KR102628219B1 - Radio frequency filter assembly for antenna - Google Patents

Abstract

The present invention relates to an RF filter assembly for an antenna, and in particular, a plurality of band pass filters (BPF, Band Pass Filter), arranged in a stack on the front of the main board, and combining the band pass filters with the front of the main board. An intermediate filter board, a band stop filter (LPF, Low Pass Filter) printed intaglio or embossed on the front of the filter board, and disposed between the filter board and the band-pass filter to filter the front of the filter board and the band-pass filter. By including an air layer forming pad that forms a predetermined air layer between the back surfaces, the insertion loss of the filter is minimized, providing the advantage of improving the overall performance of the filter product.

Description

RF filter assembly for antenna {RADIO FREQUENCY FILTER ASSEMBLY FOR ANTENNA}

The present invention relates to an RF filter assembly for an antenna, and more specifically, to an RF filter assembly for an antenna that reduces insertion loss and is easy to install and assemble.

In order to meet the increasing demand for wireless data traffic following the commercialization of the 4G (4th generation) communication system, efforts are being made to develop an improved 5G (5th generation) communication system or pre-5G communication system. For this reason, the 5G communication system or pre-5G communication system is called a Beyond 4G Network communication system or a Post LTE (Long Term Evolution) system.

To achieve high data rates, 5G communication systems are being considered for implementation in ultra-high frequency (mmWave) bands (such as the 60 GHz band). In order to alleviate the path loss of radio waves in the ultra-high frequency band and increase the transmission distance of radio waves, the 5G communication system uses beamforming, massive array multiple input/output (massive MIMO), and full dimensional multiple input/output (FD-MIMO). ), array antenna, analog beamforming, and large scale antenna technologies are being discussed.

In particular, array antenna technology requires intensive mounting of a large number of filters and antenna elements, which are one of the antenna elements, on the front of the main board in the form of a single board, while also requiring physical equipment to design impedance matching between multiple receiving and transmitting channels. It is an element array technology that requires high precision. Recently, in the 5G communication system market, the demand for ceramic waveguide filters, which are easy to design and manufacture frequency filtering among array antennas, is increasing, and mass production technology to supply ceramic waveguide filters to meet the demand is being developed. It is being demanded.

Figure 1 is a conceptual diagram showing a stacked state of RF filter assemblies for antennas according to the prior art.

As shown in FIG. 1, an example (1) of an RF filter assembly for an antenna according to the prior art is a plurality of RF filters, a type of band pass filter (BPF), on the front of the main board 10. A ceramic waveguide filter (CWF, Ceramic Waveguide Filter) (20) is mounted and arranged via the fixing PCB (5), and is a type of low pass filter (LPF) inside the fixing PCB (5). The microstrip line filter 30 is integrally stacked.

However, in an example (1) of the RF filter assembly for an antenna according to the prior art configured as described above, the microstrip line filter 30 is installed inside the fixing PCB 5 made of a dielectric material (or ceramic material). Due to its location, there is a problem in that the insertion loss of the stop-pass filter (LPF) is excessive.

That is, as a result of the dielectric material covering both the main board 10 side and the ceramic waveguide filter 20 side around the microstrip line filter 30, the insertion loss of the microstrip line filter 30 is It happens very loudly.

The present invention was developed to solve the above technical problems, and its purpose is to provide an RF filter assembly for an antenna that minimizes insertion loss.

In addition, another object of the present invention is to provide an RF filter assembly for an antenna with improved assemblyability and productivity.

The object of the present invention is not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

The RF filter assembly for an antenna according to an embodiment of the present invention includes a plurality of band pass filters (BPF, Band Pass Filters), stacked on the front of the main board, and the combination of the band pass filters with the front of the main board. A filter board that mediates a filter board, a capacitor line that acts as a capacitance on the front of the filter board, and an inductor line that acts as an inductor is printed in an engraved or embossed form, and the filter board and and an air layer forming pad disposed between the band pass filters to form a predetermined air layer between the front surface of the filter board and the back surface of the band pass filter.

