JPS59139701A - Comb-line type band-pass filter - Google Patents

Abstract

PURPOSE:To attain an overall compact structure with simple control for a comb- line type band-pass filter by giving cuts to the wall of a housing and bending these cuts into the housing to control the resonance frequency. CONSTITUTION:A comb-line type band-pass filter contains a housing 1, dielectric materials 21-2n, resonance elements 31-3n, input/output coupling elements 40.1-4n.(n+1), input/output terminals 50.1-5n.(n+1), etc. In addition, resonance frequency fine adjustment elements 101-10n are provided to the band-pass filter by forming U-shaped similar cuts to the upper wall parts of the housing 1. Then the tongue-shaped areas of those cuts are bent downward to vary the mean distance between the elements 101-10n and 31-3n. In such a way, the fine adjustment is possible for the resonance frequency. Thus, the overall structure of a comb-line type band-pass filter with simple control is miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combline type bandpass filter for very high frequency waves or microwaves. Hereinafter, the bandpass filter will be abbreviated as BPF.

Figure 1 shows the Bukocom line type B that the inventor proposed earlier.
A cross-sectional view showing an example of a PF (B-8 cross-sectional view in Figure 2), Figure 2 is a cross-sectional view along A-A in Figure 1, and in both figures, 1 is a casing made of a conductor. (n is the order of BPF) is a dielectric material made of, for example, barium titanate porcelain or magnesium titanate porcelain. 31 to 3n are resonant elements, which are made of rod-shaped or cylindrical conductors whose respective axial lengths are approximately 14 times the resonant wavelength in terms of electrical length, and are fitted into insertion holes drilled in the dielectrics 2I to 2-IL. . Incidentally, instead of forming the internal conductors 3I to 37L using rod-shaped conductors, a metal coating such as silver or copper may be attached to the inner circumferential surface of the insertion hole drilled in the dielectrics 21 to 2711m by means such as @ deposition. is also possible. 4o, r, and 4n (Yori are input/output coupling elements, such as capacitors.

501. and 5n, (□71. is an input/output terminal %) 61 or the surface is a resonant frequency fine adjustment element, an electrode plate that faces the open end of the resonant elements 31 to 3n and forms a capacitance, and this electrode plate and the resonant element 71 to 7n-/ are interstage coupling adjustment elements, for example, capacitive screws. 8I to 8n
is a set screw to fix the resonant elements 31 to 3□ in a required position. When the resonant elements 31 to 3rL are made of a cylindrical conductor or a metal film, the dielectrics 21 to 2n are fixed by set screws 81 to 8L. 9. 971M-1 are two gaps between the dielectrics.

In this BPF', a resonant current flows through the resonant element 3I, '
M.

Then, a TFfVM mode wave is generated between the resonant element 31 and the housing 1, as shown in FIGS. 3 and 4, the distributions of the electric field E and the magnetic field H. At this time, a standing wave is generated in the resonant element 3I, as shown in FIG. 15, where the voltage distribution is shown by the dotted line and the current distribution is shown by the dashed-dotted line. Resonant element 3I depending on the component
The cut-off waveguide section formed by the housing 1 between and 3Q is excited to generate an Hl-mode wave, and the subsequent resonant element 3a is excited. In addition, in Fig. 5, i is the resonant current,
iH is the electric field of the 811 mode wave, H)l is the magnetic field of the H1+ mode wave, and the electromagnetic field of the H++ mode wave causes the resonant elements 31 and 32 to be coupled. Signal transmission is performed in the same manner as described above for three or less resonant elements.

An experimental formula expressing the magnetic coupling loss (reactance loss) between each resonant element, that is, an experimental formula that compensates for the influence of disturbance of the electromagnetic field near the resonant element.In each of the above formulas, bc is (K+Q; Magnetic coupling loss between resonant elements k = 1. 2. ... nCd
C(I Cd = -10-2 Cd -8 Distance between the center axis of the resonant element and the coupling surface of the dielectric (second
(Fig.) Cjay, (remainder): Each length of the air gap 91 to 9n, W: Width of the housing 1 (Fig. 2) ε: Dielectric early entry of the dielectrics 21 to 27: Free space wavelength of the transmission signal, Frequency f (GHz)
It is between.

The first term on the right side of equation (1) is the amount of loss in the cutoff waveguide section formed by the housing I corresponding to the dielectric part, and the second term is the loss amount in the cutoff waveguide section formed by the housing I corresponding to the dielectric part. 1 is the amount of loss in the four-wave tube section.

If the dielectric is uniformly interposed between the resonant elements without creating a gap between the dielectrics, and the center spacing of the resonant elements is 09, and (K÷I), the magnetic coupling between the resonant elements is The loss Lc is expressed by Kamoyari's empirical formula.

