Ultra-wideband 3dB quadrature bridge

Abstract

The invention relates to the technical field of radio frequency and microwave, and discloses an ultra-wideband 3dB quadrature bridge which comprises five layers of printed board circuits. The five-layer printed board circuit comprises a first ground layer, a first signal layer, a second ground layer, a second signal layer and a third ground layer which are connected in sequence; the first stratum, the second stratum and the third stratum are electrically connected through the through holes, and a radio frequency ground loop is provided; the circuit layout of the first signal layer and the second signal layer is in mirror symmetry, orthogonal power division of input signals is achieved through suspension microstrip line coupling, and isolation setting of isolation ends is achieved in combination with a reverse electric field of the suspension microstrip line at an interface. According to the invention, the targets of low standing wave, low loss and miniaturization of the 3dB quadrature bridge in octave bandwidth can be realized.

Description

Technical Field

[0001] This invention relates to the field of radio frequency and microwave technology, and in particular to an ultra-wideband 3dB orthogonal bridge. Background Technology

[0002] The wideband 3dB quadrature bridge is a key component in electronic engineering, widely used in radio frequency (RF) and microwave systems. Its main function is to distribute input signals with equal amplitude and orthogonality to two output terminals, with no output at the isolation terminal. Alternatively, it can combine two input signals into a single output signal while maintaining constant signal amplitude (i.e., a 90-degree phase difference). This characteristic makes it crucial in various communication devices, radar systems, test instruments, and antenna arrays. In wireless communication systems, it is necessary to evenly distribute the power of one or more signal sources across multiple receivers or transmitters to improve system efficiency and performance. The wideband 3dB quadrature bridge achieves this by precisely controlling the phase and amplitude of the signal. In signal processing, the 3dB quadrature bridge is used to implement various functions, such as IQ modulation in analog and digital modems, and signal synthesis and separation in antenna arrays, radar systems, and satellite communications.

[0003] With the development of modern communication technology, there are higher requirements for the broadband, miniaturization, and high integration of equipment. The design of a broadband 3dB orthogonal bridge requires an operating bandwidth of at least one octave, while ensuring a low insertion loss and low VSWR design, and minimizing the circuit size. In other words, it provides high performance in a smaller size to meet the needs of various compact electronic devices. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes an ultra-wideband 3dB orthogonal bridge, specifically achieving low VSWR, low loss, and miniaturization within an octave bandwidth.

[0005] The technical solution adopted in this invention is as follows: An ultra-wideband 3dB orthogonal bridge includes a 5-layer printed circuit board, comprising a first ground layer, a first signal layer, a second ground layer, a second signal layer, and a third ground layer connected sequentially. The first ground layer, the second ground layer, and the third ground layer are electrically connected through vias to provide a radio frequency ground loop. The circuit layout of the first signal layer and the second signal layer is mirror symmetrical. Orthogonal power division of the input signal is achieved through suspension microstrip line coupling, and isolation of the isolation terminal is achieved by combining the reverse electric field of the suspension microstrip line at the interface.

[0006] Furthermore, the first signal layer includes a first stripline, a first conversion circuit, a first turning circuit, a first microstrip tapered line, a second conversion circuit, a coupling matching circuit, a third conversion circuit, a second tapered microstrip line, a second turning circuit, a fourth conversion circuit, and a second stripline connected in sequence.

[0007] Furthermore, the orthogonal power division of the input signal through suspended microstrip line coupling includes: The signal is fed into the first signal layer through the first port, then into the microstrip line after passing through the first stripline and the first conversion circuit of the first signal layer, and then into the first tapered microstrip line after passing through the first turning circuit to complete a 90-degree turn. Finally, it is fed into the suspended microstrip line, i.e. the coupling matching circuit, after passing through the second conversion circuit. The signal is coupled to the suspension microstrip line of the second signal layer by the coupling matching circuit and split into two orthogonal signals. The two orthogonal signals are transmitted orthogonally in the first signal layer and the second signal layer, respectively. One orthogonal signal is fed into the second tapered microstrip line along the third conversion circuit, and then fed into the second stripline through the second turning circuit and the fourth conversion circuit in sequence, and is output at the third port through the second stripline. The other orthogonal signal passes through the circuit symmetrical to the first signal layer in the second signal layer and is finally output at the second port.