Here, the band-pass filter may include a ceramic waveguide filter made of ceramic material.

Additionally, the filter board may include either a dielectric material or an FR4 material.

Additionally, the air layer forming pad may be made of a metal material or a dielectric.

Additionally, the band stop filter may include a microstrip line filter made of a conductive material and integrally formed to be exposed to the front of the filter board.

In addition, the microstrip line filter is printed on the front surface of the filter board in a predetermined pattern shape from the input point of the power supply signal to the output point, and the air layer forming pad is printed with a predetermined pattern shape of the microstrip line filter. The LPF circuit accommodating portion for accommodating may be cut and formed.

In addition, input and output ports for inputting and outputting power feeding signals are connected to the rear of the band pass filter to be spaced apart, and the air layer forming pad accommodates BPF ports for accommodating positions corresponding to the input and output ports of the band pass filter. Additional incisions may be formed.

In addition, the air layer forming pad includes a spacer main body that separates the bandpass filter from the front surface of the filter board by a predetermined distance, and an interior of the spacer main body spaced apart from the spacer main body, wherein the bandpass filter is spaced apart from the spacer main body. It may include an input/output port support portion that separates portions corresponding to the input/output ports provided to input/output the feed signal to the filter with respect to the filter board.

Additionally, the spacer main body and the input/output port support part may space each of the plurality of band pass filters apart by the same height.

Additionally, the spacer main body may include a support plate portion that is in contact with the rear surface of the band pass filter, and an edge support end that is bent toward the front of the filter board at an edge end of the support plate portion.

Additionally, the edge support end may be formed in a shape in which recessed portions and convex portions are repeated along the edges of the edge.

In addition, the microstrip line filter has one capacitor line serving as the capacitance, the other capacitor line arranged side by side and spaced apart from the one capacitor line, and the inductor line connecting the one capacitor line and the other capacitor line to repeat for a certain period. and some or all of the inductor line may be spaced apart from the front of the filter board.

Additionally, a spacer cutout in the form of a hole or groove may be formed on the filter board to space all or part of the inductor line.

According to the RF filter assembly for an antenna according to an embodiment of the present invention, the insertion loss of the microstrip line filter can be minimized, thereby improving the performance of the filter.

In addition, according to the RF filter assembly for an antenna according to an embodiment of the present invention, it has the effect of improving assemblyability and productivity.

1 is a conceptual diagram showing a stacked state of an RF filter assembly for an antenna according to the prior art;
2A and 2B are perspective views showing an RF filter assembly for an antenna according to an embodiment of the present invention;
Figure 3 is an exploded perspective view of Figure 2a;
Figure 4 is a perspective view showing the RF filter in the configuration of Figure 3,
Figure 5 is a perspective view showing an air layer forming pad coupled to one side of a filter board equipped with a microstrip line filter in the configuration of Figure 2a;
Figure 6 is a perspective view showing the air layer forming pad in the configuration of Figure 2a;
Figure 7 is a perspective view showing a filter board equipped with a microstrip line filter in the configuration of Figure 2a;
Figure 8 is a plan view showing a filter board equipped with a microstrip line filter in the configuration of Figure 2a;
Figure 9 is a cross-sectional view taken along line AA of Figure 8, showing a filter board of various embodiments;
Figure 10 is a cross-sectional view taken along line BB in Figure 2a;
Figure 11 is a plot chart showing the RF characteristics of a pass band filter (BPF) in the configuration of the RF filter assembly for an antenna according to an embodiment of the present invention;
Figure 12 is a plot chart showing the RF characteristics of a stop band filter (LPF) in the configuration of the RF filter assembly for an antenna according to an embodiment of the present invention;
FIG. 13 is a plot chart showing RF characteristics combining the results of FIGS. 11 and 12.

Hereinafter, an RF filter assembly for an antenna according to an embodiment of the present invention will be described in detail with reference to the attached drawings.

