A high-isolation SAR antenna feed assembly circuit structure and design method

Abstract

The present invention provides a circuit structure and design method for a high-isolation SAR antenna feeding component, which belongs to the field of microwave radio frequency circuit technology. Based on the prototype of the Wilkinson power divider circuit of the stripline structure, the signal is led out from the inner layer circuit of the stripline and interconnected with the T / R components and delay amplifier components of each level of the SAR antenna by blind plugging of high-frequency connectors, thereby solving the defect that the stripline circuit is not easy to integrate with the microwave component; the radio frequency link and the calibration link are integrated into the same component, effectively reducing the overall weight of the component; the high-power isolation resistor is configured by digging a blind groove to effectively increase the power resistance of the component; a metal shielding shell structure is provided at the connector port position and the blind groove, and metallized through holes and metallized blind buried holes are provided inside the component, effectively increasing the spatial isolation and inter-channel isolation of the component. The basic circuit structure of the present invention is compact and convenient to be manufactured using a multi-layer PCB, with low processing precision requirements, and has good engineering application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave radio frequency circuits, and in particular relates to a circuit structure and a design method of a high-isolation SAR antenna feeding component. Background Art

[0002] The spaceborne SAR satellite constellation project launches multiple radar (SAR) satellites in one rocket to form a formation multi-baseline interferometric SAR satellite system. It can quickly and efficiently produce high-precision digital surface models (DSMs) and perform 1:50,000 scale mapping tasks in the global non-polar regions, providing quantitative SAR satellite data and images for surveying and mapping, earthquake, land, disaster reduction, ocean, forestry, transportation, water conservancy and other industries.

[0003] A SAR system primarily consists of a highly integrated central electronics unit and a lightweight active phased array SAR antenna. The central electronics unit comprises a digital integration unit, a radio frequency integration unit, a radar distributor, and high-frequency cables. The SAR phased array antenna comprises the antenna radiating surface, a time-delay T / R module, a driver amplifier module, a time-delay R module, a power splitter network, a high-frequency cable network, a low-frequency cable network, a deployment, compression, and release mechanism, and a thermal control module. A phased array antenna modulates the shape of its radiation pattern by controlling the feed phase of the radiating elements in the array. Phase control can alter the direction of the antenna's maximum radiation pattern, achieving beam scanning. Mechanical antenna rotation suffers from high inertia and slow speeds, but phased array antennas overcome these drawbacks, achieving high beam scanning speeds. Their feed phase is typically computer-controlled, allowing for rapid phase changes (on the order of milliseconds), resulting in rapid changes in the antenna's maximum radiation pattern and other parameters. This is the defining characteristic of phased array antennas.

[0004] To achieve beam scanning capabilities in both range and azimuth, SAR antennas primarily utilize a two-dimensional scanning plane solid-state active phased array. The RF link is primarily fed by transmission line feeding. In this method, RF energy is transmitted from central electronic equipment to each radiating element (TR component) via microwave transmission lines such as waveguides, coaxial cables, and microstrip lines. The transmission line feed circuitry is complex, primarily consisting of various power dividers and interconnected high-frequency cable networks. When the number of antenna channels is large or the antenna spatial layout is complex, the RF transceiver links and system calibration links are interwoven. This increases the weight and complexity of the entire system feed network, hindering the miniaturization and integration of spaceborne SAR. Summary of the Invention

[0005] To address the aforementioned technical issues, the present invention provides a circuit structure and design method for a high-isolation SAR antenna feed assembly. This design utilizes a stripline power divider structure to integrate the antenna's RF transceiver link and calibration link into a single component. A high-frequency blind-plug connector directly connects the antenna's radiating element (TR) RF link, calibration link, and delay assembly. This eliminates the need for high-frequency cable assemblies between channels, conserves vertical antenna space, significantly increases antenna integration, and reduces overall weight. The use of metallized through-holes (PTHs), metallized blind and buried vias (BVBs), and a metal shielding shell for the isolation resistor / high-frequency coaxial connector effectively improves component spacing and inter-channel isolation. Furthermore, the modular design facilitates system maintenance, replacement, and troubleshooting.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A high-isolation SAR antenna feed assembly circuit structure includes a radio frequency transceiver link, a calibration transceiver link, a vertical blind slot, a high-power isolation resistor, a high-frequency coaxial connector, a metallized blind buried via, a metallized through-hole, a metal shielding shell of the isolation resistor, a metal shielding shell of the high-frequency coaxial connector, a dielectric plate, and a quasi-coaxial vertical circuit conversion structure;

