Low-cost strip line power combiner for multi-beam phased array

Abstract

The invention provides a low-cost strip line power combiner for a multi-beam phased array. Comprising a microwave multilayer printed board, a strip line input port, a strip line, two power division strip lines, a first strip line output port, a second strip line output port, an isolation end strip line feeder line via hole, a coaxial matching grounding via hole, an isolation resistor surface-mounted bonding pad and an isolation resistor. The two strip line output ports are isolated by adopting two sections of 1 / 2 wavelength isolation end strip line feeder line via holes and coaxial matched grounding via holes thereof, and the port isolation design can lead an isolation resistor surface-mounted bonding pad of an isolation resistor of the power combiner to a surface layer / bottom layer of a printed board, so that SMT welding of the isolation resistor is facilitated; therefore, the buried resistor design and the corresponding process phase procedure of the strip line power combiner are avoided, and the design cost of the microwave multilayer printed board is greatly reduced; a microwave high-frequency surface-mounted resistor is used, and the design can be applied to frequency bands above Ka.

Description

Technical Field

[0001] The invention relates to the technical field of electronic components, and in particular to a low-cost stripline power synthesizer for a multi-beam phased array. Background Art

[0002] With the development of microwave multilayer printed circuit board technology in recent years. More and more analog phased array antennas adopt low-cost phased array solutions based on microwave multilayer boards, that is, the packaged TR chip transceiver front end and the phased array antenna array are integrated on a microwave multilayer printed circuit board, thereby improving the integration and reducing the overall cost of the phased array antenna. However, with the increase in the frequency of the phased array antenna and the requirements of the phased array antenna for multiple beams, the low-cost phased array solution based on the microwave multilayer board has encountered a bottleneck in the design of the power synthesis network. On the one hand, with the increase in frequency, the "skin effect" of the traditional microstrip line power synthesis network based on the surface of the printed circuit board is enhanced, resulting in an increase in the external radiation signal of the network. This phenomenon easily leads to the "self-excitation" of the TR phased array chip component designed on the same surface of the printed circuit board as the microstrip power synthesis network, and it is necessary to select a stripline power synthesis network with higher RF signal shielding. On the other hand, the multi-beam phased array requires multiple power synthesis networks with high shielding, which requires multiple stripline power synthesis networks to be stacked and integrated in a microwave multilayer printed circuit board to meet the requirements.

[0003] Since the traditional stripline power combiner is completely designed in the middle layer of the printed circuit board, it is impossible to achieve output port isolation through the SMT isolation resistor mounting on the surface of the microstrip line. The output port isolation of the traditional stripline power combiner is generally achieved by using high-cost buried copper foil on the stripline metal layer. The main cost of the buried copper foil is NI-P alloy. The isolation resistor is achieved through the aspect ratio of the material. This material is extremely expensive, and the resistance layer of the buried copper foil is only 2um thick. It is easy to fail due to process reasons during the processing of multi-layer printed circuit boards, and it is difficult to monitor its failure. Multi-beam phased array antennas require multiple power synthesis networks, and the corresponding microwave multi-layer printed circuit boards often require multiple layers of buried copper foil. Ultimately, the processing and production costs of microwave multi-layer printed circuit boards will rise rapidly, thus losing the original intention of the "low cost" of the phased array solution.

[0004] Based on the above requirements, a low-cost power combiner based on stripline is needed, which can ensure good power combining characteristics, output port isolation and electromagnetic shielding performance. On the other hand, the isolation scheme of the output port should try to avoid the use of "buried copper foil" process, which will increase the processing cost of the printed circuit board. Summary of the invention

[0005] The present invention aims to solve the problem of the difficulty of burying resistance of a power combiner, and provides a low-cost stripline power combiner for a multi-beam phased array. Two stripline output ports are isolated by using two sections of 1 / 2 wavelength isolation end stripline feeder vias and coaxial matching ground vias. The port isolation design can lead the isolation resistor surface mount pad of the isolation resistor of the power combiner to the surface layer / bottom layer of a printed circuit board, so as to facilitate the SMT welding of the isolation resistor, thereby avoiding the buried resistance design of the stripline power combiner and the corresponding process procedures, and greatly reducing the design cost of a microwave multilayer printed circuit board; using microwave high-frequency surface mount resistors, the design can be used in frequency bands above Ka.