When adding reference numerals to components in each drawing, it should be noted that identical components are given the same reference numerals as much as possible even if they are shown in different drawings. Additionally, when describing embodiments of the present invention, if detailed descriptions of related known configurations or functions are judged to impede understanding of the embodiments of the present invention, the detailed descriptions will be omitted.

In describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, order, or order of the component is not limited by the term. Additionally, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless clearly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

FIGS. 2A and 2B are perspective views showing an RF filter assembly for an antenna according to an embodiment of the present invention, FIG. 3 is an exploded perspective view of FIG. 2A, and FIG. 4 is a perspective view showing an RF filter in the configuration of FIG. 3.

The RF filter assembly 100 for an antenna according to an embodiment of the present invention, as shown in FIGS. 2A to 4, includes a main board 110, RF filters 120 and 130, and an air layer forming pad. Includes (140).

The main board 110 is a printed circuit board (PCB) in the form of a single board, on one side of which a plurality of RF filters 120 and 130 or some of a number of electrical components (not shown) for tuning thereto can be mounted, and on the other side A plurality of electrical components (not shown) equipped with a plurality of power supply-related components capable of calibrating power supply control to the plurality of RF filters 120 and 130 may be mounted.

In one embodiment of the present invention, for convenience of understanding, a single air layer forming pad 140 is provided on one surface (upper surface in the drawing of FIG. 2A) of the main board 110 provided as a PCB in the form of a single board. Although shown and explained as such, the air layer forming pad 140 is formed in a unique shape at a location where all or part of the plurality of RF filters 120 and 130 are disposed, and is formed at multiple locations on the entire surface of the main board 110. It is not excluded that it is formed in a stacked arrangement.

Here, the RF filters 120 and 130 may include a plurality of band pass filters 120 (BPF, Band Pass Filter) and band stop filters 130 (LPF, Low Pass Filter).

The band pass filter 120 may be provided as a ceramic waveguide filter (CWF) made of ceramic material, and the band stop filter 130 may be provided as a microstrip line filter.

A plurality of ceramic waveguide filters (hereinafter referred to as '120'), which are provided as a type of band-pass filter, each include a filter body 121 made of a ceramic material, as shown in FIG. 3, and a filter body ( 121) and includes at least four resonance blocks. A corresponding resonator post 122 is installed in each resonant block, and each resonator post 122 receives a frequency signal through adjacent coupling with the adjacent resonator post 122 or cross-coupling coupled across at least one. can be filtered.

Here, the resonance blocks 11 to 16 formed in the filter body 121 do not need to be completely physically separated, but are separated by changing the width of the signal transmission path by a partition provided in the filter body 121. That's enough.

For example, as shown in FIG. 4, the filter body 121 is provided with six resonator posts 122a to 122f, and when an electrical signal is input through an input port hole (not shown), which will be described later, the input port hole It is applied through the first resonator post (122a) closest to and is sequentially applied to the second resonator post (122b) ?? Third resonator post (122c) ?? 4th resonator post (122d) ?? Fifth resonator post (122e) ?? After frequency filtering is performed via the sixth resonator post 122f, it is output through an output port hole (not shown), which will be described later.

Here, a first partition 127a is provided between the first resonator post 122a and the second resonator post 122b to partition the first resonator block 11 and the second resonator block 12, and the second resonator post 122b A second partition wall 127b is provided between the post 122b and the third resonator post 122c to partition the second resonance block 12 and the third resonance block 13, and the third resonator post 122c and A portion of the third partition 127c is provided between the fourth resonator post 122d to partition the third resonator block 13 and the fourth resonator block 14, and the fourth resonator post 122d and the fifth resonator post 122d are provided between the fourth resonator post 122d and the fifth resonator post 122d. A fourth partition wall 127d is provided between the posts 122e to partition the fourth resonance block 14 and the fifth resonance block 15, and between the fifth resonator post 122e and the sixth resonator post 122f. The remaining part of the third partition 127c is provided to partition the fifth resonance block 15 and the sixth resonance block 16. In particular, the third partition 127c is provided between the first resonator post 122a, the third resonator post 122c, and the sixth resonator post 122f to physically form three resonance blocks (first resonance block 11). , it can serve to simultaneously partition the third resonance block 13 and the sixth resonance block 16).

