Linear type notch tunable SIW filter with source and load hanging patch resonators

Abstract

The application discloses a kind of source and load suspension patch resonator's zero point adjustable SIW filter, including top layer metal layer, intermediate metal layer, bottom layer metal layer, dielectric layer, first metallized via array, second metallized via array, third metallized via array, input-output port.The application embeds metal patch as suspension resonator in SIW cavity, realizes transmission zero point while reducing the area of filter, using the second mode of suspension resonator and the main mode (third mode) of SIW cavity respectively constructs the transmission zero point and pole point of filter, respectively adjusts the width of suspension patch and the width of SIW cavity can independently control the resonant frequency of two modes, and by adjusting the position of feed port and slot line length, the external quality factor of main resonator and suspension resonator can be easily adjusted, and the design is simple.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of microwave technology and relates to a SIW zero-point adjustable filter, in particular to a linear zero-point adjustable SIW filter with source and load hanging patch resonators. BACKGROUND

[0002] In order to effectively suppress the interference of adjacent channel signals, a miniaturized, low-loss and high-selectivity filter is usually used in the front end of a wireless communication transceiver. The most direct method to improve the selectivity of the filter is to increase the order of the filter, but at the same time, the loss and size of the filter are also increased. Introducing transmission zeros in the filter response is a more effective method. In order to realize transmission zeros, cross-coupling between non-adjacent resonators of the filter is usually required, but as the number of transmission zeros increases, the structure becomes complex and difficult to control.

[0003] The basic structure of the traditional linear filter is relatively simple, but it lacks transmission zeros in the filter response and has poor frequency selectivity. Transmission zeros can be introduced by using the extracted pole (EP) technology in the traditional linear filter, and even independent control of transmission zeros can be achieved, but the complexity of its design limits its practicality. Moreover, the EP technology usually uses high-order modes as resonant modes, thereby increasing the size of the filter. The use of frequency variable coupling (FVCs) technology in the linear filter can also introduce transmission zeros, but it also faces the problems of design complexity and large area. In contrast, the linear filter based on the hanging resonator structure not only can flexibly introduce transmission zeros, but also has a simple design process and a small filter area. However, due to the difficulty in simultaneously achieving the required external quality factors of the main resonator and the hanging resonator in the SIW, there is currently no report of a linear hanging resonator structure SIW filter. SUMMARY

[0004] The purpose of the present application is to solve the problems of complex design and large size of transmission zeros in traditional SIW filters. A linear zero-point adjustable SIW filter based on a hanging patch resonator is proposed. The present application embeds a metal patch in the middle metal layer of the SIW cavity as a hanging resonator, which not only reduces the size of the filter while generating transmission zeros, but also easily adjusts the external quality factors of the main resonator and the hanging resonator by adjusting the position of the feed port, making the design simple.

[0005] The present application adopts the following technical solutions:

[0006] The linear zero-point adjustable SIW filter with source and load hanging patch resonators comprises:

[0007] a dielectric layer;

[0008] A top metal layer, located on the upper surface of the dielectric layer;

[0009] A bottom metal layer, located on the lower surface of the dielectric layer;

[0010] an intermediate metal layer, located within the dielectric layer;

[0011] a first metallized through-hole array connecting the top metal layer, the middle metal layer, and the bottom metal layer;

[0012] a second metallized through-hole array connecting the middle metal layer and the bottom metal layer;

[0013] The top metal layer, the middle metal layer, the bottom metal layer, the dielectric layer, and the first metallized through-hole array together form two SIW rectangular cavities; the two SIW rectangular cavities are connected through a coupling window on a common sidewall; the outer sidewalls of the two SIW rectangular cavities are respectively provided with a first window and a second window; the first window and the second window are both provided with a second metallized through-hole array;

[0014] The top metal layer is provided with input and output ports of the filter;

[0015] The intermediate metal layer has two axially symmetrical first and second notches, which are connected by a first slit. The first and second notches have the same structure, each comprising a rectangular slit and two strip-shaped slits, one side of the rectangular slit is connected to the first slit, and the other two ends of the rectangular slit are each connected to a strip-shaped slit.

[0016] The first notch and the second notch are respectively located in two SIW rectangular cavities; the first gap is located at the coupling window position;

[0017] The bottom metal layer covers two SIW rectangular cavities.

