T-junction power divider
By designing a T-junction power splitter including input waveguide T-junction, waveguide impedance conversion network, T-junction probe transition structure, matching transmission network and microstrip-waveguide transition structure, the problem of insufficient isolation between power split ports in the prior art is solved, and ultra-high isolation between two power split ports is achieved to meet the needs of high-power and high-resolution imaging systems.
Patent Information
- Application Number
- CN202510075866.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-17
- Publication Date
- 2025-03-11
AI Technical Summary
The existing T-junction power splitter has limited isolation between the power split ports in the millimeter wave and terahertz bands, which cannot meet the needs of high-power applications and high-resolution imaging systems.
A T-junction power splitter including an input waveguide T-junction, a waveguide impedance conversion network, a T-junction probe transition structure, a matching transmission network and a microstrip-waveguide transition structure is designed. Through the combination of asymmetric transmission line structure and different transmission modes, ultra-high isolation between the two power split ports is achieved.
The isolation between the two power split ports is achieved by more than 40dB, meeting the needs of high-power applications and high-resolution imaging systems, and ensuring a good match between the input port and the power split port.
Smart Images
Figure CN119601940A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of communication technology, and in particular to a T-junction power divider. Background Art
[0002] In most millimeter wave and terahertz wave systems, power division and synthesis of RF signals are indispensable. Especially in high-power applications (such as radar transmitters), a single power amplifier or frequency multiplier often cannot reach the required RF power level, and further power synthesis is required. At the same time, power dividers (i.e. power distributors) also play an important role in terahertz communications. For example, a high-isolation power divider is required in the IQ mixer, but due to the limitation of the basic structure, the current mainstream Y / T junction only has a port isolation of about 6dB, which is far from meeting the application requirements. In addition, in the terahertz imaging system, in order to improve the imaging resolution and reduce the focal plane area occupied by a single pixel, the radar transceiver front end will be required to share the antenna port, such as Figure 1 As shown; in this scenario, high isolation of the transmit and receive channels is crucial, otherwise the transmit power leakage will cover the received echo signal, limiting the maximum detection distance and phase noise of the imaging system.
[0003] In the related technology, T-junction or Y-junction power dividers are usually used in the power synthesis circuit of millimeter wave and terahertz frequency bands, and the isolation between the two power divider ports is also very limited (such as -6dB); although there is a solution to improve the port isolation by loading a lossy unit structure in the network, it requires the use of a high-cost resistive thin film process to achieve it, and due to the characteristics of the electric field distribution, its isolation is limited to a lower range (such as -10~-20dB), and its power capacity is limited by the thin film circuit. Therefore, how to improve the port isolation of the power divider is an urgent problem to be solved today. Summary of the invention
[0004] The object of the present invention is to provide a T-junction power divider to achieve ultra-high isolation between two power divider ports.
[0005] In order to solve the above technical problems, the present invention provides a T-junction power divider, comprising: an input waveguide T-junction, a waveguide impedance transformation network, a T-junction probe transition structure, a matching transmission network and a microstrip-waveguide transition structure;
[0006] Among them, the first side branch of the input waveguide T-junction is provided with an input port, the central branch of the input waveguide T-junction is connected to the waveguide impedance transformation network, the T-junction probe transition structure is arranged in the middle of the input waveguide T-junction, and the T-junction probe transition structure is connected to the microstrip-waveguide transition structure through the matching transmission network; the input waveguide T-junction is used to separate the signal input from the input port, and output it to two power division ports through a first power division path and a second power division path respectively; the first power division path includes the waveguide impedance transformation network, and the second power division path includes the T-junction probe transition structure, the matching transmission network and the microstrip-waveguide transition structure.
[0007] In another aspect, the matching transmission network is specifically a microstrip line transmission network or a suspended microstrip line transmission network.
[0008] On the other hand, the T-junction probe transition structure is used to insert the probe into the TE 10 A portion of the power of the mode is coupled to the matching transmission network;
[0009] The matching transmission network is used to match the port impedance between the T-junction probe transition structure and the microstrip-waveguide transition structure;
[0010] The microstrip-waveguide transition structure is used to complete the TEM mode signal to TE 10 Coupling of mode signals.