The above-described first to fourth partition walls 127a to 127d may all be formed to have a predetermined size that penetrates the filter body 121 in the vertical direction.

The outer shell of the filter body 121 is plated with a metallic film, and the flow of electrical signals can be blocked internally and externally, except for the input/output port of the power supply signal, which will be described later.

As described above, at least four resonance blocks provided in the filter body 121 are provided to perform filtering by adjacent coupling or cross-coupling of electrical signals flowing through an input port or output port (not shown). This is preferable, and in one embodiment of the present invention, it is explained by taking as an example that it is composed of six resonance blocks.

That is, in the RF filter assembly 100 for an antenna according to an embodiment of the present invention, the ceramic waveguide filter 120 is provided with six resonance blocks 11 to 16 in one filter body 121, The resonator posts 122a to 122f of each resonant block 11 to 16 may be installed in a manner in which a dielectric material having a predetermined dielectric constant is filled and fixed. Here, air is also one of the dielectric materials, so when air is selected and filled as the dielectric material constituting the resonator posts (122a to 122f), a separate filling and fixing process is not required, and the six resonator posts (122a to 122f) are used. ) Each may be formed in the form of an empty space in which a portion of the dielectric material is removed from the filter body 121.

Here, as shown in FIG. 4, a portion of one surface of the filter body 121 corresponding to the inner surface of the resonator posts 122a to 122f and the upper edge of the resonator posts 122a to 122f is provided with a coating portion of a conductive material ( 126a to 126f) may be formed by plating. Some of the coating portions 126a to 126f are formed to extend closer to the relevant resonator post 126d so that cross-coupling can be easily implemented between some of the resonator posts 122a to 122f. ) may further be included.

In one embodiment of the present invention, cross-coupling is provided so that cross-coupling can be implemented between the fourth resonator post 122d and the sixth resonator post 122f, which skips the fifth resonator post 122e by one, and the cross-coupling In order to make the implementation easier, a film extension end ( 126f-1) can be extended closely.

In addition, referring to FIG. 4, a ground portion 128 that does not form any film plating layer may be provided around each of the film portions 126a to 126f. The ground portion 128 may serve as a ground to insulate between the portion plated with a film on the outer surface of the filter body 121 and the film portions 126a to 126f of each of the above-described resonator posts 122a to 122f. .

Meanwhile, although not shown in the drawing, on the other side of the ceramic waveguide filter 120, there is an input port hole for connecting an input port (not shown) that inputs an electrical signal to any one of the six resonator posts 122 described above. And an output port hole may be formed for connection of an output port (not shown) that outputs an electrical signal from any one of the six resonator posts 122 described above. An input port and an output port connected to the main board 110 through the input/output port support 143 of the air layer forming pad 140, which will be described later, may be installed in the input port hole and the output port hole.

In addition, as shown in FIG. 3, the ceramic waveguide filter 120 is installed on one side of the opening of each resonator post 122 to perform frequency tuning using a steering angle method or a tuning screw. It may further include a filter cover 125 coupled to cover one surface of the filter body 121 including the cover 123 and the tuning cover 123.

When the frequency tuning method is a striking angle method, a striking angle pad 124 may be formed integrally with the tuning cover 123. The stamp pad 124 is spaced apart from the position corresponding to the resonator post 122, and is stamped using a stamp tool (not shown) to finely adjust the separation distance between it and the bottom surface of the resonator post 122. Frequency tuning can be performed.

On the other hand, the microstrip line filter provided as a type of band stop filter 130, as shown in FIG. 3, is printed on the front of the filter board 105 or is a band-pass filter with the front laminated on the front ( 120) The insert may be injection molded to be exposed toward the side.

