JPS58178601A - Band-pass filter - Google Patents

Abstract

PURPOSE:To provide required transmission characteristics to the titled band-pass filter optionally without changing the diameter of resonance elements and the setting interval between them by setting an interstage coupling adjusting element and fine adjusting screws for coupling degree between respective two resonance elements and adjusting the insertion length of each adjusting screw properly. CONSTITUTION:The interstage coupling adjusting elements 51, 5'1-55, 5'5 consisting of rod-like conductors are set up in parallel with the resonance elements 21-26 at proper intervals in the rectangular direction against the direction superposing the resonance elements 21-26. The coupling degree fine adjusting screws 61, 6'1-65, 6'5 are inserted into respective adjacent spaces of the resonance elements 21-25 from the upper wall and lower wall of a housing 1 in parallel with the interstage coupling adjusting elements 51, 5'1-55, 5'5 and the insertion length is finely adjusted and optionally fixed by lock nuts 71, 7'1-75, 7'5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave bandpass filter. Hereinafter, the bandpass filter will be abbreviated as BPli'.

Conventional microwave BPF requires high load Q'
In this case, the spacing between the resonant rods must be increased to make the coupling looser, resulting in a disadvantage that the overall size becomes larger.

Also, a combline type BPF' has been conventionally used, which is configured to increase the load Qt without increasing the spacing between the resonance bars by interposing two coupling adjustment rods between the resonance bars to make the coupling loose. However, it is difficult to accurately match the diameter and mounting position of the coupling adjustment rod to required values, and it is difficult to configure a PF with good voltage standing wave ratio and transmission characteristics.

The present invention has a structure that is simple and easy to manufacture, the entire structure can be made compact even when the load Q is high, and a good voltage standing wave ratio and arbitrary and good transmission characteristics can be obtained.
The purpose is to realize PF.

The first figure is a sectional view showing one embodiment of the present invention (B--
B sectional view), Figure 2 is a sectional view taken along line A-A in Figure 1, and Figure 3 is a sectional view taken along line CC in Figure 2.
2 is an electromagnetic shielding case, 21 to 2b are resonant elements made of rod-shaped conductors, 3I and 3 are input/output coaxial terminals, and 42 are input/output coupling elements, which are made of strip lines, for example. Instead of coupling using a strip line, input/output coupling may be performed by tap coupling, loop coupling, coupling using capacitance between a ribbon-shaped conductor and a resonant element, or the like. 5I and 51 to 5s and 5's are crotch coupling adjustment elements made of rod-shaped conductors, and for example, 5I and 5t are arranged parallel to the resonant elements in the space adjacent to the resonant elements 21 and 22 and with respect to the direction in which the resonant elements are connected. The upper and lower ends of the housing 1
It is firmly attached to the top and bottom walls. Although the figure shows an example in which two adjusting elements 51 and 5τ are provided in the space adjacent to the resonant elements 2I and 22, the present invention can be carried out even if the number of adjusting elements 51 and 5τ is increased as appropriate. Adjustment elements 51 are arranged at appropriate intervals in a direction substantially perpendicular to the direction in which the resonant elements are connected.
and 51 may be arranged in a diagonal direction (in case three or more adjustment elements are provided, they may be arranged irregularly instead of in a line). 5'! to 5'- are provided in the adjacent spaces of the resonant elements 22 to 2b in exactly the same way. 61 and 6; to 6S and O are screws for fine adjustment of the degree of coupling, and step-open coupling adjustment elements 5I are provided. and 5; to 5C; and housing 1 parallel to 5'g.
The resonator elements 21 to 2b are inserted from the top and bottom walls into the adjacent spaces, and the insertion length is finely adjusted, and the insertion length can be fixed at any desired length using the opening and nut nuts 7I and 71' to k and rows. It is formed. In this figure, fine adjustment screws 61 and 61 are inserted between the question coupling adjustment elements 51 and 5'+, and elements 51 and 5; The force (, screw 6
) and 6'1 may be inserted at any location other than between the elements 51 and 5;
There is no harm in omitting 1. The same applies to the case where the other screws 62 and 6'z are not provided, 65 and 6'9, and the elements 52 and 5'2 to 5S and 5Lf are installed.

In the BPF of the present invention configured in this manner, the coupling coefficient MT between adjacent resonant elements is M5°"6 (1) MS+M
It is represented by B. However, Ms: The coupling coefficient between the resonant elements when no coupling adjustment element is provided between the resonant elements, the diameter of the resonant element,
It is determined depending on the mounting position and the width of the housing (H in Figure 3).

