JPH0213102A - Dielectric coaxial resonator and frequency adjusting method for band pass filter using the same resonator - Google Patents

Abstract

PURPOSE:To simplify the adjustment of a center frequency by trimming the side of an outer conductor layer close to its short-circuit face so as to decease the resonance frequency and trimming the side of an outer conductor layer close to its open end face opposite to the short-circuit face so as to increase the resonance frequency. CONSTITUTION:In the case of adjusting the resonance frequency fr of the dielectric coaxial resonator itself, a part S1 of an outer conductor layer 4 at one side face of the coaxial resonator 1 close to its open end face is trimmed by a laser trimming device or the like, then the frequency fr is able to be increased, and a part S2 of the outer conductor layer 4 close to its short-circuit end face is trimmed conversely in a similar way, then the frequency fr i$ able to be decreased. In this case, as the distance (d) between the short-circuit end face and the trimmed part S1 or S2 is parted from the distance d=1/2.l, the shift fr of the frequency fr in the frequency decreasing and increasing direction is increased. Moreover, the shift fr of the frequency fr in both the frequency decreasing and increasing directions is larger as the area S of the trimmed part S1 or S2 is smaller and the value Q is increased as the shift fr is larger. Thus, the adjustment of the center frequency is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a coaxial resonator using a single body and a method for adjusting the frequency of a bandpass filter using this coaxial resonator.

(b) Conventional technology In recent years, dielectric coaxial resonators using ceramic dielectrics have come to be used for oscillation type and bandpass filters of several 100 MBZ to I GHz degrees. A) As shown in (B), this type of coaxial resonator (1) has an outer diameter 1lj4 on the inner and outer peripheral surfaces of a rectangular cylindrical ceramic dielectric material (3) having a through hole (2) in the center. The conductor layer (4) and the inner (IJI conductor layer (5)) are formed by baking or the like, and the conductor layer (6) short-circuiting between the two body layers (4) and (5) is made of the dielectric ( 3) is formed on one end face side of the dielectric (3), where the axial length of the dielectric (3) is e, the dielectric constant is ε, and the resonant wavelength is λ.The coaxial resonator is an input/4 type. It should be noted that from the surface on which the conductor layer (6) of the dielectric material (3) is formed on the negative side, a fourth part (7) is completely formed on the open end face opposite to the short-circuited end face. Part 4 (7
) is for fitting an insulating board for -j in resonance molding, and the end of the inner conductor layer (5) is extended (5a) into the above-mentioned four parts 7〉. The number 7 is for connection with the T pole formed on the surface of the L2 substrate.

The resonant frequency f of such a 4N dielectric coaxial coaxial 1i
1iJl in the manufacturing process! In the case of
By cutting off all or part of the dielectric with a troublesome open end using a laser trimming device, etc., as shown in Fig.
r is increased, and the conductor Jf! By similarly cutting off the negative part of (6), f'r was lowered.

(c) Problems to be Solved by the Invention However, in the conventional adjustment method as described above, f'
Since the surface to be scraped differs depending on the adjustment direction of r, there are problems such as the adjustment takes time and the trimming device becomes complicated. Furthermore, if the above-mentioned recess 7> is not completely formed on the open end surface, there is also the drawback that the open end surface cannot be trimmed freely.

Therefore, the present invention provides an adjustment method that allows adjustment of the resonant frequency of a dielectric coaxial resonator by such trimming and adjustment of the center frequency of a bandpass filter using this resonator easily and efficiently in a short time. The purpose is to provide a method.

(d) Means for Solving the Problems The adjustment method of the present invention can be applied to a dielectric coaxial resonator having the above-mentioned structure, or a human output code, a coupling capacitor, etc., to form a bandpass. The resonant frequency fr of the coaxial resonator or the center frequency ro of the bandpass filter is adjusted by trimming at least −·· of the plurality of dielectric coaxial resonators constituting the filter near the short-circuited end face of the outer conductor layer. Descend, outside the above (+11
By trimming the side near the open end surface opposite to the short-circuited surface of the 7th conductor i11, fr or f'o'2 is increased.

(Po) In the resonant mode of the working dielectric coaxial resonator, if we consider the equivalent circuit as a parallel resonant circuit of an inductance (L) and a capacitor (C), its resonant frequency fr"2, , Ti-!:
Htt t Z & hs -Cfi are both "40" By trimming the side close to the open end surface of the outer conductor layer, the L value decreases and fr increases, and conversely, by trimming the side close to the shorted end surface. The C value increases due to f
It is thought that r will decrease. Due to such an effect, the rr of the dielectric resonator and the rO of the bandpass filter determined by this rr can be adjusted both in height and in the lower direction.

(f) Examples Hereinafter, the adjustment method of the present invention will be explained based on examples. First, the resonant frequency f'r of the dielectric coaxial resonator itself
When performing the adjustment, as shown in Fig. 1 (a), the outer conductor layer (4) near the open end face of the coaxial resonator (1) is trimmed off using a laser trimming device or the like. , it is possible to raise rr, and conversely, if the portion of the conductor layer 4) near the short circuit 0#A surface (Sl) is similarly scraped off, rr can be lowered. At that time, as shown in Figure 2, the part to be trimmed from the shorted end face (
Sx)i+or the distance (d) to (Sl) is d-1/2
- The displacement amount Δfr of f'r in the frequency increasing direction and frequency decreasing direction increases as the distance from ri increases. Also, as is clear from Fig. 3, △rr in each jj direction becomes larger when the area △S of the H portion (Sl) or (Sl) is smaller, and the Q value becomes larger as △rr becomes larger. It increases.