[0006] The present invention provides a low-cost stripline power synthesizer for a multi-beam phased array, comprising a microwave multilayer printed board, a stripline input port connected to one end of the microwave multilayer printed board, a stripline connected to the stripline input port and connected in the microwave multilayer printed board, two power-dividing striplines for dividing the stripline output into two paths, a first stripline output port and a second stripline output port respectively connected to the two power-dividing stripline output ends, an isolation-end stripline feeder via hole for isolating the first stripline output port and the second stripline output port, a coaxial matching grounding via hole arranged around the isolation-end stripline feeder via hole and connected in the microwave multilayer printed board for impedance matching, and an isolation resistor surface-mount pad and an isolation resistor sequentially connected to the other end of the isolation-end stripline feeder via hole;

[0007] The impedances of the stripline input port, the stripline, the first stripline output port, and the second stripline output port are all the same;

[0008] The two power dividing strip lines divide the input power into two, and the first strip line output port and the second strip line output port output signals with equal amplitude and same phase;

[0009] The isolated end stripline feeder via hole comprises an isolated end stripline and a coaxial feeder via hole which are sequentially connected to the power dividing stripline output end, and the coaxial feeder via hole passes through the microwave multilayer printed board;

[0010] The isolation resistor surface mount pad and the isolation resistor are located on the surface or bottom layer of the microwave multilayer printed circuit board.

[0011] The low-cost stripline power combiner for a multi-beam phased array described in the present invention is the most preferred embodiment, in which the impedances of the stripline input port, the stripline, the first stripline output port and the second stripline output port are all 50 ohms, the length of the power dividing stripline is 1 / 4 wavelength, and the physical length of the stripline feeder via at the isolation end is 1 / 2 wavelength.

[0012] In the most preferred embodiment of the low-cost stripline power combiner for a multi-beam phased array described in the present invention, the impedances of the two power-dividing striplines are both 70.7 ohms.

[0013] The low-cost stripline power combiner for a multi-beam phased array described in the present invention is most preferably configured such that the number of vias of the isolation end stripline and the coaxial feed line are both two, and the two isolation end striplines are respectively connected to the output ends of the two power splitter striplines.

[0014] The low-cost stripline power combiner for multi-beam phased array described in the present invention is the most preferred mode, the wavelength of the isolated end stripline and the coaxial feed line via in the medium is the same as the wavelength in vacuum, and the physical length is consistent with the electrical length:

[0015]

[0016] in, is the wavelength of the isolation end stripline and coaxial feed line via in the medium, is the wavelength of the isolated end stripline and coaxial feed line via in vacuum.

[0017] The low-cost stripline power combiner for a multi-beam phased array described in the present invention is most preferably configured such that the length of the coaxial feed line via hole can be adjusted according to the length of the stripline at the isolation end. When the length of the coaxial feed line via hole is greater than 1 / 4 wavelength, the length of the stripline at the isolation end is less than 1 / 4 wavelength.

[0018] The low-cost stripline power combiner for a multi-beam phased array described in the present invention is preferably configured such that the characteristic impedance of the stripline feeder via at the isolation end is 70.7 ohms;

[0019] The coaxial matching ground via is a feed line via that matches around the coaxial feed line via.

[0020] In the most preferred embodiment of the low-cost stripline power combiner for a multi-beam phased array of the present invention, the resistance of the isolation resistor is 100 ohms.

[0021] In the most preferred embodiment of the low-cost stripline power combiner for a multi-beam phased array of the present invention, the isolation resistor is a packaged SMT resistor.

[0022] The low-cost stripline power combiner for a multi-beam phased array described in the present invention is the most preferred embodiment. The low-cost stripline power combiner can be applied to frequency bands above Ka.

[0023] The present invention has the following advantages:

[0024] (1) The two stripline output port isolations of the present invention use two sections of 1 / 2 wavelength isolation end stripline feeder vias and their coaxial matching ground vias. The port isolation design can lead the isolation resistor surface mount pads of the isolation resistor of the power combiner to the surface / bottom layer of the printed circuit board, which is convenient for SMT welding of the isolation resistor, thereby avoiding the buried resistor design of the stripline power combiner and the corresponding process procedures, and greatly reducing the design cost of the microwave multilayer printed circuit board.

