JPS6199401A - Multihollow microwave filter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-cavity microwave filter with minimal dimensions, electrical losses, weight and production costs, as well as simplicity of construction, repeatability and high mechanical strength.

As is known, the transmission bridge is designed to eliminate all unsuitable frequencies and residual frequencies generated by the generation of mobile signals in the T-transmission, so that only the mobile signals are allowed to pass through. For reception, a suitable microwave filter is required to cancel all undesired signals and allow only valid signals to be input.

The two filters, Tx and R, are the same and have a very good and reliable effect: they have a very strong stagnation effect within the A band, and a damping effect that gradually decreases as you move away from both ends of this band. There is a fundamental importance that must be held.

To date, microwave filters are: -1) waveguides with flange, -2) welded and machined cut ends, -3
) Manufactured by providing a large number of cavities in a solid mass.

Conventional filters made in this way have a number of deficiencies, among them large dimensions, high price, complicated manufacturing methods, low reproducibility, and difficult machining methods on numerically controlled machine tools, to name a few. I can do it.

The object of the present invention is to provide a multi-cavity microwave filter that does not have the above-mentioned defects.

Other objects of the invention include reduced dimensions and
The object is to provide a microwave filter having a structure that has high reproducibility and can be manufactured by an extremely simple and effective method.

The above and other objects consist of a substantially parallelepiped-shaped metal body in which a number of cavities are made, each having a rod-shaped resonator tuning and a connecting screw in the center of these cavities, and having n# cavities. Connection between the subsequent cavities achieved using a microwave filter whose center is placed at the vertex of the polygonal line and whose segments are at an angle of 90° to each other between them. is carried out by means of a slit placed in the axis of the appropriate section of the polygonal line. Preferably, the bottom of each cavity has a tapped hole communicating with the outer surface of the bottom of the filter body.

According to an advantageous feature of the invention, at least one of the two longitudinal sides has two holes (preferably countersunk on the outside) communicating respectively with the first and last cavities. . A number of tapped blind holes are machined on the opposing faces and parallel to the bottom.

According to an advantageous feature of the invention, the filter body with a number of suitable cavities, resonators and screws is made using an extruded central rod, which, after cutting into squares, is 7-milled, drilled, It is made by stabilizing it by countersinking, tapping, barb removal and heat treatment.

According to a preferred feature of the invention, the filter body is formed by pressure die-casting of an aluminum alloy, preferably with a highly flattened surface of a parallelepiped, vertical longitudinal and transverse surfaces (
It is provided with a large number of suitable cavities, resonators and holes created by rolling.

During the pressure die casting process, multiple resonance cavities are created with a slight draft (e.g. about 2%) and all filter bodies are made light by creating empty recesses in the solid part and wall Adjust the thickness to within 2 to 4 haze. It is advantageous to convert a plurality of blind holes into through holes.

Another object of the invention is that the ratio between the diameter Dc of the individual cavities and the diameter dr of the appropriate resonator is variable, l, preferably decreasing in the passage from the central cavity, so that the peripheral The ratio is also based on providing hierarchically larger items.

It is advantageous to use a pressure die casting alloy which has a high flowability in the die, so that its coefficient of expansion is made of a different material than the pressure die casting alloy and which is compatible with frequency fluctuations within very constrained limits. To obtain a range of temperatures, tuning rods and screws with different coefficients are used to compensate accordingly.

Various features of the invention will be more clearly understood in the non-limiting description of embodiments illustrated in the accompanying drawings.

FIG. 1 shows the general shape of the filter defined by a top face and a bottom face B, two longitudinal faces F and E and two lateral faces C and D.

According to a first feature of the present invention, this filter consists of "n' cavities C1, C2...CL...Cn, whose centers are 01, 02, -01...=On'd; n-1
pieces of section LSI.

A polygonal line L consisting of LS2...LSi...LSn-1
They are aligned along S. Each section LSI has a length Li(i
or the distance between two successive centers Oi-1 and 01) and the successive intercept LSi+1.

Each cavity Cii": a cavity C1+1 followed by a slit
The slits cannot be clearly shown in Figure 1, but are indicated by P-PL, N-N1, and M-Ml in Figure 3.

Each slit is located at the central orthogonal axis of each section of the line and comprises the entire depth of the cavity (H in Figures 4 and 4D).

Horizontal planes C and D in Fig. 1 are the first and second holes...
2l-22t, each of which is the first cavity (C1
) and into the last cavity (Cn), one of these holes made on each side is seated 9 with an outward facing step.

