Multi-mode waveguide coupler

Abstract

The multimode waveguide coupler comprises a first rectangular waveguide and a second rectangular waveguide which are arranged in parallel, metal walls are arranged at the two ends, located in the length direction, between the first rectangular waveguide and the second rectangular waveguide, a metal column is arranged in the middle, located in the length direction, between the first rectangular waveguide and the second rectangular waveguide, and gaps are formed between the metal walls and the metal column. According to the multimode waveguide coupler capable of using the multifunctional feed network, 3dB coupling of multiple field modes is achieved through a single physical structure on the basis that the advantages of low loss and high power capacity of waveguides are reserved, and therefore the number of devices is effectively reduced, the feed network is simplified, and the integration level and the adaptive capacity of a millimeter wave system are improved.

Description

Technical Field

[0001] This invention relates to the field of passive devices, and more specifically to a multimode waveguide coupler that can be used with a multifunctional feed network. Background Technology

[0002] 3 dB couplers are key passive devices that distribute input signals equally to two output ports and provide specific phase relationships (such as 90° or 180°) through electromagnetic field coupling. They are widely used in millimeter-wave power distribution / combining, balanced mixers, Butler matrices, monopulse direction-finding systems, and feed networks for phased array antennas. In the millimeter-wave band, transmission loss increases significantly, placing higher demands on the efficiency and stability of passive devices. While traditional planar structures (such as microstrip lines and coplanar waveguides) are easy to integrate, their open-field structure easily generates large conductor losses, dielectric losses, and radiation losses at high frequencies, making them difficult to meet the requirements of high-performance systems. In contrast, waveguide structures, with their closed electromagnetic field distribution, extremely low transmission loss, and excellent power capacity, exhibit natural advantages in the millimeter-wave and even terahertz bands. Therefore, the research and design of waveguide-based 3 dB couplers is essential.

[0003] In existing millimeter-wave phased array, multi-beamforming, or monopulse radar systems, complex feed networks consisting of multiple cascaded 3 dB couplers, such as Butler matrices, Blass matrices, or monopulse comparators, are often required. These networks typically contain multiple couplers, resulting in a large overall size, complex fabrication and assembly, difficulty in controlling phase consistency between channels, and a significant increase in system cost and failure rate with the number of components. If multiple coupling functions can be implemented within a single physical structure through component functional integration, the number of required couplers can be effectively reduced, thereby significantly simplifying the feed topology and improving integration and reliability. Therefore, research and design on structural innovation and functional integration of couplers are highly valuable.

[0004] Existing waveguide couplers are generally single-mode transmission devices (such as the quasi-TEM mode in microstrip lines and the TE10 mode in waveguides). While this ensures design predictability, it also introduces three major structural drawbacks: narrow bandwidth, poor robustness, and low functional density. Especially with the evolution of millimeter-wave multibeam systems towards broadband, miniaturization, and intelligence, single-mode couplers have become a performance bottleneck, struggling to meet the requirements of modern multi-functional radars, reconfigurable communication systems, or intelligent sensing platforms for dynamic beam switching and multi-mode operation. Against this backdrop, researching novel waveguide couplers with multiple operating modes (such as switchable coupling states and path multiplexing capabilities) not only overcomes the limitations of traditional single-mode devices but also holds the promise of replacing multiple traditional single-mode couplers with a "one device, multiple uses" approach, significantly improving system flexibility and compactness. Therefore, research on multi-mode waveguide couplers has both theoretical innovation significance and important engineering application value. Summary of the Invention

[0005] This invention proposes a multimode waveguide coupler that can be used with a multifunctional feed network. While retaining the advantages of waveguides such as low loss and high power capacity, it achieves 3dB coupling of multiple field modes through a single physical structure, thereby effectively reducing the number of devices, simplifying the feed network, and improving the integration and adaptability of millimeter-wave systems.

[0006] A multimode waveguide coupler includes a first rectangular waveguide and a second rectangular waveguide arranged in parallel. Metal walls are provided at both ends of the first and second rectangular waveguides along the length direction, and a metal column is provided at the middle of the first and second rectangular waveguides along the length direction, forming a gap between the metal walls and the metal column.

[0007] Preferably, the first rectangular waveguide and the second rectangular waveguide are separated by a metal wall, and two slits cut through the metal wall, connecting the first rectangular waveguide and the second rectangular waveguide to achieve energy coupling between the waveguides. The two slits are separated by a metal pillar.

