A ground patch filter

Abstract

The application discloses a ground patch filter, which comprises a top metal layer, a dielectric substrate and a bottom metal layer stacked from top to bottom; the top metal layer is two fan-shaped metal sheets; the two fan-shaped metal sheets are connected in cascade by adopting a fine strip line coupling mode; wide microstrip lines are connected to the two fan-shaped metal sheets; two metal through holes are formed in the dielectric substrate; the two metal through holes are opposite to the two fan-shaped metal sheets respectively, and the opposite parts of the fan-shaped metal sheets are close to the center of the circle. The application is a patch filter, which is composed of a dielectric substrate, two upper fan-shaped metal sheets and a lower metal sheet, and metal through holes are introduced into the dielectric substrate to generate an LC mode, so that miniaturization can be realized, and the stopband width can be widened by changing the fan-shaped angle.

Description

TECHNICAL FIELD

[0001] The present application relates to a grounded patch filter, belonging to the field of filter. BACKGROUND

[0002] With the upgrading of wireless communication system, the design size of radio frequency front-end device is further compressed, but the overall performance requirement is continuously improved. During the mixing process of the transmitter, a series of intermodulation components will be generated, if the filter has a parasitic passband at the frequency point of the intermodulation component, the harmonic signal of the transmitter will be transmitted. Therefore, there is an urgent need for a filter with small size and wide stopband. SUMMARY

[0003] The present application provides a grounded patch filter, which solves the problems disclosed in the background art.

[0004] In order to solve the above technical problems, the technical scheme adopted by the present application is:

[0005] A grounded patch filter, comprising a top metal layer, a dielectric substrate and a bottom metal layer stacked from top to bottom;

[0006] The top metal layer is two fan-shaped metal pieces, the two fan-shaped metal pieces are cascaded by fine strip line coupling, and a wide microstrip line is connected to each of the two fan-shaped metal pieces;

[0007] Two metal through holes are opened on the dielectric substrate, the two metal through holes are opposite to the two fan-shaped metal pieces respectively, and the opposite parts of the fan-shaped metal pieces are close to the center of the circle.

[0008] The radial edges of the two fan-shaped metal pieces are cascaded, and the cascaded radial edges are opposite and parallel.

[0009] The sizes of the two fan-shaped metal pieces are consistent.

[0010] The connection between the wide microstrip line and the fan-shaped metal piece is located at the center of the arc-shaped edge of the fan-shaped metal piece.

[0011] The wide microstrip line is distributed radially.

[0012] The connection between the wide microstrip line and the fan-shaped metal piece is provided with a transition groove extending into the fan-shaped metal piece.

[0013] The radial line passing through the center of the arc-shaped edge of the fan-shaped metal piece is opposite to the metal through hole.

[0014] The grounded patch filter is a mirror-symmetrical structure.

[0015] The beneficial effects achieved by the present invention are as follows: (1) The present invention is a patch filter, which is composed of a dielectric substrate, two upper fan-shaped metal sheets and a lower metal sheet. Metal vias are introduced into the dielectric substrate to generate an LC mode, which can achieve miniaturization. At the same time, the stopband width can be widened by changing the fan-shaped angle. (2) The filter of the present invention has a simple and compact overall structure, is easy to process, has low cost, and reduces the size of the filter while achieving good circuit performance. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of a ground patch filter;

[0017] Figure 2 This is a top view of a ground patch filter;

[0018] Figure 3 The waveform of the S-parameters of an existing filter;

[0019] Figure 4 The waveform diagram of the S-parameters of the ground patch filter. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0021] like Figure 1 and 2 As shown, a grounding patch filter has a mirror-symmetrical structure, including a top metal layer 1, a dielectric substrate 2, and a bottom metal layer 3 stacked from top to bottom.

[0022] The top metal layer 1 consists of two fan-shaped metal sheets with the same size and a central angle of 45° (theoretically, the smaller the angle, the better the suppression performance; 45° is chosen here for ease of processing). The radius of each sheet is 17.5mm. One radial edge of each fan-shaped metal sheet is opposite and parallel, and these two radial edges are cascaded using a fine wire coupling method.

[0023] The fine strip is perpendicular to the radial edge of the fan-shaped metal sheet. The width of the fine strip is 0.2 mm and the length is 3.4 mm, meaning the distance between the two fan-shaped metal sheets is 3.4 mm, and the distance from the center is 10.65 mm.

