A filter power divider based on copper-based micro coaxial transmission line

Abstract

This invention discloses a copper-based microcoaxial transmission line (MCP)-based power divider, relating to microwave technologies such as ultra-wideband radar and electronic reconnaissance and countermeasures. The PCP-based power divider includes a MCP-microstrip line transition structure, a filter based on a stub-loaded multimode resonator, and a power divider based on an LC network. The MCP-microstrip line transition structure is applied to the input and output ports of the power divider, achieving a smooth transition between the two structures through a microcoaxial gradient structure. The MCP consists of a conductor core, a metal outer wall, and dielectric support strips; the characteristic impedance of the transmission line is changed by altering the core width and thickness. The transition structure, filter, and power divider are all based on the MCP-based MCP design. This invention offers advantages over traditional microwave circuits in terms of smaller size, higher system integration, and lower interconnection losses, showing promising prospects in microwave technologies such as ultra-wideband radar and electronic reconnaissance and countermeasures.

Description

Technical Field

[0001] This invention relates to the field of microwave technology, such as ultra-wideband radar, electronic reconnaissance and countermeasures, and in particular to a filter power divider based on copper-based micro-coaxial transmission lines. Background Technology

[0002] With the development of microwave communication technology and the scarcity of spectrum resources, both civilian and military communication systems are gradually moving towards higher frequency bands. However, due to the high loss of traditional printed circuits in the microwave band, copper-based microcoaxial transmission lines, a new type of transmission line with low loss, high isolation, and low dispersion, have become a research hotspot. This transmission line has a quasi-planar structure, making it easy to miniaturize and integrate, and it can also be interconnected with other transmission lines. Ultra-wideband technology, due to its good anti-interference performance and strong confidentiality, has wide applications in many fields such as communication, electronic countermeasures, electronic reconnaissance, military radar, and navigation. Correspondingly, millimeter-wave ultra-wideband bandpass filters and power dividers are key components. Utilizing the low-loss characteristics of copper-based microcoaxial transmission lines, low-transmission-loss ultra-wideband microwave passive devices can be designed.

[0003] In traditional microwave transceiver systems, power dividers and filters are often used together. However, these two devices are usually designed separately and then connected by a 50-ohm transmission line, which leads to problems such as large circuit size and interconnection losses. In recent years, some scholars have proposed a combined design of filters and power dividers, namely a filter-power divider, to save circuit area and improve device performance. Summary of the Invention

[0004] The present invention aims to design a power divider based on a copper-based micro-coaxial transmission line and incorporating filtering function, which improves circuit integration, reduces circuit design size, and has good transmission performance.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a filter power divider based on a copper-based microcoaxial transmission line, comprising:

[0006] Copper-based microcoaxial transmission line-microstrip line transition structure;

[0007] A filter based on a stub-loaded multimode resonator is applied to the two equally divided output terminals of a broadband Wilkinson power divider to filter the equally divided signal before output.

[0008] The broadband Wilkinson power divider based on LC network includes one input terminal and two output terminals. The input terminal is directly connected to a copper-based microcoaxial transmission line-microstrip line transition structure to form the input port of the filter power divider. The output terminals are connected to the copper-based microcoaxial transmission line-microstrip line transition structure through filter stubs to form the first output port and the second output port of the filter power divider.

[0009] Preferably, the copper-based microcoaxial transmission line-microstrip line transition structure is surface-mounted on a dielectric substrate, and the dielectric substrate has an array of grounded metal vias.

[0010] Preferably, the copper-based microcoaxial transmission line has periodically arranged release holes and dielectric support strips.

[0011] Preferably, the filter consists of two short-circuit stubs, two coupling lines, and a high impedance ratio open line.

[0012] Preferably, the short-circuit stub, the two coupling lines, and the open line are all quarter-wavelength transmission lines. The coupling line structure of the filter consists of a metal outer wall and two parallel adjacent inner cores. The sidewalls of the metal outer wall are opened and supported by periodically arranged support columns. Both inner cores are supported by periodically arranged dielectric support strips.

[0013] Preferably, in the filter, the short-circuit stub and the open circuit are respectively connected and separated by the inner core and the outer metal wall of the copper-based micro coaxial transmission line, and the metal outer wall at the end of the short-circuit stub does not have a release hole.

[0014] Preferably, the outer metal wall, inner core, and transition structure of the copper-based microcoaxial transmission line to the microstrip line are all axisymmetric structures, and the filter and the broadband Wilkinson power divider are also symmetrical structures.

