A low profile dielectric resonator filter with wide stopband characteristics

Abstract

The application discloses a low-profile dielectric resonator filter with wide band characteristics. z 1δ Compared with the existing dielectric resonator filter, the low-profile dielectric resonator filter is mainly composed of two strip dielectric blocks loaded with a central rectangular slot and working in a TE1 mode, resonators formed by combining upper and lower substrates with partial hollowing, and a coupling feeding mode loaded with open-circuit branches, so that the dielectric resonator filter has the characteristics of low profile, wide band and easy integration.

Description

Technical Field

[0001] This invention relates to the field of microwave communication, and more particularly to a low-profile dielectric resonator filter with wide stopband characteristics. Background Technology

[0002] Dielectric resonators have become a research hotspot in recent years due to their superior characteristics such as high Q value, low manufacturing cost, temperature stability, low loss, and high design freedom. Wide-stopband filters, on the other hand, are widely used in microwave systems because of their outstanding suppression of high-frequency clutter interference. Therefore, combining wide-stopband performance with dielectric resonators in filters to construct dielectric resonator filters with wide-stopband characteristics has significant research value and importance.

[0003] Currently, there are three main methods for implementing wide-stopband dielectric resonator filters: The first method starts from the feed of the dielectric resonator, using differential feeding for mode selection to suppress some higher-order modes, but the appearance of out-of-band common-mode modes is unavoidable. The second method starts from the coupling of the dielectric resonator, using other types of resonators to couple with the dielectric resonator, achieving harmonic suppression through the frequency difference of their higher-order modes. However, combining two different types of resonators results in an excessively large filter size and complex structure. To avoid these problems, the third method starts from the dielectric resonator itself, hollowing out a cylindrical structure within the dielectric resonator to improve the separation of the dominant mode and higher-order modes, thus achieving wide-stopband suppression.

[0004] The wide-stopband dielectric resonator filters implemented using the methods described above are all achieved by loading a dielectric resonator in a metal cavity. Therefore, their profiles are relatively high, making them difficult to integrate with other PCB circuits, and their stopband bandwidth suppression is limited. Thus, it is particularly important to propose a low-profile dielectric resonator filter with wide stopband characteristics that is easy to integrate with other circuits. Summary of the Invention

[0005] Purpose of the invention: In view of the above-mentioned prior art, a low-profile dielectric resonator filter with wide stopband characteristics is proposed. While ensuring the low loss of the dielectric resonator filter, the profile height is reduced, the stopband bandwidth is extended, and the integration density is improved.

[0006] Technical solution: A low-profile dielectric resonator filter with wide stopband characteristics includes a first high dielectric constant dielectric substrate, a first low dielectric constant dielectric substrate and a second low dielectric constant dielectric substrate respectively disposed on the upper and lower surfaces of the first high dielectric constant dielectric substrate, and a second low dielectric constant dielectric substrate respectively disposed on the upper surface of the first low dielectric constant dielectric substrate and the lower surface of the second low dielectric constant dielectric substrate, and a metal ground is disposed on the outer surface of both layers of the second low dielectric constant dielectric substrate.

[0007] A cross-shaped air groove is formed on the first low dielectric constant substrate;

[0008] The first high dielectric constant dielectric substrate includes a first strip-shaped dielectric block and a second strip-shaped dielectric block arranged in parallel and spaced apart, and a rectangular groove is opened in the middle of the first strip-shaped dielectric block and the second strip-shaped dielectric block respectively.

[0009] A rectangular air slot is formed on the second low dielectric constant substrate. A first coupling feed line and a second coupling feed line are symmetrically arranged on both sides of the rectangular air slot. The first coupling feed line is connected to a first metal feed line, and the second coupling feed line is connected to a second metal feed line. The first metal feed line is connected to a first open-circuit stub, and the second metal feed line is connected to a second open-circuit stub.

[0010] The first and second strip dielectric blocks, together with the first low-dielectric-constant dielectric substrate, the second low-dielectric-constant dielectric substrate, the second low-dielectric-constant dielectric substrate, and the metal ground plane disposed on the upper and lower surfaces respectively, form two strip dielectric resonators; a signal is input from the first metal feed line, exciting the resonant mode in one of the strip dielectric resonators, and operating at TE1. z 1δ The signal is coupled to another strip dielectric resonator and then output through the second metal feed line.

[0011] Furthermore, the direction of the rectangular groove between the first and second strip-shaped medium blocks is consistent with the length direction of the medium blocks.

[0012] Furthermore, the rectangular groove is not less than one-quarter of the area of ​​the strip-shaped medium block.

