A terahertz waveguide filter based on hybrid-coupled structure

Abstract

The utility model relates to a kind of terahertz waveguide filters based on mixed coupling structure, comprising: first load and second load;First resonant cavity and second resonant cavity;First coupling resonant window, second coupling resonant window and third coupling resonant window. First coupling resonant window, second coupling resonant window and third coupling resonant window are used to realize mixed coupling, so that filter forms passband by direct coupling path, and by the bypass coupling between first coupling resonant window and second coupling resonant window, and between second coupling resonant window and third coupling resonant window, each introduce a transmission zero point on the both sides of passband. The utility model wide frequency band: 3dB bandwidth is 270-305GHz, relative bandwidth is 12.1%;High return loss: return loss in passband is better than-15dB;Additional introduce two zero points, greatly improve out-of-band rejection.

Description

Technical Field

[0001] This utility model relates to the technical field of terahertz waveguide filters, and in particular to a terahertz waveguide filter based on a hybrid coupling structure. Background Technology

[0002] Terahertz waves (0.1-10THz) have enormous potential in fields such as communication (e.g., 6G), imaging, and security detection due to their high bandwidth and strong directivity. Filters are crucial and indispensable in all these fields. As frequency selective devices, filters are primarily used to select frequency signals, that is, to allow useful signals to pass while filtering out interference signals.

[0003] However, traditional filters face the following problems in the terahertz band: 1. Insufficient out-of-band suppression: Traditional designs (such as TE101 single-mode resonator cascade) rely on horizontal coupling and only support TE10 transmission mode. They cannot introduce additional resonant points or transmission zeros, resulting in insufficient stopband suppression. Furthermore, increasing the order will sacrifice size and insertion loss.

[0004] 2. Inflexible transmission zero control: The transmission zero position of the dual-mode resonant cavity is strongly correlated with the passband frequency, making it difficult to adjust flexibly.

[0005] 3. Balancing high suppression with miniaturization: While increasing the order or number of resonant cavities can improve suppression performance, it will lead to an increase in device size and losses.

[0006] Therefore, the key technology is to excite higher-order modes (such as TM110 and TM120) through structural innovation (such as vertically coupled cavity and magnetically coupled cavity) without adding an extra resonant cavity, and to generate multiple transmission zeros by utilizing the phase cancellation effect.

[0007] In view of the above-mentioned shortcomings, the designer actively researched and innovated in order to create a terahertz waveguide filter based on a hybrid coupling structure, making it more valuable for industrial applications. Utility Model Content

[0008] To address the aforementioned technical problems, the purpose of this invention is to provide a terahertz waveguide filter based on a hybrid coupling structure.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A terahertz waveguide filter based on a hybrid coupling structure includes: First load and second load; First resonant cavity and second resonant cavity; First coupled resonant window, second coupled resonant window and third coupled resonant window; The first load is coupled to the first resonant cavity through the first coupling resonant window; The first resonant cavity is coupled to the second resonant cavity through the second coupling resonant window; The second resonant cavity is coupled to the second load through a third coupling resonant window; The first, second, and third coupled resonant windows are all used to achieve hybrid coupling, so that the filter forms a passband through a direct coupling path, and introduces a transmission zero on each side of the passband through bypass coupling between the first and second coupled resonant windows and between the second and third coupled resonant windows.

[0010] As a further improvement of this utility model, the first load is an input port and the second load is an output port.

[0011] As a further improvement of this utility model, both the first load and the second load are standard WR-3.4 waveguides.

[0012] As a further improvement of this utility model, the first coupling resonant window, the second coupling resonant window and the third coupling resonant window are all rectangular diaphragms.

[0013] As a further improvement of this utility model, the rectangular structure diaphragm is composed of a sensitive diaphragm.

[0014] As a further improvement of this invention, the filter has a 3dB bandwidth of 270–305 GHz and a relative bandwidth of 12.1%.

[0015] By means of the above solution, this utility model has at least the following advantages: 1. Wideband: 3dB bandwidth is 270-305GHz, with a relative bandwidth of 12.1%; 2. High return loss: The return loss within the passband is better than -15dB; 3. Two additional zeros are introduced, significantly improving out-of-band suppression; 4. Compact structure and easy to process.

[0016] The above description is only an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, the following are the preferred embodiments of this utility model and are described in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a terahertz waveguide filter based on a hybrid coupling structure according to this utility model; Figure 2 This is a schematic diagram of the filter topology of this utility model; Figure 3 This is a schematic diagram of the simulation results of the filter of this utility model.