[0015] Preferably, the broadband Wilkinson power divider consists of two quarter-wavelength transmission lines, an isolation resistor, and an isolation RLC circuit stub.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. A power divider based on a copper-based micro-coaxial transmission line with embedded filtering functionality is developed, integrating the power divider and filter into a single design and manufacturing process. This allows the device to simultaneously perform power distribution and filtering functions. Furthermore, this design reduces the circuit size, facilitating the high integration of microwave circuits.

[0018] 2. Copper-based microcoaxial transmission lines have advantages such as low loss, high isolation, and self-encapsulation. Based on this technology, stub-loaded multimode resonators and LC network-based power dividers have good transmission characteristics.

[0019] 3. The designed copper-based micro-coaxial transmission line-microstrip line transition structure realizes the interconnection between traditional microwave circuits and novel transmission structures, and also greatly expands the collaborative design of different processes. Attached Figure Description

[0020] Figure 1 This is a structural diagram of an embodiment of the present invention;

[0021] Figure 2 This is an exploded view of the structure located on the dielectric substrate according to an embodiment of the present invention;

[0022] Figure 3 This is a top view of an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of the inner core structure;

[0024] Figure 5 The transition structure and simulation results of the present invention are shown in the embodiments.

[0025] Figure 6 and Figure 7 The results are simulation results for an embodiment of the present invention.

[0026] Reference numerals: 1-Input port, 2-First output port, 3-Second output port, 11-Metal outer wall, 12-Inner core, 13-Release hole, 14-Dielectric support strip, 15-Dielectric substrate, 16-Copper-based microcoaxial transmission line-microstrip line transition structure, 17-Ground metal via array, 18-Coupled line, 19-Short-circuit stub, 20-Open line, 21-0402 package resistor pad, 22-0402 package capacitor pad, 23-Filter, 24-Wideband Wilkinson power divider. Detailed Implementation

[0027] 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 some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] For the purpose of understanding and explanation, the following describes in detail a copper-based microcoaxial transmission line-based filter power divider provided by an embodiment of the present invention.

[0029] Please refer to Figures 1-7 As shown, the 6-18GHz power divider based on a copper-based microcoaxial transmission line with embedded filtering function provided by the present invention includes a dielectric substrate 15, a copper-based microcoaxial transmission line-microstrip line transition structure 16, a copper-based microcoaxial transmission line, a filter 23 based on a stub-loaded multimode resonator, and a broadband Wilkinson power divider 24 based on an LC network. The copper-based microcoaxial line-microstrip line transition structure 16 is surface-mounted on the dielectric substrate 15 with a metal ground via array 17.

[0030] The copper-based microcoaxial transmission line includes a metal outer wall 11, an inner core 12, and a dielectric support strip 14 for supporting the inner core. The cavity between the metal outer wall 11 and the inner core 12 is filled with air, which greatly reduces transmission loss. The copper-based microcoaxial transmission line-microstrip line transition structure 16 is composed of a metal sheet, a metal outer wall 11, and an inner core 12. The two coupling lines 18, a high impedance ratio open line 20, and two short-circuit stubs 19 connected to the input / output ports of the filter based on the stub-loaded multimode resonator are all designed based on the copper-based microcoaxial transmission line. The quarter-wavelength transmission line and inductor L of the broadband Wilkinson power divider 24 based on the LC network are also designed based on the copper-based microcoaxial transmission line. The isolation resistor and isolation capacitor use 0402 packaged components. The filter power divider includes three ports: input port 1, first output port 2, and second output port 3. The impedance of all three ports is matched to a 50-ohm microstrip line. The broadband Wilkinson power divider 24 based on an LC network includes one input terminal and two output terminals. The input terminal is directly connected to the copper-based microcoaxial transmission line-microstrip line transition structure 16, forming the input port 1 of the filter power divider. The output terminals are connected to the copper-based microcoaxial transmission line-microstrip line transition structure 16 through filter stubs, forming the first output port 2 and the second output port 3 of the filter power divider. The outer metal wall 11, inner core 12 of the copper-based microcoaxial transmission line, and the copper-based microcoaxial transmission line-microstrip line transition structure 16 are all axisymmetric structures. The filter 23 based on a stub-loaded multimode resonator and the broadband Wilkinson power divider 24 based on an LC network are both symmetrical structures.

[0031] When the device is in use, the RF signal is input from input port 1. First, the power distribution structure splits one RF signal into two signals with equal amplitude and phase. The filter resonant structure then selects which RF signal to pass through. Based on a 3D copper-based microcoaxial transmission line structure, the filter structure and Wilkinson power divider structure are integrated into a single design, enabling the device to have both filtering and power distribution functions. This reduces the device size and achieves miniaturization while maintaining good performance, which is beneficial for the miniaturization and integration of RF communication systems. The designed copper-based microcoaxial transmission line-microstrip line transition structure 16 is also more convenient for co-design with traditional processes. In addition, the use of this process for lumped components greatly reduces the circuit size and also reduces interference caused by the introduction of other forms of capacitors and inductors.

