JPH02177701A - Input and output structure of dielectric filter - Google Patents

Abstract

PURPOSE:To easily adjust the center frequency by directing a shortcircuit face of a semi- coaxial resonator formed with a metal coated dielectric block toward a printed circuit board and directing an open face of the semi-coaxial resonator whose dielectric block is not metal- coated toward a side opposite to the printed circuit board. CONSTITUTION:An open side 10 of a semi-coaxial resonator being a side of a rectangular dielectric block 100 not subject to metal coating is directed to a side opposite to a mounted printed circuit board 5, and a side 20 of the block 100 subject to metal coating being a shortcircuit side of the semi-coaxial resonator is directed toward the side of the printed circuit board and they are connected directly to eliminate an undesired metallic case. Moreover, a couple of holes 21,22 whose both ends are opened with a proper diameter for inputting and outputting a signal from/to the printed circuit board 5 are made to the dielectric block 100 in addition to resonance holes 11, 12 whose one end is short-circuited and whose other end is opened, metallic rods 41,42 supported by supports 31, 32 with a low dielectric constant are penetrated to the input/output holes 21, 22 to form the line of the coaxial structure. Then the input/output signal is led to an open face 10 of the semi-coaxial resonator through the coaxial line and coupled with the open end of the resonator holes 11, 12 of the semi-coaxial resonator in terms of the electric field through capacitors 61, 62 and excited.

Description

[Detailed Description of the Invention] [Summary] A dielectric filter using a miniaturized semi-coaxial resonator using a metal-coated dielectric used in mobile radio equipment with frequencies of several hundred meters (2 bands and above). Regarding the input/output structure of the , the aim is to create an input/output structure with good impedance characteristics that can cope with the further miniaturization of dielectric filters and the future increase in frequencies. The short-circuited surface of the semi-coaxial resonator made by opening the dielectric block faces the printed board that supplies input/output signals, and the open surface of the semi-coaxial resonator that is not coated with metal of the dielectric block faces the opposite side from the printed board. A pair of holes with an appropriate diameter are opened in the dielectric block, and a metal rod supported by a low dielectric constant support is passed through the holes to create a coaxial structure.The metal rods in the coaxial structure are used to connect input and output to the printed board side. The signal is transmitted to the open surface side of the semi-coaxial resonator, and is electrically coupled to the open surface of the semi-coaxial resonator using a capacitor for input/output.

[Industrial application field]

The present invention relates to filters for several hundred M) lz bands and higher frequency bands used in mobile radio equipment such as automobile radio telephones, and particularly relates to a rectangular parallelepiped dielectric in which one side of the resonator constituting the filter is coated with metal and the other side is coated with metal. This paper relates to the input/output structure of a small dielectric filter using a semi-coaxial resonator with a resonant hole in the block.

Small semi-coaxial resonator dielectric filters in the several hundred Mllz band are becoming ultra-miniaturized into chip components that allow other components of wireless devices to be mounted from the surface of a printed circuit board. Therefore, it is desired to make the device even smaller than it is now. Furthermore, since the dielectric loss of the dielectric material is considerably reduced, it is becoming practical even in high frequency bands such as quasi-microwaves of IGIIz or higher. For this reason, several hundred M
There is a need for an input/output structure for a dielectric filter that can be connected to an external circuit without impedance mismatch even in a frequency band higher than the Hz band.

[Conventional technology]

The input/output structure of a conventional dielectric filter is as shown in Figure 3.
A dielectric internal resonator I having only one surface 10 out of six surfaces of a rectangular parallelepiped dielectric block 100A that is not coated with metal.
The open surfaces of the semi-coaxial resonator consisting of A, 2A and the hollow external resonator 3A, that is, the surfaces 21, 22, 23, and 24 of the dielectric without metal coating, are on the side of the printed board 5A,
Human power capacitor 11A and resonator 2 that electrically couple external input signals to open surfaces 21.23 of resonators IA and 3A.
^, Connect the metal rods 31A and 32A attached to the printed board 5A to the input/output wires of the printed board 5A by soldering etc. to the output capacitor 12A that electrically couples the output signal taken out to the outside on the open surface 22.24 of the 3A. do. Then, by appropriately scraping off the metal coating portion 25 on the printed board 5A side that connects the open ends of the internal resonators IA and 2A, and adjusting the capacitance between the open ends of the internal resonators IA and 2A. , the center frequency of a semi-coaxial dielectric filter consisting of internal resonators IA, 2A and external resonator 3A is adjusted.

[Problem to be solved by the invention]

However, the work of adjusting the center frequency by cutting the metal coating portion 25 connecting the open ends of the internal resonators IA, 2^ requires that the open ends of the resonators IA, 2A, 3A be on the printed board 5A side. , it was either impossible or extremely difficult to do so. In addition, the open surfaces of the resonators LA, 2A, and 3A are 21°22
．． When 23 and 24 come close to the printed circuit board 5A on which the resonator is mounted, capacitance enters there, the resonant frequency of the semi-coaxial resonator changes, and the predetermined filter characteristics are disrupted. Therefore, a metal case 4A was required to separate the open surface of the resonator from the printed circuit board 5A. For this reason, the dielectric filter is larger by the size of the metal case 4A than the size of the dielectric block forming the actual filter.