[0008] The radio frequency transceiver link and the calibration transceiver link are located on different signal layers of different dielectric boards; the different dielectric boards are stacked by a printing process;

[0009] The radio frequency transceiver link and the calibration transceiver link each include at least one set of vertical blind slots and a high-power isolation resistor. The number of the vertical blind slots and the high-power isolation resistor is N, and the two are configured in a one-to-one correspondence. N is an integer greater than or equal to 1. The number N is the same as the number of stages of the Wilkinson power divider circuit prototype. The number of stages of the Wilkinson power divider circuit prototype is determined by the operating frequency band and bandwidth of the SAR antenna. The size of the vertical blind slot is determined according to the packaging structure of the high-power isolation resistor. The depth of the vertical blind slot is determined according to the number of layers of the striplines at each level of the Wilkinson power divider circuit prototype.

[0010] The high-frequency coaxial connector passes through all dielectric boards in a straight-in manner through a quasi-coaxial vertical circuit conversion structure and is respectively connected to the radio frequency transceiver link and the calibration transceiver link;

[0011] There are a number of metallized blind buried vias. When the metallized blind buried via passes through the signal layer where each RF transceiver link or each calibration transceiver link is located, both ends are connected to the two ground layers adjacent to the signal layer where each RF transceiver link or each calibration transceiver link is located. When the metallized blind buried via is arranged around the high-frequency coaxial connector, it only passes through the signal layer where the calibration transceiver link is located and both ends are connected to the two ground layers adjacent to the signal layer where the calibration transceiver link is located, or it only passes through the signal layer where the RF power splitter transceiver link is located and both ends are connected to the two ground layers adjacent to the signal layer where the RF power splitter transceiver link is located.

[0012] The metallized through-hole is hollow and penetrates the entire dielectric plate, and a plurality of metallized through-holes are arranged in a linear outline to surround all signal lines of the dielectric plate;

[0013] The isolation resistor metal shielding shell is arranged on the top layer of the dielectric plate and covers all vertical blind slots including the high-power isolation resistor;

[0014] The high-frequency coaxial connector metal shielding shell is arranged at and completely covers the output end of the high-frequency coaxial connector signal pin and the shell pin;

[0015] The quasi-coaxial vertical circuit conversion structure includes a first metallized via and a circle of equidistant metallized vias around the first metallized via. The diameter of the first metallized via is larger than the diameter of the central conductor of the high-frequency coaxial connector.

[0016] Furthermore, the number of the quasi-coaxial vertical circuit conversion structures is the same as the number of the high-frequency coaxial connectors and the two correspond one to one.

[0017] On the other hand, the present invention also provides a method for designing a circuit structure of a high-isolation SAR antenna feed assembly, comprising the following steps:

[0018] Step S1: Determine the routing method and the required number of dielectric layers for the interface between the RF transceiver link and the calibration transceiver link based on the SAR antenna layout and the number and location of the T / R component channels;

[0019] Step S2: Select the number of stages of the Wilkinson power divider circuit prototype according to the operating frequency band and bandwidth and calculate the stripline width of each stage;

[0020] Step S3: Opening vertical blind slots at corresponding positions of the high-power isolation resistors at each level. The size of the vertical blind slots is determined according to the packaging structure of the high-power isolation resistors, and the depth of the vertical blind slots is determined according to the number of layers of the strip lines at each level.

[0021] Step S4: Designing metal shielding shells for the isolation resistors at the vertical blind slots corresponding to the positions of the high-power isolation resistors at each level, and performing simulation optimization on the dimensions of the metal shielding shells for the isolation resistors with the goal of not generating resonance within the circuit operating frequency band;

[0022] Step S5: inserting the high-frequency coaxial connector through the dielectric board through the quasi-coaxial vertical circuit conversion structure and connecting the RF transceiver link and the calibration transceiver link respectively, placing a high-frequency coaxial connector metal shielding shell on the welding surface of the high-frequency coaxial connector to cover all pins of the high-frequency coaxial connector, and adjusting the size of the high-frequency coaxial connector metal shielding shell according to the operating frequency band of the circuit;

[0023] Step S6: setting metallized through holes through all dielectric plates, wherein the metallized through holes completely surround the strip lines transmitting signals, and the metallized through holes do not interfere with any non-ground layers;

[0024] Step S7: Designing metalized blind buried vias for the routing layer of the RF transceiver link and the routing layer of the calibration transceiver link, respectively. The two ends of the metalized blind buried vias are connected to two ground layers adjacent to the signal layer where the RF transceiver link or the calibration transceiver link is located.