[0013] Furthermore, the first coupling feed line and the second coupling feed line are arranged along the length direction of the rectangular air slot, the first metal feed line and the second metal feed line are perpendicular to the first coupling feed line and the second coupling feed line respectively, and the first open-circuit stub and the second open-circuit stub are arranged parallel to the first coupling feed line and the second coupling feed line.

[0014] Furthermore, on the first high dielectric constant dielectric substrate, the first strip dielectric block and the second strip dielectric block are respectively connected to the dielectric fixing strips on both sides through dielectric connecting strips on both sides.

[0015] Beneficial effects: 1. Compared with existing dielectric resonator filters, this structure operates at TE1. z 1δ The module is mainly composed of a strip-shaped dielectric block loaded with a central rectangular slot, combined with a resonator composed of partially hollowed-out substrates on the upper and lower layers. By using a coupling feeding method with loaded open stubs, a dielectric resonator filter with low profile, wide stopband and easy integration characteristics is realized.

[0016] 2. A single rectangular groove is introduced at the center of each of the two main dielectric blocks on a high dielectric constant substrate. The groove direction is consistent with the length direction of the dielectric block, and the groove size is relatively large. This is used to suppress the high-order mode with strong field strength at the center of the dielectric resonator and improve the out-of-band suppression level of the filter.

[0017] 3. The coupling feed line is parallel to the length direction of the high dielectric constant block and perpendicular to the input and output feed lines. At the same time, the loaded open stub is parallel to the coupling feed line, which effectively reduces assembly error while improving out-of-band suppression. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of the dielectric resonator filter of the present invention;

[0019] Figure 2 This is a top view of the low dielectric constant dielectric substrate in the dielectric resonator filter of the present invention;

[0020] Figure 3 This is a top view of the high dielectric constant dielectric substrate in the dielectric resonator filter of the present invention;

[0021] Figure 4 This is a top view of the low dielectric constant dielectric substrate in the dielectric resonator filter of the present invention;

[0022] Figure 5 The frequency response simulation diagram for the invented dielectric resonator filter. Detailed Implementation

[0023] The invention will now be further explained with reference to the accompanying drawings.

[0024] like Figure 1 As shown, a low-profile dielectric resonator filter with wide stopband characteristics includes a high dielectric constant dielectric substrate 4, a low dielectric constant dielectric substrate 3 and a low dielectric constant dielectric substrate 5 respectively disposed on the upper and lower surfaces of the high dielectric constant dielectric substrate 4, a low dielectric constant dielectric substrate 2 respectively disposed on the upper surface of the low dielectric constant dielectric substrate 3 and the lower surface of the low dielectric constant dielectric substrate 5, and a metal ground 1 disposed on the outer surface of both low dielectric constant dielectric substrates 2.

[0025] like Figure 2 As shown, a cross-shaped air groove 31 is formed on the low dielectric constant dielectric substrate 3.

[0026] like Figure 3As shown, strip-shaped dielectric blocks 41 and 42 are arranged parallel to each other in the middle of the high dielectric constant dielectric substrate 4. A rectangular groove 49 is formed in the middle of strip-shaped dielectric block 41, and a rectangular groove 410 is formed in the middle of strip-shaped dielectric block 42. The grooves 49 and 410 are oriented in the same direction as the length of the dielectric block, and the rectangular grooves are not less than one-quarter of the area of ​​the strip-shaped dielectric block. Strip-shaped dielectric blocks 41 and 42 are connected to dielectric fixing strips 47 and 48 on both sides via dielectric connecting strips 43-46 on both sides, respectively.

[0027] like Figure 4 As shown, a rectangular air slot 57 is formed on the second low dielectric constant substrate 5. Coupled feed lines 53 and 54 are symmetrically arranged on both sides of the rectangular air slot 57, and the coupled feed lines 53 and 54 are arranged along the length direction of the rectangular air slot 57. A metal feed line 51 is vertically connected to the coupled feed line 53, and a metal feed line 52 is vertically connected to the coupled feed line 54. An open-circuit stub 55 is vertically connected to the metal feed line 51, and an open-circuit stub 56 is vertically connected to the metal feed line 52.

[0028] In the above structure, strip dielectric blocks 41 and 42, together with low-dielectric-constant dielectric substrates 3, 5, and 2 on their upper and lower surfaces, and a metal ground 1, respectively, form two strip dielectric resonators. A signal is input from the metal feed line 51, exciting the resonant mode in one of the strip dielectric resonators, which then operates at TE1. z 1δ The signal is then coupled to another strip dielectric resonator and output through the metal feed line 52.