[0008] Preferably, the metal wall is composed of a first metal wall with a rectangular cross-section and a second metal wall with an isosceles triangular cross-section, with the gap located between the second metal wall and the metal column, the cross-section of which is a polygon with a symmetrical structure.

[0009] Preferably, a first waveguide port and a second waveguide port are respectively provided at both ends of the length direction of the first rectangular waveguide, and a third waveguide port and a fourth waveguide port are respectively provided at both ends of the length direction of the second rectangular waveguide. The first waveguide port and the third waveguide port are located at the same end, and the second waveguide port and the fourth waveguide port are located at the same end; the width of the four rectangular waveguide ports is at least greater than 1. λ In order to enable higher-order TE 20 It propagates within a rectangular waveguide.

[0010] Preferably, when the first waveguide port (111) excites TE10, the third waveguide port is an isolation port. Ideally, there is no energy distribution. The TE10 mode distributes energy equally to the second waveguide port and the fourth waveguide port through the first rectangular waveguide, the slot, and the second rectangular waveguide. At this time, the phase of the TE10 mode on the second waveguide port is 90° ahead of the phase of the TE10 mode on the fourth waveguide port.

[0011] Preferably, when the first waveguide port excites the higher-order mode TE20, the third waveguide port is an isolation port. Ideally, there is no energy distribution. The TE20 mode distributes its energy equally to the second and fourth waveguide ports through the first rectangular waveguide, the slot, and the second rectangular waveguide. At this time, the phase of the TE20 mode on the second waveguide port is 90° ahead of the phase of the TE20 mode on the fourth waveguide port.

[0012] This invention focuses on the multiple transmission modes of waveguide couplers, aiming to solve the key bottlenecks of existing millimeter-wave couplers in practical system applications: on the one hand, traditional feed networks (such as Butler matrices, single-pulse comparators, etc.) require a large number of cascaded couplers, resulting in a large overall size, complex assembly, and difficulty in ensuring channel consistency; on the other hand, existing waveguide couplers usually only support a single mode state and cannot be reused or switched in different working scenarios, which limits the compactness and flexibility of the system architecture.

[0013] This invention proposes a multi-transmission mode 3dB coupler based on a waveguide structure. Its core lies in the innovative design of multi-field mode slot coupling and path multiplexing, enabling a single four-port waveguide device to achieve 3dB coupling under different field modes (such as TE10 and TE20 modes) excitation states, thereby realizing the integration and multiplexing of multiple couplers. Compared to existing technologies, this solution, while retaining the low transmission loss and high power capacity of traditional waveguides, significantly reduces the number of couplers required in complex feed networks (such as Butler matrices or single-pulse comparators), effectively reducing assembly complexity. Simultaneously, the path multiplexing of multiple transmission modes allows the coupler to achieve multiple operating modes (such as multi-polarization and multi-band), greatly improving the compactness, flexibility, and functional density of millimeter-wave front-end systems. Attached Figure Description

[0014] Figure 1 This is a three-dimensional view of the multimode waveguide coupler of the present invention; Figure 2 This is a three-dimensional cross-sectional view of the multimode waveguide coupler of the present invention; Figure 3 This is a cross-sectional schematic diagram of the top view of the multimode waveguide coupler of the present invention; Figure 4 The port mode (TE) of the multimode waveguide coupler excitation of this invention10 ); Figure 5 The excitation port mode TE of the multimode waveguide coupler of this invention 10 Electric field distribution across the cross section; Figure 6 The port mode (TE) of the multimode waveguide coupler excitation of this invention 20 ); Figure 7 The excitation port mode TE of the multimode waveguide coupler of this invention 20 Electric field distribution across the cross section; Figure 8 This invention relates to the multimode waveguide coupler in the W-band excitation port mode (TE). 10 and TE 20 S-parameter curves at ( ) time; Figure 9 This invention relates to the multimode waveguide coupler in the W-band excitation port mode (TE). 10 and TE 20 The phase difference curve between the output ports. Detailed Implementation

[0015] A multimode waveguide coupler includes a first rectangular waveguide 11 and a second rectangular waveguide 12 arranged in parallel. Metal walls 13 are provided at both ends of the first rectangular waveguide 11 and the second rectangular waveguide 12 in the length direction. A metal column 15 is provided at the middle of the first rectangular waveguide 11 and the second rectangular waveguide 12 in the length direction. A gap 14 is formed between the metal walls 13 and the metal column 15.

[0016] Furthermore, the first rectangular waveguide 11 and the second rectangular waveguide 12 of the present invention are separated by a metal wall 13, and two gaps 14 cut through the metal wall 13. The gaps 14 connect the first rectangular waveguide 11 and the second rectangular waveguide 12 to achieve energy coupling between the waveguides. The two gaps 14 are separated by a metal pillar 15.