[0025] Step S8: Metalized blind and buried vias are provided around the high-frequency coaxial connector, passing through the signal layer where the calibration transceiver link is located and connecting two ground layers adjacent to the signal layer where the calibration transceiver link is located at both ends; or passing through the signal layer where the RF transceiver link is located and connecting two ground layers adjacent to the signal layer where the RF transceiver link is located at both ends;

[0026] Step S9: Modeling, simulation and optimization are performed on the entire high-isolation SAR antenna feeding component circuit structure to complete the circuit function design.

[0027] Furthermore, the method further comprises the following steps:

[0028] Step S10: Assuming that the circuit structure of the high-isolation SAR antenna feed assembly includes multiple circuit layers stacked from top to bottom, etching a first circular matching structure at the top circuit location where the high-frequency coaxial connector is located, so that the center conductor of the high-frequency coaxial connector is located at the center of the first circular matching structure;

[0029] Step S11: providing a first metallized via hole at the center of the high-frequency coaxial connector, wherein the diameter of the first metallized via hole is larger than the diameter of the center conductor of the high-frequency coaxial connector;

[0030] Step S12: four second metallized vias are provided at the pin positions of the high-frequency coaxial connector housing to keep the high-frequency coaxial connector fixed for welding assembly;

[0031] Step S13: etching a second circular matching structure at the bottom circuit position where the high-frequency coaxial connector is located;

[0032] Step S14: a disc-shaped structure is provided at a position perpendicular to the center conductor of the high-frequency coaxial connector at the signal layer where the RF transceiver link and the calibration transceiver link are located, respectively, to electrically connect the center conductor of the high-frequency coaxial connector to each other;

[0033] Step S15: With the center of the first metallized via as the center of the circle, a circle of equidistant metallized vias is arranged to connect the top-layer circuit and the bottom-layer circuit. The circle of equidistant metallized vias and the first metallized via form a quasi-coaxial vertical circuit conversion structure. The inner conductor radius of the quasi-coaxial vertical circuit conversion structure is the radius of the first metallized via, and the outer conductor radius is the distance from the circle of equidistant metallized vias to the first metallized via.

[0034] Step S16: cascaded quarter-wavelength conversion lines are set according to the circuit operating frequency band to compensate for the impedance jump caused by the transformation from the quasi-coaxial vertical circuit conversion structure to the stripline feeding structure;

[0035] Step S17: adjusting the first circular matching structure and the second circular matching structure, and adjusting the quasi-coaxial vertical circuit conversion structure according to the dielectric constant of the dielectric plate, to optimize the overall transmission performance and obtain a final design result.

[0036] The beneficial effects of the present invention are:

[0037] Compared with the traditional microstrip line structure, the internal routing of the present invention does not need to consider the structural metal shell, saving a lot of weight; it has high integration and flexible circuit design, and makes full use of the vertical space of the printed circuit board, which is in line with the new modular system development direction of SAR antennas, effectively reducing the use of cables between modules, relying on metallized through-holes to achieve electromagnetic isolation, and has good anti-electromagnetic interference capability; blind buried metallized holes with different penetration layers are designed to achieve high isolation between calibration RF links, effectively reducing the risk of antenna self-excitation; in actual production, only the connector position needs to be welded, which is convenient for mass production and debugging on the assembly line, and effectively reduces production costs; in addition, the present invention has no external exposed signal lines and has good electromagnetic compatibility effects; the design of high-power isolation resistors solves the problem of insufficient power resistance in the buried resistor process; since the isolation resistor position is a blind slot, some signal lines inside are exposed to the outside of the medium and the signal pins at some positions of the connector are exposed, metal shielding caps are provided to effectively prevent external signal crosstalk. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the first hierarchical structure of a circuit structure of a high-isolation SAR antenna feeding component according to the present invention;