The front face E has two holes E1 and E2 (facing outwards) communicating with the first and second cavities C1 and C2.

Figure 2 shows the hole AS for the rod-shaped resonator and seven holes for the connection screw. The top surface A has n tapped holes A1...k
o f, and they are generally located on the sides of the cavity in order to close the cavity by a suitable cover (not shown).

According to a preferred feature, the filter has cavities distributed along a polygonal line, the sections of which have equal length symmetrically with respect to the central cavity. For example, LSI =
LSn, LS2 ” LSn-1, LS3 =L
Such as Sn-2.

The filters according to FIGS. 1 and 2 can be easily made starting from a solid parallelepiped rod with paired faces of equal dimensions, ie a=b + czd + exf, where: ＆ r b r e r d rs
+f is the side of the appropriate plane A, B, C, D, E, F, in this case A=B, CD, EF.

The filter is a solid rod, for example. Corrosion resistant'When made from a solid extruded rod, the same rod has body parts A X CX
E is cut, and then the main body part is processed into a square shape, and the subsequent machining process is fline processing (making a cavity).
This was done using chip removal machine tools such as screw taps and burrowers. The material of the machined rod is preferably stabilized in a furnace.

According to another object of the invention, it has been found that the body AXCXE can be surprisingly advantageously made by pressure die casting, as shown in FIG.

This solution was found to be ideal as it optimizes the following items: That is, dimension optimization is as follows: - electrical loss - weight - lining function - mechanical strength - production cost obtained by the distribution of cavities in the hand drum, and those cavities form this filter along the fold line, but the fold line is critical at 90°.
It has interior angles of: In practice, the distribution along the fold AM (2 patterns) with an internal angle of 90' fZ) was not used.

This is because this solution optimized the overall length of the filter, but required a large width.

The final result is that for cavities arranged along perpendicular polygon lines, the width is kept equal to 1.5 times the dimension of the same cavity;
I was able to shorten it by about 15 inches.

- Regarding electrical losses: Optimal ratio aE Dc/dr CDe= for those losses! 2 sinus diameter, dr
= resonator diameter) -3,33 By obtaining larger losses are caused by the central cavity rather than by the peripheral cavity, in effect i! Ff Preferably, using a linear flow, the ratio DJa, = 2.6 for the first and last cavities.
7, the hierarchical importance of the central cavity was decisively used.

Preferably, the diameter dr of the rod is kept constant, while the diameter Dct of the cavity varies with respect to the above-mentioned ratio.

If a solution with a cavity with pc/at = constant -3,33 is chosen, the length of the filter can be increased by about 10 to 15%, with only a small advantage in terms of the above losses. will be required.

On the contrary, the ratio Dc/d4 is set to always remain constant, but if a constant ratio is selected to suppress the expansion of the cavity within a predetermined length, the ratio DJar becomes disadvantageous with respect to the above-mentioned loss. Regarding the weight, the material used in the construction is an aluminum alloy (Silmin) with at least 83 and some traces of other elements, the filter weight for the single unit - 3359 and = connector, resonance rod, adjustment screw of the connection for a complete filter with a cover and a cover (as opposed to 935I for the same filter machined from solid rod and 1.9 U for a conventional filter).

- Regarding construction features, the choice of aluminum alloy allowed the filter to be made by pressure die casting, simplifying its design despite the complexity of the filter structure.

- In addition, some lightening of the solid part was introduced, the thickness of the filter wall was designed in the range of 2 to 4 mm, and the outer shape of the filter was made easier to position in the processing machine.
Care was taken to have as few regular shapes as possible, while at the same time obtaining a suitably strong structure.

One solution according to the invention is to fill the ham with a cover.
Rb helmet 1z l:l:l +-Shi L Th 1-TJ
(-4/ f Th 1-TJ -e- It was possible to make it in the through-hole type, but it is difficult to make it in the through-hole type using conventional 'Dk construction unless you invest in a large amount of machining cost. , which is practically impossible.

Remember that the presence of blind holes is a major problem for components that have to be plated (in this case silver plated), as the presence of blind holes retains acids in the finishing bath and subsequently corrodes the final treatment. It is important to note that with respect to the selected materials (aluminum alloys, in particular "Silumin"), aluminum alloys have proven to be one of the most advantageous from the cost and weight point of view and are also extremely Due to its high flowability, it is an excellent material for use in pressure die casting.The use of this material has been much explored due to its high coefficient of expansion.

