Hybrid different-wavelength resonant bandpass filter with capacitively coupled metal patterns

Abstract

The present invention discloses a hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern, comprising a ceramic substrate, wherein the ceramic substrate comprises a first surface and a second surface opposite to the first surface, and a first resonant cavity, a second resonant cavity, a third resonant cavity, a fourth resonant cavity, a fifth resonant cavity, a sixth resonant cavity, a seventh resonant cavity, an eighth resonant cavity and a ninth resonant cavity are formed between the first surface and the second surface and are sequentially distributed along the length direction of the ceramic substrate; a metal pattern is arranged on the first surface, characterized in that the metal pattern comprises a first pattern area surrounding the third resonant cavity and a second pattern area surrounding the fourth resonant cavity; wherein a first gap is formed between the first pattern area and the second pattern area, so that the first pattern area and the second pattern area form a capacitive coupling under the separation of the first gap.

Description

Technical Field

[0001] The invention relates to the field of filters, in particular to a hybrid different-wavelength resonant bandpass filter with a capacitive coupling metal pattern. Background Art

[0002] Ceramic filters are divided into band-stop filters (also known as notch filters) and band-pass filters (also known as filters) according to their amplitude-frequency characteristics. They are mainly used in frequency selection networks, intermediate frequency tuning, frequency discrimination and filtering circuits to separate currents of different frequencies. They have the characteristics of high Q value, good amplitude-frequency and phase-frequency characteristics, small size and high signal-to-noise ratio. However, a band-pass filter is a filter that only allows signals within a specified frequency band to pass through and suppresses signals of other frequencies; while a band-stop filter is a filter that suppresses signals of a specific frequency band and allows signals of other frequencies to pass through. Existing ceramic filters generally have the defect of being single in function and form and cannot meet the frequency band usage under full-frequency requirements.

[0003] Prior art 1-CN202010153329.7 discloses a hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern, which forms five first resonant cavities, two second resonant cavities and two third resonant cavities that penetrate in the horizontal direction between the first and second surfaces; the two second resonant cavities and the five first resonant cavities are coupled to form a fifth-order bandpass filter, and the second resonant cavity and the third resonant cavity are respectively coupled to form two band-stop filters, thereby integrating filters of various forms and functions into one, and having good out-of-band suppression capability at low frequencies (see Figure 1 and Figure 2 )

[0004] However, in some specific occasions, the out-of-band suppression capability of the prior art 1 at low frequencies is still insufficient. Summary of the invention

[0005] In view of this, the present invention provides a hybrid different-wavelength resonant bandpass filter with a capacitive coupling metal pattern, which can improve the out-of-band suppression capability at low frequencies.

[0006] The present invention adopts the following technical measures:

[0007] A hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern comprises a ceramic substrate, wherein the ceramic substrate comprises a first surface and a second surface opposite to the first surface, and a first resonant cavity, a second resonant cavity, a third resonant cavity, a fourth resonant cavity, a fifth resonant cavity, a sixth resonant cavity, a seventh resonant cavity, an eighth resonant cavity and a ninth resonant cavity are formed between the first surface and the second surface and are sequentially distributed along the length direction of the ceramic substrate; a metal pattern is arranged on the first surface; the metal pattern comprises a first pattern area surrounding the third resonant cavity and a second pattern area surrounding the fourth resonant cavity; wherein a first gap is formed between the first pattern area and the second pattern area, so that the first pattern area and the second pattern area form capacitive coupling under the separation of the first gap.

[0008] Preferably, the metal pattern further includes a third pattern region surrounding the sixth resonant cavity and a fourth pattern region surrounding the seventh resonant cavity; wherein a second gap is formed between the third pattern region and the fourth pattern region.

[0009] Preferably, the first gap and the second gap have the same shape and are symmetrical about a fifth resonant cavity located in the middle.

[0010] Preferably, the adjacent surfaces of the first pattern area and the second pattern area are twisted regularly or irregularly to equivalently increase the electrode plate area.

[0011] Preferably, adjacent surfaces of the first pattern area and the second pattern area are formed with a plurality of curved portions.

