A dielectric filter that can optimize in-band echo

Abstract

The application discloses a medium filter capable of optimizing in-band echo, which comprises a body made of solid dielectric material, a plurality of resonance cavities arranged in the body, a first conductive layer coated on the outer surface of the body, electrode contact surfaces respectively formed at the two ends of an electrode surface of the body, the electrode surface being adjacent to a circuit surface, the two electrode contact surfaces respectively extending to the circuit surface, input-output coupling holes respectively formed at the outer sides of the first and last resonance cavities, the two input-output coupling holes being respectively located on the circuit surface and the two electrode contact surfaces, a second conductive layer formed in the input-output coupling holes and connected to the electrode contact surfaces, and a third conductive layer formed in the interiors of the first and last resonance cavities. The application can solve the problem of poor in-band echo index of a wide-band medium filter caused by weak tap coupling, thereby improving the overall performance of the filter.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of communication, and particularly relates to a medium filter capable of optimizing in-band echo. BACKGROUND

[0002] The conjoined medium filter is provided with N (N>=2) resonant through holes on a single block medium, the medium surface is composed of an electrode surface, a circuit surface (open circuit surface) and a short circuit surface, and the medium surface and the resonant through holes are coated with a certain silver layer. The electrode surface is composed of input and output electrode silver layers and a grounding silver layer, the electrode is connected with the electrode of the circuit surface to form an input and output port, the input and output port silver layer and the silver layer of the first and last resonant cavities on the circuit surface form a coupling capacitor, which is commonly called a tap coupling. The signal can enter the filter to realize the filtering function through the tap coupling, and the strength of the tap coupling of the filter directly affects the in-band echo of the medium filter.

[0003] Figure 1 The simulation diagram of a medium filter with a 5-cavity structure is shown in the figure, the center frequency of the filter is 5500 MHz, the bandwidth is 700 MHz, the solder mask groove of the electrode surface is designed in a U-shaped structure, and the input and output port and the first and last cavities are designed in a zigzag shape to maximize the tap coupling capacitor. It can be seen from the simulation optimization that the absolute value of the in-band echo index is only about 5 dB, and the effect is poor. It is quite difficult to continue to optimize on the basis of the existing design.

[0004] For the medium filter with small volume and wide passband, the strength of the tap coupling of the conventional structure is mainly related to the distance and silver layer area between the input and output port silver layer and the silver layer of the first and last resonant cavities. The strength of the tap coupling required by the filter is directly proportional to the bandwidth of the filter. In addition, due to the limitation of processing technology and power requirements, the distance between the input and output port silver layer and the silver layer of the first and last resonant cavities of the medium filter cannot be designed too small, and it is generally recommended to be greater than or equal to 0.1 mm. The specific size is recommended to be determined according to the power requirement of the customer. The design of the silver layer with too small spacing has the risk of reliability. SUMMARY

[0005] The purpose of the present application is to provide a medium filter capable of optimizing in-band echo, which can solve the problem of poor in-band echo index of a type of wideband medium filter caused by weak tap coupling, and improve the overall performance of the filter.

[0006] The in-band echo is a main index for measuring whether the signal in the passband of the filter is well matched for transmission, and the in-band echo index directly affects the insertion loss and in-band flatness in the passband.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0008] The application discloses a medium filter capable of optimizing in-band echo, which comprises a body made of solid dielectric material, a plurality of resonance cavities arranged in the body, a first conductive layer coated on the outer surface of the body, electrode contact surfaces respectively formed at the two ends of an electrode surface of the body, the electrode surface being adjacent to a circuit surface, the two electrode contact surfaces respectively extending to the circuit surface, input-output coupling holes respectively formed at the outer sides of the first and last resonance cavities, the two input-output coupling holes being respectively located on the circuit surface and the two electrode contact surfaces, a second conductive layer formed in the input-output coupling holes and connected to the electrode contact surfaces, a third conductive layer formed in the interiors of the first and last resonance cavities, a fourth conductive layer formed on a short-circuit surface of the body and extended from the third conductive layer, the fourth conductive layer being extended to the circuit surface and connected to the first conductive layer, and a solder mask groove formed at the outer side of the fourth conductive layer and spaced from the first conductive layer.

[0009] Preferably, in the above-mentioned medium filter capable of optimizing in-band echo, the resonance cavities are provided in plurality.

[0010] Preferably, in the above-mentioned medium filter capable of optimizing in-band echo, the two ends of the electrode surface are respectively formed with U-shaped exposed surfaces through the removal of the conductive layer, and the electrode contact surfaces are formed between the U-shaped exposed surfaces and one edge of the electrode surface.

[0011] Preferably, in the above-mentioned medium filter capable of optimizing in-band echo, one side of the U-shaped exposed surface is the other edge of the electrode surface.

[0012] Preferably, in the above-mentioned medium filter capable of optimizing in-band echo, the solid dielectric material is ceramic.