The equivalent path is shown in Fig. 6 both with and without a gap between the dielectrics, and the magnetic field coupling coefficient between each stage is Ml,a,M,...・M(n-1)
, W is generally MK, (X++), then the magnetic field coupling coefficient MK, (K publication) of each sharp divergence is expressed as 1.

Since the transmission mode in this BPF is the H1+ mode wave as described above, as shown in FIG. By inserting 71 in the electric field width direction of the 811 mode wave, the electric field is concentrated on the element 71 and the lines of electric force are made dense, as in the case of the waveguide BPF, and as a result, the magnetic flux (HH) is made dense and the groin The degree of coupling can be increased. Therefore, by changing the insertion length of the element 71 into the housing 1, it is possible to adjust the degree of coupling in a direction in which the degree of coupling becomes higher than when the insertion length is zero.

This interstage coupling adjustment element has the advantage that the insertion length of the element into the housing can be changed by operating from outside the housing, and the degree of joint coupling between the legs can be freely adjusted. However, the outer end of the element protrudes outside the housing. Therefore, the overall shape becomes complicated and large, which obstructs the purpose of using dielectric resonators to reduce the overall size. This also applies to the resonant frequency fine adjustment elements 6I to 6rL, and since the outer ends of each element protrude outside the housing 1, there is a drawback that it impedes overall miniaturization.

The present invention has an extremely simple structure, has no protruding parts outside the casing, and has an adjustment element that can perform fine adjustment of the resonance frequency and interstage coupling adjustment by operating from outside the casing, making the entire structure compact. The purpose of this invention is to realize a combline type BPF for very short waves or microwaves.

FIG. 8 is a sectional view (B in FIG. 9) showing one embodiment of the present invention.
9 is a sectional view taken along line A-A in FIG. 8, and in both figures, 1 is the housing, 2. or 2n is a dielectric, 3I
thru 3n are resonance elements, 4o, and 4n, (n+υ are input/output coupling elements %, 5o, + and 571.(no+> are input/output terminals, 8s and 8 are set screws, 9t and 9n-1 are air gaps. These are the same as those shown in Figs. 1 and 2. 10. to +On are resonant frequency fine adjustment elements which are the gist of the present invention.
As shown in the plan view of the upper wall of
The top wall of the casing l facing each open end of n consists of a notch shaped like a square or a U-shape, and the tongue-shaped part of this notch is placed downward (within the casing). ) By bending and changing the average distance between the elements +01 to +10n and the open ends of the resonant elements 31 to 31, the elements 10I to +O are bent.
The resonance frequency can be finely adjusted by changing the capacitance formed between n and each open end of the resonance elements 3I to 3n. 111 to Il, n-, which is also the gist of the present invention, is the interstage coupling adjustment element, and the resonant elements 31 to 3. In the earthen wall of the casing 1 facing each open end of t, a U-shape is provided between the resonant elements (ideally at a location corresponding to the center of the interval between the resonant elements facing each other in FA contact). Alternatively, it consists of a cut similar to a U-shape, and the length of insertion into the case is changed by bending the tongue-shaped part of this cut in the r direction (into the housing) and changing the bending angle. As in the case of the crotch joint adjustment element made of conventional capacitive screws,
It is possible to change the degree of groin connection.

Incidentally, FIG. 10 shows resonant frequency fine adjustment elements 10I to IOF+ and crotch coupling adjustment elements 111 to 1I? L-
In this example, the cutting direction of the notch forming the casing 1 is made to coincide with the longitudinal direction of the casing 1. Able to carry out inventions.

Also in the present invention, the question coupling adjustment element 11. Or IIy
As the insertion length of L- into the housing 1 increases, the coupling becomes denser, so when designing the BPF, determine the spacing between the resonant elements so that the degree of coupling between the legs is lower than the required value. During assembly, by appropriately bending the groin connection adjustment cables 11+ to 11-1 into the housing, the degree of interstage connection can be made to accurately match the required value.

Instead of determining the spacing between the resonant elements so that the degree of crotch coupling is lower than the required value during design, the spacing between the resonant elements is made smaller than the required value, and
As shown in FIG. 12, which is a sectional view taken along line A-A in FIG. 11, each dielectric 2. or 2□ bonding surface 1
This metal coating 12 forms a coupling window in the same direction as the resonant element.
11 and I 21J (either 12rt or 12 saws may be used) or 12tn-0, r and 12t
As shown in FIG. 13 is a cross-sectional view of the main part (B-8 cross-sectional view in FIG. 14), and FIG. 14 is a cross-sectional view taken along A-A in FIG. 13. Resonant element 3. or 3rL
conductor plates 132 . and +3
1 (either + 3. or 132. may be omitted) or l 3 < n-z), and 13 (71-υ
, and to lower the degree of crotch connection, and by adjusting the bending angle of the groin connection adjustment elements I+, -1-, and -1- into the housing to an appropriate value during assembly, the degree of connection can be accurately matched to the required value. Alternatively, instead of providing a coupling window formed by a metal film or a conductive plate, an inductive coupling blocking rod made of a conductor may be interposed between the resonant elements, and in either case, the resonant element spacing may be can be made relatively small, making it possible to downsize the whole.