This is the coupling coefficient of the H-width two-stage coupling adjustment element itself, and is determined depending on the diameter of the element, the number of elements attached, and the attachment position.

Next, +l is the geometric coefficient of BPF', the coupling coefficient MK between each stage expressed by the load Q or the 3 dB reduction frequency band width and center frequency of the transmission signal, etc. However, gK and 41 are the geometric coefficients. where, n: order QL: load Q 8w3': 3 dB reduction frequency bandwidth f0 of transmission signal
: Center frequency k in equation (2) takes a value of 1 or up to 6 when six resonant elements are provided as in this example, and for example, = 1.
When , the coupling coefficient M between the resonant elements 2I and 22 is
+/ : MI, 2, geometric coefficients related to the resonant elements 21 and 22 g8 = g1 and g ÷ + = gz, (
3) Find gl by substituting 1 for k in equation (3), and
Substitute 2 into to find g2.

In equation (2), g is equal to g total f%QL%BW3 and fO
etc., and calculate +l for the coupling coefficient MK between each stage, and the coupling coefficient MT between each stage in equation (1) becomes MK
, and the diameters of the interstage coupling adjustment elements 51 and 51' to 55 and 5-, and the number and installation of the interstage coupling adjustment elements to be installed in the adjacent spaces of the resonance elements 2I to 2b, respectively. By determining the position and adjusting the coupling degree fine adjustment screws 61 and 6'1 to 6 and the insertion length of the washers, a BPF' with maximally flat type characteristics can be constructed, and its transmission characteristics are expressed by the following formula. It is expressed as

L, (aB)=+oflog (I+x'3")
・・−−・(4) L: Attenuation amount of transmission signal 2Δf x3=−QL f.

Δf: Detuning frequency of the transmission signal of the center frequency trace Next, a case will be explained in which the passband constitutes a BPF' having a Chebyshev type characteristic and an attenuation area having a Wagner type characteristic.

In this case, the geometric coefficients gK and gKya in equation (2) are determined from equations (5) and (6).

26K (5) gx
= □ γ 4aw-+'aK ・・・・・・ (6) b
-l ag -f When k=1, g)c=g+ is 1 for k in equation (5)
%g(+1"gz is k in equation (6)
Find it by substituting 2 into . When k in equation (2) is 2, gK is obtained by substituting k[2] in equation (6), and y1 is obtained by substituting 3 into k in equation (6) for g. k is 3
The same applies to the case of none λ and 6. Furthermore, equation (5) is gl
Used only when calculating.

In equations (5) and (6), S: Permissible voltage standing wave ratio within the passband The transmission characteristics of a BPF with a Chebyshev type characteristic in the passband and a Wagner type characteristic in the attenuation area are the measured voltage standing wave ratio in the passband. By giving the ratio S and the order n, it is expressed by the following equation.

・・・・・・(7) 〉1, then L(X) = coBh' (n cash
In the formula, it is necessary to hold, and from this, we can find the standardization part of 3 dB lower, the frequency x3, and the center frequency fa, the allowable passband width Bar, and the standard frequency of 3 dB lower of the transmission signal. Once x3 is determined, the frequency WABws below 3 decibels can be found from the following equation.

BW3 = BWF 1X3 Also, the load Q - Qt can be found from e Q and "□ W3, so these values and (5) and (6)
Substituting g6, g, y and Diameter and resonant cord2. Appropriately determine the number and mounting position of the interstage coupling adjustment elements to be installed in each adjacent space of 2b to 2b, and adjust the insertion length of the fine adjustment screws 61 and 61 to 6s and 6 colors for the degree of coupling (1) By matching the coupling coefficient meter between each stage in the formula to M and +1, respectively, the passband has Chebyshev type characteristics and the attenuation area has BP with Wagner type characteristics.
It is possible to construct F.

In this BPF', for example, by indirectly coupling between the resonant elements 22 and 25, it is possible to configure a BPIi' having a Chebyshev type characteristic in the passband and jtL attenuation in the attenuation range.

8 shown with a dotted line in FIG. 2 is an indirectly coupled line consisting of a coaxial ll#l path or a strip line, etc. 91 and 9 are coupling elements of the resonant elements 2z and 2C and the indirectly coupled line 8, which are loops or resonant lines. It consists of electrodes and the like that form a capacitance between the electrodes 22 and 29.