Surprisingly, this difficulty is especially true for frequency displacement versus iRL
This has been overcome by using materials with different coefficients of expansion, such as alloys of iron and copper, in order to keep the temperature below 10 p, p-rn, 7° C., and by rolling out rods, tuning screws, and joint screws.

Figure 2 is a bottom view of the pressure die-casting filter, and its surface B has a hole for the @all-in portion ALL...ALn + rod AS and a hole VAi for the adjustment screw, and 21 and 22 are used for the connector. It is a hole where Having already disclosed the most important aspects of the invention, FIG. 3 suggests and illustrates a preferred implementation, showing a central cavity CO and symmetrical cavity pairs CI -C1', C2-C2 about the X-X axis. ', C3-
C3' is shown.

If the diameters of the symmetric pair C1-C1' are equal to each other but different from the diameter of the symmetric pair C2-02', then the pair C2
- the diameters of C2' are equal to each other, but the symmetrical pair C3
- unlike the diameter of C3', the diameters of the pair C3-03' are equal to each other, but different from the diameter of the central cavity CO; Preferably, they are different.

The diameter of CO is larger than the diameter of the next pair C3-C3';
In j@, the diameter of C3-C3' is the diameter of the pair C2-C2' υ
The diameter of pair C2-02' is also larger, and the diameter of pair C2-02' is larger than that of pair C1-CI'.
, is preferably larger than the diameter of .

Preferably, these diameters decrease in a linear fashion from the center to the periphery.

The length of the section LSi between the centers of both successive cavities also decreases according to the linear law. The same thing applies to the slit in the Shin-do.

3 (top view of a die-cast filter with unthreaded holes), FIG.
Preferred features of the invention, as shown in the bottom view of the finished filter shown in the figure, include tuning rod pairs AS7-AS6;
The diameters of the holes AS5-AS4 and AS3-AS2 are all the same, and the connecting threads are VA6-VA5.

The diameters of VA4-VA3 and VA2-VAI are equal◎
Other advantages of pressure tie-cast filters are the top ALI,
AL2, AL3, AL4...AL6 (Figures 3 and 4) have numerous lightweight recesses and lower surfaces (stripe 5).
Due to the large number of lightweight recesses in Figure), it has become possible to reduce its weight to a total minimum value.

In the A-A cross-sectional view of Figure 4, that is, the fourth person's figure, the lighter part at the bottom extends almost the entire height H of the cavity, while the lighter part at the top extends with an extremely short cross-sectional height. Show that. The same figure 4A shows external walls PA and E, and cavity wall PA.
-C and the thickness of the bottom wall PA -F, all of which consist of a narrow space, e.g.
As a result, this filter has excellent strength combined with minimal weight.

4B (cross-section F-F in FIG. 4) and FIG. 4c (cross-section G-C in FIG. 4) show advantageous implementations of through holes (and non-blind holes) in connection with the covers FPCO and FPCO'. It shows.

Fig. 4D (C-C cross section in Fig. 4) shows the moderate lower part (AL'4) * and the top part (AL4) as shown in the cross section.
Of particular interest is the construction of a central symmetrical cavity CO with a lightening section and a tapped hole FPCO.

The total height H of the cavity is kept constant at t, while its diameter varies, for example, from about 30 for CO to C1-C1'
It varies up to about 250. The diameter of the following symmetrical pair is 2
・Decreases according to a linear law between two extreme values.

As mentioned above, the difference between the top views of FIGS. 3 and 4 is that the filter of FIG. ASI> and connecting screw hole VA
6 to 7 persons 1 (none of which are tapped), while the filter shown in FIG. 4 has the above-mentioned tapping hole and furthermore a tapping through hole for the covers AI4 to A1.

Figure 4E shows a front view of the side C of the finishing filter of Figure 4, which includes a head hole 21 with a stepped seat 01 for a connector.

Figure 5 is a bottom view of the filter in Figure 4, and the bottom view of the filter shown in Figure 4.
In the weight reduction recesses ALL', AL2', A
L3'.

AL4'...AL7"i indicates the structure and shape of the recesses L1 to AL7 in the top surface A due to the need for these recesses to combine minimum weight and maximum strength. Another advantageous feature of the invention is that the holes for the connectors 21 and 22 on the lateral surfaces C and D are not coaxial; They are placed on two different longitudinal axes, so that the position of one of the holes, for example the input hole 21, is kept constant, and the Rotate this filter around a longitudinal axis passing through the center of one connector to open the other hole 2 with the second connector.
2 can occupy different positions, allowing very active branching.