[0011] In another aspect, the matching transmission network is specifically a coplanar waveguide transmission line network.
[0012] On the other hand, the phase difference between the output signals of the two power division ports corresponds to the transmission line length of the matching transmission network.
[0013] In another aspect, the waveguide impedance transformation network is used to complete the impedance change from the standard waveguide to the reduced waveguide at the input waveguide T-junction.
[0014] On the other hand, the input waveguide T-junction is made of metal.
[0015] On the other hand, the T-junction power divider further includes: a terahertz absorption load connected to the second side branch of the input waveguide T-junction.
[0016] On the other hand, the isolation between the two power splitter ports is greater than 40db.
[0017] A T-junction power divider provided by the present invention comprises: an input waveguide T-junction, a waveguide impedance transformation network, a T-junction probe transition structure, a matching transmission network and a microstrip-waveguide transition structure; wherein, a first side branch of the input waveguide T-junction is provided with an input port, a central branch of the input waveguide T-junction is connected to the waveguide impedance transformation network, a T-junction probe transition structure is provided in the middle of the input waveguide T-junction, and the T-junction probe transition structure is connected to the microstrip-waveguide transition structure through the matching transmission network; the input waveguide T-junction is used to separate a signal input from an input port, and output the signal to two power division ports through a first power division path and a second power division path respectively; the first power division path comprises a waveguide impedance transformation network, and the second power division path comprises a T-junction probe transition structure, a matching transmission network and a microstrip-waveguide transition structure.
[0018] It can be seen that the present invention realizes power distribution by setting up an asymmetric transmission line structure of the first power division path and the second power division path, adopts different transmission modes, and utilizes mode isolation of different transmission modes to achieve ultra-high isolation between the two power division ports; and can achieve the symmetry of the core T-junction electric field under the premise of ensuring good matching between the input port and the two power division ports, thereby ensuring the mode isolation between the two power division ports. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.
[0020] Figure 1 A schematic diagram of a transmitting and receiving shared antenna architecture of a terahertz array imaging system in the related art;
[0021] Figure 2 Schematic diagram of the structure of the commonly used waveguide lossless T-junction power divider;
[0022] Figure 3 A schematic diagram of the structure of a high isolation power divider loaded with a lossy plane structure;
[0023] Figure 4 A schematic structural diagram of a T-junction power divider provided in an embodiment of the present invention;
[0024] Figure 5 A schematic diagram of the circuit principle of a T-junction power divider provided in an embodiment of the present invention;
[0025] Figure 6 A schematic diagram of a partial structure of a T-junction power divider provided in an embodiment of the present invention;
[0026] Figure 7 A schematic structural diagram of a terahertz absorption load of a T-junction power divider provided in an embodiment of the present invention;
[0027] Figure 8 This is a diagram showing the high-mode isolation characteristics of the electric field of a power splitter port when the absorption load is well matched;
[0028] Fig. 9 This is a diagram showing the high-mode isolation characteristics of the electric field of another power splitter port when the absorbing load is well matched;
[0029] Fig.10 This is a diagram showing the deterioration of electric field isolation and electric field leakage of a power splitter port when absorbing load mismatch;
[0030] Fig.11 This is a diagram showing the deterioration of the electric field isolation and the electric field leakage of another power splitter port when absorbing load mismatch;
[0031] Fig.12 The characteristic diagram of the T-junction power divider when the isolation port adopts ideal absorption port matching;
[0032] Fig.13 The characteristic diagram of the T-junction power divider when the isolation port adopts absorptive load matching. DETAILED DESCRIPTION
[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0034] In the related art, the circuit structure of a common T-junction or Y-junction power divider is as follows: Figure 2 As shown in Figure 1, this is the most commonly used structure in millimeter wave and terahertz frequency band power synthesis circuits. Taking the E-plane split T-junction power divider as an example, the input TE 10 The mode electromagnetic field is split into two after passing through the junction area, and the original electric field direction changes Figure 2 The change in the power divider causes the electric fields of the two power divider ports (Port2 and Port3) to be in opposite directions, that is, they have a phase difference of 180°. However, this type of structure is essentially a lossless three-port network. According to microwave network theory, it is impossible for this three-port network to simultaneously meet the conditions of lossless, reciprocal, and full-port matching. Therefore, it is impossible for a traditional T-junction power divider to achieve matching of the three ports, and the isolation between the two power divider ports is also very limited (e.g., -6dB).