Among the signals transmitted through the main circuit made up of the resonant elements 2t to 2b, signals with a higher frequency than the passband have a voltage/current phase of 9 in each resonant circuit made up of the resonant elements 2I to 2&.
Since the phase advances by 0 degrees and the phase advances by 270 degrees in the phase shift circuit formed between each resonance circuit, the resonance port f consisting of the resonance element 22
The phase of the signal at fH and the phase of the signal at the resonant circuit consisting of the resonant wire 25 are in phase, but the coupling element 91
and 9zk loops, if the polarities of both loops are adjusted appropriately, the resonant circuit from the resonant circuit consisting of the resonant element 2z to the resonant element via the interrogative coupling circuit consisting of the coupling element 91% and the snake line 8 and Q. The phase of the signal transmitted to the two-piece resonant circuit produces a 180 degree phase difference between the two resonant circuits. Therefore, by adjusting the degree of coupling of coupling elements 9I and 92 to equalize the magnitude of the signal transmitted through the indirect coupling circuit and the magnitude of the signal transmitted through the main circuit, an attenuation pole is created at the frequency position of this signal. It can be painted.

Among the signals transmitted through the main circuit, signals with frequencies lower than the passband have a phase delay of 90 degrees in each resonant circuit, and a phase delay of 27,070 degrees at the phase shift opening formed between each common circuit, so that the resonant element 22 The phases of the signals in both the resonant circuits consisting of the coupling elements 9 and 25 are in phase, and the phases of the signals transmitted through the indirect coupling circuit are opposite. By appropriately adjusting the degrees of coupling of the signals and the signals transmitted through the main circuit and the indirect coupling circuit, an attenuation pole can be created at the frequency position of the signal.

When the degree of coupling between the coupling elements 91 and 92 is lowered, the frequency position of the attenuation pole moves away from the passband, and conversely, when the degree of coupling is increased, the frequency position of the attenuation pole moves closer to the passband.

The transmission characteristics of the polarized BPF configured in this way are expressed by the following equation.

When the order n is 6 as in this example, that is, when n is an even number, when n h < fraction, the difference in frequency that produces an attenuation pole is Δf, : center frequency f, and Δfse7 + center frequency. Difference in frequency of the band edge that gives the allowable voltage standing wave ratio Rc: The meaning of taking the real part: The meaning of taking the imaginary part Furthermore, if the frequency position of the attenuation pole is relatively far from the passband, B'PP, where the passband is a Chebyshev type characteristic and the attenuation area is a Wagner type characteristic, has a coupling characteristic that is equal to If, and if the attenuation pole is located at a frequency position relatively close to the west region of the passband, an indirect coupling loop or Generally, there is a difference between the theoretical value and the experimental value due to the influence of capacitance, etc., and appropriate correction is required to obtain the above-mentioned m4 and h.

FIG. 4 is a sectional view (B in FIG. 5) showing another embodiment of the present invention.
5 is a sectional view taken along line A-A in FIG. 4, and FIG. 6 is a sectional view taken along line C-C in FIG. are similar to those in FIGS. 1 to 3.

In this embodiment as well, the diameters of the crotch coupling adjustment elements 51 and 5; to 5f and 51, the number of crotch coupling adjustment elements to be attached to each adjacent space of the resonant element, and the mounting positions are adjusted appropriately.
! A BPF having transmission characteristics similar to those of the previous embodiment can be constructed by adjusting the insertion length of the fine adjustment screws 61 and 6 to 65 and 6'3.
In this embodiment, since the resonant elements 2I to 26 are arranged in a U-shape, the entire structure can be made smaller than in the previous embodiment.

In addition, in this embodiment, for example, as shown in the cross-sectional view in FIG.
1, or by indirectly coupling the resonant elements 22 and 25 via the loop 12, as shown in the cross-sectional view of FIG. At the same time, an attenuation pole can be generated in the attenuation region, but in this embodiment, since the resonant elements 22 and 25 are in contact with each other through the partition wall 10, there is no need to use a coaxial line or the like as in the previous embodiment. Since indirect coupling can be performed by a coupling element inserted in the hole of the partition wall 10, the structure can also be simplified from this point of view.

In each of the above embodiments, an ink digital type BPF was constructed using six resonant elements.
The present invention can be carried out even when a PF is configured, and the number of resonant elements is not limited to six, but can be increased or decreased as appropriate, and instead of providing an indirect coupling circuit between the resonant elements 22 and 25. The resonant elements 21 and 2b are provided between the resonant elements 21 and 2b, but they may also be installed between the resonant elements 22 and 2 and between the resonant elements 2I and 2&.The present invention can be achieved by appropriately increasing or decreasing the number of indirect coupling ports as well as increasing or decreasing the number of resonant elements. It can be implemented. That is, among the resonant elements in a cascade connection relationship, the present invention can be carried out by indirectly coupling one set or any plurality of resonant cables separated by two or an integral multiple of the resonant elements. I can do it.