Here, the filter board 105 may include either a dielectric material or an FR4 material. When the filter board 105 is made of a dielectric material, the structure of the filter board 105 is changed as described later in order to minimize the insertion loss of the microstrip line filter printed with the band stop filter 130 on the front surface. You can set it up. Specific details regarding this will be explained in more detail later.

When filtering of a specific frequency band is completely performed using the band-pass filter 120, there is no need to provide a separate band-stop filter 130, but in one embodiment of the present invention, the band-pass filter 120 is used as a ceramic When used as the waveguide filter 120, spurious phenomena may occur at one end of the pass band due to the nature of the ceramic material, so the spurious phenomenon can be removed by adding a band stop filter 130.

Here, the band-stop filter 130 employed as a microstrip line filter takes a form in which the front part of the fixing PCB made of dielectric material (or ceramic material) is removed compared to the conventional PCB referred to in FIG. 1, so that the dielectric material (or ceramic material) is removed. or ceramic material) to minimize insertion loss due to contact.

However, the ceramic waveguide filter 120, which is a type of band-pass filter 120, stacked on the front of the microstrip line filter provided as the band stop filter 130, is also made of ceramic material. Therefore, the RF filter assembly 100 for an antenna according to an embodiment of the present invention is designed to minimize the influence of insertion loss of the microstrip line filter, which is the band stop filter 130, due to the ceramic material of the band pass filter 120. An air layer forming pad 140 may be further provided.

As shown in FIGS. 2A to 4, the air layer forming pad 140 is disposed between the filter board 105 and the plurality of ceramic waveguide filters 120 to form a ceramic waveguide filter (from the front of the filter board 105). 120) It plays the role of separating each.

The air layer forming pad 140 may be entirely made of metal or dielectric. The metal material here may include any one of steel, SUS (Stainless steel), and pure copper (Cu).

Figure 5 is a perspective view showing an air layer forming pad coupled to one side of a filter board equipped with a microstrip line filter in the configuration of Figure 2a, and Figure 6 is a perspective view showing the air layer forming pad in the configuration of Figure 2a, FIG. 7 is a perspective view showing a filter board equipped with a microstrip line filter in the configuration of FIG. 2A, FIG. 8 is a plan view showing a filter board equipped with a microstrip line filter in the configuration of FIG. 2A, and FIG. 9 is a view of FIG. 8. This is a cross-sectional view taken along line A-A.

Referring to FIGS. 3 and 5, the air layer forming pad 140 is formed in a shape corresponding to the outer shape of the filter board 105, and the band-pass filter 120 is positioned on the front surface of the filter board 105 at a predetermined angle. Spacer main bodies 141 and 142 that are spaced apart from each other are provided inside the spacer main bodies 141 and 142 to be spaced apart from each other in the same direction as the spacer main bodies 141 and 142, and input and output power signals to a plurality of ceramic waveguide filters 120. It may include an input/output port support portion 143 that separates parts corresponding to the input/output ports provided to handle the filter board 105. Here, the input/output port support portion 143 may be provided as a pair to correspond to the input port hole and output port hole formed in each of the ceramic waveguide filters 120.

The spacer main bodies 141 and 142 and the input/output port supporter 143 may space each of the plurality of ceramic waveguide filters 120 apart from each other by the same height with respect to the front surface of the filter board 105. This will be explained in more detail later.

As shown in FIG. 6, the spacer main bodies 141 and 142 include a support plate portion 141 that is adhered to the back of a plurality of ceramic waveguide filters provided as band-pass filters 120, and an edge edge of the support plate portion 141. may include an edge support end 142 bent toward the front of the filter board 105.

Here, the edge support end 142 is formed along the outer edge end of the support plate part 141, and is bent from the outer edge end of the support plate part 141 toward the rear side of the support plate part 141 to form the filter board 105. It may be formed to extend a predetermined length toward the front of.

Such an edge support end 142 may be formed in a concave-convex shape in which concave portions 142a and convex portions 142b are repeated along the outer edge edge of the support plate portion 141. This minimizes the solder bonding area to the filter board 105 by the cut portion of the concave portion 142a of the edge support end 142, while also minimizing the filter board 105 by the protruding portion of the convex portion 142b of the edge support end 142. This is to facilitate soldering by inserting each into the previously formed solder holes and to form a predetermined air layer from the front of the filter board 105 to the back of the ceramic waveguide filter 120.