[0035] In order to improve the port isolation of the T-junction power splitter, the relevant technology is implemented by loading a lossy unit structure in the network; by loading lossy elements, the three-port network can be changed from lossless to lossy, and the network will be able to achieve the characteristics of three-port matching and reciprocity, and the isolation between its output two ports will also be greatly improved. Among them, the most representative terahertz high isolation power splitter can be as follows Figure 3 As shown in the figure, its design combines the traditional T-junction power divider and microstrip conversion structure to absorb the reflected signal from the output port (Port2 and Port3), thereby improving the port isolation. At the same time, combined with Chebyshev impedance matching, the working bandwidth of the power divider is improved. However, its power divider structure requires a more expensive resistive thin film process to achieve, and due to the characteristics of the electric field distribution, its isolation is limited to a lower range (such as -10~-20dB), and its power capacity is limited by the thin film circuit.
[0036] Therefore, in view of the problems existing in the above-mentioned existing waveguide power division technology, Figure 2 and Figure 3 The main reason for the limited isolation of the waveguide power splitter structure shown is that the main electric field modes of the input port and the two power splitter ports are both the main mode TE. 10 mode (a transverse electric wave mode), there is no additional isolation between its port modes, and a relatively low level of isolation can only be guaranteed by loading a lossy structure. In order to achieve three-port matching of the power divider while ensuring high isolation between the power divider ports, the embodiments of the present invention adopt different transmission modes to achieve power distribution, and utilize mode isolation of different transmission modes to achieve ultra-high isolation between the two power divider ports; and it can achieve the symmetry of the core T-junction electric field under the premise of ensuring good matching between the input port and the two power divider ports, thereby ensuring the mode isolation between the two power divider ports.
[0037] For details, please refer to Figure 4 , Figure 4 A schematic diagram of the structure of a T-junction power divider provided by an embodiment of the present invention. The T-junction power divider may include: an input waveguide T-junction 10, a waveguide impedance transformation network 20, a T-junction probe transition structure 30, a matching transmission network 40 and a microstrip-waveguide transition structure 50;
[0038] Among them, the first side branch of the input waveguide T-junction 10 is provided with an input port, the central branch of the input waveguide T-junction 10 is connected to the waveguide impedance transformation network 20, and a T-junction probe transition structure 30 is arranged in the middle of the input waveguide T-junction 10, and the T-junction probe transition structure 30 is connected to the microstrip-waveguide transition structure 50 through the matching transmission network 40; the input waveguide T-junction 10 is used to separate the signal input from the input port, and output it to two power division ports through the first power division path and the second power division path respectively; the first power division path includes the waveguide impedance transformation network 20, and the second power division path includes the T-junction probe transition structure 30, the matching transmission network 40 and the microstrip-waveguide transition structure 50.
[0039] It can be understood that in this embodiment, the input port (such as Figure 5 Input port 1) Input TE 10 The signal of the mode (such as a rectangular waveguide) is input to the input waveguide T-junction 10 (such as Figure 5 and Figure 6 The first side branch of the structure 1) in the input waveguide T-junction 10 is used to split the input signal into two, so as to realize a signal pair with the same amplitude and adjustable phase difference and output the signal to two power division ports (such as Figure 5 The power splitter ports 2 and 3 in the figure are used to realize a high isolation T-junction power splitter based on an asymmetric transmission mode. By setting an asymmetric T-junction structure, different transmission modes can be used to realize power distribution, and mode isolation of different transmission modes can be used to realize ultra-high isolation between the two power splitter ports.
[0040] Correspondingly, the waveguide impedance transformation network 20 (such as Figure 5 The structure 2) in the second power splitting path can be used to realize the impedance change of the waveguide from the standard waveguide to the input waveguide T-junction 10. Correspondingly, the T-junction probe transition structure 30 (such as Figure 5 and Figure 6 The structure 3) can be used to insert the probe into the TE 10 The partial power of the mode is coupled to the matching transmission network 40 (such as Figure 5 and Figure 6 The matching transmission network 40 in the second power splitting path can be used to match the T-junction probe transition structure 30 with the microstrip-waveguide transition structure 50 (such as Figure 5 and Figure 6 The port impedance between the structure 5) in the power division path is adjusted to achieve port impedance matching between the T-junction probe transition structure 30 and the microstrip-waveguide transition structure 50, thereby ensuring low reflection transmission of the signal flow on this power division path.