[0025] (2) The frequency applicability of the present invention is relatively high, and is only limited by the frequency response of the isolation resistor. Using microwave high-frequency surface mount resistors, the design can be used in the frequency band above Ka. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the front structure of a low-cost stripline power combiner for multi-beam phased arrays;

[0027] Figure 2 A schematic diagram of the reverse structure of a low-cost stripline power combiner for multi-beam phased array;

[0028] Figure 3 A rendering of a low-cost stripline power combiner for multibeam phased arrays.

[0029] Reference numerals:

[0030] 1. Microwave multilayer printed circuit board; 2. Stripline input port; 3. Stripline; 4. Power dividing stripline; 5. First stripline output port; 6. Second stripline output port; 7. Isolation end stripline feeder via; 71. Isolation end stripline; 72. Coaxial feeder via; 8. Coaxial matching ground via; 9. Isolation resistor surface mount pad; 10. Isolation resistor. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0032] Example 1

[0033] like Figure 1 , 2 A low-cost stripline power combiner for multi-beam phased arrays is shown in FIG.

[0034] A low-cost stripline power combiner based on a microwave multilayer printed circuit board 1, wherein a signal is input from a stripline input port 2, is divided into two paths after passing through a stripline 3 with a characteristic impedance of 50 ohms, and then is output through a first stripline 50 ohm output port 5 and a second stripline 50 ohm output port 6 after passing through two 1 / 4 wavelength power splitting striplines 4 with a characteristic impedance of 70.7 ohms. This structure can divide the input power into two, and the power is outputted at the first stripline 50 ohm output port 5 and the second stripline 50 ohm output port 6 with equal amplitude and phase.

[0035] The output port isolation of the first stripline 50 ohm output port 5 and the second stripline 50 ohm output port 6 adopts the design of two 1 / 2 wavelength isolation end stripline feeder vias 7 and its coaxial matching ground vias 8. The port isolation design can lead the isolation resistor surface mount pad 9 of the isolation resistor 10 of the power combiner to the surface / bottom layer of the printed circuit board, which is convenient for SMT welding of the isolation resistor 10. Thereby avoiding the buried resistor design of the stripline power combiner and the corresponding process procedures, thereby greatly reducing the design cost of the microwave multilayer printed circuit board.

[0036] The biggest feature of this structure is that the output port isolation design of the first stripline 50 ohm output port 5 and the second stripline 50 ohm output port 6 adopts the isolation end stripline 71 with a characteristic impedance of 70.7 ohms and a coaxial feed line via 72 of 1 / 2 wavelength length. This structure can lead the pad 9 of the isolation resistor 10 (100 ohm 0402 packaged ordinary SMT resistor) to the surface layer. The requirement for the isolation end stripline 71 and the coaxial feed line via 72 is that the sum of their lengths is 1 / 2 medium wavelength.

[0037] The advantage of this design method is that the isolation resistor position of this structure is increased by 1 / 2 wavelength compared with the traditional stripline power combiner position, which makes the isolation resistor position far away from the output port position. On the one hand, the transfer of the isolation resistor from the middle layer of the printed circuit board to the surface / bottom layer of the printed circuit board through the via hole has the support of the physical electrical length of 1 / 2 wavelength. On the other hand, the electrical length of 1 / 2 wavelength is equivalent to a 360° rotation in the impedance Smith original diagram, which is consistent with the electrical performance of the previous traditional stripline power synthesis network.

[0038] Since the characteristic impedance of the isolated end stripline 71 and the coaxial feed line via 72 is 70.7 ohms, it is necessary to add a coaxial matching ground via 8 around the coaxial feed via 72 to ensure that the coaxial feed line via meets the characteristic impedance requirement of 70.7 ohms.

[0039] Since both stripline and coaxial line are TEM transmission lines, the wavelength length in the medium is:

[0040]

[0041] That is, the physical length and electrical length of the stripline and coaxial line are exactly the same. This makes the design very flexible. For a multi-beam multi-layer power synthesis network, the electrical length of each power synthesis network to the surface / bottom printed circuit board is different. When the power synthesis network is far from the surface, the length of the coaxial feeder via 72 is longer, and the length of the isolation end stripline 71 becomes shorter accordingly. The sum of the physical lengths of the two is 1 / 2. That's it.

[0042] The pad of the isolation resistor 10 on the surface of this solution is recommended to be a small-area 0402 SMT resistor pad. On the one hand, the smaller the surface / bottom pad 9 is, the better the electromagnetic shielding is. On the other hand, the smaller the resistor volume is, the higher the response frequency is.