Furthermore, Figures 4(a) and 4(b) show a bandpass filter using two dielectric coaxial resonators (with the same f'r) shown in Figure 1, and Figure 4(c) shows this filter. In other words, the equivalent circuit of the bandpass filter in the figure is shown as shown in Figure 5, and the figure number (IHI') in the figure is
correspond to the coaxial resonator (1)<1') in FIG. 4, respectively. In addition, as shown in Fig. 4 (b), the human power capacitor (C1) has human power electrodes (10) and (11) formed on both the front and back sides of the alumina substrate (9), respectively, and the output capacitor (C2) is also Output electrodes (12) (13)
The coupling capacitor (C3) has input and output electrodes (10) and (12) on the surface side connected to a gap (14).
) are sandwiched and confronted.

In addition, in the 4th Ward (a) and (b), (15) (15
> are the input terminal (Tl) and output terminal (Tl) in Fig. 5, respectively.
(17) is a shield plate that also serves as a holding frame and has four legs (17a) corresponding to the common terminal (T3) in FIG. is directly soldered (18) to the outer conductor layer (4) of the coaxial resonator (1) (1').

In order to adjust the center frequency rO of the bandpass filter shown in Fig. 4, as shown in Fig. 4 (b), the shield plate (17) is not soldered. (Both sides in the long plane direction of 1'l (l a) (1'
The outer conductor layer in a) may be trimmed in the same manner as in FIG.
) by trimming the part (Sl), the coaxial resonator (
1) The rO and passband of the bandpass filter determined by the resonance frequency f'r of (1'l) move from the solid line in Fig. 6 to the higher direction as shown by the broken line. Misalignment in trimming the portion (Sl) of the solid side (1aH1'a) will cause them to move in opposite directions.

In addition, in the case of the above band-pass filter, trimming is not necessarily performed on the image plane 1 (1) of the two coaxial resonators (1) (1').
It is not necessary to apply both 1a) and (1'a), and the amount of adjustment (
If the amount of frequency displacement △ro) is at least good, trimming may be performed on only one side.Also, when adjusting the resonant frequency ``r'' of a single coaxial resonator, trimming may be performed on any of the four outer circumferential surfaces. Furthermore, the direction of the trimming is not necessarily perpendicular to the axial direction of the coaxial resonator as shown in the figure.

(G) Effects of the Invention According to the present invention, by trimming the outer conductor layer on the same surface of the dielectric coaxial resonator, the resonant frequency rr of the resonator is reduced, and the center frequency f of the bandpass filter using the Ebiko resonator is (Since + adjustments are made, these adjustments can be made while measuring the frequencies fr and 0, making it easy and efficient to make adjustments in a short time.

[Brief explanation of the drawing]

1(a) and 1(b) are respectively a perspective view and a sectional view taken along the line A-A' of the dielectric coaxial resonator which is the object of the present invention, and FIG.
The figure is a characteristic diagram showing the relationship between the trimming position and the resonance frequency displacement amount, Figure 3 is a characteristic diagram showing the relationship between the trimming area, the resonance frequency displacement amount, and the Q value, and Figure 4 (A) (
(b) and (c) are respectively a perspective view of a bandpass filter using the dielectric resonator shown in Fig. 1, its sectional view along the line A-A', and a perspective view of the substrate, and Fig. 5 is an equivalent circuit of this bandpass filter. FIG. 6 is a diagram of its frequency characteristics. (1) (1'): Dielectric coaxial resonator, (4): Outer conductor layer, (5): Inner conductor layer, (S 1) (Sl): l
-Rimi 7・G part

Claims (2)

[Claims] (1) An inner conductor layer and an outer conductor layer are formed on the outer circumferential surface of a cylindrical dielectric, and a conductor layer that short-circuits both conductor layers is formed on one end surface of the dielectric. In a dielectric coaxial resonator having a short-circuited end surface, the resonant frequency is lowered by trimming the side of the outer conductor layer close to the short-circuit surface, and the open end surface of the outer conductor on the opposite side to the short-circuit surface is trimmed. A frequency adjustment method for a dielectric coaxial resonator in which the resonant frequency is increased by trimming the side closer to the . (2) An inner conductor layer and an outer conductor layer are respectively formed on the outer peripheral surface of the cylindrical dielectric, and a conductor layer that short-circuits both conductor layers is formed on one end surface of the dielectric. In a bandpass filter, a plurality of dielectric coaxial resonators each having a short-circuited end face are arranged in parallel on an insulating substrate so as to be connected to an input/output capacitor and a coupling capacitor formed on an insulating substrate. The center frequency is lowered by trimming the side of at least one outer conductor layer of the resonator near the short-circuit surface, and the center frequency is lowered by trimming the side of the outer conductor layer near the open end surface opposite to the short-circuit surface. A frequency adjustment method for a bandpass filter using a dielectric coaxial resonator that increases the center frequency.