[0041] That is, in this embodiment, by setting the T-junction probe transition structure 30 and the matching transmission network 40, the signal in the second power division path adopts the same signal transmission mode (such as TE) as that in the first power division path. 10 Mode) different transmission modes are used for transmission, realizing mode isolation between the two power division ports of the T-junction power divider, thereby achieving its ultra-high isolation.
[0042] Among them, the specific types of the T-junction probe transition structure 30 and the matching transmission network 40 can be set by the designer according to practical scenarios and user needs. For example, the matching transmission network 40 can adopt a microstrip line transmission network or a suspended microstrip line transmission network to utilize the planar microstrip line or the suspended microstrip line and the corresponding probe structure to realize the signal transmission of the quasi-TEM mode (a transverse electric wave mode) of the planar transmission line in the second power division path. The matching transmission network 40 can also adopt a coplanar waveguide transmission line network, and the T-junction probe transition structure 30 can also adopt a corresponding probe structure. As long as the T-junction probe transition structure 30 and the matching transmission network 40 can realize the signal transmission mode in the second power division path and the signal transmission mode in the first power division path (such as TE 10 Mode) is different, and this embodiment does not impose any restriction on this.
[0043] Accordingly, the microstrip-waveguide transition structure 50 (eg Figure 5 and Figure 6 The structure 5) in the figure can be used to complete the transmission mode coupling of the signal on the second power splitting path to the signal on the first power splitting path, so that the two power splitting ports output signals of the same signal transmission mode. For example, the microstrip-waveguide transition structure 50 can complete the TEM mode signal (such as the quasi-TEM mode signal mentioned above) to the TE 10 The coupling of mode signals makes the two power division ports output signals of the same signal transmission mode.
[0044] Among them, the phase difference between the output signals of the two power splitter ports of the T-junction power splitter in this embodiment corresponds to the transmission line length of the matching transmission network 40. In other words, the phase difference between the two power splitter ports can be adjusted to any value by adjusting the transmission line length of the matching transmission network 40 (such as the length of the standard microstrip line), so the phase difference between the power splitter output ports can be continuously adjustable, so that the T-junction power splitter provided in this embodiment has a higher degree of freedom in millimeter wave system and circuit applications.
[0045] It should be noted that the input waveguide T-junction 10 in this embodiment may include a central branch and two side branches (i.e., a first side branch and a second side branch) arranged opposite to each other. The T-junction power splitter in this embodiment may use the input waveguide T-junction 10 to split the signal input from the first side branch into two, and output the signal to the two power splitting ports through the first power splitting path corresponding to the central branch and the second power splitting path corresponding to the probe inserted in the middle of the input waveguide T-junction 10.
[0046] Correspondingly, in this embodiment, the second side branch (i.e., the isolation port) of the input waveguide T-junction 10 can be left vacant or grounded; in order to ensure the balance of the electric field distribution inside the entire T-junction power divider structure, ensure that the power division port (e.g., Figure 5 The signal in the power split port 2) direction cannot excite the signal transmission mode of the second power split path (such as the microstrip line quasi-TEM mode) at the probe inserted into the input waveguide T-junction 10, ensuring the ultra-high isolation between ports 2 and 3; in this embodiment, the second side branch of the input waveguide T-junction 10 can be connected to the terahertz absorption load 60 or other matching. At the same time, the terahertz absorption load 60 is essentially a lossy component, which can achieve better matching of the three ports and high isolation between the power split ports for the quasi-three-port network of the T-junction power splitter.
[0047] Correspondingly, the specific structure of the terahertz absorption load 60 can be set by the designer, for example, it can be implemented in the same or similar manner as the structure of the absorption load in the related art. For example, the terahertz absorption load 60 can be Figure 7 As long as the terahertz absorption load 60 can absorb the signals leaked from the two power splitting ports, this embodiment does not impose any limitation on this.
