CN108448221B - A Broadband Multilayer Microstrip Butler Beamforming Network Matrix Device - Google Patents

Abstract

The invention discloses a broadband multilayer microstrip Butler beam forming network matrix device, and belongs to the technical field of electronic communication. The broadband multilayer microstrip Butler beam forming network matrix has the advantages of easiness in manufacturing, low cost, high port phase shifting precision, small port amplitude fluctuation, low loss, wide working frequency, high port isolation and the like, and can meet the requirements of modern civil mobile communication systems and military radar systems on a new generation of multi-beam array antennas and antenna tests.

Description

A Broadband Multilayer Microstrip Butler Beamforming Network Matrix Device

technical field

The invention belongs to the technical field of electronic communication.

Background technique

With the rapid development of communication technology, the simpler implementation and accurate pointing of multi-beam antennas make it play an increasingly important role in radar and communication systems, especially 4G and 5G mobile communication systems. The core of the multi-beam antenna is the beam forming circuit feed network, and the Butler matrix has great application prospects due to its simple structure, low insertion loss, and easy fabrication.

At present, the existing Butler matrix technology is mainly composed of multiple single-layer microstrip couplers and transmission microstrip line phase shifters to change the amplitude and phase of each output port signal. After feeding into the phased array antenna, beamforming is realized. And the signal processing function of power spectrum estimation to determine the direction of the incoming wave of the signal, and further orient the signal accurately. The technology is simple but has defects such as narrow operating frequency, large port phase shift error, and poor port amplitude flatness, resulting in poor platform versatility and narrow application scenarios. The invention uses the multi-layer printed board technology to develop a multi-layer microstrip Butler beam-forming network matrix that is miniaturized, easy to manufacture, low-cost, high-performance, and covers a wide frequency band, and can be widely used in multiple scenarios in multiple scenarios. Beam antenna beamforming circuit feed network.

SUMMARY OF THE INVENTION

The invention solves the defects of the current existing Butler matrix, such as narrow operating frequency, large port phase shift error, poor port amplitude flatness, etc. The realized broadband multi-layer microstrip Butler beam forming network matrix has the advantages of easy fabrication, low cost, and port phase shift. It has the advantages of high precision, small port amplitude fluctuation, low loss, wide operating frequency and high port isolation, which can meet the requirements of modern civil mobile communication systems and military radar systems for the new generation of multi-beam array antennas and antenna testing.

The technical solution of the present invention is a broadband multi-layer microstrip Butler beam forming network matrix device. A forming network matrix, a second dielectric layer, and a lower metal ground; the Butler beam forming network matrix disposed on the substrate is shown in Figure 2, including: a first 90° 3dB broadband tight-coupling directional coupler, the first to third 180° 3dB broadband tight coupling directional coupler; the first 90° 3dB broadband tight coupling directional coupler includes: two output ports A and B and two input ports C and D, the 180° 3dB broadband tight coupling directional coupler includes: The coupler includes: two output ports A and B and two input ports △ and Σ; the A port of the first 90°3dB wideband tight coupling directional coupler and the △ port of the first 180°3dB wideband tight coupling directional coupler Port connection, the B port of the first 90° 3dB broadband tight coupling directional coupler is connected to the △ port of the second 180° 3dB broadband tight coupling directional coupler; the A port of the third 180° 3dB broadband tight coupling directional coupler It is connected with the Σ port of the first 180° 3dB broadband tight coupling directional coupler, and the B port of the third 180° 3dB broadband tight coupling directional coupler is connected with the Σ port of the second 180° 3dB broadband tight coupling directional coupler; the All input ports of the first 90° 3dB broadband tightly coupled directional coupler and the third 180° 3dB broadband tightly coupled directional coupler are used as feed ports for the broadband multi-layer microstrip Butler beamforming network matrix device, the first and third All output ports of the two 180° 3dB broadband tightly coupled directional couplers are broadband multi-layer microstrip Butler beamforming network matrix device antenna ports.

It is characterized in that the first 90° 3dB broadband tight-coupling directional coupler, as shown in FIG. 3 , includes: a circuit substrate and metal microstrip lines arranged on the upper surface and the lower surface of the circuit substrate, and the upper and lower surfaces of the The metal microstrip line is composed of two gradual tight coupling 8.34dB directional couplers cascaded, with the same shape and opposite positions; the feeding port of the metal microstrip line on the upper surface is the C port of the first 90°3dB broadband tight coupling directional coupler , the antenna port is the A port of the first 90°3dB broadband tight coupling directional coupler; the lower surface metal microstrip line feed port is the D port of the first 90°3dB broadband tight coupling directional coupler, and the antenna port is the first 90 °3dB broadband close-coupled directional coupler B port.