[0008] Furthermore, the isolation setting of the isolation terminal by combining the reverse electric field of the suspended microstrip line at the interface includes: at the second conversion circuit, the electric field directions in the gradient microstrip lines of the first signal layer and the second signal layer are opposite, so that the two circuit layers are isolated from each other, thereby realizing the isolation from the first port to the fourth port.

[0009] Furthermore, the first signal layer, together with the first and second ground layers, forms a stripline, and the second signal layer, together with the second and third ground layers, forms a stripline, serving as an input / output interface.

[0010] Furthermore, the side of the first gradient microstrip line connected to the second conversion circuit gradually widens, and the side of the second gradient microstrip line connected to the third conversion circuit gradually widens.

[0011] Furthermore, the first and second graded microstrip lines adopt a dielectric microstrip transmission mode.

[0012] Furthermore, the operating frequency of the entire bridge can be adjusted by changing the width and length of the suspended microstrip line.

[0013] Furthermore, a rectangular through-hole is provided in the middle of the suspended microstrip line. By adjusting the length and width of the rectangular through-hole, the coupling coefficient of the suspended microstrip line can be adjusted, thereby adjusting the working bandwidth of the entire bridge.

[0014] Furthermore, the third ground layer is not copper-clad in the region below the suspended microstrip line. The input and output standing waves of the entire bridge can be adjusted by adjusting the width of the non-copper-clad region.

[0015] The beneficial effects of this invention are as follows: 1. This invention utilizes multilayer printed circuit boards to construct transmission lines such as striplines, tapered microstrip lines, and suspended microstrip lines, and designs an ultra-wideband orthogonal coupling and matching circuit. This invention achieves orthogonal power division of the input signal through loading slotted suspended microstrip line coupling, and combines a tapered microstrip line-to-suspended microstrip line conversion circuit with a reverse electric field at the interface to achieve isolation at the isolation terminal. This invention features octave band operating bandwidth, low VSWR, and small size.

[0016] 2. This invention uses a dielectric microstrip line to protect the microstrip circuit, eliminating the need for secondary encapsulation protection.

[0017] 3. The present invention has a simple structure, can be manufactured using current mature technology, and has good engineering feasibility.

[0018] 4. This invention provides a novel technical solution for the design of microwave and millimeter-wave 3dB orthogonal bridge circuits, and is applicable to the design of microwave and millimeter-wave power dividers, combiners, and phase distribution circuits. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the multilayer printed circuit board of an ultra-wideband 3dB orthogonal bridge according to Embodiment 1 of the present invention.

[0020] Figure 2 This is a schematic diagram of the overall circuit of an ultra-wideband 3dB orthogonal bridge according to Embodiment 1 of the present invention.

[0021] Figure 3 This is a schematic diagram of the first ground circuit in Embodiment 1 of the present invention.

[0022] Figure 4 This is a schematic diagram of the first signal layer circuit of Embodiment 1 of the present invention.

[0023] Figure 5 This is a schematic diagram of the second ground layer circuit in Embodiment 1 of the present invention.

[0024] Figure 6 This is a schematic diagram of the second signal layer circuit of Embodiment 1 of the present invention.

[0025] Figure 7 This is a schematic diagram of the third ground layer circuit in Embodiment 1 of the present invention.

[0026] Figure 8 This is a schematic diagram of the simulation results of Embodiment 2 of the present invention.

[0027] Reference numerals: 1-First stripline, 2-First conversion circuit, 3-First turning circuit, 4-First microstrip tapered line, 5-Second conversion circuit, 6-Coupled matching circuit, 7-Third conversion circuit, 8-Second tapered microstrip line, 9-Second turning circuit, 10-Fourth conversion circuit, 11-Second stripline. Detailed Implementation

[0028] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments are now described. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the invention, not all of them. 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.

[0029] Example 1 like Figure 1 As shown, this embodiment provides an ultra-wideband 3dB orthogonal bridge, including a 5-layer printed circuit board, which comprises a first ground layer, a first signal layer, a second ground layer, a second signal layer, and a third ground layer connected sequentially; as shown... Figure 3 , Figure 5 , Figure 7 As shown, the first, second, and third ground layers are electrically connected through vias to provide a radio frequency ground loop; as Figure 4 and Figure 6 As shown, the circuit layouts of the first and second signal layers are mirror-symmetrical. Orthogonal power division of the input signal is achieved through suspension microstrip line coupling, and isolation of the isolation terminal is achieved by combining the reverse electric field of the suspension microstrip line at the interface.