[0017] Furthermore, the metal wall 13 of the present invention is composed of a first metal wall 131 having a rectangular cross section and a second metal wall 132 having an isosceles triangular cross section. The gap 14 is located between the second metal wall 132 and the metal column 15. The cross section of the metal column 15 is a polygon with a symmetrical structure.

[0018] Furthermore, the first rectangular waveguide 11 of the present invention has a first waveguide port 111 and a second waveguide port 112 respectively provided at both ends of its length direction, and the second rectangular waveguide 12 has a third waveguide port 121 and a fourth waveguide port 122 respectively provided at both ends of its length direction. If the first waveguide port 111 is regarded as an output port, then the third waveguide port 121 is an isolation port, and the second waveguide port 112 and the fourth waveguide port 122 are output ports. The first waveguide port 111 and the third waveguide port 121 are located at the same end, and the second waveguide port 112 and the fourth waveguide port 122 are located at the same end. The width of the four rectangular waveguide ports is at least greater than 1. λ In order to enable higher-order TE 20 It propagates within a rectangular waveguide.

[0019] Furthermore, when the first waveguide port 111 excites TE10, the third waveguide port 121 is an isolation port. Ideally, there is no energy distribution. The TE10 mode distributes energy equally to the second waveguide port 112 and the fourth waveguide port 122 through the first rectangular waveguide 11, the slot 14, and the second rectangular waveguide 12. At this time, the phase of the TE10 mode on the second waveguide port 112 is 90° ahead of the phase of the TE10 mode on the fourth waveguide port 122.

[0020] Furthermore, when the first waveguide port 111 excites the higher-order mode TE20, the third waveguide port 121 is an isolation port. Ideally, there is no energy distribution. The TE20 mode distributes its energy equally to the second waveguide port 112 and the fourth waveguide port 122 through the first rectangular waveguide 11, the slot 14, and the second rectangular waveguide 12. At this time, the phase of the TE20 mode on the second waveguide port 112 is 90° ahead of the phase of the TE20 mode on the fourth waveguide port 122.

[0021] A multimode waveguide coupler operates based on a rectangular waveguide capable of propagating multiple field modes (such as the dominant mode TE10 and higher-order modes TE20). Utilizing the slot coupling characteristics between adjacent waveguides, amplitude and phase redistribution of different field modes is achieved within a four-port 3dB coupler. When the dominant mode TE10 is excited at the input port of the coupler, it is distributed to the two output ports with equal amplitude and a 90° phase difference through waveguide and slot coupling, resulting in the output ports still displaying the TE10 mode. Similarly, when the higher-order mode TE20 is excited at the input port, it is distributed to the two output ports with equal amplitude and a 90° phase difference through slot coupling, again resulting in the output ports displaying the TE20 mode. In this process, both modes achieve 3dB coupling using the same coupler structure, thus enabling coupler multiplexing.

[0022] This invention discloses a multimode waveguide coupler that can be used with a multifunctional feed network, such as... Figure 1 , Figure 2 , Figure 3 As shown, the first rectangular waveguide 11 and the second rectangular waveguide 12 are parallel. The first rectangular waveguide 11 has two waveguide ports: a first waveguide port 111 and a second waveguide port 112. The second rectangular waveguide 12 has two waveguide ports: a third waveguide port 121 and a fourth waveguide port 122. The first rectangular waveguide 11 and the second rectangular waveguide 12 are separated by a metal wall 13. The metal wall 13 is composed of a first metal wall 131 with a rectangular cross section and a second metal wall 132 with an isosceles triangular cross section. A gap 14 is between the second metal wall 132 and a metal pillar 15. The gap 14 connects the first rectangular waveguide 11 and the second rectangular waveguide 12 to achieve energy coupling between the waveguides. The two gaps 14 are separated by a metal pillar 15, and the cross section of the metal pillar 15 is rhomboid. The four rectangular waveguide ports (111, 112, 121, and 122) have the same cross-sectional dimensions of 0.9 mm × 6.0 mm; the width of the metal wall is 1.1 mm; the height of the isosceles triangular cross-section of the second metal wall 132 is 1 mm; the width of the slot 14 is 1.3 mm; and the diagonals of the rhomboid cross-section of the metal column 15 are 1.0 mm and 1.3 mm, respectively.

