A dielectric waveguide filter with independently controllable dual transmission zeros

Abstract

The present invention relates to a dielectric waveguide filter with dual transmission zero points that are independently controllable. The dielectric waveguide resonator is a fifth-order dielectric waveguide resonator composed of five regular hexagonal dielectric waveguide resonators, including first to fifth resonators arranged in an M-type, a partition window for separating the two resonators is provided between the second resonator and the fourth resonator, and adjacent resonators are coupled through surface metallized coupling blind holes; the dielectric waveguide resonator has two independently controllable transmission zero points, the two transmission zero points are respectively located in the lower sideband and the upper sideband, and the lower sideband transmission zero point is adjusted by the coupling coefficient between the first resonator and the third resonator; the upper sideband transmission zero point is adjusted by the coupling coefficient between the third resonator and the fifth resonator. The two transmission zero points are independently controllable and do not interfere with each other, thereby improving the controllability of the stopband suppression performance. At the same time, compared with the existing similar dielectric waveguide filters, the present invention has better design flexibility.

Description

Technical Field

[0001] The present invention relates to the technical field of communication equipment components, and in particular to a dielectric waveguide filter with independently controllable dual transmission zero points. Background Art

[0002] With the development of wireless communication technology, people's demand for the growth of mobile communication data traffic is also growing. 5G communication is the most cutting-edge communication technology at present. Among them, multi-antenna MIMO technology is widely used. This technology will cause the number of channels to grow exponentially. Therefore, a large number of filters need to be integrated in the RF front end. The 5G communication system uses active antenna units. The antenna and the RF front end are directly connected, and the cable connection is cancelled. This makes the filter with small size, light weight, strong frequency selectivity and low in-band insertion loss become the microwave devices urgently needed at present. The dielectric waveguide filter is realized by metallizing the surface of the one-piece high dielectric constant and low loss dielectric ceramic structure, which can well meet the requirements of low loss, miniaturization and lightweight of 5G and future mobile communication systems. However, in practical applications, some frequency points / bands outside the filter band need to have greater suppression performance. For this reason, it is necessary to use cross-coupling technology to introduce two or more transmission zeros at these frequencies. By using cross-coupling technology to introduce two or more transmission zeros, the desired out-of-band suppression effect can be achieved without increasing the number of resonators while ensuring the in-band filtering performance. This is of great significance to maintaining the compactness of the filter and improving the performance of the filter. On the other hand, different communication standards or different communication channels may have different requirements for out-of-band suppression, so the transmission zero point of the filter needs to be adjusted accordingly according to different requirements, that is, it is also very meaningful that two or more transmission zero points of the filter are independently controllable.

[0003] The main disadvantage of the existing technology is that the transmission zero point is uncontrollable and multiple transmission zero points cannot be independently controlled, which limits its application space to a certain extent. With the rapid development of modern communication needs, the available spectrum resources are becoming increasingly tight, and the controllability of the filter stopband suppression performance is increasingly required, that is, there is a higher requirement for the independent controllability of the transmission zero point. Therefore, designing a bandpass filter with dual transmission zero points independently controllable is of great significance to controlling the stopband suppression performance of the filter.

[0004] Based on this, the invention proposes a dielectric waveguide filter with independently controllable dual transmission zero points, which has the advantages of miniaturization, low loss and independently controllable dual transmission zero points (ie, controllable suppression performance). Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies in the above-mentioned prior art. The present invention proposes a dielectric waveguide filter with independently controllable dual transmission zero points. The dielectric waveguide filter has the advantages of miniaturization, low loss and independently controllable dual transmission zero points, and the passband range of the designed embodiments can cover 3400MHz to 3500MHz (China Telecom's 5G main frequency band).

[0006] In order to achieve the purpose of the present invention, the present invention provides a dielectric waveguide filter with independently controllable dual transmission zeros, including a dielectric waveguide resonator with metallized surface, characterized in that: the dielectric waveguide resonator is a fifth-order dielectric waveguide resonator, including first to fifth resonators arranged in an M shape from the input end to the output end, a partition window for separating the two resonators is provided between the second resonator and the fourth resonator, and adjacent resonators are coupled through surface metallized coupling blind holes respectively; the dielectric waveguide resonator has two independently controllable transmission zeros, the two transmission zeros are respectively located in the lower sideband and the upper sideband, the lower sideband transmission zero is adjusted by the coupling coefficient between the first resonator and the third resonator; the upper sideband transmission zero is adjusted by the coupling coefficient between the third resonator and the fifth resonator.