In this way, using the edge support ends 142 of the spacer main bodies 141 and 142, the ceramic waveguide filter 120 is spaced a predetermined distance from the front of the filter board 105 to form an air layer, and at the same time, the filter board 105 ) It is possible to uniformly support the ceramic waveguide filter 120 with respect to the front surface.

Meanwhile, the input/output port support portion 143 may be opened in a direction opposite to the edge support end 142 of the spacer main bodies 141 and 142, or may be formed in a shape in which protruding grooves and convex portions are repeated.

Here, the edge support ends 142 of the spacer main bodies 141 and 142 and the ends of the input/output port support parts 143 are preferably formed at the same height from one surface of the support plate part 141. This is so that the support plate portions 141 of the spacer main bodies 141 and 142 are spaced apart from the filter board 105 at the same distance so that the height of the plurality of ceramic waveguide filters 120 stacked on the front surface of the support plate portion 141 is uniform. It is for this purpose.

In the filter board 105, a plurality of solder grooves 137 may be formed into which the convex portions 142b of the edge support ends 142 of the spaced main bodies 141 and 142 are respectively inserted or positioned, and a plurality of solder grooves ( Only the ends of the edge support ends 142 of the spaced part bodies 141 and 142 that are inserted and fixed into the 137) can be soldered together with solder cream applied.

Here, the solder cream is a component for joining the spacer main bodies 141 and 142 to the front of the filter board 105 through a soldering method, and is not applied to the entire front area of the filter board 105, but is applied as described above. As shown, the coating may be applied only to the portion corresponding to the convex portion of the edge support end 142 among the spaced portion main bodies 141 and 142, respectively. This is because the solder area can be relatively minimized compared to the case where solder cream is applied to the entire area of the filter board 105.

Meanwhile, in the spacer main bodies 141 and 142, as shown in FIGS. 3 to 6, a BPF port receiving portion 145 is formed with a circular cut in order to install a pair of input/output port supports 143 spaced apart from each other on the same surface. ) can be provided, respectively.

Here, the microstrip line filter 130 provided as a band-stop filter on the filter board 105 is the input of the ceramic waveguide filter 120 in the BPF port receiving portion 145, as shown in FIGS. 5 and 7. The same position as the port hole area is placed as the input port position (131a), and it extends from the input port position (131a) in a predetermined pattern shape, but outputs a position that is unrelated to the output port hole area of the ceramic waveguide filter (120). It may be formed to extend to be placed at the port location (131b).

The input port of the ceramic waveguide filter, which is the band pass filter 120, and the input port location 131a of the microstrip line filter, which is the band stop filter 130, are located in the same BPF port receiving portion 145, and are not shown in the drawing. However, a power supply signal can be received through the input port terminal of the main board 110 to avoid short circuiting the input port position 131a of the microstrip line filter, which is the band stop filter 130. At this time, short circuit with the outside can be prevented by one of the input/output port supports 143.

Meanwhile, an LPF circuit receiving portion 149 for accommodating a predetermined pattern shape of a microstrip line filter, which is a band stop filter 130, may be cut and formed in the spaced main bodies 141 and 142 of the air layer forming pad 140. there is. More specifically, the LPF circuit accommodating part 149 is configured as a microstrip line filter, which is a band stop filter 130, and the input point of the feeding signal is shared with the above-described BPF port accommodating part 145. The incision may be formed to extend from the input port position 131a of the microstrip line filter, which is the band stop filter 130, to the output port point, which is the output point.

In addition, in the spaced main bodies 141 and 142 of the air layer forming pad 140, a support plate portion is provided from the BPF port receiving portion 145 formed at a position corresponding to the output port hole in the configuration of the ceramic waveguide filter, which is the band pass filter 120. A signal line cutout 150 may be further formed by cutting up to the end of 141. A signal line related to the output signal path may be accommodated and placed inside the signal line cutout 150.