[0032] The copper-based microcoaxial metal outer wall 11, the inner core 12, and the copper-based microcoaxial transmission line-microstrip line transition structure 16 are all symmetrical structures.

[0033] The copper-based microcoaxial transmission line-microstrip line transition structure 16 is a widening gradient structure, with the metal outer wall 11 and the inner core 12 widening synchronously.

[0034] The characteristic impedance of the quarter-wavelength transmission line of the broadband Wilkinson power divider based on the LC network is determined by the width and thickness of the copper-based micro-coaxial transmission line core, with three standard thicknesses: 60µm, 100µm, and 260µm. The lumped component inductors are all designed based on the copper-based micro-coaxial process. The isolation resistors and capacitors are designed with corresponding pads 21 and 22 according to their size standards, and the pads are located on the core.

[0035] The filter based on the stub-loaded multimode resonator is connected to the two first output ports 2 and the second output port 3 of the Wilkinson power divider, respectively, realizing the collaborative design of the multimode resonator and the power divider.

[0036] The filter's short-circuit stub 19, two coupling lines 18, and a high-impedance-ratio open line 20 are all quarter-wavelength transmission lines with a center frequency of 12 GHz.

[0037] More specifically, the short-circuit stub of the filter is formed by the connection between the outer metal wall 11 and the inner core 12 of the copper-based micro-coaxial transmission line; the coupling line is composed of two adjacent inner cores 12 inside the outer metal wall 11 of the copper-based micro-coaxial transmission line, and the coupling coefficient is determined by the distance between the inner cores 12 and the outer metal wall 11. The opening of the side wall of the outer metal wall significantly enhances the coupling strength of the coupling line; the open line includes two quarter-wavelength transmission lines with different characteristic impedances, thereby increasing the resonant mode and widening the transmission bandwidth.

[0038] The copper-based microcoaxial transmission line has periodically arranged release holes 13 and dielectric support bars 14.

[0039] More specifically, the outer metal wall 11 has periodic release holes 13, the inner core is wrapped in the outer metal wall 11, and there are periodically arranged medium support bars 14 passing through the inner core to support the inner core 12.

[0040] In the filter 23 based on the stub-loaded multimode resonator, the short-circuit stub 19 and the open line 20 are respectively connected and separated by the inner core 12 of the copper-based micro coaxial transmission line and the metal outer wall 11. To ensure good grounding, the metal outer wall of the short-circuit stub 19 terminal does not have a release hole 13.

[0041] The basic structure of this embodiment is a copper-based microcoaxial transmission line, fabricated using electrochemical additive manufacturing technology. The rectangular microcoaxial line fabrication process used in this study involves 9 layers, each with a thickness of 60-100 μm. It should be noted that although circular coaxial lines have lower losses compared to rectangular coaxial lines, air-filled circular coaxial lines are difficult to fabricate, and rectangular coaxial lines are more suitable for this layer-by-layer sequential manufacturing process.

[0042] The copper-based microcoaxial transmission line has a height of only 860µm and can be considered a quasi-planar structure. It transmits TEM waves with extremely low loss. During the fabrication of the copper-based microcoaxial transmission line, periodically arranged release holes are required to release the photoresist used in the manufacturing process. The number of release holes 13 should not be too many or too few; too many will cause electromagnetic leakage, while too few will result in incomplete photoresist removal, leading to residue and affecting the transmission line quality and transmission performance. The characteristic impedance of the copper-based microcoaxial transmission line is determined by the width and thickness of the core.

[0043] In the filter based on the stub-loaded multimode resonator, the coupling line 18 section requires windows on the sidewalls of its metal outer wall 11 to enhance coupling. It should be noted that the periodically arranged support pillars should be neither too many nor too few; too many will reduce coupling strength, while too few will affect the stability and robustness of the structure, thus impacting the overall usability of the device.

[0044] More specifically, the inner core 12 of the copper-based microcoaxial transmission line coincides with and remains parallel to the axis of the outer metal wall 11. The copper-based microcoaxial transmission line is supported by periodically arranged dielectric support strips 14, which penetrate the inner core and are embedded in the outer metal wall 11 at both ends. In addition, the dielectric support strips 14 should be arranged periodically at an appropriate interval. Too dense an arrangement will result in excessive electromagnetic loss, while too sparse an arrangement will result in insufficient support for the inner core 12, affecting the structure and strength of the device.