[0030] Preferably, such as Figure 2 As shown, the first signal layer includes a first stripline 1, a first conversion circuit 2, a first turning circuit 3, a first microstrip tapered line 4, a second conversion circuit 5, a coupling matching circuit 6, a third conversion circuit 7, a second tapered microstrip line 8, a second turning circuit 9, a fourth conversion circuit 10, and a second stripline 11 connected in sequence.

[0031] Preferably, orthogonal power division of the input signal is achieved through suspension microstrip line coupling, including: The signal is fed into the first signal layer through the first port P1, then fed into the microstrip line after passing through the first stripline 1 and the first conversion circuit 2 of the first signal layer, and then fed into the first tapered microstrip line 4 after completing a 90-degree turn through the first turning circuit 3, and then fed into the suspended microstrip line, i.e. the coupling matching circuit 6, after passing through the second conversion circuit 5. The signal is coupled to the suspended microstrip line of the second signal layer in the coupling matching circuit 6 and split into two orthogonal signals. The two orthogonal signals are transmitted orthogonally in the first signal layer and the second signal layer, respectively. One orthogonal signal is fed into the second tapered microstrip line 8 along the third conversion circuit 7, and then passes through the second turning circuit 9 and the fourth conversion circuit 10 in sequence to become the second stripline 11, and is output at the third port P3 through the second stripline 11. The other orthogonal signal passes through the circuit symmetrical to the first signal layer in the second signal layer and is finally output at the second port P2.

[0032] Preferably, the isolation of the isolation terminal is achieved by combining the reverse electric field of the suspended microstrip line at the interface, including: at the second conversion circuit 5, the electric field directions in the gradient microstrip lines of the first signal layer and the second signal layer are opposite, so that the two circuits are isolated from each other, thereby achieving isolation from the first port P1 to the fourth port P4.

[0033] Preferably, the first signal layer, the first formation, and the second formation form a strip, and the second signal layer, the second formation, and the third formation form a strip, serving as an input / output interface.

[0034] Preferably, the first gradient microstrip line 4 is gradually widened on one side connected to the second conversion circuit 5, and the second gradient microstrip line 8 is gradually widened on one side connected to the third conversion circuit 7.

[0035] Preferably, the first gradient microstrip line 4 and the second gradient microstrip line 8 adopt the dielectric microstrip line transmission mode. The entire bridge has no exposed circuitry, requires no secondary encapsulation, and is easy to integrate, install, and use.

[0036] Preferably, the operating frequency of the entire bridge can be adjusted by adjusting the width and length of the suspended microstrip line.

[0037] Preferably, a rectangular through-hole is provided in the middle of the suspended microstrip line. By adjusting the length and width of the rectangular through-hole, the coupling coefficient of the suspended microstrip line can be adjusted, thereby adjusting the working bandwidth of the entire bridge.

[0038] Preferably, the third stratum is not copper-clad in the region below the suspended microstrip line. The input and output standing waves of the entire bridge can be adjusted by adjusting the width of the non-copper-clad region.

[0039] Example 2 This embodiment is based on embodiment 1: This embodiment provides an ultra-wideband 3dB orthogonal bridge, employing LTCC multilayer printed circuit board technology, with a ceramic dielectric constant of 5.9 and a ceramic layer thickness of 0.1mm. In this embodiment, the stripline width is 0.18mm, the microstrip line width is 0.15mm, the gradient microstrip line width is widened from 0.15mm to 0.9mm, the suspended microstrip line width is 0.9mm and length is 0.9mm, the slot width in the middle of the suspended microstrip line is 0.1mm and length is 1.35mm, and the spacing between the two ground circuits on the left and right sides of the second ground layer is 2.15mm.

[0040] Specifically, the simulation results are as follows: Figure 8 As shown in the figure, within the 12.5GHz-25GHz bandwidth, the reflection coefficient of the ultra-wideband 3dB orthogonal bridge in this embodiment is better than -20dB, and the isolation is greater than 20dB.