[0039] Figure 2 This is a schematic diagram of a second hierarchical structure of a circuit structure of a high-isolation SAR antenna feeding component according to the present invention;

[0040] Figure 3 This is a schematic diagram of the third hierarchical structure of a circuit structure of a high-isolation SAR antenna feeding component according to the present invention;

[0041] Figure 4 This is a schematic diagram of a fourth layered structure of a circuit structure of a high-isolation SAR antenna feeding assembly according to the present invention;

[0042] Figure 5 A schematic diagram of component stacking of a circuit structure of a high-isolation SAR antenna feed assembly according to the present invention;

[0043] Figure 6 Schematic diagram of a coaxial stripline conversion structure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0045] A power divider (or power splitter) is a multi-port passive microwave network that splits the input signal power into several equal or unequal output signals. It is widely used for power distribution or power combining. The Wilkinson power splitter structure, ideally, achieves matching and lossless operation at all circuit ports. The addition of port isolation resistors effectively improves port isolation, leading to its widespread application. Wilkinson power splitters are widely used in radar antenna feed systems. External isolation resistors effectively improve circuit isolation. Utilizing the quarter-wavelength line theory, the amplitude and phase balance of the output ports depends primarily on circuit symmetry, resulting in a wide bandwidth.

[0046] The present invention provides a circuit structure and design method for a high-isolation SAR antenna feeding component. Based on a Wilkins power divider circuit prototype with a stripline structure, a high-frequency blind-plug connector is used to lead the signal from the inner layer circuit of the stripline to connect it to the TR interface of each level, thereby solving the defect that the stripline circuit is not easy to integrate with the microwave component. For the traditional microstrip line circuit structure, the signal of the present invention is located in the inner layer of the printed circuit board, which has a good electromagnetic shielding effect. For the defect of low power tolerance of the traditional buried resistor process, the present invention adopts a blind groove scheme and sets a high-power radio frequency resistor to improve the power tolerance of the component. For the application scenario of SAR antenna, the radio frequency channel and the calibration channel are integrated into the same component, such as Figure 1-4As shown in the figure, it is a layered schematic diagram of the structure of the circuit structure of an embodiment of the present invention. The RF transceiver link 1 and the calibration transceiver link 2 are placed on the same circuit board in a plug-in manner via a high-frequency coaxial connector 3. Both links have power distribution and power synthesis functions. The signal is transmitted to the corresponding T / R RF transceiver interface and TR calibration transceiver interface through power division, which effectively reduces the overall weight of the component; the inner layer of the circuit is provided with metallized blind buried vias (first metallized blind buried via 7 and second metallized blind buried via 8) of different through-layers for shielding, which effectively isolates the crosstalk between the RF transceiver link 1 and the calibration transceiver link 2, thereby increasing the isolation between the links; the solution of the present invention is only at the connector port position and the high-power isolation resistor (such as Figure 1 The second high power isolation resistor 4 and Figure 2 The blind slot (such as the first high power isolation resistor 11) is located Figure 2 The second blind groove 12 and Figure 3 A metal shielding shell (such as Figure 1 The high power isolation resistor shielding shell 5 and Figure 4 The high-frequency coaxial connector metal shielding shell (9) structure shown prevents electromagnetic wave leakage and enhances the electromagnetic compatibility of the antenna module. Compared to traditional microstrip line structures, it eliminates the need for a large metal shell and utilizes numerous internal metallized through-holes to achieve shielding from complex external electromagnetic environments. This effectively reduces weight and allows for flexible vertical space adjustment based on antenna configuration. This invention features a simple basic circuit principle, a simple design and implementation process, and a compact structure, making it easy to manufacture using multi-layer PCBs. It also requires low circuit processing precision and has excellent engineering application value.

[0047] The present invention is described in detail below. On the one hand, Figure 5 Figure 1 shows a schematic diagram of a stacked circuit structure of a high-isolation SAR antenna feed assembly. The circuit structure includes a radio frequency transceiver link 1, a calibration transceiver link 2, a vertical blind slot, a high-power isolation resistor, a high-frequency coaxial connector 3, metallized blind buried vias, a metallized through-hole, an isolation resistor metal shielding shell 5, a high-frequency coaxial connector metal shielding shell 9, a dielectric board, and a quasi-coaxial vertical circuit conversion structure.