[0012] Preferably, the first resonant cavity, the third resonant cavity, the fourth resonant cavity, the fifth resonant cavity, the sixth resonant cavity, the seventh resonant cavity and the ninth resonant cavity are half-wavelength resonant cavities, and the second resonant cavity and the eighth resonant cavity are quarter-wavelength resonant cavities.

[0013] Preferably, the second resonant cavity, the third resonant cavity, the fourth resonant cavity, the fifth resonant cavity, the sixth resonant cavity, the seventh resonant cavity, and the eighth resonant cavity are arranged at the same height on the ceramic substrate and are approximately located at the center of the first surface of the ceramic substrate; the first resonant cavity and the ninth resonant cavity are arranged at the same height on the ceramic substrate, and the height of the first resonant cavity is slightly lower than the height of the second resonant cavity.

[0014] Preferably, the first resonant cavity and the ninth resonant cavity both include a coaxial first section hole and a second section hole, the second section hole is close to the first surface, the ratio of the diameters of the first section hole and the second section hole is 1:1.1 to 1:2.5, and the ratio of the lengths of the first section hole and the second section hole is 1:1 to 1:1.5.

[0015] Preferably, the first resonant cavity and the ninth resonant cavity are holes of equal diameter.

[0016] Preferably, it further comprises input / output electrodes, and the input / output electrodes are electrically connected to each resonant cavity through the metal pattern.

[0017] The hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern provided in this embodiment forms a capacitive coupling between the first pattern area and the second pattern area, and between the third pattern area and the fourth pattern area by setting a first gap and a second gap, so that the transmission zero-point energy of the bandpass filter is concentrated on the left side of the frequency domain, thereby making the attenuation slope outside the band larger and the suppression effect better improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an electrical curve diagram of out-of-band attenuation at the first zero point of prior art 1.

[0019] Figure 2 It is an electrical curve diagram of out-of-band attenuation at the second zero point of prior art 1.

[0020] Figure 3 It is a stereoscopic diagram of a hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern provided by an embodiment of the present invention.

[0021] Figure 4 It is a schematic plan view of a first surface of a hybrid different-wavelength resonant bandpass filter with a capacitive coupling metal pattern provided by an embodiment of the present invention.

[0022] Figure 5 This is an electrical curve diagram of the out-of-band attenuation of the hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern provided by an embodiment of the present invention at the first zero point.

[0023] Figure 6 This is an electrical curve diagram of the out-of-band attenuation of the hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern provided by an embodiment of the present invention at the second zero point. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0025] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0026] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0027] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0029] Please refer to Figure 3 and Figure 4, a hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern provided by an embodiment of the present invention comprises a ceramic substrate 10, wherein the ceramic substrate 10 comprises a first surface 11 and a second surface 12 opposite to the first surface 11, and a first resonant cavity 21, a second resonant cavity 22, a third resonant cavity 23, a fourth resonant cavity 24, a fifth resonant cavity 25, a sixth resonant cavity 26, a seventh resonant cavity 27, an eighth resonant cavity 28 and a ninth resonant cavity 29 are formed between the first surface 11 and the second surface 12 and are sequentially distributed along the length direction of the ceramic substrate 10; a metal pattern 30 is arranged on the first surface 11; the metal pattern 30 comprises a first pattern area 31 surrounding the third resonant cavity 23 and a second pattern area 32 surrounding the fourth resonant cavity 24; wherein a first gap 41 is formed between the first pattern area 31 and the second pattern area 32, so that the first pattern area 31 and the second pattern area 32 form a capacitive coupling under the separation of the first gap 41.

[0030] Specifically, in this embodiment, the ceramic substrate 10 is a substantially rectangular structure, and the ceramic substrate 10 can be made of dielectric ceramic or other organic dielectric materials. Preferably, the ceramic substrate 10 is a high dielectric (ε γ =8~20) microwave materials.

[0031] In this embodiment, the third resonant cavity 23, the fourth resonant cavity 24, the fifth resonant cavity 25, the sixth resonant cavity 26 and the seventh resonant cavity 27 are located near the middle of the first surface 11 of the ceramic substrate 10, the second resonant cavity 22 and the eighth resonant cavity 28 are located on the outside of the third resonant cavity 23 and the seventh resonant cavity 27, respectively, and the first resonant cavity 21 and the ninth resonant cavity 29 are located on the outside of the second resonant cavity 22 and the eighth resonant cavity 28, respectively.