[0013] Preferably, in the above-mentioned medium filter capable of optimizing in-band echo, the fourth conductive layer is circular or rectangular, and the solder mask groove has the same shape as the fourth conductive layer.

[0014] Preferably, in the above-mentioned medium filter capable of optimizing in-band echo, the resonance cavities and the input-output coupling holes are circular, rectangular or other polygons.

[0015] Compared with the prior art, the advantage of the present application is that: by adding one through hole on each side of the original structure as the input and output coupling hole of the signal, the silver layer of the coupling hole is connected with the electrode of the bottom circuit surface for short circuit treatment, and the tap coupling capacitor is formed between the silver layer of the front and rear resonant cavities, the size of the coupling capacitor is related to the distance between the two silver layers; the design distance between the input and output coupling holes and the front and rear resonant cavities also directly affects the size of the coupling capacitor, considering the processability of the medium body (the hole distance cannot be too small to affect the processing of the medium), the distance between the input and output through holes and the front and rear resonant through holes can be obtained by simulation to obtain the minimum distance, and the silver layer of the front and rear resonant cavities on the front circuit surface needs to be connected with the upper surface, the side surface and the bottom surface for short circuit treatment.

[0016] The circuit silver layer of the front and rear resonant cavities of the structure needs to be designed on the rear end short circuit surface, that is, on the parallel surface of the front end circuit surface and is treated as open circuit (the short circuit surface of the front and rear resonant cavities is separated from the ground silver layer by the resistive slot), and the silver layer of the front and rear resonant cavities at the rear end of the filter can be designed as a circular ring or a rectangle, and the resistive slot corresponding thereto can also be designed as a circular ring or a rectangle. The size of the silver layer of the front and rear resonant cavities directly affects the frequency of the front and rear cavities, and through simulation, it can be obtained that when the width size of the resistive slot of the rear end front and rear resonant cavities is unchanged, the frequency will decrease when the silver layer of the resonant cavity increases; the width size of the resistive slot will also affect the frequency of the front and rear cavities, and through simulation, it can be obtained that when the size of the silver layer of the rear end front and rear resonant cavities is unchanged, the frequency will increase when the width of the resistive slot increases. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0018] Figure 1 The simulation diagram in the background art is shown;

[0019] Figure 2 The perspective view of the dielectric filter capable of optimizing in-band echo in the specific embodiment of the present application is shown;

[0020] Figure 3 The perspective view of the dielectric filter capable of optimizing in-band echo in the specific embodiment of the present application is shown from another angle;

[0021] Figure 4 The simulation diagram of the specific embodiment of the present application is shown. DETAILED DESCRIPTION

[0022] With reference to the drawings and embodiments of the present application, the technical solutions in the embodiments of the present application will be described in detail. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0023] Next, we take a 5-cavity structure dielectric filter as an example. The center frequency of the filter is 5500 MHz, and the bandwidth is 700 MHz, which is consistent with the index setting of the conventional scheme. The solder mask groove of the electrode surface is designed as a U-shaped structure. Through simulation adjustment, as shown in Figure 4 , the in-band echo index of the dielectric filter can be adjusted to an optimal state. As can be seen from the example, the absolute value of the in-band echo of the dielectric filter designed by the new scheme can be adjusted from 5 dB of the conventional scheme to about 20 dB, greatly improving the performance index of the filter.

[0024] Referring to Figures 2-3 , the dielectric filter capable of optimizing in-band echo includes a body 100 made of solid dielectric material and a plurality of resonant cavities 101 formed in the body 100. The outer surface of the body 100 is coated with a first conductive layer 102. The two ends of an electrode surface 103 of the body 100 are respectively formed with electrode contact surfaces 104. The electrode surface 103 is adjacent to a circuit surface 105. The two electrode contact surfaces 104 respectively extend to the circuit surface 105. The outer sides of the first and last resonant cavities 101 are respectively formed with input and output coupling holes 106. The two input and output coupling holes 106 are respectively located on the two electrode contact surfaces 104 of the circuit surface 105. A second conductive layer is formed inside the input and output coupling holes 106 and connected to the electrode contact surfaces 104. A third conductive layer is formed inside the first and last resonant cavities 101. The third conductive layer extends to a short-circuit surface of the body 100 and is formed with a fourth conductive layer 107. The third conductive layer extends to the circuit surface 105 and is connected to the first conductive layer 102. The outer side of the fourth conductive layer 107 is formed with a solder mask groove 108 spaced apart from the first conductive layer 102.

[0025] The improved scheme can greatly improve the performance under the condition that the size of the dielectric filter is unchanged or a small size is sacrificed, mainly reflected in the in-band echo index. The implementation of the scheme is as follows: on the basis of the conventional design, one input and output coupling hole is added on each side. The coupling hole is connected to the bottom input and output electrode and is short-circuited to form the input and output port of the filter. The silver layer of the input and output port and the silver layer of the front end first and last resonant cavities form a coupling capacitor. On the other hand, the coupling capacitors formed by the mutual coupling between the coupling hole and the first and last resonant holes are superimposed with each other, which can greatly increase the tap coupling of the dielectric filter, so as to improve the in-band echo index of the dielectric filter.

