RU36571U1 - DIELECTRIC FILTER - Google Patents

Description

2003131479

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200J1J147, DIELECTRIC FILTER

The inventive utility model relates to microwave technology and can find application in frequency-selective paths of various systems of communications equipment (satellite communications equipment, cellular, mobile communications, etc.).

One of the aural problems of dielectric filters, in particular filters based on ceramic blocks, is the adjustment of their electrical characteristics in the production process. This problem is not always solved effectively due to the impact on the electrical characteristics of the filters of a number of design factors.

In known dielectric filters, the resonant frequency of the circuits is adjusted by resizing the conductive pads surrounding the metallized holes of the coaxial resonators on the upper face of the dielectric block and in electrical contact with these holes.

Closest to the proposed device for the technical nature and combination of essential features is a dielectric filter according to US patent No. 4768003, CL. NPK 333/202, published on 08/30/08. This filter, selected as a prototype, contains a ceramic block in the form of a parallelepiped with metallized side and lower parts and a partially metallized top fan. In the ceramic block, at least two through metallized holes are made, passing parallel to each other from the upper to the lower fan, the input and output contacts

 HOIP 1/205

filter, while the edges of the metallized holes on the upper face are connected to the conductive pads surrounding them. The size of these pads affects the resonant frequency of the filter.

At the upper face of the dielectric block, the conductive pads surrounding the metallized openings have at least one conductive pad. By changing the width of this pad, you can adjust the frequency response of the filter (in particular, the filter bandwidth).

Adjusting the resonant frequency in the prototype filter involves reducing the size of the metal conductive areas surrounding the metallized holes of the ceramic block on its upper face. This allows you to reduce the capacitance of the respective filter loops and, thereby, increase the resonant frequency of these loops. However, with subsequent filtering, the resonant frequency of the loops set when the filter is tuned may change. The consequence of this is a high percentage of defects and a low yield of products according to the given electrical parameters.

The objective of the proposed utility model is to increase the yield of suitable filters during their manufacturing.

This problem is solved in that in a dielectric filter containing a ceramic block in the form of a parallelepiped with metallized side and bottom faces and a partially metallized upper fan, in which at least two through metallized holes are made, passing parallel to each other from the upper to the lower fan , the input and output contacts of the filter, and the metallized holes on the upper face are connected to metal platforms surrounding them or adjacent to them, on

the bottom face of the ceramic block between at least one of the metallized holes and the edge of the ceramic block is a selection of a conductive layer of rectangular or oval shape to expose the surface of the ceramic block. A sample of the conductive layer on the bottom fan of a ceramic block of a rectangular or oval shape can be made from two or three sides of one or more holes.

The technical result of the utility model is to provide the ability to more accurately fine-tune the resonant circuits, a higher yield of suitable products, material saving, and reducing the cost of manufacturing filters.

The achievement of the specified technical result is determined by the fact that the selection of a conductive layer of a rectangular or oval shape on the lower fan of the ceramic block between at least one of the holes and the edge of the ceramic block causes a change in the flow of currents in the conducting layer of the lower fan of the ceramic block, which leads to an increase in inductance and, consequently, to a decrease in the resonance frequency of the corresponding resonant circuit.

Such a selection of the conductive layer can be carried out on two sides of each of the holes, which expands the limits of the adjustment of the resonant frequency of the filter loops. In addition, for the extreme holes of the bottom fan of the ceramic block, the selection of the conductive layer is possible on three sides of these holes.

The proposed design allows to reduce the resonant frequency of the filter loops even after shielding its upper face. Due to the fact that in the proposed design it is possible to produce as an increase in the resonant frequency of the circuits by reducing the size of the areas around the metallized

holes on the upper face of the ceramic block, as well as lowering the resonant frequency (even after filter shielding) by sampling the conductive layer on the lower face, it is possible to more accurately adjust the filter to a given frequency and, therefore, a higher yield of products in comparison with the prototype.

The proposed utility model is illustrated: FIG. 1a and 16, which respectively show a general view and a side view of the lower face of a filter variant with two metallized holes in a ceramic block, and FIG. 2, which shows an equivalent circuit of this filter.