[0048] The RF transceiver link 1 and the calibration transceiver link 2 are located on different signal layers of different dielectric boards, have the same number of channels, and have adjacent interfaces.

[0049] The number of the vertical blind slots and the high-power isolation resistors is N, and the two correspond one to one, N is an integer greater than or equal to 1, the number N is the same as the number of stages of the Wilkinson power divider circuit prototype, the number of stages of the Wilkinson power divider circuit prototype is determined by the operating frequency band and bandwidth of the SAR antenna, the size of the vertical blind slot is determined according to the packaging structure of the high-power isolation resistor, the depth of the vertical blind slot is determined according to the number of layers of the strip lines of each level of the Wilkinson power divider circuit prototype, and the RF transceiver link 1 and the calibration transceiver link 2 respectively include at least one group of vertical blind slots and high-power isolation resistors;

[0050] The high-frequency coaxial connector 3 passes through all dielectric boards in a straight-in manner through a quasi-coaxial vertical circuit conversion structure and is respectively connected to the RF transceiver link 1 and the calibration transceiver link 2;

[0051] The dielectric board includes a plurality of metalized blind buried vias. When the metalized blind buried via passes through the signal layer where each RF transceiver link 1 or each calibration transceiver link 2 is located, the two ends are connected to the two ground layers adjacent to the signal layer where each RF transceiver link 1 or each calibration transceiver link 2 is located; when the metalized blind buried via is arranged around the high-frequency coaxial connector 3, it only passes through the signal layer where the calibration transceiver link 2 is located and the two ends are connected to the two ground layers adjacent to the signal layer where the calibration transceiver link 2 is located, or it only passes through the signal layer where the RF transceiver link 1 is located and the two ends are connected to the two ground layers adjacent to the signal layer where the RF transceiver link 1 is located;

[0052] The metallized through holes are hollow and penetrate the entire dielectric plate, and a plurality of metallized through holes are arranged in a linear outline to surround all signal lines of the dielectric plate;

[0053] The isolation resistor metal shielding shell 5 is arranged on the top layer of the dielectric board and covers all blind slots including the high-power isolation resistor;

[0054] The high-frequency coaxial connector metal shielding shell 9 is arranged at and completely covers the output ends of the signal pins and the shell pins of the high-frequency coaxial connector 3 .

[0055] The quasi-coaxial vertical circuit conversion structure is installed at all high-frequency coaxial connector locations to connect external signals to the internal stripline circuit. The quasi-coaxial vertical circuit conversion structure includes a first metallized via and a circle of equidistant metallized vias 6 around the first metallized via. The diameter of the first metallized via is larger than the diameter of the center conductor of the high-frequency coaxial connector 3. The number of quasi-coaxial vertical circuit conversion structures is the same as the number of high-frequency coaxial connectors 3, and the two correspond one-to-one. The stacking relationship of each component is further explained as shown in Table 1 below.

[0056] Table 1

[0057] name effect First circuit layer, third circuit layer, fourth circuit layer, sixth circuit layer Component metal ground layer, mainly used for grounding and isolating signals on different layers Second circuit layer, fifth circuit layer Signal lines, different layers of routing respectively complete RF transceiver / calibration transceiver functions First prepreg layer, second prepreg layer, third prepreg layer Prepreg, press the material required for PCB board and play a bonding role First dielectric layer, second dielectric layer, third dielectric layer, fourth dielectric layer PCB board substrate materials, pressed together in pairs with the second and fifth circuit layers to form strip lines First blind groove 13, second blind groove 12 The printed circuit board is obtained by laser milling, from the top layer of the circuit to the bottom, the second and fifth circuit layers of the required inner layer signal lines are exposed in a small area The first high power isolation resistor 11 and the second high power isolation resistor 4 The basic principle of the power divider is required. The specific resistance value is calculated according to the number of stages, and the package is selected according to the power resistance performance of the component. Isolation resistor metal shielding shell 5, high-frequency coaxial connector metal shielding shell 9 Limit the radiation of exposed signal lines to the inside of the cavity to prevent interference between channels and modules Metalized through holes The different layers inside the PCB are electrically interconnected, and the coaxial conversion structure at the connector of the present invention plays the role of forming a coaxial structure. First metallized blind buried via 7, second metallized blind buried via 8 Connected to the circuit ground layer of different layers of links to shield the signal Connector shell pins Connected to the connector housing for grounding Connector signal pins Interconnected with the components to transmit signals