[0032] In this embodiment, in particular, the second resonant cavity 22, the third resonant cavity 23, the fourth resonant cavity 24, the fifth resonant cavity 25, the sixth resonant cavity 26, the seventh resonant cavity 27, and the eighth resonant cavity 28 are arranged at the same height on the ceramic substrate 10 and are approximately located at the center of the first surface 11 of the ceramic substrate 10; the first resonant cavity 21 and the ninth resonant cavity 29 are arranged at the same height on the ceramic substrate 10, and the height of the first resonant cavity 21 is slightly lower than (or slightly higher than) the height of the second resonant cavity 22. In this way, the overall length of the ceramic substrate 10 can be shortened, and the overall volume of the filter can be reduced.

[0033] In this embodiment, the resonant frequency of the filter can be adjusted by adjusting the height of the resonant cavity on the ceramic substrate 10 so that the resonant frequency of the filter reaches the desired frequency point to form resonance. The specific height depends on the situation and is not specifically limited in the present invention.

[0034] In this embodiment, the first resonant cavity 21, the third resonant cavity 23, the fourth resonant cavity 24, the fifth resonant cavity 25, the sixth resonant cavity 26, the seventh resonant cavity 27 and the ninth resonant cavity 29 are half-wavelength resonant cavities, and the second resonant cavity 22 and the eighth resonant cavity 28 are quarter-wavelength resonant cavities. Wherein, the first resonant cavity 21 and the ninth resonant cavity 29 both include a coaxial first section hole and a second section hole, the second section hole is close to the first surface 11, the ratio of the diameter of the first section hole and the second section hole is 1:1.1 to 1:2.5, and the ratio of the length of the first section hole to the second section hole is 1:1 to 1:1.5. Of course, it should be noted that the diameter ratio or length ratio of the two sections of the hole can be adjusted according to actual needs, and these schemes are within the protection scope of the present invention.

[0035] In this embodiment, each resonant cavity is coated with metal, and the first resonant cavity 21, the third resonant cavity 23, the fourth resonant cavity 24, the fifth resonant cavity 25, the sixth resonant cavity 26, the seventh resonant cavity 27 and the ninth resonant cavity 29 are all coated with metal at one end located on the second surface 12. The third resonant cavity 23, the fourth resonant cavity 24, the fifth resonant cavity 25, the sixth resonant cavity 26 and the seventh resonant cavity 27 are coupled to form a fifth-order bandpass filter, the first resonant cavity 21 and the second resonant cavity 7 are coupled to form a bandstop filter, and the ninth resonant cavity 29 and the eighth resonant cavity 28 are also coupled to form a bandstop filter.

[0036] In this embodiment, since a first gap 51 is formed between the first pattern area 41 and the second pattern area 42, the first pattern area 41 and the second pattern area 42 form a capacitive coupling under the separation of the first gap 51, that is, the two adjacent surfaces of the first pattern area 41 and the second pattern area 42 constitute two electrode plates of a capacitor, and the first gap 51 in the middle serves as an insulating medium of the capacitor.

[0037] It should be noted that, in this embodiment, in order to enhance the coupling capability of the capacitor, the adjacent surfaces of the first pattern area 41 and the second pattern area 42 may be formed with regular or irregular distortions to equivalently increase the area of ​​the electrode plate. For example, the adjacent surfaces of the first pattern area 41 and the second pattern area 42 may be formed with a plurality of continuous and mutually matching bends to maximize the area of ​​the electrode plate.

[0038] In this embodiment, by forming capacitive coupling between the first pattern area 41 and the second pattern area 42, the transmission zero-point energy can be concentrated on the left side of the frequency domain, thereby making the attenuation slope outside the band larger and the suppression effect better improved.

[0039] It should be noted that, similarly, the metal pattern 40 also includes a third pattern area 43 surrounding the sixth resonant cavity 26 and a fourth pattern area 44 surrounding the seventh resonant cavity 27; wherein a second gap 52 is formed between the third pattern area 43 and the fourth pattern area 44, so that the third pattern area 43 and the fourth pattern area 44 also form a capacitive coupling.