[0041] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

[0042] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship conventionally placed when using this invention. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

Claims

1. An ultra-wideband 3dB orthogonal bridge, characterized in that, The circuit includes a 5-layer printed circuit board, comprising a first ground layer, a first signal layer, a second ground layer, a second signal layer, and a third ground layer connected in sequence. The first ground layer, the second ground layer, and the third ground layer are electrically connected through vias to provide a radio frequency ground loop. The circuit layout of the first signal layer and the second signal layer is mirror symmetrical. Orthogonal power division of the input signal is achieved through suspension microstrip line coupling, and isolation of the isolation terminal is achieved by combining the reverse electric field of the suspension microstrip line at the interface.

2. The ultra-wideband 3dB orthogonal bridge according to claim 1, characterized in that, The first signal layer includes a first stripline (1), a first conversion circuit (2), a first turning circuit (3), a first microstrip tapered line (4), a second conversion circuit (5), a coupling matching circuit (6), a third conversion circuit (7), a second tapered microstrip line (8), a second turning circuit (9), a fourth conversion circuit (10), and a second stripline (11) connected in sequence.

3. The ultra-wideband 3dB orthogonal bridge according to claim 2, characterized in that, The method of achieving orthogonal power division of the input signal through suspended microstrip line coupling includes: The signal is fed into the first signal layer through the first port (P1), and after passing through the first stripline (1) and the first conversion circuit (2) of the first signal layer, it is fed into the microstrip line. After passing through the first turning circuit (3) to complete a 90-degree turn, it is fed into the first tapered microstrip line (4). After passing through the second conversion circuit (5), it is fed into the suspended microstrip line, i.e. the coupling matching circuit (6). The signal is coupled to the suspension microstrip line of the second signal layer in the coupling matching circuit (6) and then split into two orthogonal signals. The two orthogonal signals are transmitted orthogonally in the first signal layer and the second signal layer, respectively. One orthogonal signal is fed into the second tapered microstrip line (8) along the third conversion circuit (7), and then fed into the second stripline (11) through the second turning circuit (9) and the fourth conversion circuit (10) in sequence. It is then output at the third port (P3) through the second stripline (11). The other orthogonal signal passes through the circuit symmetrical to the first signal layer in the second signal layer and is finally output at the second port (P2).

4. The ultra-wideband 3dB orthogonal bridge according to claim 3, characterized in that, The isolation setting of the isolation terminal by combining the reverse electric field of the suspended microstrip line at the interface includes: at the second conversion circuit (5), the electric field directions in the gradient microstrip lines of the first signal layer and the second signal layer are opposite, so that the two circuits are isolated from each other, thereby realizing the isolation from the first port (P1) to the fourth port (P4).

5. The ultra-wideband 3dB orthogonal bridge according to claim 3, characterized in that, The first signal layer, together with the first and second formations, forms a strip, and the second signal layer, together with the second and third formations, forms a strip, serving as an input / output interface.

6. The ultra-wideband 3dB orthogonal bridge according to claim 3, characterized in that, The first gradient microstrip line (4) is gradually widened on one side of the second conversion circuit (5), and the second gradient microstrip line (8) is gradually widened on one side of the third conversion circuit (7).

7. The ultra-wideband 3dB orthogonal bridge according to claim 3, characterized in that, The first gradient microstrip line (4) and the second gradient microstrip line (8) adopt the dielectric microstrip line transmission mode.

8. The ultra-wideband 3dB orthogonal bridge according to claim 3, characterized in that, The operating frequency of the entire bridge can be adjusted by changing the width and length of the suspended microstrip line.

9. The ultra-wideband 3dB orthogonal bridge according to claim 3, characterized in that, A rectangular through-hole is provided in the middle of the suspended microstrip line. By adjusting the length and width of the rectangular through-hole, the coupling coefficient of the suspended microstrip line can be adjusted, thereby adjusting the working bandwidth of the entire bridge.

10. The ultra-wideband 3dB orthogonal bridge according to claim 3, characterized in that, The third stratum is not copper-clad in the area below the suspended microstrip line. The input and output standing waves of the entire bridge can be adjusted by adjusting the width of the non-copper-clad area.

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