Interpose a crotch coupling adjustment element made of a rod-shaped conductor J and a fine coupling adjustment screw between the vibrating elements, and select the diameter, number, and mounting position of the coupling adjustment element appropriately, and tighten the coupling adjustment fine adjustment screw together with the screw. By adjusting the insertion length appropriately, it is possible to provide desired transmission characteristics without changing the diameter and installation spacing of the resonant elements, and the overall structure can be made compact even when a high load Q is required. has.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing one embodiment of the present invention, and FIGS. 4 to 8 are cross-sectional views showing other embodiments of the present invention. or 2b: resonant element, 31 and 32: input/output coaxial terminal, 4) and 4-coni input/output coupling element, 51 and 51 or sleeve and 5-: crotch coupling adjustment element, 61 and 61 or 6s and 6: coupling degree Fine adjustment screws, 7I and 7; to 7c and L:
8: indirect coupling line, 9+ and -: coupling element, 10: partition wall, 1: capacitance forming electric wire, 12: loop. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (+)! A plurality of resonant elements consisting of rod-shaped conductors arranged in a row at wide intervals, and both ends of which are fixed to the top and bottom walls of an electromagnetic shielding case in each adjacent space of the plurality of resonant elements. and a plurality of crotch coupling adjustment elements made of rod-shaped conductors provided in parallel with the resonance elements, and the interstage coupling adjustment from the wall surface of the electromagnetic shielding casing corresponding to each adjacent space of the plurality of resonance elements. 1. A band-pass filter comprising: a plurality of coupling degree fine adjustment screws inserted into a housing in parallel with an element and having variable insertion lengths. (2) A plurality of resonant elements made of rod-shaped conductors arranged at appropriate intervals to form a U-shaped signal transmission path, and each adjacent space C of the plurality of resonant elements; both ends of which are electromagnetically shielded. a plurality of crotch coupling adjustment elements made of rod-shaped conductors fixed to the soil wall and bottom wall of the housing and provided in parallel with the resonant elements; and the electromagnetic elements corresponding to adjacent spaces of the plurality of resonant elements. A band-pass filter characterized by comprising a plurality of coupling degree fine adjustment screws that are inserted from the wall surface of the shielding casing into the casing in parallel with the groin coupling adjusting element and whose insertion lengths are made variable. Wave equipment. - (3) A plurality of resonant elements made of rod-shaped conductors arranged in a row at appropriate intervals, and in each adjacent space of the plurality of resonant elements, both ends are connected to the top wall and bottom of an electromagnetic shielding case. a plurality of interstage coupling adjustment elements made of bar-shaped conductors fixed to a wall and provided in parallel with the resonant elements; and a mural on the electromagnetic shielding casing corresponding to each adjacent space of the plurality of resonant elements. A plurality of coupling degree fine adjustment screws are inserted into the housing in parallel with the flat coupling adjustment element and whose insertion length is variable, and an indirect coupling circuit for indirectly coupling the plurality of resonant elements. A band-pass filter characterized by comprising: (4) a plurality of common wire elements arranged at appropriate intervals and consisting of rod-shaped conductors Q forming the U-shaped signal transmission path 2; a plurality of crotch coupling adjustment elements each consisting of a rod-shaped conductor which is fixed to the soil wall and the bottom wall of the electromagnetic shielding case at both ends in each adjacent space of the resonant elements, and is bifurcated parallel to the resonant elements; a plurality of coupling degrees that are inserted into the housing parallel to the groin coupling adjustment element from the wall surface of the electromagnetic shielding housing corresponding to each adjacent space of the plurality of resonant elements, and whose insertion lengths are made uniform; The present invention is characterized by comprising a fine adjustment screw and an indirect coupling element that indirectly couples two or an integral multiple of the plurality of resonance elements in a cascade connection with each other. (5) A band pass filter according to any one of claims 1 to 4, in which a plurality of resonant elements are arranged in an interdigital manner by sequentially reversing the installation polarity. Pass filter. (6) A band pass filter according to any one of claims 1 to 4, wherein a plurality of resonant elements have the same polarity and are arranged in a combline shape. wave device 0