Further, the input/output capacitors IIA, 12A and the printed board 5A are separated for the above reason, and the metal rods 31A, 32A connecting them do not have a coaxial structure, resulting in deterioration of impedance characteristics.

In particular, when the frequency of the filter transmission signal becomes high, inductance components of the input and output metal rods 31A and 32A enter, which adversely affects the filter characteristics. Therefore, even though conventional dielectric filters use dielectric materials, they cannot be made much smaller, it is difficult to adjust the center frequency, and the impedance characteristics of the input and output sections are poor in response to future high frequencies, which will have a negative impact on filter characteristics. There is a problem that it causes

The present invention aims to solve these problems.

[Means to solve the problem]

Referring to FIG. 1, in order to make it easier to adjust the center frequency of the dielectric filter, this problem is solved by using an open surface 10 of a semi-coaxial resonator, which is a surface without metal coating of a rectangular parallelepiped dielectric block 100 made of the material. is placed on the side opposite to the mounting printed board 5, and the dielectric metal-coated surface 20, which is the short-circuit surface of the semi-coaxial resonator, is placed on the printed board 5 side and directly connected to remove the unnecessary metal case.

In addition to the resonance holes 11 and 12, which have one end short-circuited and the other end open, the dielectric block 100 also has a pair of open-ended holes of suitable diameter for inputting and outputting signals to and from the printed board 5. Hole 21.
22 is opened, and metal rods 41 and 42 supported by low dielectric constant supports 31 and 32 are passed through the input/output holes 21 and 22 to create a line with a coaxial structure, and the input and output signals are semi-coaxially resonant with the coaxial line. Connect the capacitor 61.6 to the open surface 10 side of the container.
This problem is solved by the present invention, which is configured to cause electric field coupling to the open ends of the resonance holes 11 and 12 of the semi-coaxial resonator in order to excite the semi-coaxial resonator.

In the principle diagram of FIG. 1 showing the structure of the dielectric filter of the present invention, 100 is a rectangular parallelepiped dielectric block which is the material of the dielectric filter of the semi-coaxial resonator. One of the six sides of the body block is not coated with metal and has one hole for resonance.
1.12 is provided as the open surface 10 of the semi-coaxial resonator, and the other 5
The surfaces are coated with metal, and a surface 20 facing the one surface is used as a short-circuit surface of the semi-coaxial resonator.

10 is one of the six sides of the dielectric block 100 in the shape of a rectangular parallelepiped that is not coated with metal, and is an open side of a semi-coaxial resonator provided with holes 11 and 12 for resonance, and is used for mounting the semi-coaxial resonator. It is located on the side opposite to the printed board 5 for use.

11 and 12 are holes for resonance of a semi-coaxial resonator with one end open and the other end short-circuited.

Reference numeral 20 denotes a metal-coated surface opposite to one of the five metal-coated surfaces of the rectangular parallelepiped dielectric block 100, excluding one of the six surfaces, and serves as a short-circuit surface of the semi-coaxial resonator.

Reference numerals 21 and 22 are a pair of holes for human output signals, which are open at both ends and have an appropriate diameter.

31.32 is a low dielectric constant support that supports the metal rod 41.42 to pass through the hole 21.22;
It is a metal rod that is supported by 22 and has a coaxial structure and exhibits an appropriate line impedance.

5 is a printed board to which the short-circuited surface of the semi-coaxial resonator is soldered and supplies input/output signals.

Reference numerals 61 and 62 designate capacitors that electrically couple input and output signals input and output from the printed board 5 to the open ends of the semi-coaxial resonance holes 11 and 12.

The capacitors 61 and 62 connect the input/output hole 21.
．． Coaxial structure metal rod 41°42 supported inside 22
The impedance-matched human output signal input/output via the filter is configured to be electrically coupled to the open surface 10 of the resonant hole 11, 12 of the filter.

[Effect]

In the dielectric filter of the present invention, since the open end surface of the semi-coaxial resonator is located on the opposite side from the printed board 5, the center frequency can be easily adjusted.

Furthermore, the short-circuit surface of the semi-coaxial resonator is placed on the side of the printed board 5 and can be directly fixed to the ground pattern of the printed board 5, resulting in miniaturization.

Furthermore, the metal rods 41.42, which serve as input/output terminals for signals input/output from the printed board 5, are inserted into the holes 21.22 with both ends open and the periphery coated with metal, so that the input/output lines have a coaxial structure. , even if the input and output lines become longer,
Basically, if the line impedance is equal to the signal source impedance and the load impedance, input and output impedance matching can be achieved, so even if the frequency of the input and output signals increases, the filter characteristics will not deteriorate.