[0007] The present invention proposes a dielectric waveguide filter with independently controllable dual transmission zeros. The filter has two transmission zeros, and the two transmission zeros are independently controllable. The two transmission zeros are located in the lower sideband and the upper sideband, respectively. The position of the lower sideband transmission zero is controlled by the coupling coefficient between the first resonator and the third resonator, and the position of the upper sideband transmission zero is controlled by the coupling coefficient between the third resonator and the fifth resonator. In this way, the dual transmission zeros are independently controllable.

[0008] Compared with the traditional dielectric waveguide filter, the present invention realizes that two transmission zero points are independently controllable and has better out-of-band suppression controllability. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention will be further described below in conjunction with the accompanying drawings;

[0010] Figure 1 It is a three-dimensional structural diagram of an independently controllable dielectric waveguide filter according to an embodiment of the present invention.

[0011] Figure 2 It is a coupling topology diagram of the independently controllable dielectric waveguide filter according to an embodiment of the present invention.

[0012] Figure 3 is a normalized coupling matrix of an embodiment of the present invention.

[0013] Figure 4 This is the conclusion of the theoretical and simulation comparison of the independently controllable dielectric waveguide filter in the embodiment of the present invention.

[0014] Figure 5 It is a graph showing the relationship between the coupling coefficient of the independently controllable dielectric waveguide filter and the depth of the coupling blind hole according to an embodiment of the present invention.

[0015] Figure 6 It is a schematic diagram of independent control of the transmission zero point on the left side of the passband of the independently controllable dielectric waveguide filter according to an embodiment of the present invention.

[0016] Figure 7 It is a schematic diagram of independent control of the transmission zero point on the right side of the passband of the independently controllable dielectric waveguide filter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0018] like Figure 1 As shown, the dielectric waveguide filter with independently controllable dual transmission zeros in this embodiment is a fifth-order dielectric waveguide resonator composed of five regular hexagonal dielectric waveguide resonators, and the surface of the fifth-order dielectric waveguide resonator is metallized (except for the first non-metallized ring 51 and the second first non-metallized ring 52). The fifth-order dielectric waveguide resonator includes a first resonator R1, a second resonator R2, a third resonator R3, a fourth resonator R4 and a fifth resonator R5 arranged in an M shape from the input end to the output end, and a partition window 6 for separating the two resonators is provided between the second resonator R2 and the fourth resonator R4. At the same time, the partition window 6 is also provided to prevent the dielectric waveguide filter from being severely deformed during the cooling process after firing, and its coupling coefficient is very small, and has little effect on the filter performance, which can be ignored.

[0019] The upper surface of each resonator is provided with a frequency adjustment blind hole for adjusting the resonant frequency. Specifically, the first resonator R1 is provided with a first frequency adjustment blind hole 11 with a metallized surface for adjusting the resonant frequency, the second resonator R2 is provided with a second frequency adjustment blind hole 12 with a metallized surface for adjusting the resonant frequency, the third resonator R3 is provided with a third frequency adjustment blind hole 13 with a metallized surface for adjusting the resonant frequency, the fourth resonator R4 is provided with a fourth frequency adjustment blind hole 14 with a metallized surface for adjusting the resonant frequency, and the fifth resonator R5 is provided with a fifth frequency adjustment blind hole 15 with a metallized surface for adjusting the resonant frequency.

[0020] Adjacent resonators are coupled through surface metallized coupling blind holes. Specifically, a first coupling blind hole 21 for adjusting the coupling coefficient between the first resonator R1 and the second resonator R2 is provided; a second coupling blind hole 22 for adjusting the coupling coefficient between the second resonator R2 and the third resonator R2 is provided; a third coupling blind hole 23 for adjusting the coupling coefficient between the third resonator R3 and the fourth resonator R4 is provided; a fourth coupling blind hole 24 for adjusting the coupling coefficient between the fourth resonator R4 and the fourth resonator R5 is provided; a fifth coupling blind hole 26 for adjusting the coupling coefficient between the first resonator R1 and the third resonator R3 is provided; and a sixth coupling blind hole 25 for adjusting the coupling coefficient between the third resonator R3 and the fifth resonator R5 is provided.