[0058] On the other hand, the present invention also provides a method for designing a circuit structure of a high-isolation SAR antenna feed assembly, comprising the following steps:

[0059] Step S1: Determine the interface location and routing method and the required number of dielectric layers for the RF transceiver link 1 and the calibration transceiver link 2 based on the SAR antenna layout and the number and location of TR channels;

[0060] Step S2: Select the number of stages of the Wilkinson power divider circuit prototype according to the operating frequency band and bandwidth and calculate the required stripline widths of each stage. In Example A, the operating frequency band is the L band and a second-order Wilkinson power divider circuit prototype is used;

[0061] Step S3: Taking the RF transceiver and calibration link as an example, vertical blind slots are opened at the positions corresponding to the isolation resistors at each level of the circuit, such as Figure 2 The second blind groove 12 and Figure 3 The first blind groove 13 shown in FIG. 1 has a size determined by the selected RF resistor package and a depth determined by the number of layers where the signal line is located, thereby retaining sufficient high-power isolation resistors (such as Figure 1 The second high power isolation resistor 4 and Figure 2 The first high power isolation resistor 11) is shown as a welding space;

[0062] Step S4: Design a high-power isolation resistor metal shielding shell 5 at the isolation resistor blind slot position, and optimize the size through simulation to ensure that no resonance occurs within or near the circuit operating frequency band;

[0063] Step S5: Modeling and simulation optimization of the entire circuit to complete the basic functional design of the circuit;

[0064] Step S6: Taking the RF transceiver and calibration links as an example, which both include a four-channel configuration, including a first dielectric layer, a second dielectric layer, and first to third circuit layers, a first circular matching structure is designed and etched at the connector mounting position on the first circuit layer to ensure that the connector center conductor is located at the center of the circle;

[0065] Step S7: Set a metalized via hole at the center position, with a diameter slightly larger than the diameter of the connector center conductor to ensure that the center conductor can be freely inserted;

[0066] Step S8: providing metallized vias at corresponding locations of the connector fixing pins so that the connector can remain fixed for welding assembly;

[0067] Step S9: Design and etch a second circular matching structure at a position on the third circuit layer just below the first circuit layer;

[0068] Step S10: The second circuit layer is a stripline structure, and a disc-shaped structure is provided at a position perpendicular to the connector conductor to ensure that the center conductor is electrically connected to the connector conductor;

[0069] Step S11: Set the cascaded quarter-wavelength impedance transformation matching structure (such as Figure 6 The quarter-wavelength impedance transformation and matching structure 10 shown in FIG1 (1 / 2 in FIG1) is connected to the RF transceiver link 1 or the calibration transceiver link 2) to compensate for the impedance jump caused by the transformation of the coaxial line to the stripline feeding structure. In the embodiment, only a single-stage transformation line structure is shown. Multiple quarter-wavelength transformation line structures can be used for compensation according to bandwidth requirements.

[0070] Step S12: With the center of the central metallized hole as the center of the circle, a circle of equidistant metallized vias 6 (connecting the first and third circuit layers) is set to form a vertical quasi-coaxial structure with the central metallized via structure, such as Figure 6 As shown (the metallized via 6 shown in the figure forms a vertical quasi-coaxial structure with the central hole). The inner conductor radius of the quasi-coaxial structure is the radius of the central metallized via, and the outer conductor radius is the distance from the surrounding metallized holes to the central metallized hole.

[0071] Step S13: Adjust the circular matching structure, including the first circular matching structure and the second circular matching structure on the first and third circuit layers, and adjust the coaxial line structure, i.e., the distance from the metallized vias in a circle to the center, according to the dielectric constant of the dielectric plate used. Adjust the quarter-wavelength impedance transformation line structure according to the center frequency of the circuit design to optimize the overall transmission performance and obtain the final design result.

[0072] Step S14: a high-frequency coaxial connector metal shielding shell 9 is provided at the welding surface of the high-frequency coaxial connector 3 to cover all pins. The size of the shielding shell is adjusted according to the operating frequency band of the circuit so that the shielding shell does not resonate with the circuit within the operating frequency band and prevents electromagnetic wave leakage. The function is the same as step S4.