Therefore, the dielectric filter of the present invention solves all the problems of the input/output structure of the conventional dielectric filter.

〔Example〕

FIG. 2 is a structural diagram showing the input/output structure of a dielectric filter according to an embodiment of the present invention, showing an example in which a dielectric filter consisting of two semi-coaxial resonators is mounted on a printed circuit board 5. The hole 21.22 of the coaxial structure into which the metal rod 41.42 serving as the input/output terminal for the signal input/output from 5 is inserted is filled with a low-loss dielectric material such as Teflon.

In the structural diagram of FIG. 2, the input signal coming from the left side of the printed board 5 passes through the input signal line (1) of the printed board 5 and enters the input hole 21 of the coaxial structure, which is a feature of the dielectric filter of the present invention. The metal rod 41 inserted and soldered to the input terminal leads to the capacitor 61, and is electrically coupled to the open end of the resonance hole 11 of one of the two semi-coaxial resonators 11.12 of the dielectric filter. The signal electrically coupled to the open end of the resonant hole 11 is coupled to the open end of the resonant hole 13 of the other 13.14, and both resonators 11.12.13
．． 14 to the desired characteristics.

The filtered output is then passed through a conductive wire from the electric field coupling capacitor 62 provided at the open end of the resonance hole 14 of the output side resonator 13, 14 to the output of the coaxial structure in the same manner as the input. The signal is output by a metal rod 42 inserted into the hole 22 and soldered, and connected to the output signal line (2) of the printed board 5.

Also in the dielectric filter of the embodiment shown in FIG.
, 42 are inserted into the holes 21 and 22, which are open at both ends and surrounded by a metal coating and whose interior is filled with a low-loss dielectric material such as Teflon, so that the input and output lines form a coaxial structure with a constant impedance. Even if the input/output line becomes long, if the constant line impedance is equal to the signal source impedance and load impedance, input/output impedance matching can be achieved, so even if the frequency of the input/output signal increases, the filter characteristics will not deteriorate. It doesn't happen.

Therefore, there is no problem with the input/output structure of the dielectric filter according to the embodiment of the present invention shown in FIG.

〔Effect of the invention〕

As explained above, according to the present invention, since the dielectric filter (1) has the open surface of the resonator facing away from the mounting printed board, the center frequency can be easily adjusted. ■Since the short-circuit surface of the resonator faces the mounting printed board side, it can be directly connected to the ground surface of the printed board, eliminating the need for a metal case, resulting in a smaller size.

■Unnecessary capacitance between the resonator and printed board is eliminated, so there is no change in the required filter characteristics.

(2) Since the input/output signal line has a coaxial structure provided within the dielectric block, impedance matching is easy to achieve and the desired filter characteristics are guaranteed up to high frequencies.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram showing the configuration of the input/output structure of the dielectric filter of the present invention, Fig. 2 is a structural diagram showing the configuration of the input/output structure of the dielectric filter of the embodiment of the present invention, and Fig. 3 is a conventional diagram. FIG. 2 is a structural diagram of an input/output structure of a dielectric filter. In the figure, 100 is a rectangular dielectric block, 10 is a surface without metal coating, 20 is a surface with metal coating, 11.12 is a resonance hole, 21.22 is an input/output hole, and 31 and 32 are supports. , 4
1°42 is a metal rod, and 61.62 is a capacitor. The input/output tree of this filter (showing the end of this filter)
Slippery prisoner Jllllff1

Claims (1)

[Scope of Claims] One of the six sides of a rectangular parallelepiped dielectric block (100) is not coated with metal and has resonance holes (11, 12) as an open surface (10) of a semi-coaxial resonator; The other five surfaces are coated with metal, and the metal coated surface (20) opposite to the first surface is used as a short-circuit surface of the semi-coaxial resonator, and the open surface (10) of the semi-coaxial resonator is used for input/output with the printed board (5). The signal is connected to a capacitor (61,
In the input/output structure of a dielectric filter that performs electric field coupling and input/output at 62), the short-circuit surface (20) of the semi-coaxial resonator in which the dielectric block (100) is coated with metal is directed toward the printed board (5), With the open surface (10) of the non-metallic semi-coaxial resonator of the dielectric block (100) facing away from the printed board (5), a pair of suitable diameters with both ends open are attached to the dielectric block (100). holes (21, 22) are drilled, and the pair of holes (21, 22) are opened.
22) are passed through metal rods (41, 42) supported by low dielectric constant supports (31, 32) to form a coaxial structure, and the metal rods (41, 42) of the coaxial structure are used to connect the printed board (5) side. The input/output signal is transmitted to the open side of the semi-coaxial resonator, and the capacitor (61, 62) connects the open side (1) of the semi-coaxial resonator.
1. An input/output structure of a dielectric filter, characterized in that input/output is performed by electric field coupling to 0).