More specifically, the microstrip line filter 130 provided as a band stop filter is made of a conductive material, as shown in FIG. 7, and has an input port location 131a, an output port location 131b, and both. It may include a pattern shape portion 133 that connects without interruption.

Some of the pattern forming portions 133 serve as transmission lines for transmitting signals from the input port position 131a to the output port position 131b, and some of the pattern forming portions 133 serve as capacitance. The capacitor lines 135a and 135b that act as an inductor and the inductor line 135c that acts as an inductor may be formed in a repeated shape.

That is, the microstrip line filter, which is the band stop filter 130, includes one capacitor line 135a that acts as a capacitor, the other capacitor line 135b arranged side by side and spaced apart from the one capacitor line 135a, and one capacitor line ( The inductor line 135c connecting 135a) and the other capacitor line 135b may be formed in a pattern to repeat for a certain period. Here, all of the patterned portions 133 of the microstrip line filter, which is the band stop filter 130 described above, can be accommodated inside the LPF circuit accommodating portion 149 of the air layer forming pad 140.

Here, as described above, the filter board 105 is made of either a dielectric material or a ceramic material, which may cause insertion loss of the microstrip line filter, which is the band stop filter 130.

In order to prevent such insertion loss, as shown in (a) and (b) of FIG. 9, all or part of the inductor line 135c is installed in the filter board 105 from the front of the filter board 105. A separation cutout 137 in the form of a hole or groove may be formed to separate the devices. Therefore, the insertion loss of the microstrip line filter 130 due to the material of the filter board 105 can be minimized, thereby improving the overall performance of the filter product.

FIG. 10 is a cross-sectional view taken along line B-B in FIG. 2A.

As shown in FIG. 10, the RF filter assembly 100 for an antenna according to an embodiment of the present invention stacks the filter board 105 on the front of the main board 110, and the front of the filter board 105 A plurality of RF filters 100 may be mounted.

Here, a microstrip line filter, which is a type of band stop filter 130 among the plurality of RF filters 100, may be integrally printed on the front of the filter board 105, and may be formed by printing through the air layer forming pad 140. Among the plurality of RF filters 100, a plurality of ceramic waveguide filters, which are a type of bandpass filter 120, may be stacked and arranged at a predetermined distance from the front of the filter board 105.

In this way, by the air layer forming pad 140, the back side of the microstrip line filter, which is the band stop filter 130, and the ceramic waveguide filter, which is the band pass filter 120, are formed integrally with each other on the front side of the filter board 105. Since they are spaced apart to form a predetermined air layer, insertion loss can be minimized.

Figure 11 is a plot chart showing the RF characteristics of the ceramic waveguide filter, Figure 12 is a plot chart showing the RF characteristics of the microstrip line filter, and Figure 13 shows the ceramic waveguide filter of Figure 11 and the microstrip line filter of Figure 12 used together. This is a plot chart showing the RF characteristics in the current state.

As shown in FIG. 11, when a ceramic waveguide filter is used as the band pass filter 120, there is a problem in that spurious (S) exists outside the frequency pass band due to the characteristics of the ceramic material. In order to remove the spurious S of the band-pass filter 120, the above-described stop-band filter 130 having RF characteristics as shown in FIG. 12 is employed.

That is, as shown in FIG. 12, spurious (S) occurs around 5.3 GHz outside the pass band, and the stop band of the microstrip line filter, which is the band stop filter 130, is as shown in FIG. 13. Likewise, if designed to be around 5.3 GHz, which is approximately the point where spurious (S) first occurs, a stop band is designed in a frequency band other than the pass band desired by the designer, as shown in FIG. 13.

In particular, in the RF filter assembly 100 for an antenna according to an embodiment of the present invention, the insertion loss of the microstrip line filter, which is the band stop filter 130, can be minimized by the air layer forming pad 140, This has the advantage of making it easy to design the passband frequency of the frequency band desired by the designer.