[0023] Furthermore, such as Figure 4 and 5 As shown, in the multimode waveguide coupler 1, when the rectangular first waveguide port 111 excites TE10, the third waveguide port 121 is an isolation port. Ideally, there is no energy distribution. The TE10 mode distributes its energy equally to the second waveguide port 112 and the waveguide port 122 through the first rectangular waveguide 11, the slot 14, and the second rectangular waveguide 12. At this time, the phase of the TE10 mode on the second waveguide port 112 is 90° ahead of the phase of the TE10 mode on the fourth waveguide port 122.

[0024] Furthermore, such as Figure 6 and 7 As shown, in the multimode waveguide coupler 1, for the higher-order mode TE20, when the rectangular first waveguide port 111 excites TE20, the third waveguide port 121 is an isolation port, and ideally there is no energy distribution. The TE20 mode distributes energy equally to the second waveguide port 112 and the fourth waveguide port 122 through the first rectangular waveguide 11, the slot 14, and the second rectangular waveguide 12. At this time, the phase of the TE20 mode on the second waveguide port 112 is 90° ahead of the phase of the TE20 mode on the fourth waveguide port 122.

[0025] Figure 8The S-parameter curves for the multimode waveguide coupler in the millimeter-wave W-band (75GHz-110GHz) with excitation port modes (TE10 and TE20) are presented. It can be seen that the proposed multimode coupler's reflection coefficient and isolation are better than -10dB throughout the entire W-band, and in the 85GHz-105GHz band, both modes can achieve approximately equal-amplitude energy distribution between the two output ports. Figure 9 As shown, in both modes, the two output ports achieve a phase difference of approximately 90° across the entire W-band. Simulation results confirm the feasibility and effectiveness of the proposed multimode coupler.

[0026] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A multimode waveguide coupler, characterized in that... The first rectangular waveguide (11) and the second rectangular waveguide (12) are arranged in parallel. Metal walls (13) are set at both ends of the first rectangular waveguide (11) and the second rectangular waveguide (12) in the length direction. Metal pillars (15) are set at the middle of the first rectangular waveguide (11) and the second rectangular waveguide (12) in the length direction. A gap (14) is formed between the metal walls (13) and the metal pillars (15).

2. The multimode waveguide coupler according to claim 1, characterized in that... The first rectangular waveguide (11) and the second rectangular waveguide (12) are separated by a metal wall (13). Two gaps (14) cut through the metal wall (13) and connect the first rectangular waveguide (11) and the second rectangular waveguide (12) to achieve energy coupling between the waveguides. The two gaps (14) are separated by a metal pillar (15).

3. The multimode waveguide coupler according to claim 1, characterized in that... The metal wall (13) is composed of a first metal wall (131) with a rectangular cross section and a second metal wall (132) with an isosceles triangular cross section. The gap (14) is located between the second metal wall (132) and the metal column (15). The cross section of the metal column (15) is a polygon with a symmetrical structure.

4. The multimode waveguide coupler according to claim 1, characterized in that... A first waveguide port (111) and a second waveguide port (112) are respectively provided at both ends of the length direction of the first rectangular waveguide (11), and a third waveguide port (121) and a fourth waveguide port (122) are respectively provided at both ends of the length direction of the second rectangular waveguide (12). The first waveguide port (111) and the third waveguide port (121) are located at the same end, and the second waveguide port (112) and the fourth waveguide port (122) are located at the same end. The width of the four rectangular waveguide ports is at least greater than 1. λ In order to enable higher-order TE 20 It propagates within a rectangular waveguide.

5. The multimode waveguide coupler according to claim 4, characterized in that... When the first waveguide port (111) excites TE10, the third waveguide port (121) is an isolation port. Ideally, there is no energy distribution. The TE10 mode distributes energy equally to the second waveguide port (112) and the fourth waveguide port (122) through the first rectangular waveguide (11), the slot (14), and the second rectangular waveguide (12). At this time, the phase of the TE10 mode on the second waveguide port (112) is 90° ahead of the phase of the TE10 mode on the fourth waveguide port (122).

6. The multimode waveguide coupler according to claim 4, characterized in that... When the first waveguide port (111) excites the higher-order mode TE20, the third waveguide port (121) is an isolation port. Ideally, there is no energy distribution. The TE20 mode distributes energy equally to the second waveguide port (112) and the fourth waveguide port (122) through the first rectangular waveguide (11), the slot (14), and the second rectangular waveguide (12). At this time, the phase of the TE20 mode on the second waveguide port (112) is 90° ahead of the phase of the TE20 mode on the fourth waveguide port (122).

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