[0021] The dielectric waveguide resonator of this embodiment has two independently controllable transmission zeros, which are located in the lower sideband and the upper sideband respectively. The lower sideband transmission zero is adjusted by the coupling coefficient M13 between the first resonator R1 and the third resonator R3; the upper sideband transmission zero is adjusted by the coupling coefficient M35 between the third resonator R3 and the fifth resonator R5. The coupling coefficient M13 between the first resonator R1 and the third resonator R3 is adjusted by the fifth coupling blind hole 26; the coupling coefficient M35 between the third resonator R3 and the fifth resonator R5 is adjusted by the sixth coupling blind hole 25.

[0022] like Figure 1 As shown, five frequency adjustment blind holes and six coupling blind holes are all located on the upper surface of the dielectric waveguide filter; the lower surface of the first resonator R1 is provided with an input-end feeding blind hole 31 and an input-end feeding disc 41 connected to the input-end feeding blind hole 31, and a first non-metallic ring 51 is arranged outside the input-end feeding disc 41; the lower surface of the fifth resonator R5 is provided with an output-end feeding blind hole 32 and an output-end feeding disc 42 connected to the output-end feeding blind hole 32, and a second non-metallic ring 52 is arranged outside the output-end feeding disc 42.

[0023] Among the six coupling blind holes, there is one coupling blind hole, and the two resonators corresponding to it are capacitively coupled; the resonators corresponding to the other coupling blind holes are inductively coupled. In this embodiment, the first resonator R1 and the second resonator R2 are capacitively coupled, and the other adjacent resonators are inductively coupled.

[0024] The coupling topology of the dielectric waveguide filter with independently controllable dual transmission zeros in this embodiment is as follows: Figure 2 The coupled topology structure is designed to set two transmission zeros, and the two transmission zeros are independently controllable, and the two transmission zeros are determined by the coupling coefficient M13 between the first resonator R1 and the third resonator R3, and the coupling coefficient M35 between the third resonator R3 and the fifth resonator R5. Figure 2 The solid line in the middle represents that the corresponding coupling is inductive coupling, and the dotted line represents that the corresponding coupling is capacitive coupling.

[0025] Figure 2 The normalized coupling matrix corresponding to the coupling topology is as follows: Figure 3 The theoretical results corresponding to the normalized coupling matrix are compared with the filter simulation results, as shown in Figure 4 As shown. It can be seen that the simulation results are in good agreement with the theoretical results. The echo in the passband is greater than 20dB, the insertion loss is about -0.75dB, and the transmission zero point is at 3.36GHz and 3.54GHz. The coupling between the resonators of the present invention adopts electromagnetic hybrid coupling. The polarity and size of the coupling are changed by the depth of the blind hole. The relationship between the coupling coefficient and the depth of the coupling blind hole is shown in Figure 5 As shown, it can be seen that when the blind hole depth is less than 3mm, the coupling between the two cavities is inductive, and as the depth increases, the coupling coefficient increases; when the blind hole depth is greater than 3mm, the coupling polarity changes from inductive coupling to capacitive coupling, and as the depth continues to increase, the coupling coefficient decreases. In summary, when the depth of the coupling blind hole is shallow, the two resonant cavities are inductively coupled, but when the blind hole depth exceeds a certain value (usually half the height of the dielectric resonator), the coupling between the two resonant cavities will change from inductive to capacitive, and as the blind hole continues to deepen, the capacitive coupling coefficient gradually decreases after reaching a peak value. In this example, the depth of the first coupling blind hole 21 is greater than 1 / 2 of the height of the dielectric resonator, and the depths of the second coupling blind hole 22, the third coupling blind hole 23, the fourth coupling blind hole 24, the fifth coupling blind hole 26, and the sixth coupling blind hole 25 are less than 1 / 2 of the height of the dielectric resonator.

[0026] The transmission zeros of the present invention are independently controllable on both sides of the passband, such as Figure 6 and Figure 7 As shown: H6 is the depth of the fifth coupling blind hole 26, that is, the depth of the blind hole between the first resonator R1 and the third resonator R3. When H6 is larger, the frequency of the transmission zero point on the left side of the passband is higher, while the frequency of the transmission zero point on the right side of the passband remains unchanged, thereby realizing independent controllable transmission zero point on the left side of the passband; H5 is the depth of the sixth coupling blind hole 25, that is, the depth of the blind hole between the third resonator R3 and the fifth resonator R5. When H5 is larger, the frequency of the transmission zero point on the right side of the passband is smaller, while the frequency of the transmission zero point on the left side of the passband remains unchanged, thereby realizing independent controllable transmission zero point on the right side of the passband.