The first to third 180° 3dB broadband tight coupling directional couplers, as shown in FIG. 4 , include: a second 90° 3dB broadband tight coupling directional coupler and a 90° Schiffman broadband tight coupling differential phase shifter; °Schiffman broadband tightly coupled differential phase shifter includes: a reference microstrip transmission line and a 90° phase shifter; the reference microstrip transmission line is a serpentine zigzag microstrip line arranged on the upper surface of the circuit substrate, and one end is 90°3dB with the second The A port of the broadband tightly coupled directional coupler is connected, and the other end is used as output; the 90° phase shifter includes three-segment gradient coupling lines located on the upper and lower surfaces of the circuit substrate, and a three-segment gradient located on the lower surface of the circuit substrate. One end of the coupling line is connected to the B port of the second 90°3dB broadband tight coupling directional coupler, the other end is connected to one end of the three-segment gradient coupling line located on the upper surface of the circuit substrate through a metallized via, and the other end is used as an output; the The C and D ports of the second 90°3dB broadband close-coupled directional coupler are respectively the Δ and Σ ports of the 180°3dB broadband close-coupled directional coupler. The output end of the serpentine microstrip line is located on the upper surface of the circuit substrate. The output ends of the three-section gradient coupling line are the A and B ports of the 180° 3dB broadband tight coupling directional coupler.

其中λ_g为Butler矩阵的工作中心频率。Further, the three-segment gradient coupling line located on the upper surface and the lower surface of the circuit substrate in the 90° phase shifter is projected into a "V" shape, one side of the three-segment gradient coupling line is flush, and the other side is flush. The middle section of the bump is wider than the front section and the rear section. The middle section of the bump is located on the outside of the three-section gradient coupling line projected "V" shape on the upper and lower surfaces of the circuit substrate, and the length of each section of the coupling line is

where λ _g is the working center frequency of the Butler matrix.

Further, the gradual tight coupling 8.34dB directional coupler in the first or second 90° 3dB broadband tight coupling directional coupler includes: an input section, a transition section, and an output section, wherein the input section includes: a 50-ohm rectangular transmission line input Port, tip-shaped impedance gradient transition transmission line branch, input branch microstrip line, the 50 ohm rectangular transmission line input port is perpendicular to the input branch microstrip line, and the tip-shaped impedance gradient transition transmission line branch is the input branch microstrip line at the connection with the input port. Extend outward; the input section and the transition section form an obtuse-angle connection, and the input section and the output section are center-symmetrical; the two gradual tight coupling 8.34dB directional couplers are cascaded into a "U" shape, and the cascaded input Ports and output ports are located on the outside of the "U" shape.

Further, the serpentine reference microstrip transmission line sequentially includes from the input end: a first "U"-shaped bend, a second "U"-shaped bend, a third "U"-shaped bend, and a fourth "U"-shaped bend. U" bend, first right angle bend, second right angle bend, fifth "U" bend, sixth "U" bend, seventh "U" bend, third right angle bend , the fourth right-angle bend, the eighth "U"-shaped bend, the fifth right-angle bend, and the sixth right-angle bend; the bending directions of the first and second right-angle bends are opposite; The bending directions of the four right-angle bends are opposite; the bending directions of the fifth and sixth right-angle bends are opposite, and the length of the entire reference microstrip transmission line is

Further, the A port of the first 90° 3dB broadband tight coupling directional coupler is connected to the Δ port of the first 180° 3dB broadband tight coupling directional coupler through a "U"-shaped bent microstrip line; The B port of a 90°3dB broadband tight-coupling directional coupler is connected to the microstrip line through the intersection of the transmission line and is connected to the △ port of the second 180°3dB broadband tight-coupling directional coupler through a metallized via; the third 180° The A port of the 3dB broadband close-coupled directional coupler is connected to the microstrip line through the intersection of the transmission line and then connected to a "U"-shaped bent microstrip line, and then connected to the first 180° 3dB broadband close-coupled directional coupler through metallized vias. The Σ port is connected; the B port of the third 180°3dB broadband tight coupling directional coupler is connected to the first section of the microstrip line, and then connected to the second section of the microstrip line through the metallized via, and then tightly coupled with the second 180°3dB broadband The Σ port of the directional coupler is connected, and the first section and the second section of the microstrip line are projected into a "U" shape.

