Ku to K band microstrip directional coupler

Abstract

The present invention provides a Ku-to-K band microstrip directional coupler, comprising: a straight-through microstrip line; and a coupling microstrip line spaced apart from the straight-through microstrip line. The coupling microstrip line comprises two chamfered microstrip lines, a middle microstrip line, and two resonant units. The two chamfered microstrip lines are symmetrically spaced apart on either side of the middle microstrip line, and the two resonant units are symmetrically positioned on either side of the middle microstrip line and located between the corresponding chamfered microstrip lines and the middle microstrip line. By introducing the resonant units into the circuit, the bandwidth of the coupler is expanded while maintaining the same overall dimensions, thereby improving the in-band flatness of the coupling.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a Ku to K band microstrip directional coupler. Background Art

[0002] Microstrip directional couplers are microwave passive devices that are directional and can distribute microwave signal power in a specific ratio. In microwave solid-state circuits, directional couplers are one of the most widely used microwave components and are required in various microwave transceiver systems.

[0003] Traditional microstrip directional coupler designs generally utilize direct coupling. When two microstrip lines are brought close together, electromagnetic energy is coupled from one line to the other. Port 1 is the input port, Port 2 is the through port, Port 3 is the coupled port, and Port 4 is the isolated port. The coupled line length is 1 / 4 wavelength of the center frequency. This type of directional coupler offers simple construction, excellent performance, and ease of fabrication, making it widely used. However, due to the quarter-wavelength length of the coupled line, a single-section directional coupler is limited in bandwidth. To expand the bandwidth, a multi-section design is typically used.

[0004] With the development of modern materials technology and processing technology, directional couplers are developing towards broadband, miniaturization, and integration. In particular, for broadband microwave systems, the requirements for the bandwidth and in-band flatness of the directional coupler are becoming increasingly stringent. Therefore, designing directional couplers with broadband and high in-band flatness is necessary to meet the application of broadband microwave systems and is also the future development trend of directional couplers. Summary of the Invention

[0005] In view of this, embodiments of the present specification provide a Ku-to-K band microstrip directional coupler to achieve the purpose of expanding the operating bandwidth of the directional coupler.

[0006] The embodiments of this specification provide the following technical solutions: A Ku-to-K band microstrip directional coupler, comprising: a straight-through microstrip line; a coupled microstrip line, spaced apart from the straight-through microstrip line, the coupled microstrip line comprising two chamfered microstrip lines, an intermediate microstrip line, and two resonant units, the two chamfered microstrip lines being symmetrically spaced apart on both sides of the intermediate microstrip line, the two resonant units being symmetrically spaced on both sides of the intermediate microstrip line and located between the corresponding chamfered microstrip lines and the intermediate microstrip line.

[0007] Furthermore, each resonant unit includes an upper high-impedance line and a lower high-impedance line, and the upper high-impedance line and the lower high-impedance line are arranged in parallel and spaced apart.

[0008] Furthermore, one end of the upper high-impedance line is connected to the adjacent chamfered microstrip line, and the other end of the upper high-impedance line is spaced apart from the middle microstrip line; one end of the lower high-impedance line is fixedly connected to the middle microstrip line, and the other end of the lower high-impedance line is flush with the inner side of the adjacent chamfered microstrip line.

[0009] Furthermore, the spacing distance between the upper high-impedance line and the lower high-impedance line is 0.1 mm to 0.2 mm.

[0010] Furthermore, the distance between the other end of the upper high-impedance line and the middle microstrip line is 0.1 mm to 0.2 mm.

[0011] Furthermore, the spacing distance between the lower high-impedance line and the through microstrip line is 0.7 mm to 0.9 mm.

[0012] Compared with the prior art, the beneficial effects achieved by at least one of the above-mentioned technical solutions adopted in the embodiments of this specification include at least the following: by introducing a resonant unit into the circuit, the bandwidth of the coupler is expanded while the overall size of the coupler remains the same, thereby achieving the purpose of improving the in-band flatness of the coupling degree. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0014] Figure 1 It is a structural diagram of an embodiment of the present invention;

[0015] Figure 2 This is a comparison chart of the S-parameter curves of a conventional microstrip direct-coupled directional coupler and this embodiment;

[0016] Figure 3 This is a comparison chart of the insertion loss curves of the traditional microstrip direct-coupled directional coupler and the through-end of this embodiment;

[0017] Figure 4 This is a comparison diagram of the coupling degree curves of the coupling end of a traditional microstrip direct-coupled directional coupler and this embodiment.

[0018] Reference numerals in the figure: 1, chamfered microstrip line; 2, resonant unit; 21, upper high-impedance line; 22, lower high-impedance line; 4, middle microstrip line; 15, straight-through microstrip line. DETAILED DESCRIPTION

[0019] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0020] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0021] like Figure 1 As shown, an embodiment of the present invention provides a Ku-to-K band microstrip directional coupler, comprising: a straight-through microstrip line 15 and a coupled microstrip line. The coupled microstrip line is spaced apart from the straight-through microstrip line 15. The coupled microstrip line comprises two chamfered microstrip lines 1, an intermediate microstrip line 4, and two resonant units 2. The two chamfered microstrip lines 1 are symmetrically spaced apart on either side of the intermediate microstrip line 4. The two resonant units 2 are symmetrically arranged on either side of the intermediate microstrip line 4 and located between the corresponding chamfered microstrip lines 1 and the intermediate microstrip line 4.

[0022] By introducing a resonant unit into the circuit, the bandwidth of the coupler is expanded while keeping the overall size the same, thereby achieving the purpose of improving the in-band flatness of the coupling degree.