[0027] It can be seen from the above that the dual transmission zeros of the invention are fully independently controllable. The filter passband of the dielectric waveguide filter designed by the present invention covers 3400MHz to 3500MHz (China Telecom's 5G main frequency band), and it is highly feasible and practical. (The above simulation results are all computer simulation results)

[0028] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A dielectric waveguide filter with dual transmission zeros that are independently controllable, comprising a surface metallized dielectric waveguide resonator, characterized in that: The dielectric waveguide resonator is a fifth-order dielectric waveguide resonator, comprising first to fifth resonators (R1, R2, R3, R4, R5) arranged in an M shape from the input end to the output end, the first resonator (R1) is connected to the input end, the fifth resonator (R5) is connected to the output end, a partition window (6) for separating the two resonators is arranged between the second resonator (R2) and the fourth resonator (R4), the third resonator (R3) is coupled to the first resonator (R1) and the fifth resonator (R5) respectively, and adjacent resonators are coupled through surface metallized coupling blind holes; the dielectric waveguide resonator has two independently controllable transmission zero points, the two transmission zero points are respectively located in the lower sideband and the upper sideband, the lower sideband transmission zero point is adjusted by the coupling coefficient (M13) between the first resonator (R1) and the third resonator (R3); the upper sideband transmission zero point is adjusted by the coupling coefficient (M35) between the third resonator (R3) and the fifth resonator (R5); A first coupling blind hole (21) for adjusting the coupling coefficient between the first resonator (R1) and the second resonator (R2) is provided between the first resonator (R1) and the second resonator (R2); a second coupling blind hole (22) for adjusting the coupling coefficient between the second resonator (R2) and the third resonator (R3); a third coupling blind hole (23) for adjusting the coupling coefficient between the third resonator (R3) and the fourth resonator (R4); and a fourth coupling blind hole (24) for adjusting the coupling coefficient between the fourth resonator (R4) and the fourth resonator (R5); A fifth coupling blind hole (26) for adjusting the coupling coefficient between the first resonator (R1) and the third resonator (R3) is provided between the first resonator (R1) and the third resonator (R3); a sixth coupling blind hole (25) for adjusting the coupling coefficient between the third resonator (R3) and the fifth resonator (R5) is provided between the third resonator (R3) and the fifth resonator (R5); Among the six coupling blind holes (21, 22, 23, 24, 26, 25), there is one coupling blind hole, and the corresponding two resonators are capacitively coupled; the resonators corresponding to the remaining coupling blind holes are inductively coupled.

2. The dielectric waveguide filter with independently controllable dual transmission zeros according to claim 1, characterized in that: The first to fifth resonators (R1, R2, R3, R4, R5) are respectively provided with first to fifth frequency adjustment blind holes (11, 12, 13, 14, 15) with surface metallization for adjusting the resonance frequency.

3. The dielectric waveguide filter with independently controllable dual transmission zeros according to claim 2, characterized in that: The five frequency adjustment blind holes (11, 12, 13, 14, 15) and the six coupling blind holes (21, 22, 23, 24, 26, 25) are all located on the upper surface of the dielectric waveguide filter; the lower surface of the first resonator (R1) is provided with an input end feeding blind hole (31) and an input end feeding disc (41) connected to the input end feeding blind hole (31), and a first non-metallic circular ring (51) is provided outside the input end feeding disc (41); the lower surface of the fifth resonator (R5) is provided with an output end feeding blind hole (32) and an output end feeding disc (42) connected to the output end feeding blind hole (32), and a second non-metallic circular ring (52) is provided outside the output end feeding disc (42).

4. The dielectric waveguide filter with independently controllable dual transmission zeros according to claim 3, characterized in that: When the depth of the coupling blind hole between adjacent resonators is less than 1 / 2 of the height of the dielectric resonator, the adjacent resonators are inductively coupled; When the depth of the coupling blind hole between adjacent resonators is greater than 1 / 2 of the height of the dielectric resonator, the adjacent resonators are capacitively coupled.

5. The dielectric waveguide filter with independently controllable dual transmission zeros according to claim 4, characterized in that: The first resonator (R1) and the second resonator (R2) are capacitively coupled, and the other adjacent resonators are inductively coupled; the depth of the first coupling blind hole (21) is greater than 1 / 2 of the height of the dielectric resonator, and the depths of the second to sixth coupling blind holes (22, 23, 24, 26, 25) are less than 1 / 2 of the height of the dielectric resonator.

6. The dielectric waveguide filter with independently controllable dual transmission zeros according to claim 1, characterized in that: The dielectric waveguide filter is composed of five regular hexagonal dielectric waveguide resonators.

Images