[0019] The meanings of the labels in the figures are as follows.

[0020] First load S, second load L, first resonant cavity R1, second resonant cavity R2, first coupling resonant window T1, second coupling resonant window T2, and third coupling resonant window T3. Detailed Implementation

[0021] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit its scope.

[0022] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] The first embodiment of this utility model: This embodiment relates to the design of a terahertz waveguide filter based on a hybrid coupling structure. Specifically, the coupling between different resonant cavities is not based on traditional electrical or magnetic coupling structures, but on a hybrid coupling method. Direct coupling forms the passband, and bypass coupling forms the transmission zero, thereby improving out-of-band selectivity and ultimately realizing a terahertz waveguide filter based on a hybrid coupling structure.

[0024] like Figures 1-3 As shown, a terahertz waveguide filter based on a hybrid coupling structure in this embodiment includes: The first load S (input port) and the second load L (output port) are both standard WR-3.4 waveguides; At least two resonant cavities (first resonant cavity R1 and second resonant cavity R2); At least three coupling resonant windows (first coupling resonant window T1, second coupling resonant window T2, and third coupling resonant window T3) are used to achieve hybrid coupling; The resonant window and the coupled resonant window are connected by a combination of direct coupling and bypass coupling.

[0025] Specifically, The first load S is coupled to the first resonant cavity R1 through the first coupling resonant window T1; the first resonant cavity R1 is coupled to the second resonant cavity R2 through the second coupling resonant window T2; and the second resonant cavity R2 is coupled to the second load L through the third coupling resonant window T3. The first coupling resonant window T1, the second coupling resonant window T2, and the third coupling resonant window T3 are all used to achieve hybrid coupling, so that the filter forms a passband through the direct coupling path, and introduces a transmission zero on each side of the passband through the bypass coupling between the first coupling resonant window T1 and the second coupling resonant window T2, and between the second coupling resonant window T2 and the third coupling resonant window T3.

[0026] The first coupling resonant window T1, the second coupling resonant window T2, and the third coupling resonant window T3 are all rectangular diaphragms, which are composed of inductive diaphragms.

[0027] The filter has a 3dB bandwidth of 270–305 GHz and a relative bandwidth of 12.1%.

[0028] A brief description of the working principle of this embodiment: This filter is a terahertz filter that achieves a hybrid coupling structure through a resonant window diaphragm and realizes a quasi-elliptic response. Compared with traditional magnetic field coupling or electric field coupling, the hybrid coupling structure realized through the resonant window diaphragm is equivalent to adding a diaphragm to both the wide and narrow sides of the waveguide cavity at the same time, increasing the electric and magnetic field densities simultaneously, and possessing the characteristics of parallel resonance of capacitor and inductor.

[0029] Meanwhile, by using bypass coupling between the first coupled resonant window T1 and the second coupled resonant window T2, and between the second coupled resonant window T2 and the third coupled resonant window T3, a transmission zero is introduced on each side of the passband, which greatly improves the passband selectivity of the filter.

[0030] Meanwhile, to facilitate design and manufacturing, the filter has a chamfer radius of 0.1mm.

[0031] This embodiment improves the coupling structure and ultimately realizes a high-performance terahertz filter through a hybrid coupling structure, proposing a high-performance terahertz filter scheme with a 300GHz, miniaturized structure, high return loss, high out-of-band rejection, and easy fabrication.

[0032] The second embodiment of this utility model: like Figure 1 and Figure 2 As shown, this embodiment provides a terahertz waveguide filter based on a hybrid coupling structure, specifically a fixed-frequency filter operating at a center frequency of 300 GHz.

[0033] Cavity structure: The filter body is a metal cavity based on the standard WR-3.4 waveguide. The whole is made of two parts, upper and lower, through precision milling. The material can be oxygen-free copper or aluminum, etc., and the surface is gold-plated to reduce conductor loss.

[0034] The resonant unit contains two main resonant cavities (first resonant cavity R1 and second resonant cavity R2) and three resonant window diaphragms as coupling structures (first coupling resonant window T1, second coupling resonant window T2, and third coupling resonant window T3). The dimensions of the first resonant cavity R1 and the second resonant cavity R2 are designed to resonate near their operating frequencies.

[0035] Coupled structure: Direct coupling: The input port (first load S) is coupled to the first resonant cavity R1 through the first coupling resonant window T1; the first resonant cavity R1 is coupled to the second resonant cavity R2 through the second coupling resonant window T2; the second resonant cavity R2 is coupled to the output port (second load L) through the third coupling resonant window T3. These three constitute the main path of signal transmission.