[0023] It should be noted that the characteristic impedances of the straight-through microstrip line 15 , the chamfered microstrip line 1 , and the middle microstrip line 4 are all 50Ω.

[0024] Each resonant unit 2 includes an upper high-impedance line 21 and a lower high-impedance line 22, which are arranged in parallel and spaced apart. One end of the upper high-impedance line 21 is connected to the adjacent chamfered microstrip line 1, and the other end is spaced apart from the middle microstrip line 4. One end of the lower high-impedance line 22 is fixedly connected to the middle microstrip line 4, and the other end of the lower high-impedance line 22 is flush with the inner side of the adjacent chamfered microstrip line 1. The upper and lower high-impedance lines 21, 22 form a parallel coupled line structure, which effectively expands the bandwidth of the coupler.

[0025] Specifically, the spacing between the upper high-impedance line 21 and the lower high-impedance line 22 is 0.1 mm to 0.2 mm. In a preferred embodiment, the spacing between the upper high-impedance line 21 and the lower high-impedance line 22 is 0.1 mm. Setting the spacing between the upper high-impedance line 21 and the lower high-impedance line 22 within the above distance range can significantly improve the in-band flatness of the coupling degree, and the spacing between the upper high-impedance line 21 and the lower high-impedance line 22 is 0.1 mm, which reaches the optimal value.

[0026] Furthermore, the distance between the other end of the upper high-impedance line 21 and the middle microstrip line 4 is 0.1 mm to 0.2 mm. In a preferred embodiment, the distance between the other end of the upper high-impedance line 21 and the middle microstrip line 4 is 0.1 mm.

[0027] Furthermore, the spacing between the lower high-impedance line 22 and the straight-through microstrip line 15 is 0.7 mm to 0.9 mm. In a preferred embodiment, the spacing between the lower high-impedance line 22 and the straight-through microstrip line 15 is 0.8 mm, which is larger than the conventional spacing of 0.6 mm. This allows this embodiment to achieve the purpose of improving the in-band flatness of the coupling degree.

[0028] Compared with the traditional microstrip direct-coupled directional coupler, the circuit of this embodiment has obvious ultra-wideband characteristics while having the same overall size, and the in-band flatness of the coupling degree is greatly improved. Figures 2 to 4 A comparison chart between the conventional microstrip direct-coupled directional coupler and this embodiment is shown in the figure. Figures 2 to 4 Above are the parameters of the microstrip direct-coupled directional coupler. Figures 2 to 4 Below are the parameters of the embodiment of the present invention, Figures 2 to 4 It can be seen that the coupling flatness of a conventional microstrip direct-coupled directional coupler is greater than 7dB within the frequency range of 12GHz to 26.5GHz, with a relatively steep flatness. In the 12GHz to 26.5GHz frequency range, the embodiment of the present invention achieves insertion loss of less than 0.23dB at the through-end, coupling of 16±0.5dB at the coupled-end, coupling flatness of less than 1dB, isolation greater than 20dB, and return loss greater than 37dB. The directional coupler has an absolute bandwidth of 14.5GHz and a relative bandwidth of 75.3%.

[0029] The detailed S parameter comparison is shown in the table below. As can be seen from Table 1, the microstrip directional coupler of the present invention has advantages over the traditional type in terms of insertion loss, coupling flatness within the band and return loss.

[0030] Table 1 Comparison of S parameters of two directional couplers

[0031]

[0032] At the same time, the present invention has the advantages of strong versatility, simple structure, easy processing and mass production, and can be widely used in Ku to K full-band microwave solid-state circuits.

[0033] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, substitutions of equivalent components, or equivalent changes and modifications made within the scope of patent protection, should still fall within the scope of this patent. Furthermore, the technical features of the present invention may be freely combined with one another, with other technical solutions, and with other technical solutions.

Claims

1. A Ku-to-K band microstrip directional coupler, characterized in that: include: straight-through microstrip line (15); A coupled microstrip line is arranged at intervals from a straight-through microstrip line (15), wherein the coupled microstrip line comprises two chamfered microstrip lines (1), an intermediate microstrip line (4), and two resonant units (2), wherein the two chamfered microstrip lines (1) are arranged symmetrically on both sides of the intermediate microstrip line (4), and the two resonant units (2) are symmetrically arranged on both sides of the intermediate microstrip line (4) and located between the corresponding chamfered microstrip lines (1) and the intermediate microstrip line (4); the Ku-to-K band microstrip directional coupler is characterized in that each resonant unit (2) comprises an upper high-impedance line (21) and a lower high-impedance line (22), and the upper high-impedance line (21) and the lower high-impedance line (22) are arranged in parallel and at intervals.

2. The Ku-to-K band microstrip directional coupler according to claim 1, wherein: One end of the upper high-impedance line (21) is connected to the adjacent chamfered microstrip line (1), and the other end of the upper high-impedance line (21) is spaced apart from the middle microstrip line (4); One end of the lower high-impedance line (22) is fixedly connected to the middle microstrip line (4), and the other end of the lower high-impedance line (22) is flush with the inner side of the adjacent chamfered microstrip line (1).

3. The Ku-to-K band microstrip directional coupler according to claim 2, wherein: The spacing distance between the upper high-impedance line (21) and the lower high-impedance line (22) is 0.1 mm to 0.2 mm.

4. The Ku-to-K band microstrip directional coupler according to claim 2, wherein: The distance between the other end of the upper high impedance line (21) and the middle microstrip line (4) is 0.1 mm to 0.2 mm.

5. The Ku-to-K band microstrip directional coupler according to claim 2, wherein: The spacing distance between the lower high impedance line (22) and the straight-through microstrip line (15) is 0.7 mm to 0.9 mm.

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