[0048] Likewise, the present embodiment does not limit the specific material of the input waveguide T-junction 10 . For example, the input waveguide T-junction 10 may be made of metal, such as aluminum, copper or other metal materials.
[0049] For example, Figure 8 and Fig. 9 The electric field distribution inside the structure is shown when the terahertz absorption load 60 achieves good signal absorption. When the absorption rate of the absorption load decreases, the port matching deteriorates, resulting in an obvious standing wave at the port, which in turn destroys the electric field distribution at the probe inserted in the input waveguide T-junction 10, causing the signal from the power splitter port 2 to leak into the matching transmission network 40, thereby reducing its isolation, and vice versa (e.g. Fig.10 and Fig.11 As shown). It can be seen that the terahertz absorption load 60 plays a relatively important role in the port isolation of the power division structure in this embodiment. Fig.12As shown, when the second side branch of the input waveguide T-junction 10 is connected to an ideal match (ideal absorption port), it has a good input impedance matching characteristic under ideal matching conditions, and the isolation between the two power splitter ports (ports 2 and 3) can be greater than 55dB under ideal conditions; Fig.13 As shown, when the second side branch of the input waveguide T-junction 10 is connected to the hand washing load (i.e., the terahertz absorption load 60), the structure of the T-junction power splitter also has good port input impedance matching characteristics, and the isolation between the two power splitting ports (ports 2 and 3) is greater than 40dB, which makes the T-junction power splitter of this embodiment have a significant improvement in isolation compared with the traditional T-junction power splitter.
[0050] In this embodiment, the embodiment of the present invention uses an asymmetric transmission line structure setting of the first power division path and the second power division path, adopts different transmission modes to achieve power distribution, and utilizes mode isolation of different transmission modes to achieve ultra-high isolation between the two power division ports; and can achieve the symmetry of the core T-junction electric field under the premise of ensuring good matching between the input port and the two power division ports, thereby ensuring the mode isolation between the two power division ports.
[0051] The above is a detailed introduction to a T-junction power divider provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the present invention.
Claims
1. A T-junction power divider, characterized in that: include: Input waveguide T-junction, waveguide impedance transformation network, T-junction probe transition structure, matching transmission network and microstrip-waveguide transition structure; Among them, the first side branch of the input waveguide T-junction is provided with an input port, the central branch of the input waveguide T-junction is connected to the waveguide impedance transformation network, the T-junction probe transition structure is arranged in the middle of the input waveguide T-junction, and the T-junction probe transition structure is connected to the microstrip-waveguide transition structure through the matching transmission network; the input waveguide T-junction is used to separate the signal input from the input port, and output it to two power division ports through a first power division path and a second power division path respectively; the first power division path includes the waveguide impedance transformation network, and the second power division path includes the T-junction probe transition structure, the matching transmission network and the microstrip-waveguide transition structure.
2. The T-junction power divider according to claim 1, characterized in that: The matching transmission network is specifically a microstrip line transmission network or a suspended microstrip line transmission network.
3. The T-junction power divider according to claim 2, characterized in that: The T-junction probe transition structure is used to insert the probe into the TE 10 A portion of the power of the mode is coupled to the matching transmission network; The matching transmission network is used to match the port impedance between the T-junction probe transition structure and the microstrip-waveguide transition structure; The microstrip-waveguide transition structure is used to complete the TEM mode signal to TE 10 Coupling of mode signals.
4. The T-junction power divider according to claim 1, characterized in that: The matching transmission network is specifically a coplanar waveguide transmission line network.
5. The T-junction power divider according to claim 1, characterized in that: The phase difference between the output signals of the two power division ports corresponds to the transmission line length of the matching transmission network.
6. The T-junction power divider according to claim 1, characterized in that: The waveguide impedance transformation network is used to complete the impedance change from the standard waveguide to the height-reducing waveguide at the T-junction of the input waveguide.
7. The T-junction power divider according to claim 1, characterized in that: The material of the input waveguide T-junction is metal.
8. The T-junction power divider according to any one of claims 1 to 7, characterized in that: Also includes: The second side branch of the input waveguide T-junction is connected to a terahertz absorbing load.
9. The T-junction power divider according to claim 8, characterized in that: The isolation between the two power division ports is greater than 40db.