[0018] Preferably, the positions T of the first feeding microstrip line and the second feeding microstrip line are IN , the broadband W of the first window and the second window IN , the length of the groove line L S and width W S , which can control the external quality factor of input and output ports;

[0019] Preferably, the distances between the middle metal layer and the top metal layer and the bottom metal layer are equal;

[0020] Preferably, the first feeding microstrip line and the second feeding microstrip line adopt 50 ohm impedance, and the distance between their center lines and the center line of the SIW cavity is T IN ;

[0021] As preferred, the metal inside the SIW rectangular cavity of the intermediate metal layer is a suspended patch, the suspended patch width W of the two SIW cavities P The width W and the length L of the two SIW cavities are equal.

[0022] As preferred, the size and shape of all the strip gaps of the intermediate metal layer are the same.

[0023] As preferred, the metal inside the SIW rectangular cavity of the intermediate metal layer is a suspended patch, by adjusting the suspended patch width W of the intermediate metal layer P , thereby controlling the resonant frequency of the second mode without changing the resonant frequency of the third mode.

[0024] As preferred, by adjusting the width W of the SIW rectangular cavity, the resonant frequency of the third mode is adjusted without changing the resonant frequency of the second mode.

[0025] As preferred, the passband of the filter is set near 15GHz.

[0026] As preferred, the first mode, the second mode of the suspended patch resonator, and the main mode of the SIW rectangular cavity are respectively regarded as the first mode, the second mode, and the third mode of the filter; the magnetic field intensity of the third mode is the highest at the center of the common side wall of the two SIW rectangular cavities, and the magnetic field intensity of the second mode is zero, so when the coupling window is opened at the center of the common side wall, the third mode can pass through smoothly, realizing the coupling of the third mode, which can be used to construct the transmission pole of the filter, while the second mode cannot pass through, which cannot realize the coupling of the second mode, which can be used to construct the transmission zero point of the filter.

[0027] The present application has the following advantages:

[0028] (1) The present application embeds a metal patch in the SIW cavity as a suspended resonator, which not only can produce a transmission zero point, but also reduces the area of the filter while maintaining the shielding performance of the SIW filter; the second mode of the suspended resonator and the main mode (third mode) of the SIW cavity are used to construct the transmission zero point and the pole of the filter respectively, and adjusting the width of the suspended patch and the width of the SIW cavity can independently control the resonant frequencies of the two modes, and by adjusting the position of the feeding port and the length of the slot line, the external quality factor of the main resonator and the suspended resonator can be easily adjusted, and the design is simple.

[0029] (2) The external quality factor required by the main resonator and the suspended resonator of the present application can be easily adjusted by adjusting the physical parameters of the feeding port.

[0030] (3) The resonant frequencies of the main resonator and the suspended resonator of the present application can be adjusted independently, and the design is relatively simple. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is the overall structure schematic diagram of the present application;

[0032] Figure 2 (a), (b) are respectively the top metal layer, the middle metal layer schematic diagram of the filter of the present application;

[0033] Figure 3 (a), (b) are respectively the second, third mode electric field amplitude distribution diagram and the electric field direction diagram embedded in the SIW cavity of the suspended patch structure;

[0034] Figure 4 (a), (b) are respectively the second, third mode resonance frequency change curve when the width W of the suspended patch structure of the middle metal layer is changed P and the SIW cavity width W is changed;

[0035] Figure 5 is the topology structure diagram of the filter, S and L represent the source and the load respectively, 1, 2 represent the third mode in the first and second cavities respectively, 3, 4 represent the second mode in the first and second cavities respectively;

[0036] Figure 6 (a), (b) are respectively the second, third mode external quality factor Qe IN and Qe S change curve and Qe Ⅰ / Qe Ⅱ change curve when the feed port offset T Ⅰ and the slot line length L Ⅱ are changed;

[0037] Figure 7 is the mode two and mode three coupling coefficient change curve when the coupling window width L1 is changed;

[0038] Figure 8 (a), (b) are respectively the response curve of the transmission zero point distribution of the filter of the present application on the right and left sides of the passband;

[0039] Marked in the figure: top metal layer 1, middle metal layer 2, bottom metal layer 3, dielectric layer 4, first metallized via array 5, second metallized via array 6, third metallized via array 7, first feed microstrip line 1a1, second feed microstrip line 1a2, slot line 1b, rectangular metal patch 1c, strip-shaped gap 2a, rectangular gap 2b, first gap 2c. DETAILED DESCRIPTION

[0040] The present application will be further described below in conjunction with the drawings.

[0041] Figure 1The application provides a linear type zero point adjustable SIW filter of source and load hanging patch resonator, which comprises a top metal layer 1, a middle metal layer 2, a bottom metal layer 3, a dielectric layer 4, a first metalized via array 5 and a second metalized via array 6.