[0073] Step S15: Based on the internal circuit routing of the component, metallized through holes are set to penetrate the entire printed circuit board and completely surround the signal lines. The metallized through holes are set to not interfere with any non-ground circuit layers, which can effectively increase the anti-interference ability of external signals;

[0074] Step S16: The RF link routing layer is the second circuit layer, with blind slots running through the first to third circuit layers, and the calibration link routing layer is the fifth circuit layer, with blind slots running through the first to fifth circuit layers, as shown in the stackup diagram. Figure 5 As shown, the first metallized blind buried via 7 and the second metallized blind buried via 8 can effectively isolate the signal transmitted through the side wall of the blind groove and then through the medium, effectively increasing the isolation between the RF / calibration link;

[0075] Step S17: Similarly, since the signal pins in each high-frequency coaxial connector 3 vertically penetrate the entire component printed circuit board, most of the signal enters the internal stripline circuit through the link to which it belongs, but a small amount of signal still leaks through the dielectric layer to non-links. Therefore, the metallized blind buried vias arranged near the connector also have an isolation effect;

[0076] Step S18: Simulate and optimize the overall circuit structure to achieve the design technical indicators.

[0077] The present invention is also applicable to designs of vertical structures with more layers and more channels.

[0078] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-isolation SAR antenna feed assembly circuit structure, characterized in that: Including RF transceiver link, calibration transceiver link, vertical blind slot, high-power isolation resistor, high-frequency coaxial connector, metallized blind buried via, metallized through hole, isolation resistor metal shielding shell, high-frequency coaxial connector metal shielding shell, dielectric board, quasi-coaxial vertical circuit conversion structure; The radio frequency transceiver link and the calibration transceiver link are located on different signal layers of different dielectric boards; the different dielectric boards are stacked by a board manufacturing process; The radio frequency transceiver link and the calibration transceiver link each include at least one set of vertical blind slots and a high-power isolation resistor. The number of the vertical blind slots and the high-power isolation resistor is N, and the two are configured in a one-to-one correspondence. N is an integer greater than or equal to 1. The number N is the same as the number of stages of the Wilkinson power divider circuit prototype. The number of stages of the Wilkinson power divider circuit prototype is determined by the operating frequency band and bandwidth of the SAR antenna. The size of the vertical blind slot is determined according to the packaging structure of the high-power isolation resistor. The depth of the vertical blind slot is determined according to the number of layers of the striplines at each level of the Wilkinson power divider circuit prototype. The high-frequency coaxial connector passes through all the dielectric boards of the circuit through the quasi-coaxial vertical circuit conversion structure in a straight-in manner and is respectively connected to the radio frequency transceiver link and the calibration transceiver link; There are a number of metallized blind buried vias. When the metallized blind buried via passes through the signal layer where each RF transceiver link or each calibration transceiver link is located, both ends are connected to the two ground layers adjacent to the signal layer where each RF transceiver link or each calibration transceiver link is located. When the metallized blind buried via is arranged around the high-frequency coaxial connector, it only passes through the signal layer where the calibration transceiver link is located and both ends are connected to the two ground layers adjacent to the signal layer where the calibration transceiver link is located, or it only passes through the signal layer where the RF transceiver link is located and both ends are connected to the two ground layers adjacent to the signal layer where the RF transceiver link is located. The metallized through holes are hollow and penetrate all dielectric plates, and a plurality of metallized through holes are arranged in a linear outline to surround all signal lines of the dielectric plates; The isolation resistor metal shielding shell is arranged on the top layer of the dielectric plate and covers all vertical blind slots including the high-power isolation resistor; The high-frequency coaxial connector metal shielding shell is arranged at and completely covers the output end of the high-frequency coaxial connector signal pin and the shell pin; The quasi-coaxial vertical circuit conversion structure includes a first metallized via and a circle of equidistant metallized vias around the first metallized via. The diameter of the first metallized via is larger than the diameter of the central conductor of the high-frequency coaxial connector.

2. The high-isolation SAR antenna feeding component circuit structure according to claim 1, characterized in that: The number of the quasi-coaxial vertical circuit conversion structures is the same as the number of the high-frequency coaxial connectors, and the two correspond one to one.

