
1.15 and between the polarized pattern 26 and the opposite open end of the main resonator groove 12.14, capacitances are formed between the input/output pattern 24 and the open end of the main resonator groove 12.15.
．． 25, the input/output terminals are led out from the first and fifth resonators through capacitance coupling, and the polarized pattern 26 is connected to the capacitive part that couples the second and fourth resonators. Polarization by the transmission line portions is achieved by conductive patterns provided on the upper surface of the dielectric substrate 10, respectively. Furthermore, a rejection filter for countermeasures against third harmonic waves is also constructed on the same dielectric substrate 10.

The attenuation curve Q2 in FIG.
As shown in , the so-called third harmonic can be significantly reduced.

In this way, it is possible to obtain a dielectric filter with a rejection filter that is compact, can be surface-mounted, and can be constructed with high reliability and low cost without installing any parts separate from the dielectric substrate 10. can.

FIG. 3 shows another embodiment of the invention.

In this embodiment, the capacitive coupling between the resonator formed by the main resonator groove 11.15 and the cover turn 24.25 is provided by a chip capacitor 30.31 and by the main resonator groove 12.14. The difference from the embodiment shown in FIG. 1 is that the capacitance coupling between the configured resonator and the polarized pattern 26 is performed by chip capacitors 32 and 33, and there are other differences between the two. There is no. With this configuration as well, it is possible to achieve the same functions and effects as the embodiment shown in FIG.

In addition, in this embodiment, the third harmonic countermeasure resonator groove 2
The coupling between the open end of 0.21 and the input/output patterns 24 and 25 is achieved by capacitance coupling using a capacitance formed by using the dielectric substrate 10 as a capacitance element, and this capacitance is also obtained by a chip capacitor. be able to.

As described in detail above, a compact dielectric filter with a glue displacement filter that is compact, surface-mountable, and low-cost and highly reliable is constructed without the need for additional parts separate from the dielectric substrate 10. be able to.

In the above-described embodiment, one resonator groove for 3rd harmonic countermeasures is provided on each side of the dielectric substrate 10. There may be modified embodiments, such as one provided only on either side, or two provided only on either side.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a common dielectric substrate is used without providing a separate printed circuit board, and a compact, surface-mountable, low-cost, and highly reliable A dielectric filter with a glue displacement filter can be provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention, and FIG. 2 is a perspective view showing one embodiment of the present invention.
Fig. 3 is a perspective view showing the second embodiment of the present invention; Fig. 4 shows a dielectric material with large attenuation at a frequency three times the center frequency. Figure 5 is an attenuation curve diagram showing the attenuation characteristics of the filter. Figure 5 is an attenuation curve diagram of a rejection filter used to improve the characteristics at a frequency three times that of Figure 4. Figure 6 is a perspective view of a conventional dielectric filter. be. 10...Dielectric substrate, 11.12.13,14°15
...Main resonator groove, 16.17, 18.19...Coupling groove, 20.21...Resonator groove for third harmonic countermeasure, 22...
・Conductive layer, 24.25... Input/output pattern, 26...
・Polarized pattern, 27.28...Terminal pin, 29・
... Non-conductive part, 30.31, 32.33... Chip capacitor.

Claims (1)

[Claims] Main resonator grooves and coupling grooves are formed on the upper surface of the dielectric substrate alternately along the longitudinal direction, substantially perpendicular to the longitudinal direction,
One end that is a short-circuit end penetrates one side of the dielectric substrate, and the other end that is an open end does not reach the other side of the dielectric substrate, and at least one of the dielectric substrates A third harmonic resonator groove having a length of about 1/3 of the main resonator groove is formed at the end, and the side and back surfaces of the dielectric substrate and each of the resonator grooves are electrically conductive to each other by metallization. A layer is provided on the other side surface side of the upper surface of the dielectric substrate, one end facing the open end of the main resonator groove which becomes the input/output end of the main resonator groove, and the other end facing the A dielectric filter having an input/output pattern formed of a conductive layer facing the open end of a wave resonator groove and connected to an input/output terminal.