[0042] The first metalized via array 5 is enclosed into two communicating rectangles for connecting the top metal layer 1, the middle metal layer 2 and the bottom metal layer 3; the two communicating rectangles share a common side wall, and the common side wall is provided with a coupling window; the outer side walls of the rectangles are respectively provided with first windows and second windows; the first windows and the second windows are both provided with the second metalized via array 6; and the second metalized via array 6 connects the middle metal layer 2 and the bottom metal layer 3.

[0043] The top metal layer 1 is located on the upper surface of the dielectric layer 4 and comprises a first feeding microstrip line 1a1, a second feeding microstrip line 1a2 and a rectangular metal patch 1c; one end of the first feeding microstrip line 1a1 is connected with one side of the rectangular metal patch 1c, and the other end serves as an input / output port of the filter; one end of the second feeding microstrip line 1a2 is connected with the other side of the rectangular metal patch 1c, and the other end serves as an input / output port of the filter; the rectangular metal patch 1c is respectively provided with a concave slot line 1b on the two sides of the first feeding microstrip line 1a1 and the second feeding microstrip line 1a2; the first feeding microstrip line 1a1 and the two slot lines 1b are both located in the first window, and the second feeding microstrip line 1a2 and the two slot lines 1b are both located in the second window.

[0044] The top metal layer 1, the middle metal layer 2, the bottom metal layer 3, the dielectric layer 4 and the first metalized via array 5 jointly construct two SIW rectangular cavities; and the two SIW rectangular cavities are communicated through the coupling window of the common side wall.

[0045] The middle layer metal layer 2 is located in the dielectric layer 4 and is provided with an axially symmetric first notch and a second notch; the first notch and the second notch are communicated through a first gap 2c; the first notch and the second notch are of the same structure and both comprise a rectangular gap 2b and two strip-shaped gaps 2a; one side of the rectangular gap 2b is connected with the first gap 2c, and the other side is respectively connected with one strip-shaped gap 2a at each end.

[0046] The first notch and the second notch are respectively located in the two SIW rectangular cavities; and the first gap 2c is located at the position of the coupling window.

[0047] The bottom metal layer 3 is located on the lower surface of the dielectric layer 4 and covers the rectangle enclosed by the first metalized via array 6.

[0048] The positions of the first feeding microstrip line 1a1 and the second feeding microstrip line 1a2 are TIN , the first window and the second window have a wideband W IN , the length L of the slot line S and the width W S , the external quality factor of the controllable input and output port can be controlled;

[0049] The distance between the intermediate metal layer 2 and the top metal layer 1 and the bottom metal layer 3 is equal;

[0050] The first feeding microstrip line 1a1 and the second feeding microstrip line 1a2 have a 50-ohm impedance, and the distance between the center line and the center line of the SIW cavity is T IN ;

[0051] The internal metal of the intermediate metal layer 2 in the SIW rectangular cavity is a suspended patch, and the width W P of the suspended patch of the two SIW cavities is equal, and the width W and the length L of the two SIW cavities are the same;

[0052] All the strip-shaped slits 2a of the intermediate metal layer 2 are the same in size and shape;

[0053] The coupling window position is located at the center of the common side wall;

[0054] The dielectric layer 4 is stacked by two layers of dielectric substrates, and the intermediate metal layer 2 is located between the two layers of dielectric substrates;

[0055] The dielectric substrate adopts Tanconic TLY-5 dielectric substrate with a relative dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 0.508mm;

[0056] The passband of the proposed filter is set near 15GHz.

[0057] Specific working principle:

[0058] The SIW rectangular cavity embedded with the suspended patch structure has multiple resonance modes, including the first mode of the suspended patch resonator, the second mode, and the main mode of the SIW rectangular cavity. For the sake of simplicity, the above three resonance modes are referred to as the first, second, and third modes.

[0059] In the center of the common side wall of the two SIW rectangular cavities, the magnetic field intensity of the third mode is the highest, and the magnetic field intensity of the second mode is zero, so when the coupling window is opened at this place, the third mode can pass smoothly, realizing the coupling of the third mode, which can be used to construct the transmission pole of the filter, while the second mode cannot pass, and the coupling of the second mode cannot be realized, which can be used to construct the transmission zero of the filter.

[0060] By adjusting the width W PThe resonant frequency of the second mode can be controlled without changing the resonant frequency of the third mode. By changing the width W of the SIW rectangular cavity, the resonant frequency of the third mode can be adjusted without changing the resonant frequency of the second mode.