Above, the RF filter assembly for an antenna according to an embodiment of the present invention has been described in detail with reference to the attached drawings. However, the embodiments of the present invention are not necessarily limited to the above-described embodiment, and it is natural that various modifications and equivalent implementations can be made by those skilled in the art. will be. Therefore, the true scope of rights of the present invention will be determined by the claims described later.

100: RF filter assembly for antenna 105: Filter board
110: main board 120: ceramic waveguide filter
121: Filter body 122: Resonator post
123: Tuning cover 124: Steering wheel pad
125: Filter cover 130: Microstrip line filter
131a: Input port location 131b: Output port location
133: pattern shape portion 135a: one side capacitor line
135b: Other capacitor line 135c: Inductor line
137: Solder groove 140: Air layer forming pad
141,142: Separated portion main body 141: Support plate portion
142: border support 143: input/output port support
145: BPF port accommodating part 149: LPF circuit accommodating part
150: Signal line cut S: Spurious

Claims (13)

Multiple band pass filters (BPF, Band Pass Filter);
a filter board arranged in a stack on the front of the main board and mediating coupling of the band-pass filter to the front of the main board;
A band stop filter (LPF, Low Pass Filter) with a capacitor line serving as a capacitance and an inductor line serving as an inductor printed on the front of the filter board in an engraved or embossed form; and
an air layer forming pad disposed between the filter board and the band-pass filter to form a predetermined air layer between the front surface of the filter board and the back surface of the band-pass filter; Including,
The air layer forming pad is,
a spacer main body that separates the bandpass filter a predetermined distance from the front of the filter board; and
an input/output port support unit provided inside the spacer main body; RF filter assembly for an antenna, including a. In claim 1,
The band pass filter is an RF filter assembly for an antenna including a ceramic waveguide filter made of ceramic material. In claim 1,
The filter board is an RF filter assembly for an antenna comprising any one of a dielectric material and an FR4 material. In claim 1,
The air layer forming pad is an RF filter assembly for an antenna made of metal or dielectric. In claim 1,
The band stop filter is made of a conductive material and includes a microstrip line filter integrally formed to be exposed to the front of the filter board. In claim 5,
The microstrip line filter is printed on the front surface of the filter board in a predetermined pattern shape from the input point of the feed signal to the output point,
An RF filter assembly for an antenna, wherein an LPF circuit receiving portion is cut into the air layer forming pad to accommodate a predetermined pattern shape of the microstrip line filter. In claim 5,
On the back of the band-pass filter, input and output ports for inputting and outputting a power supply signal are connected to be spaced apart from each other,
An RF filter assembly for an antenna in which a BPF port receiving portion is cut into the air layer forming pad to accommodate positions corresponding to the input and output ports of the band pass filter. In claim 1,
The input/output port support portion is spaced apart from the spacer main body, and separates portions corresponding to input/output ports provided to input/output the feed signal to the bandpass filter with respect to the filter board. RF filter assembly for an antenna. In claim 8,
An RF filter assembly for an antenna, wherein the spacer main body and the input/output port support part space each of the plurality of bandpass filters by the same height. In claim 8,
The main body of the spaced part is,
A support plate portion adhered to the back of the band pass filter; and
an edge support end bent from an edge end of the support plate portion toward the front of the filter board; RF filter assembly for an antenna, including a. In claim 10,
The edge support end is an RF filter assembly for an antenna in which recessed portions and convex portions are formed in a shape that is repeated along the edge edge. In claim 5,
The microstrip line filter,
One capacitor line serving as the capacitance, the other capacitor line arranged side by side and spaced apart from the one capacitor line, and the inductor line connecting the one capacitor line and the other capacitor line are formed to be repeated for a certain period,
An RF filter assembly for an antenna, wherein some or all of the inductor line is spaced apart from the front of the filter board. In claim 12,
An RF filter assembly for an antenna, wherein the filter board is formed with a separation cutout in the form of a hole or groove to separate all or part of the inductor line.