[0026] The circuit silver layer and the solder mask groove of the first and last resonant cavities of the improved scheme are both formed on the rear end short circuit surface, and the frequency of the first and last cavities can be adjusted by changing the size of the circuit silver layer of the first and last resonant cavities or the width of the solder mask groove.

[0027] For a small-size wideband dielectric filter, the existing technology is difficult to implement, mainly reflected in poor in-band echo index and obvious design limitation, and the improved scheme can greatly improve the performance by adding two coupling through holes without changing the size of the dielectric filter or sacrificing a small size. The design is flexible, easy to process, and there is no process difficulty. It is more practical for wideband dielectric filters.

[0028] The circuit silver layer and the solder mask groove of the dielectric filter of the improved scheme can be designed as a circular ring, a rectangle, or other irregular shapes, but for the convenience of processing, it is preferred to be designed as a circular ring or a rectangle, and the circular ring is used in the above example.

[0029] The resonant through hole and the coupling through hole of the dielectric filter of the improved scheme can be designed as a circle, a rectangle, an ellipse, or other polygons, but for the convenience of processing, it is preferred to be a circle or an ellipse, and the circle is used in the above example.

[0030] Further, the two ends of the electrode surface 103 are formed with a U-shaped exposed surface 109 through the removal of the conductive layer, and the U-shaped exposed surface 109 and one edge of the electrode surface 103 form an electrode contact surface 104. One side of the U-shaped exposed surface 109 is the other edge of the electrode surface 103.

[0031] Further, the solid dielectric material is ceramic.

[0032] Ceramic has high dielectric constant, good hardness, and good high-temperature resistance, and therefore becomes a commonly used solid dielectric material in the field of radio frequency filters.

[0033] Further, the conductive layer is silver.

[0034] The conductive layer is preferably a high-conductivity material such as silver.

[0035] It is to be noted that, as used in this document, the term "indicia" is intended to encompass any type of data, information, or other content, whether in the form of text, graphics, images, video, audio, or otherwise. It is to be further noted that, as used in this document, the terms "coupled" and "connected," along with derivatives thereof, can be used to mean one or more of the following: in electrical communication with; physically touching; in working communication with; and / or information can be shared between any two components. In addition, the term "coupled" or "connected" describes one or more direct connections between components and / or one or more indirect connections between components through one or more other components and / or interfaces. As used herein, the term "exemplary" is used to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. The terms "comprises," "comprising," "includes," "including," and the like can be used in various implementations. The term "consisting of" can be used to refer to a situation where there are no additions to a given implementation. The term "consisting essentially of" can be used to refer to a situation where an addition can be present, but it does not substantially change the characteristics of a given implementation. In some implementations, as used herein, the term "or" as used in a list of items prefaced by "at least one of" can mean many be selected from the list. For example, "A, B, or C, at least one of A and B" can mean "A" can be selected from the group comprising A, B, and C; "B" can be selected from the group comprising A, B, and C; "C" can be selected from the group comprising A, B, and C; "A and B" can be selected from the group comprising A, B, and C; or "none of the above," i.e., neither A, B, nor C can be selected. In addition, use of the "term "another" can be used in a similar way to "at least one of." Also, the term "another" as used herein, unless otherwise stated, can mean at least a second or that a plurality of elements can exist.

[0036] The foregoing is merely illustrative of the principles of this application and various modifications can be made by those skilled in the art, without

Claims

1. A dielectric filter capable of optimizing in-band echo, comprising a body made of a solid dielectric material and a plurality of resonant cavities formed within the body, wherein the outer surface of the body is coated with a first conductive layer, electrode contact surfaces are formed at both ends of the electrode surfaces of the body, the electrode surfaces are adjacent to a circuit surface, and the two electrode contact surfaces extend to the circuit surface, characterized in that, The input-output coupling holes are connected with the bottom input-output electrodes and are short-circuited to form input-output ports of the filter, the silver layer of the input-output ports is connected with the circuit silver layer of the first and last resonant cavities to form a coupling capacitor, the coupling capacitor formed by the mutual coupling between the input-output coupling holes and the first and last resonant cavities is superimposed with the former, the tap coupling of the dielectric filter is increased, and the in-band echo index of the dielectric filter is improved. The circuit silver layer and the solder mask groove of the first and last resonant cavities are arranged on the rear short-circuit surface, and the frequency of the first and last resonant cavities is adjusted by changing the size of the circuit silver layer or the width of the solder mask groove. The solid dielectric material is ceramic.

2. The medium filter of claim 1, wherein, The fourth conductive layer is a circular ring or a rectangle, and the solder mask groove has the same shape as the fourth conductive layer.

3. The medium filter of claim 1, wherein, The resonant cavity and the input-output coupling hole are circular, rectangular or other polygons.

4. The medium filter of claim 1, wherein, ​

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