[0040] like Figure 5 As shown, compared with the prior art 1, at the first zero point, the suppression effect of this embodiment is Figure 1 The -40dB is increased to -50dB, and the suppression of the second zero is increased by Figure 2 The -50dB increases to Figure 6 -60dB. In terms of attenuation slope, Figure 2 The 100~300MHz is reduced to Figure 6 100~200MHz.

[0041] In summary, the hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern provided in this embodiment forms a capacitive coupling between the first pattern area 41 and the second pattern area 42, and between the third pattern area 43 and the fourth pattern area 44 by setting the first gap 51 and the second gap 52, so that the transmission zero-point energy of the bandpass filter is concentrated on the left side of the frequency domain, thereby making the attenuation slope outside the band larger and the suppression effect better improved.

[0042] Preferably, in this embodiment, a first input / output electrode 61 and a second input / output electrode 62 are further included, and the first input / output electrode 61 and the second input / output electrode 62 are disposed on the first surface 11 and are respectively connected to each resonant cavity. The first input / output electrode 61 and the second input / output electrode 62 can be covered on the ceramic substrate 10 by screen printing, or by high-temperature metallization of silver electrodes to connect the silver electrodes to the ceramic substrate 10, or by laser etching or the like to cover the outer surface of the ceramic substrate 10 with a conductive metal layer.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern, comprising a ceramic substrate, wherein: The ceramic substrate comprises a first surface and a second surface opposite to the first surface, wherein a first resonant cavity, a second resonant cavity, a third resonant cavity, a fourth resonant cavity, a fifth resonant cavity, a sixth resonant cavity, a seventh resonant cavity, an eighth resonant cavity and a ninth resonant cavity are sequentially distributed along the length direction of the ceramic substrate between the first surface and the second surface; the first resonant cavity, the third resonant cavity, the fourth resonant cavity, the fifth resonant cavity, the sixth resonant cavity, the seventh resonant cavity and the ninth resonant cavity are half-wavelength resonant cavities, and the second resonant cavity and the eighth resonant cavity are quarter-wavelength resonant cavities; A metal pattern is arranged on the first surface, characterized in that the metal pattern includes a first pattern area surrounding the third resonant cavity and a second pattern area surrounding the fourth resonant cavity; wherein a first gap is formed between the first pattern area and the second pattern area, so that the first pattern area and the second pattern area form a capacitive coupling under the separation of the first gap; the metal pattern also includes a third pattern area surrounding the sixth resonant cavity and a fourth pattern area surrounding the seventh resonant cavity; wherein a second gap is formed between the third pattern area and the fourth pattern area.

2. The hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern according to claim 1, characterized in that: The first gap and the second gap have the same shape and are symmetrical with respect to the fifth resonant cavity located in the middle.

3. The hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern according to claim 1, characterized in that: The adjacent surfaces of the first pattern area and the second pattern area are twisted regularly or irregularly to equivalently increase the area of ​​the electrode plate.

4. The hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern according to claim 3, characterized in that: A plurality of curved portions are formed on adjacent surfaces of the first pattern area and the second pattern area.

5. The hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern according to claim 1, characterized in that: The second resonant cavity, the third resonant cavity, the fourth resonant cavity, the fifth resonant cavity, the sixth resonant cavity, the seventh resonant cavity, and the eighth resonant cavity are arranged at the same height on the ceramic substrate and are approximately located at the center of the first surface of the ceramic substrate; the first resonant cavity and the ninth resonant cavity are arranged at the same height on the ceramic substrate, and the height of the first resonant cavity is slightly lower than the height of the second resonant cavity.

6. The hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern according to claim 1, characterized in that: The first resonant cavity and the ninth resonant cavity both include a coaxial first section hole and a second section hole, the second section hole is close to the first surface, the ratio of the diameters of the first section hole and the second section hole is 1:1.1 to 1:2.5, and the ratio of the lengths of the first section hole and the second section hole is 1:1 to 1:1.

5.

7. The hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern according to claim 6, characterized in that: The first resonant cavity and the ninth resonant cavity are holes of equal diameter.

8. The hybrid different-wavelength resonant bandpass filter with a capacitively coupled metal pattern according to claim 1, characterized in that: It also includes input / output electrodes, which are electrically connected to each resonant cavity through the metal pattern.

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