[0043] Another advantage of this design is its high frequency applicability, which is limited only by the frequency response of the isolation resistor 10. By using microwave high-frequency surface mount resistors, this design can be used in the frequency band above Ka.

[0044] In addition, the bandwidth of the stripline power synthesis network designed by this solution can cover 17% of the center frequency (ensuring that the port standing wave is less than 1.5 and the port isolation is more than 25dB). Figure 3 This is the typical design result at 6.9GHz~8.2GHz.

[0045] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A low-cost stripline power combiner for multi-beam phased arrays, characterized in that: The invention comprises a microwave multilayer printed board (1), a stripline input port (2) connected to one end of the microwave multilayer printed board (1), a stripline (3) connected to the stripline input port (2) and connected to the microwave multilayer printed board (1), two power-dividing striplines (4) for dividing the output of the stripline (3) into two paths, a first stripline output port (5) and a second stripline output port (6) respectively connected to the output ends of the two power-dividing striplines (4), an isolated-end stripline feeder via (7) for isolating the first stripline output port (5) and the second stripline output port (6), a coaxial matching grounding via (8) arranged around the isolated-end stripline feeder via (7) and connected to the microwave multilayer printed board (1) for impedance matching, and an isolation resistor surface-mount pad (9) and an isolation resistor (10) connected in sequence to the other end of the isolated-end stripline feeder via (7); The impedances of the stripline input port (2), the stripline (3), the first stripline output port (5) and the second stripline output port (6) are all the same; The two power dividing strip lines (4) divide the input power into two, and the first strip line output port (5) and the second strip line output port (6) output signals with equal amplitude and same phase; The isolated end stripline feeder via (7) comprises an isolated end stripline (71) and a coaxial feeder via (72) which are sequentially connected to the output end of the power dividing stripline (4), and the coaxial feeder via (72) passes through the microwave multilayer printed board (1); The isolation resistor surface mount pad (9) and the isolation resistor (10) are located on the surface layer or bottom layer of the microwave multilayer printed board (1).

2. A low-cost stripline power combiner for a multi-beam phased array according to claim 1, characterized in that: The impedances of the stripline input port (2), the stripline (3), the first stripline output port (5) and the second stripline output port (6) are all 50 ohms, the length of the power dividing stripline (4) is 1 / 4 wavelength, and the physical length of the isolation end stripline feeder via (7) is 1 / 2 wavelength.

3. A low-cost stripline power combiner for a multi-beam phased array according to claim 2, characterized in that: The impedance of the two power dividing strip lines (4) is 70.7 ohms.

4. A low-cost stripline power combiner for a multi-beam phased array according to claim 1, characterized in that: The number of the isolation end stripline (71) and the number of the coaxial feed line vias (72) are both two, and the two isolation end striplines (71) are respectively connected to the output ends of the two power dividing striplines (4).

5. A low-cost stripline power combiner for a multi-beam phased array according to claim 1, characterized in that: The wavelength of the isolation end stripline (71) and the coaxial feed line via (72) in the medium is in the same ratio as the wavelength in vacuum, and the physical length is consistent with the electrical length: in, is the wavelength of the isolation end stripline (71) and the coaxial feed line via (72) in the medium, is the wavelength of the isolation end stripline (71) and the coaxial feed line via (72) in vacuum.

6. A low-cost stripline power combiner for a multi-beam phased array according to claim 1, characterized in that: The length of the coaxial feed line via (72) can be adjusted according to the length of the isolated end strip line (71); when the length of the coaxial feed line via (72) is greater than 1 / 4 wavelength, the length of the isolated end strip line (71) is less than 1 / 4 wavelength.

7. A low-cost stripline power combiner for a multi-beam phased array according to claim 1, characterized in that: The characteristic impedance of the isolated end stripline feeder via (7) is 70.7 ohms; The coaxial matching grounding via (8) is a feeder via that matches around the coaxial feeder via (72).

8. A low-cost stripline power combiner for a multi-beam phased array according to claim 1, characterized in that: The resistance of the isolation resistor (10) is 100 ohms.

9. A low-cost stripline power combiner for a multi-beam phased array according to claim 8, characterized in that: The isolation resistor (10) is a packaged SMT resistor.

10. A low-cost stripline power combiner for a multi-beam phased array according to any one of claims 1 to 9, characterized in that: Low-cost stripline power combiners can be used in the Ka band and above.

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