[0036] Bypass Coupling: Simultaneously, the input port (first load S) also has a certain field coupling with the second coupling resonant window T2 through the first coupling resonant window T1, forming a bypass path that bypasses the first resonant cavity R1. Similarly, there is also bypass coupling between the second coupling resonant window T2 and the third coupling resonant window T3, forming a path that bypasses the second resonant cavity R2. These two bypass paths are key to generating the transmission zero.

[0037] Process features: All internal sharp edges are designed with a 0.1 mm chamfer, which avoids the difficulties in processing and the risk of breakdown caused by high electric field concentration, and is more in line with actual processing capabilities.

[0038] The working process of this embodiment: Signal input: Terahertz signal is fed from the standard WR-3.4 input port (first load S).

[0039] Main path transmission and resonance: Most signals are transmitted through the main path (first load S → first coupled resonant window T1 → first resonant cavity R1 → second coupled resonant window T2 → second resonant cavity R2 → third coupled resonant window T3 → second load L). When the signal frequency is close to the inherent resonant frequencies of the first resonant cavity R1 and the second resonant cavity R2 (i.e., passband 270-305GHz), the signal resonates and passes through efficiently, forming the passband.

[0040] Bypass coupling and phase cancellation: A small portion of the signal is transmitted through two bypass coupling paths (such as first load S → first coupling resonant window T1 → second coupling resonant window T2 → third coupling resonant window T3 → second load L).

[0041] At a specific frequency point near the passband (such as 280 GHz and 315 GHz), the signal transmitted through the main path and the signal transmitted through the bypass path will be exactly 180 degrees out of phase and approximately equal in amplitude when they reach the output port due to the difference in path length and coupling phase.

[0042] like Figure 3 According to the principle of electromagnetic wave interference, the two signals undergo destructive interference, that is, they cancel each other out, resulting in the output signal energy at that frequency point being almost zero, which is represented by a steep transmission zero point on the S21 curve.

[0043] Signal output: Signals within the passband are efficiently selected and output through the output port; signals outside the passband, especially those near the transmission zero frequency, are greatly suppressed.

[0044] Brief description of the advantages of this embodiment: High out-of-band selectivity: The two transmission zeros are adjacent to both sides of the passband (e.g., Figure 3 As shown in the figure, this makes the out-of-band attenuation curve of the filter extremely steep, which can effectively suppress interference from adjacent channels and improve frequency selectivity.

[0045] High performance and miniaturization are balanced: out-of-band rejection levels that typically require higher-order (more resonant cavities) filters are achieved using only two resonant cavities. The structure is very compact, reducing device size and insertion loss.

[0046] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0047] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0048] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A terahertz waveguide filter based on a hybrid coupling structure, characterized in that, include: First load (S) and second load (L); First resonant cavity (R1) and second resonant cavity (R2); First coupling resonant window (T1), second coupling resonant window (T2), and third coupling resonant window (T3); The first load (S) is coupled to the first resonant cavity (R1) through the first coupling resonant window (T1); The first resonant cavity (R1) is coupled to the second resonant cavity (R2) through the second coupling resonant window (T2); The second resonant cavity (R2) is coupled to the second load (L) through the third coupling resonant window (T3); The first coupling resonant window (T1), the second coupling resonant window (T2), and the third coupling resonant window (T3) are all used to achieve hybrid coupling, so that the filter forms a passband through a direct coupling path, and introduces a transmission zero on each side of the passband through bypass coupling between the first coupling resonant window (T1) and the second coupling resonant window (T2), and between the second coupling resonant window (T2) and the third coupling resonant window (T3).

2. A terahertz waveguide filter based on a hybrid coupling structure as described in claim 1, characterized in that, The first load (S) is an input port, and the second load (L) is an output port.

3. A terahertz waveguide filter based on a hybrid coupling structure as described in claim 1, characterized in that, Both the first load (S) and the second load (L) are standard WR-3.4 waveguides.

4. A terahertz waveguide filter based on a hybrid coupling structure as described in claim 1, characterized in that, The first coupled resonant window (T1), the second coupled resonant window (T2), and the third coupled resonant window (T3) are all rectangular diaphragms.

5. A terahertz waveguide filter based on a hybrid coupling structure as described in claim 4, characterized in that, The rectangular diaphragm is composed of a sensory diaphragm.

6. A terahertz waveguide filter based on a hybrid coupling structure as described in claim 1, characterized in that, The filter has a 3dB bandwidth of 270–305 GHz and a relative bandwidth of 12.1%.

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