3. A design method for a high-isolation SAR antenna feed assembly circuit structure, characterized in that: The steps include: Step S1: Determine the routing method and the required number of dielectric layers for the interface between the RF transceiver link and the calibration transceiver link based on the SAR antenna layout and the number and location of the T / R component channels; Step S2: Select the number of stages of the Wilkinson power divider circuit prototype according to the operating frequency band and bandwidth and calculate the stripline width of each stage; Step S3: Opening vertical blind slots at corresponding positions of the high-power isolation resistors at each level. The size of the vertical blind slots is determined according to the packaging structure of the high-power isolation resistors, and the depth of the vertical blind slots is determined according to the number of layers of the strip lines at each level. Step S4: Designing metal shielding shells for the isolation resistors at the vertical blind slots corresponding to the positions of the high-power isolation resistors at each level, and performing simulation optimization on the dimensions of the metal shielding shells for the isolation resistors with the goal of not generating resonance within the circuit operating frequency band; Step S5: inserting the high-frequency coaxial connector through the dielectric board through the quasi-coaxial vertical circuit conversion structure and connecting the RF transceiver link and the calibration transceiver link respectively, placing a high-frequency coaxial connector metal shielding shell on the welding surface of the high-frequency coaxial connector to cover all pins of the high-frequency coaxial connector, and adjusting the size of the high-frequency coaxial connector metal shielding shell according to the operating frequency band of the circuit; Step S6: setting a metallized through hole through the entire dielectric plate, wherein the metallized through hole completely surrounds the strip line transmitting the signal, and the metallized through hole does not interfere with any non-ground layer; Step S7: Designing metalized blind buried vias for the routing layer of the RF transceiver link and the routing layer of the calibration transceiver link, respectively. The two ends of the metalized blind buried vias are connected to two ground layers adjacent to the signal layer where the RF transceiver link or the calibration transceiver link is located. Step S8: Metalized blind and buried vias are provided around the high-frequency coaxial connector, passing through the signal layer where the calibration transceiver link is located and connecting two ground layers adjacent to the signal layer where the calibration transceiver link is located at both ends; or passing through the signal layer where the RF transceiver link is located and connecting two ground layers adjacent to the signal layer where the RF transceiver link is located at both ends; Step S9: Modeling, simulation and optimization are performed on the entire high-isolation SAR antenna feeding component circuit structure to complete the circuit function design.

4. The method for designing a circuit structure of a high-isolation SAR antenna feed assembly according to claim 3, wherein: The design method further comprises the following steps: Step S10: Assuming that the circuit structure of the high-isolation SAR antenna feed assembly includes multiple circuit layers stacked from top to bottom, etching a first circular matching structure at the top circuit location where the high-frequency coaxial connector is located, so that the center conductor of the high-frequency coaxial connector is located at the center of the first circular matching structure; Step S11: providing a first metallized via hole at the center of the high-frequency coaxial connector, wherein the diameter of the first metallized via hole is larger than the diameter of the center conductor of the high-frequency coaxial connector; Step S12: four second metallized vias are provided at the pin positions of the high-frequency coaxial connector housing to keep the high-frequency coaxial connector fixed for welding assembly; Step S13: etching a second circular matching structure at the bottom circuit position where the high-frequency coaxial connector is located; Step S14: a disc-shaped structure is provided at a position perpendicular to the center conductor of the high-frequency coaxial connector at the signal layer where the RF transceiver link and the calibration transceiver link are located, respectively, to electrically connect the center conductor of the high-frequency coaxial connector to each other; Step S15: With the center of the first metallized via as the center of the circle, a circle of equidistant metallized vias is arranged to connect the top-layer circuit and the bottom-layer circuit. The circle of equidistant metallized vias and the first metallized via form a quasi-coaxial vertical circuit conversion structure. The inner conductor radius of the quasi-coaxial vertical circuit conversion structure is the radius of the first metallized via, and the outer conductor radius is the distance from the circle of equidistant metallized vias to the first metallized via. Step S16: cascaded quarter-wavelength conversion lines are set according to the circuit operating frequency band to compensate for the impedance jump caused by the transformation from the quasi-coaxial vertical circuit conversion structure to the stripline feeding structure; Step S17: adjusting the first circular matching structure and the second circular matching structure, and adjusting the quasi-coaxial vertical circuit conversion structure according to the dielectric constant of the dielectric plate, to optimize the overall transmission performance and obtain a final design result.

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