[0061] According to the electric field distribution diagrams of the second mode and the third mode, it can be seen that at the center of the cavity, the electric field intensity of the second mode is almost zero, and the electric field intensity of the third mode is the highest. At the edge of the cavity, the electric field intensity of the second mode is the highest, and the electric field intensity of the third mode is the lowest. When the first feeding microstrip line 1a1 and the second feeding microstrip line 1a2 deviate from the center of the SIW cavity, the second mode and the third mode can be excited at the same time. By adjusting the position T of the center line of the first feeding microstrip line 1a1 and the second feeding microstrip line 1a2 IN And the feed port slot length L S , the external quality factors of the second and third modes can be controlled, thereby controlling the position of the transmission zero point.

[0062] Figure 2 (a) and (b) are schematic diagrams of the top metal layer and the middle metal layer of the present invention. The width of the microstrip lines 1a1 and 1a2 in the top metal layer is P W There are two concave slot lines 1b at the connection between microstrip lines 1a1 and 1a2 and rectangular metal sheet 1c. The length of the concave slot line is L. S , width is W S The distance between the two rows of metal pillars along the Y axis is W, the distance between the two rows of metal pillars along the Y axis is L, and the width of the two metal patches is W P , length L P , the width of the rectangular gap is G; the width of the coupling window L1 at the common side wall of the two resonant cavities plays a role in adjusting the coupling between the cavities.

[0063] Table 1 Parameters and dimensions of filter 1 (unit: mm)

[0064] W L P W ]]> D D W ]]> <![CDATA[W IN ]]> [WC P <!-- 4 -->]]> 9.2 10.2 1.5 0.4 0.6 2.8 4.16 G [TECHNICAL FIELD] IN ]] L S ]]> <![CDATA[W S ]]> ​ L P ]]> 0.45 1.67 3.14 0.36 3.14 8.7

[0065] Figure 3 (a) and (b) are the electric field distribution diagrams of the second and third modes in the SIW cavity embedded with the suspended patch structure. As can be seen from the figure, the electric field of the second mode is mainly distributed on the suspended patch of the middle metal layer (2), and the electric field of the third mode is distributed in the entire cavity.

[0066] Figure 4 (a) and (b) are the changes in the width W of the intermediate metal layer suspension structure. P The resonant frequency variation curves of the second and third modes when the SIW cavity width W is . As can be seen from the figure, with the increase of W PWith the increase of W, the resonant frequency of the second mode decreases significantly, while the resonant frequency of the third mode remains basically unchanged. With the increase of W, the resonant frequency of the third mode decreases significantly, while the resonant frequency of the second mode remains basically unchanged.

[0067] Figure 5 is the coupling topology of the filter, S and L represent the source and the load respectively, 1 and 2 represent the third mode in the first and second cavities respectively, and 3 and 4 represent the second mode in the first and second cavities respectively. As can be seen from the figure, the filter is a straight-line structure, and there is no coupling between non-adjacent resonators.

[0068] Figure 6 (a) and (b) are the change curves of the external quality factors Qe IN and Qe S of the second mode and the third mode when the feed port offset T Ⅰ and the slot line length L Ⅱ are changed respectively, and the change curves of Qe Ⅰ / Qe Ⅱ , as can be seen from the figure, with the increase of the port offset T IN , the external quality factor Qe Ⅰ of the second mode decreases, the external quality factor Qe Ⅱ of the third mode increases, with the increase of the slot line L S , the external quality factors Qe Ⅰ and Qe Ⅱ of the second mode and the third mode gradually decrease, while the ratio Qe Ⅰ / Qe Ⅱ remains basically unchanged; therefore, T Ⅰ can be determined according to the required ratio Qe Ⅱ / Qe IN , and then L S is adjusted to obtain the required Qe Ⅰ and Qe Ⅱ .

[0069] Table 2: Parameter sizes of filter two (unit: mm)

[0070] W L P W ]]> D D W ]]> [WC IN ]]> [WC P ]]> 9 10.4 1.5 0.4 0.6 2.96 4.89 G [TECHNICAL FIELD] IN ]] [[ L S ]]> [WC S ]] ​ [[ L P ]]> 0.54 1.65 4.24 0.25 3.48 8.7

[0071] Figure 7 is the change curve of the coupling coefficients of the second mode and the third mode when the width L1 of the coupling window is changed; as can be seen from the figure, with the increase of the width L1 of the coupling window, the coupling coefficient K 34 of the second mode remains basically unchanged and is close to zero, and the coupling coefficient K 12 of the third mode gradually increases.