The filter in figure 1 contains a ceramic block 1 in the form of a parallelepiped with metallized side and bottom fans and a partially metallized upper face. Two of the side fans in Fig. 1a are indicated by the numbers 2 and 3, the lower fan by the number 4, the upper face by the number 5. In the ceramic block 1 there are two through holes 6 and 6 extending parallel to each other from the upper 5 to the lower 4 faces. These holes on the upper face 5 of the ceramic block 1 are surrounded and in contact with the wire conducting areas 7 and 7, respectively. The ceramic block 1 has an input and output contacts 8 and 9. Between the conductive pads 7 and 7 there is an electrically conductive pad 10. On the lower fan 4 of the ceramic block 1 (Fig. 1 b), samples 12 and 12 of a rectangular are made between the metallized holes 6 and 6 and the edge 11 forms.

Samples 12 and 12 can be located between holes 6 and 6 and rib 13, or between holes b and 6 and ribs 14 and 15. Samples 12 and 12 can also be oval. Щ Thus, there are several possible applications of samples of the conductive layer of the lower fan 4: -using one sample 12 between one of the holes 6 or 6 and one of the edges of the lower fan, -using two or 1 or more samples 12 and 12 in any combination, provided that the essence of the proposed technical solution. An example of one possible combination is the topology of the lower lady 4 in FIG. 16. The greater the length and number of samples 12 around the metallized hole, the more the resonance frequency of the corresponding circuit decreases. This makes it possible to fine tune the filter to a given frequency. A similar effect is achieved when the number of metallized holes is greater than two .: The equivalent circuit of the filter shown in figa and 16, is presented in figure 2. The input and output contacts 8 and 9 of the filter are indicated on the equivalent circuit as Input and Output, connected through the input (output) capacitors Cvx (Cv) with resonant circuits formed, respectively, by capacitance Ci, inductances LI and LiAon (primary circuit) and capacitance C2 , by the inductances La and Liadop (second circuit). The first circuit is connected to the second through the mutual inductance of M. The capacitances and inductances of Ci and Li, as well as Cr and L2, are the equivalent representation of the first and second coaxial filter resonators, and the additional inductances and L2Aon are the equivalent representation of samples 12 and 12 (see Fig. 1b) .

The proposed filter works as follows. The input signal is supplied to the input terminal 8 (Fig. 1a), designated as Input in FIG. 2, then through the input capacitance Cvx it enters the first resonant circuit formed by the capacitance Ci and the inductors LI and Linon. If the frequency of the input signal lies within the filter passband, current resonance occurs in the circuit. Through the connecting loops, the mutual inductance M is transmitted to the second loop, formed by the capacitance Ca and the inductances La and L2Aon, then through the output capacitance Cwi to the output pin 9 (figa), designated as Output in Fig.2. Additional inductances and b2dop are tuning elements of the device.

The prototype of the proposed filter was made of ceramic based on titanium oxide with a dielectric constant of 37, a size of 7x7.5x3.5 mm, had two resonant holes with a diameter of 1.2 mm The samples were 1 mm long and 0.2 mm wide. The filter was designed to work in the receiver of the GLONASS / GPS coordinate system determinant and had the following characteristics:

bandwidth, MHz: 1565-1610

- direct loss in a passband, dB: 1,2

- CVSN in bandwidth: 1.6

-the frequency of the lower cut-off of the band at the level of the boom - 20 dB, MHz: 1450

- the frequency of the upper cut-off of the band at the level of grating - 20 dB, MHz: 1710.

From the description of the design and test results of the prototype, it follows that the proposed utility model can be implemented in industrial production using standard methods described in the prototype (US patent No. 4768003): the formation of a dielectric block with holes, metallization of the dielectric block and holes in it, drawing a picture on the upper face of the dielectric block. Sampling of the metal coating on the bottom fan of the filter is carried out by a rotating diamond bur.

Claims (3)

1. A dielectric filter containing a ceramic block in the form of a parallelepiped with metallized side and bottom faces and a partially metallized upper face, in which at least two through metallized holes are made, passing parallel to each other from the upper to the lower face, the input and output contacts a filter, wherein the metallized holes on the upper face are connected to electrically conductive areas surrounding them or adjacent to them, characterized in that on the lower face of the ceramic block between at least one of the metallized holes of the ceramic block and the rib is formed of the conductive layer sample rectangular or oval shape of the ceramic block to expose the surface. 2. The dielectric filter according to claim 1, characterized in that the samples of the conductive layer of the lower face of the ceramic block are made on both sides of one or more metallized holes. 3. The dielectric filter according to claim 1 or 2, characterized in that the sample of the conductive layer of the lower face of the ceramic block is made on three sides of any of the extreme metallized holes.