Further, the outer corners of the bends of the microstrip lines in the broadband multi-layer microstrip Butler beamforming network matrix device are all treated as right angles.

Further, the thickness of the first dielectric layer is 0.1-3 mm; the thickness of the second dielectric layer is 0.1-3 mm; the diameter of the metallized via is 0.1-1 mm.

Advantages of the present invention include:

1. Using multi-layer printed board technology, the circuit is compact, the production is simple, and the cost is low;

2. Using the circuit wide-side tight coupling technology, the multi-layer microstrip Butler matrix has the advantages of wide operating frequency, high port phase shift accuracy, small port amplitude fluctuation, low loss and high port isolation.

Description of drawings

FIG. 1 is a schematic diagram of the layer structure of the multilayer circuit substrate of the present invention.

FIG. 2 is a schematic diagram of the broadband multi-layer microstrip Butler4×4 matrix circuit of the present invention.

FIG. 3 is a circuit diagram of a 90° 3dB wideband tightly coupled directional coupler according to the present invention.

FIG. 4 is a circuit diagram of a 180° 3dB wideband tightly coupled directional coupler according to the present invention.

FIG. 5 is a circuit diagram of a broadband multi-layer microstrip Butler 4×4 matrix in a specific implementation of the present invention.

FIG. 6 is a data diagram of signal phases of antenna ports 5 to 8 when the feed port 1 of the Butler 4×4 matrix is excited in a specific implementation of the present invention. The abscissa is the frequency, the unit is GHz, and the ordinate is the signal phase, the unit is Degree.

FIG. 7 is a graph of signal phase data of antenna ports 5 to 8 when the feed port 2 of the Butler 4×4 matrix is excited in a specific implementation of the present invention. The abscissa is the frequency, the unit is GHz, and the ordinate is the signal phase, the unit is Degree.

FIG. 8 is a data diagram of signal phases of antenna ports 5 to 8 when the feed port 3 of the Butler 4×4 matrix is excited in a specific implementation of the present invention. The abscissa is the frequency, the unit is GHz, and the ordinate is the signal phase, the unit is Degree.

FIG. 9 is a data diagram of signal phases of antenna ports 5 to 8 when the feed port 4 of the Butler4×4 matrix is excited in a specific implementation of the present invention. The abscissa is the frequency, the unit is GHz, and the ordinate is the signal phase, the unit is Degree.

10 is a data diagram of signal insertion loss and feeder port isolation at antenna ports 5 to 8 when the feeder port 1 of the Butler 4×4 matrix is excited in a specific implementation of the present invention. The abscissa is the frequency, the unit is GHz, and the ordinate is the signal insertion loss, the unit is dB.

FIG. 11 is a data diagram of signal insertion loss and feeder port isolation at antenna ports 5 to 8 when the feeder port 2 of the Butler 4×4 matrix is excited in a specific implementation of the present invention. The abscissa is the frequency, the unit is GHz, and the ordinate is the signal insertion loss, the unit is dB.

FIG. 12 is a data diagram of signal insertion loss and feeder port isolation at antenna ports 5 to 8 when the feeder port 3 of the Butler 4×4 matrix is excited in a specific implementation of the present invention. The abscissa is the frequency, the unit is GHz, and the ordinate is the signal insertion loss, the unit is dB.

13 is a data diagram of signal insertion loss and feeder port isolation at antenna ports 5 to 8 when the feeder port 4 of the Butler 4×4 matrix is excited in a specific implementation of the present invention. The abscissa is the frequency, the unit is GHz, and the ordinate is the signal insertion loss, the unit is dB.

FIG. 14 is the signal input/output standing wave ratio of each port of the Butler 4×4 matrix in a specific implementation of the present invention. The abscissa is frequency, the unit is GHz, and the ordinate is VSWR (standing wave ratio).