[0072] Figure 8The frequency response curves of filter one (transmission zero point on the right side of the passband) and filter two (transmission zero point on the left side of the passband) of the application are shown in (a) and (b) respectively. As shown in the figures, the center frequency of filter one is 15.3 GHz, the -3dB bandwidth is 0.68 GHz, the relative bandwidth is 4.6%, the minimum insertion loss is 0.71 dB, and the transmission zero point is located at 15.68 GHz. The center frequency of filter two is 15 GHz, the -3dB bandwidth is 0.93 GHz, the relative bandwidth is 6.4%, the minimum insertion loss is 0.61 dB, and the transmission zero point is located at 14.51 GHz.

[0073] The above only describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of the present application.

Claims

1. Linear zero-adjustable SIW filter with source and load suspended patch resonators, including: A dielectric layer (4), a top metal layer (1), a bottom metal layer (3), an intermediate metal layer (2), a first metallized through-hole array (5) for connecting the top metal layer (1), the intermediate metal layer (2), and the bottom metal layer (3), and a second metallized through-hole array (6) for connecting the intermediate metal layer (2) and the bottom metal layer (3); The top metal layer (1), the middle metal layer (2), the bottom metal layer (3), the dielectric layer (4) and the first metallized through-hole array (5) together form two SIW rectangular cavities; the two SIW rectangular cavities are connected via a coupling window on a common side wall; the outer side walls of the two SIW rectangular cavities are each provided with a first window and a second window; the first window and the second window are both provided with a second metallized through-hole array (6); The top metal layer (1) is located on the upper surface of the dielectric layer (4), includes a first feeding microstrip line (1a1) and a second feeding microstrip line (1a2), and is also provided with input and output ports of the filter; The bottom metal layer (3) is located on the lower surface of the dielectric layer (4) and covers two SIW rectangular cavities; Its characteristics are: The intermediate metal layer (2) is located in the dielectric layer (4), and has two axially symmetrically arranged first notches and second notches, the first notches and the second notches being connected via a first gap (2c); the first notches and the second notches have the same structure, both comprising a rectangular gap (2b) and two strip-shaped gaps (2a), one side of the rectangular gap (2b) being connected to the first gap (2c), and the two ends of the other side being respectively connected to a strip-shaped gap (2a); The first notch and the second notch are respectively located in two SIW rectangular cavities; the first gap (2c) is located at the coupling window position; The metal of the intermediate metal layer (2) located inside the SIW rectangular cavity is a suspended patch; The first mode and second mode of the suspended patch resonator and the main mode of the SIW rectangular cavity are regarded as the first mode, second mode and third mode of the filter, respectively.

2. The filter according to claim 1, characterized in that By regulating the positions of the first feeding microstrip line (1a1) and the second feeding microstrip line (1a2) T IN , broadband of the first window and the second window W IN , the length of the slot line (1b) L S and width W S , to control the external quality factor of the filter input and output ports, and thus control the position of the transmission zero point.

3. The filter according to claim 1, wherein: The distances between the middle metal layer (2), the top metal layer (1), and the bottom metal layer (3) are equal.

4. The filter according to claim 1, characterized in that The first feeding microstrip line (1a1) and the second feeding microstrip line (1a2) adopt 50 ohm impedance, and the distance between their center lines and the center line of the SIW rectangular cavity is T IN .

5. The filter according to claim 1, characterized in that The metal of the intermediate metal layer (2) located inside the SIW rectangular cavity is a suspension patch, and the width of the suspension patches of the two SIW rectangular cavities is W P Equal, the width of the two SIW rectangular cavities W and length L same.

6. The filter according to claim 1, characterized in that All the strip-shaped gaps (2a) of the intermediate metal layer (2) have the same size and shape.

7. The filter according to claim 1, characterized in that By adjusting the width of the suspended patch of the middle metal layer (2) W P , thereby controlling the resonant frequency of the second mode of the filter without changing the resonant frequency of the third mode of the filter.

8. The filter according to claim 1, characterized in that By adjusting the width of the SIW rectangular cavity W , thereby adjusting the resonant frequency of the third mode of the filter without changing the resonant frequency of the second mode of the filter.

9. The filter according to claim 1, characterized in that The passband of the filter is set at around 15 GHz.

10. The filter according to claim 1, characterized in that: At the center of the common side wall of the two SIW rectangular cavities, the magnetic field intensity of the third mode of the filter is the highest, and the magnetic field intensity of the second mode of the filter is zero. Therefore, when the coupling window is opened at the center of the common side wall, the third mode of the filter passes smoothly, realizing the coupling of the third mode of the filter, which is used to construct the transmission pole of the filter, while the second mode of the filter cannot pass, and the coupling of the second mode of the filter cannot be realized, which is used to construct the transmission zero point of the filter.

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