[0045] To make the entire structure more compact and smaller, the embodiments of the present invention bend the short-circuit stub 19 and the open line 20, so as to reduce the overall size of the broadband filter power divider as much as possible while ensuring the transmission effect.

[0046] After the copper-based microcoaxial portion is fabricated, the entire structure needs to be mounted onto the fabricated dielectric substrate. The bottom surface of the metal outer wall 11 of the copper-based microcoaxial portion is on the same horizontal plane as the upper surface of the dielectric substrate 15. Then, a metal sheet extends from the copper-based microcoaxial transmission line-microstrip line transition structure 16 to both ends of the dielectric substrate. At this point, the 6-18GHz copper-based microcoaxial transmission line filter embedded power divider with a microstrip transition structure is manufactured. In this embodiment, the metal material used is copper, and the dielectric substrate material is Rogers 5880.

[0047] like Figure 5 , 6As shown in Figures 7 and 8, the characteristics of the 6-18 GHz copper-based microcoaxial transmission line filter embedded in the power divider with a microstrip transition structure of the present invention are simulated. The simulation results show that the return loss of the transition structure is better than 30 dB in the 6-18 GHz range; the center frequency of the ultra-wideband filter power divider is 11.95 GHz, the 3 dB operating bandwidth is 11.90 GHz, the operating frequency covers 6.0-17.9 GHz, the minimum insertion loss in the passband is 0.4665 dB, the return loss is better than 14.5 dB in the 6.2-17.9 GHz range, the isolation is better than 16.99 dB in the passband, and better than 20 dB in most areas of the passband.

[0048] The above-described embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited thereto. Any simple changes or equivalent substitutions of the technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention shall fall within the scope of protection of the present invention.

Claims

1. A filter power divider based on a copper-based microcoaxial transmission line, characterized in that, include: Copper-based microcoaxial transmission line-microstrip line transition structure (16); the copper-based microcoaxial transmission line-microstrip line transition structure (16) is surface-mounted on a dielectric substrate (15), the dielectric substrate (15) having an array of ground metal vias (17); The filter (23) based on the stub-loaded multimode resonator is loaded onto the two equally divided output terminals of the broadband Wilkinson power divider (24) to filter the equally divided signal and output it. The broadband Wilkinson power divider (24) based on LC network includes one input terminal and two output terminals. The input terminal is directly connected to the input port (1) of the copper-based microcoaxial transmission line-microstrip line transition structure (16) to form the filter power divider. The output terminal is connected to the first output port (2) and the second output port (3) of the filter power divider through the copper-based microcoaxial transmission line-microstrip line transition structure (16) via a filter stub.

2. The filter power divider based on copper-based microcoaxial transmission lines as described in claim 1, characterized in that, The copper-based microcoaxial transmission line has periodically arranged release holes (13) and dielectric support strips (14).

3. A filter power divider based on a copper-based microcoaxial transmission line as described in claim 2, characterized in that, The filter (23) consists of two short-circuit stubs (19), two coupling lines (18), and a high impedance ratio open line (20).

4. A filter power divider based on a copper-based microcoaxial transmission line as described in claim 3, characterized in that, The short-circuit stub (19), the two coupling lines (18), and the open line (20) are all quarter-wavelength transmission lines. The structure of the coupling line (18) of the filter consists of a metal outer wall (11) and two parallel adjacent inner cores (12). The sidewall of the metal outer wall (11) is opened and supported by periodically arranged support columns. The two inner cores (12) are supported by periodically arranged dielectric support strips (14).

5. A filter power divider based on a copper-based microcoaxial transmission line as described in claim 4, characterized in that, In the filter (23), the short-circuit stub (19) and the open line (20) are connected and separated by the inner core (12) of the copper-based micro coaxial transmission line and the metal outer wall (11), respectively. The metal outer wall at the end of the short-circuit stub (19) does not have a release hole (13).

6. A filter power divider based on a copper-based microcoaxial transmission line as described in claim 5, characterized in that, The outer metal wall (11), inner core (12), and copper-based microcoaxial transmission line-microstrip line transition structure (16) of the copper-based microcoaxial transmission line are all axisymmetric structures, and the filter (23) and broadband Wilkinson power divider (24) are also symmetrical structures.

7. A filter power divider based on a copper-based microcoaxial transmission line as described in claim 1, characterized in that, The broadband Wilkinson power divider (24) consists of two quarter-wavelength transmission lines, isolation resistors, and isolation RLC circuit stubs.

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