Detailed ways

The invention is a kind of broadband multi-circuit substrate layer microstrip Butler matrix based on multi-layer printed board technology. On the metal layer, a broad-side tightly coupled circuit is formed to form strong coupling for broadband applications. There are metallized vias on the circuit substrate to connect the upper and lower circuits; the microstrip Butler matrix is a 4×4 matrix with 4 feed ports. , 4 antenna ports, a 90 ° 3dB broadband tight coupling directional coupler and three 180 ° 3dB broadband tight coupling directional coupler. The C and D feed ports of the first 90° 3dB broadband tight coupling directional coupler are respectively the 1 and 2 input ports of the device of the present invention, and the Δ and Σ feed ports of the third 180° 3dB broadband tight coupling directional coupler are respectively. The electrical ports are respectively the 3 and 4 input ports of the device of the present invention, the A and B antenna ports of the first 180° 3dB broadband tight-coupling directional coupler are respectively the 5 and 6 antenna ports of the device of the present invention, and the second 180 The A and B antenna ports of the °3dB wideband tight coupling directional coupler are respectively the 7 and 8 antenna ports of the device of the present invention; the 90°3dB wideband tight coupling directional coupler is composed of two gradient tight coupling 8.34dB directional couplers cascaded together; The 180°3dB broadband tightly coupled directional coupler is composed of a 90°3dB broadband tightly coupled directional coupler and a 90°Schiffman broadband tightly coupled differential phase shifter; the 90°Schiffman broadband tightly coupled differential phase shifter is composed of a reference micro It is composed of a strip transmission line and a 90° phase shifter; the reference microstrip transmission line adopts the structure of a serpentine zigzag line; the 90° phase shifter adopts a structure of three sections of up and down gradient tightly coupled coupling lines connected by metallized vias at the ends. The thickness of the first dielectric layer is 0.1-3 mm; the thickness of the circuit substrate is 0.1-3 mm; the thickness of the second dielectric layer is 0.1-3 mm; the diameter of the metallized via is 0.1-1 mm.

Feeding ports 1 to 4 are excited respectively, and equal-amplitude power outputs are generated at antenna ports 5 to 8, and the phase differences are 90°, -90°, 180°, and 0° in turn: that is, feed port 1 is excited, then at There is a 90° phase difference between the antenna port 5 and port 6, between port 6 and port 7, and between port 7 and port 8; when the feed port 2 is excited, between the antenna port 5 and port 6, between port 6 and port 6 A phase difference of -90° is generated between port 7 and between port 7 and port 8; when the feed port 3 is excited, there will be a difference between antenna port 5 and port 6, between port 6 and port 7, and between port 7 and port 8. A phase difference of 180° is generated between the antenna ports; when the feed port 4 is excited, a phase difference of 0° is generated between the antenna port 5 and port 6, between port 6 and port 7, and between port 7 and port 8.

The circuit diagram of the broadband multi-layer microstrip Butler4×4 matrix is made, and the outline diagram is shown in Figure 5. The first medium is air with a thickness of 0.8mm, the circuit substrate is Rogers5880 with a thickness of 0.254mm, the second medium is air with a thickness of 0.8mm, and the circuit is etched on the metal layer on the upper and lower surfaces of the circuit substrate, and the circuit area is not greater than 170mm ×90mm. The results are shown in Figure 6 to Figure 14. The operating frequency band covers 1700 to 2200 MHz, the relative bandwidth is greater than 25%, the maximum port standing wave VSWR is 1.3, the port isolation is greater than 20dB, and the in-band phase fluctuation of each port is less than +/-2°. The in-band amplitude flatness of the ports is less than +/-0.3dB, the feeder ports 1 to 4 are excited respectively, and the equal-amplitude power output is generated at the antenna ports 5 to 8, and the port phase difference is 90°+/-2°, -90° °+/-2°, 180°+/-2° and 0°+/-2°, the antenna port insertion loss is 6.5+/-0.5dB.

The above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the present invention. within the scope of protection of the invention.

Claims (7)