This advantage is particularly advantageous when a large number of filters are provided (in near-parallel devices)9, each of which has one hole in the fixed position Rh or in the restrained position, but with one hole in the restrained position. The other hole can be located at a relatively convenient position among the positions obtained by rotating the same filter about a longitudinal axis 9 passing through the center.

Although the invention has been described by way of example with reference to the preferred embodiments illustrated in the accompanying drawings, it is clear that any non-inventions that may occur to one of ordinary skill in the art are conceivable. It is obvious that modifications, modifications, and updates are automatically included within the scope and spirit of the invention.

[Brief explanation of drawings]

Figures 1 and 2 are schematic perspective views and partial perspective views; Figures 3 and 4 are plan views of a low-pressure dicanut filter (Figure 3) and the same finished filter (Figure 4). , Figure 5 is a bottom view of the finished filter shown in Figure 4, Figures 4 to 4D are side views of the filter shown in Figures 4 and 5, partially in section; FIG. 4E is a lateral front view of the filter shown in FIG. 4; C1, C2...C1...Cn...Upper side, 01.0
2...Oi...On...center, LS...broken line.

Claims (1)

[Claims] 1. In a microwave filter consisting of a substantially parallelepiped metal body in which a plurality of resonant cavities are created and a rod-shaped resonator and a tuning and connection screw are provided at the center of the resonant cavity, “n” The center of the cavity is placed at the vertex of the polyline,
A filter characterized in that the segments of the polygonal lines make an angle of 90° or more between them. 2. The connection between each subsequent cavity and each cavity is made by a slit provided in the lateral central axis of the appropriate section of the polygonal line, having a depth approximately equal to the depth of the cavity, and having a tapped hole for the adjustment screw of the connection. The filter according to claim 1, characterized in that it is made into a sheet for use in. 3. According to claim 2, characterized in that at least one of the two longitudinal sides is provided with two holes (preferably counterbore on the outer side) communicating with the first and last cavities, respectively. Filters listed. 4. Filter according to claim 3, characterized in that the surface parallel to the bottom surface has a number of blind tapped holes for the closure cover. 5. A filter body with a plurality of suitable cavities, resonators and threads is made using an extruded solid rod, the solid rod is cut and squared, then milled, counterbore, tapped and burred. Any one of claims 1 to 4, characterized in that it is stabilized by removal and heat treatment.
Filters listed in. 6. The filter body with multiple cavities, resonators and holes is made by pressure die casting of aluminum alloy, preferably with mild flattening of the parallelepiped faces, counterbore of the holes in the vertical longitudinal and transverse faces and 2. Filter according to claim 1, characterized in that it is followed by rolling. 7. During the pressure die-casting process, multiple resonant cavities are created with a slight draft angle, and all filter bodies are molded with empty recesses inside to reduce weight. The filter according to claim 6, wherein: 8. Filter according to claim 7, characterized in that the initial blind holes are advantageously converted into transparent holes in order to make the recesses lighter. 9. Individual cavity diameter D_c and appropriate resonator diameter d_
5, or Filter according to paragraph 6. 10. Filter according to claim 9, characterized in that the ratio D_c/d_r is reduced from about 3.5 to about 2.5. 11. The filter according to claim 9 or 10, characterized in that the diameter of the cavity is variable and the diameter of the resonator is constant. 12. A pressure die casting alloy with high flowability is used in the die and a suitable coefficient of expansion is made from a material different from the pressure die casting alloy and obtaining a range of frequency variation vs. temperature within very constrained limits. 7. A filter according to claim 6, characterized in that the compensation is performed using tuning rods and screws with different coefficients. 13. Claim 1, characterized in that the plurality of cavities are an aluminum-silicon alloy (with more copper and a trace amount of iron), and the rod and screw are made of iron-lead or copper-zinc alloy.
The filter described in Section 2. 14. Filter according to claim 7, characterized in that the draft angle of the cavity is approximately 2% and that the weight reduction of the solid wall is achieved by creating a wall thickness within the limit of 2 to 4 mm. . 15. Filter according to one of claims 1 to 14, characterized in that the cavity diameter and line segment are equal for cavity pairs arranged symmetrically with respect to the central cavity. 16. With input and output connector holes provided in two different longitudinal axes, if the first hole of the two holes is fixed in the restrained position, the filter can be rotated about the axis of the fixed hole and the second 16. Filter according to claim 1, characterized in that the pores occupy different positions. 17. A multi-cavity microwave filter generally as described and illustrated.