The equivalent circuit and transmission characteristics of the BPF of the present invention are the same as those of the BPF shown in FIGS. 1 and 2.

The above example illustrates a case in which the entire structure is made smaller by providing a dielectric material around each resonant element to form a dielectric resonator, but it is of course possible to implement the present invention even if the dielectric material is omitted. .

As is clear from the above description, the resonant frequency fine adjustment elements io+ to 1o+1 and the interstage coupling adjustment elements +1+ to Ih-I in the BPF of the present invention are both U-shaped or U-shaped provided on the housing wall. There are 9 similar notches, and this notch is bent into the housing to adjust the resonance frequency and inter-stage coupling, so there is no protrusion outside the housing, making the overall shape simpler and smaller. In addition, the bending angle of the cut can be freely changed by sweeping from outside the casing, making adjustment extremely easy. Also, the structure of each element is extremely simple, making it suitable for mass production. The practical effect is enormous.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing a conventional bandpass filter, FIGS. 3 to 5, and 7 are explanatory diagrams of its operation, and FIG. 6 is its equivalent circuit diagram. 8 and 9 are cross-sectional views showing one embodiment of the present invention, FIG. 10 is a plan view showing an example of the main structure, and FIGS. 11 to 14 are main views of other embodiments. 1: housing, 21 to 2n: g% dielectric 3I to 3yL: resonant element, 4a,
1 and 4n, (n+su: input/output coupling element, 5a, 1 and 5 n, (n spear: input/output terminal, 6I to 6n and 1
0. to 10n: resonant frequency fine adjustment element, 71 to 7t, and 111 to lIn-,: interstage coupling adjustment element, 8I to 8yL = set screw, 9. or 9nt
: air gap, metal coating forming +2/l and 12/coni bond windows, conductor plate forming +3/l and 13/coni bond windows. Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 II

Claims (1)

[Scope of Claims] (1) A resonant element consisting of a plurality of rod-shaped or cylindrical conductors arranged with the same polarity and having an electrical length and an axial length of a resonant wavelength σ14; provided around each resonant element. J electric body and a resonator consisting of an i-shaped or U-shaped notch provided on the housing wall portion facing each open end of the plurality of resonant elements and bent into the housing. A combline type band pass characterized by comprising a frequency fine adjustment element and an input/output coupling element interposed between the first and final stage resonant elements and the input/output terminal among the plurality of resonant elements. Wow, sebum. (A resonant element consisting of a plurality of rod-shaped or cylindrical conductors with an electrical length of 2 mm and an axial length of approximately 14 resonant wavelengths and arranged with the same polarity, and a resonant element provided around each of the plurality of resonant elements. A U-shaped or U-shaped U-shaped or U-shaped U-shaped or U-shaped U-shaped or U-shaped dielectric, which is provided in the housing wall facing each of the open ends of the plurality of resonant elements and between each of the resonant elements, and is bent into the housing. It is characterized by comprising a crotch coupling adjustment element made of a cut similar to a letter shape, and an input/output coupling element interposed between the first and final stage resonance elements and the input/output terminal among the plurality of resonance elements. Combline type bandpass filter. (3) A resonant element consisting of a plurality of rod-shaped or cylindrical conductors arranged with the same polarity and having an axial length that is approximately 1/4 of the co-spreading wavelength in terms of electrical length; A dielectric material provided around each of the plurality of resonant elements and a U-shaped or U-shaped part provided on the casing wall portion facing each open end of the plurality of resonant elements and bent into the casing. A resonant frequency fine adjustment element consisting of a notch similar to the type, and a resonant frequency fine adjustment element provided in the housing wall portion corresponding to the plurality of resonant elements in the housing wall in which this resonant frequency fine adjustment element is provided, and bent into the housing. interstage coupling A commutator consisting of a "0-shaped" or U-shaped similar notch, interposed between the first and final stage resonant elements and the input/output terminals among the plurality of resonant elements; 1 consists of an input/output coupling element.
．． A combline-type band pass filter with the following characteristics: (4) Claim 1 in which the dielectric is replaced with air
The combline type bandpass filter according to any one of Items 1 to 3.