[0029] This dielectric resonator filter has three structural features: 1) A high-dielectric-constant dielectric substrate structure is loaded within a low-dielectric-constant dielectric substrate with loaded metal ground, which effectively confines energy between the two metal grounds, reducing the profile and facilitating integration with other PCB circuits; 2) The feeding method adopts coupled feeding with loaded open-circuit stubs, which can filter out some unwanted stray modes and avoid direct contact with the dielectric blocks during assembly, reducing processing errors and improving assembly accuracy; 3) By creating rectangular slots on two strip-shaped dielectric blocks on the high-dielectric-constant dielectric substrate, the higher-order modes of the dielectric resonator can be effectively suppressed, achieving good harmonic suppression. Therefore, this dielectric resonator filter has the characteristics of low profile, high integration, and wide stopband.

[0030] Specifically, when excited by a signal, the TE in the strip dielectric resonator can be excited. 11 z δ The mode, signal coupling excites the TE in another strip dielectric resonator. 11 zδ The rectangular slots 49 and 410 introduced at the center of the strip dielectric resonator can effectively suppress the high-order modes with strong field strength at the center of the dielectric resonator. Combined with the coupled feeding method of loading open-circuit stubs, the bandwidth of the stopband is effectively extended.

[0031] In this embodiment, the filter's physical dimensions are 50mm × 50mm × 5.366mm. The dielectric substrates 2 and 3 are RO4003C substrates with a dielectric constant of 3.55, a loss angle of 0.0027, and thicknesses of 0.203mm and 0.913mm, respectively. The dielectric substrate 4 has a dielectric constant of 89.5, a loss angle of 0.00015, and a thickness of 3mm. The center frequency is set to 4.57GHz, and the frequency response simulation diagram is shown below. Figure 5 As shown, the transmission zeros on both sides of the passband are located at 4.28 GHz and 4.808 GHz, respectively. Its 3-dB relative bandwidth is 0.99%, the minimum insertion loss is only 1.09 dB, and the out-of-band rejection level reaches 1.53f0 above 20 dB and 2.61f0 above 13.6 dB, achieving good out-of-band rejection performance.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-profile dielectric resonator filter with wide stopband characteristics, characterized in that, The first high dielectric constant dielectric substrate (4) is provided with a first low dielectric constant dielectric substrate (3) and a second low dielectric constant dielectric substrate (5) on its upper and lower surfaces, respectively. The upper surface of the first low dielectric constant dielectric substrate (3) and the lower surface of the second low dielectric constant dielectric substrate (5) are provided with a third low dielectric constant dielectric substrate (2), and the outer surfaces of the two third low dielectric constant dielectric substrates (2) are provided with a metal ground (1). A cross-shaped air groove (31) is formed on the first low dielectric constant dielectric substrate (3); The first high dielectric constant dielectric substrate (4) includes a first strip dielectric block (41) and a second strip dielectric block (42) arranged in parallel intervals. A rectangular groove is formed in the middle of the first strip dielectric block (41) and the second strip dielectric block (42). The direction of the rectangular groove in the middle of the first strip dielectric block (41) and the second strip dielectric block (42) is consistent with the length direction of the dielectric block. The rectangular groove is not less than one-quarter of the area of ​​the strip dielectric block. A rectangular air slot (57) is formed on the second low dielectric constant substrate (5). A first coupling feed line (53) and a second coupling feed line (54) are symmetrically arranged on both sides of the rectangular air slot (57). The first coupling feed line (53) is connected to the first metal feed line (51), and the second coupling feed line (54) is connected to the second metal feed line (52). The first metal feed line (51) is connected to the first open stub (55), and the second metal feed line (52) is connected to the second open stub (56). The first strip dielectric block (41) and the second strip dielectric block (42) respectively form two strip dielectric resonators with the first low dielectric constant dielectric substrate (3), the second low dielectric constant dielectric substrate (5), the third low dielectric constant dielectric substrate (2) and the metal ground (1) disposed on the upper and lower surfaces, respectively; the signal is input from the first metal feed line (51), exciting the resonant mode in one of the strip dielectric resonators, and it operates in The signal is coupled to another strip dielectric resonator and then output through the second metal feed line (52).

2. The low-profile dielectric resonator filter with wide stopband characteristics according to claim 1, characterized in that, The first coupling feed line (53) and the second coupling feed line (54) are arranged along the length direction of the rectangular air slot (57). The first metal feed line (51) and the second metal feed line (52) are perpendicular to the first coupling feed line (53) and the second coupling feed line (54) respectively. The first open-circuit stub (55) and the second open-circuit stub (56) are arranged parallel to the first coupling feed line (53) and the second coupling feed line (54).

3. The low-profile dielectric resonator filter with wide stopband characteristics according to claim 2, characterized in that, On the first high dielectric constant dielectric substrate (4), the first strip dielectric block (41) and the second strip dielectric block (42) are connected to the dielectric fixing strips (47-48) on both sides through dielectric connecting strips (43-46) on both sides respectively.

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