[0024] Wide microstrip lines are connected to both fan-shaped metal sheets, each with an impedance of 50 ohms. The wide microstrip lines are radially distributed, and the connection between the wide microstrip lines and the fan-shaped metal sheets is located at the center of the arc edge of the fan-shaped metal sheets. The microstrip lines are fed at the weakest points of several higher-order mode electric fields. The width of the wide microstrip lines is 1.1 mm.

[0025] The transition groove extending into the fan-shaped metal sheet is opened at the connection between the wide microstrip line and the fan-shaped metal sheet, and the width of the transition groove is 1.9 mm. The transition grooves on both sides of the wide microstrip line are symmetrically distributed with respect to the angular bisector.

[0026] The medium substrate 2 and the bottom metal layer 3 have the same shape and area, which are an isosceles triangle upward and a rectangle downward.

[0027] The medium substrate 2 is a Rogers 4003 medium plate, and the dielectric constant is 3.55 and the thickness is 0.508 mm. Two metal through holes 4 are opened on the medium substrate 2, and the diameter of the metal through hole 4 is 1 mm. The two metal through holes 4 are opposite to the two fan-shaped metal sheets, specifically opposite to the radial lines passing through the centers of the arc edges of the fan-shaped metal sheets, and the opposite parts of the fan-shaped metal sheets are close to the center of the circle, about 2 mm away from the center of the circle. In order to facilitate processing, the metal through hole 4 is punched from the top metal layer 1 to the bottom metal layer 3.

[0028] The above filter can achieve the purpose of miniaturization by introducing a metal column on the patch resonant cavity to generate an LC resonant mode with a lower frequency than the main mode of the original patch resonator.

[0029] The above filter can change the fan angle. The frequency of the first few high-order modes of the filter, i.e. the first few modes of the patch resonator without introducing the metal column, will increase as the angle decreases. The multiple of the high-order mode frequency and the LC mode frequency increases, widening the stopband width.

[0030] Figure 3 The S parameter waveform graph of the existing dual-passband patch filter shows that the filter does not suppress the mode of the parasitic stopband, and does not have the effect of wide stopband. In the graph, measure S11 is the measured return loss, measure S21 is the measured insertion loss, simulation S11 is the simulated return loss, and simulation S21 is the simulated insertion loss.

[0031] Figure 4 The S parameter simulation waveform graph of the above patch filter, the horizontal coordinate is frequency (unit: GHz), and the vertical coordinate is S parameter (unit: dB). The solid line and the dashed line respectively represent the relationship between the electromagnetic wave reflection coefficient and the frequency, and the relationship between the electromagnetic wave transmission coefficient and the frequency.

[0032] The -3dB operating bandwidth of the above patch filter is 1.71~2.61GHz, the center frequency is 2.16GHz, the relative bandwidth is 41%, the return loss of the input port and the output port is greater than 20dB, the stopband bandwidth at -20dB is 12.18GHz, and the insertion loss is -0.38dB. It can be seen that the stopband bandwidth of the filter is large, the insertion loss is maintained at a good level, and it is suitable for the current demand of the filter.

[0033] The patch filter has small overall volume, compact structure, small insertion loss, large bandwidth, easy processing, low cost, and reduces the size of the filter while realizing good circuit performance.

[0034] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of the present application, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A grounded patch filter, characterized by, The top metal layer, the medium substrate and the bottom metal layer are stacked from top to bottom; The top metal layer is two fan-shaped metal pieces which are cascaded by fine strip line coupling, and each of the two fan-shaped metal pieces is connected with a wide microstrip line; The medium substrate is provided with two metal through holes which are opposite to the two fan-shaped metal pieces respectively, and the opposite parts of the fan-shaped metal pieces are close to the center of the circle; The band-stop width is widened by changing the fan-shaped angle; The connection between the wide microstrip line and the fan-shaped metal piece is located at the center of the arc-shaped edge of the fan-shaped metal piece.

2. The ground patch filter of claim 1, wherein, The radial edges of the two fan-shaped metal pieces are cascaded, and the cascaded radial edges are opposite and parallel.

3. The ground patch filter of claim 2, wherein, The two fan-shaped metal pieces have the same size.

4. The ground patch filter of claim 1, wherein, The wide microstrip lines are distributed radially.

5. The ground patch filter of claim 4, wherein, The connection between the wide microstrip line and the fan-shaped metal piece is provided with a transition groove which extends into the fan-shaped metal piece.

6. The ground patch filter of claim 1, wherein, The radial line passing through the center of the arc-shaped edge of the fan-shaped metal piece is opposite to the metal through hole.

7. The ground patch filter according to any one of claims 1 to 6, characterized in that The ground patch filter is a mirror-symmetrical structure.

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