1. A broadband multilayer microstrip Butler beam forming network matrix device, the device comprising: the antenna comprises an upper metal ground, a first dielectric layer, a circuit substrate, a Butler beam forming network matrix arranged on the substrate, a second dielectric layer and a lower metal ground; the Butler beam forming network matrix arranged on the substrate comprises: the first 90-degree 3dB broadband tight coupling directional coupler, and the first to third 180-degree 3dB broadband tight coupling directional couplers; the first 90 ° 3dB broadband tightly coupled directional coupler comprises: A. b two output ports and C, D two input ports, the 180 ° 3dB wide-band tightly-coupled directional coupler comprising: A. b two output ports and delta and sigma two input ports; the port A of the first 90-degree 3dB broadband tight coupling directional coupler is connected with the port delta of the first 180-degree 3dB broadband tight coupling directional coupler, and the port B of the first 90-degree 3dB broadband tight coupling directional coupler is connected with the port delta of the second 180-degree 3dB broadband tight coupling directional coupler; the port A of the third 180-degree 3dB broadband tight coupling directional coupler is connected with the port sigma of the first 180-degree 3dB broadband tight coupling directional coupler, and the port B of the third 180-degree 3dB broadband tight coupling directional coupler is connected with the port sigma of the second 180-degree 3dB broadband tight coupling directional coupler; all input ports of the first 90-degree 3dB broadband tight coupling directional coupler and the third 180-degree 3dB broadband tight coupling directional coupler are used as feed ports of a broadband multilayer microstrip Butler beam forming network matrix device, and all output ports of the first 180-degree 3dB broadband tight coupling directional coupler and the second 180-degree 3dB broadband tight coupling directional coupler are antenna ports of the broadband multilayer microstrip Butler beam forming network matrix device;

characterized in that said first 90 ° 3dB broadband tight coupling directional coupler comprises: the circuit comprises a circuit substrate and metal microstrip lines arranged on the upper surface and the lower surface of the circuit substrate, wherein the metal microstrip lines on the upper surface and the lower surface are formed by cascading two gradually-changed tightly-coupled 8.34dB directional couplers, and are identical in shape and opposite in arrangement position; the feed port of the metal microstrip line on the upper surface is a port C of the first 90-degree 3dB broadband tight coupling directional coupler, and the antenna port is a port A of the first 90-degree 3dB broadband tight coupling directional coupler; the feed port of the metal microstrip line on the lower surface is a D port of the first 90-degree 3dB broadband tight coupling directional coupler, and the antenna port is a B port of the first 90-degree 3dB broadband tight coupling directional coupler;

the first to third 180 DEG 3dB broadband tight coupling directional couplers comprise: a second 90-degree 3dB broadband tightly-coupled directional coupler and a 90-degree Schiffman broadband tightly-coupled differential phase shifter; the 90 DEG Schiffman broadband tightly-coupled differential phase shifter comprises: a reference microstrip transmission line and a 90 ° phase shifter; the reference microstrip transmission line is a snakelike zigzag microstrip line arranged on the upper surface of the circuit substrate, one end of the reference microstrip transmission line is connected with an A port of the second 90-degree 3dB broadband tight coupling directional coupler, and the other end of the reference microstrip transmission line is used as output; the 90-degree phase shifter comprises three-section type gradually-changed coupling lines positioned on the upper surface and the lower surface of the circuit substrate, one end of the three-section type gradually-changed coupling line positioned on the lower surface of the circuit substrate is connected with a port B of a second 90-degree 3dB broadband tight coupling directional coupler, the other end of the three-section type gradually-changed coupling line positioned on the upper surface of the circuit substrate is connected with one end of the three-section type gradually-changed coupling line through a metalized through hole, and the other end of the; the C, D ports of the second 90-degree 3dB broadband tight coupling directional coupler are respectively the delta and sigma ports of the 180-degree 3dB broadband tight coupling directional coupler, and the output end of the serpentine microstrip line and the output end of the three-section type gradually-changed coupling line positioned on the upper surface of the circuit substrate are respectively A, B two ports of the 180-degree 3dB broadband tight coupling directional coupler.

2. The broadband multilayer microstrip Butler beam forming network matrix device according to claim 1, wherein the projections of the three-segment gradually-changed coupling lines on the upper surface and the lower surface of the circuit substrate in the 90 ° phase shifter are in a V shape, one side of the three-segment gradually-changed coupling line is flush, the middle section of the other side of the three-segment gradually-changed coupling line is convex, the width of the middle section of the three-segment gradually-changed coupling line is larger than that of the front section and the rear section of the three-segment gradually-changed coupling line, the convex of the middle section is located on the outer side of the projection of the three-segment gradually-changed coupling line on

Wherein λ_gThe wavelength of the operating center frequency of the Butler matrix.

3. The wideband multi-layer microstrip Butler beamforming network matrix device of claim 1 wherein the tapered tightly coupled 8.34dB directional coupler of the first or second 90 ° 3dB wideband tightly coupled directional couplers comprises: input section, changeover portion, output section, wherein the input section includes: the 50 ohm rectangular transmission line input port is perpendicular to the input stub microstrip line, and the tip-shaped impedance gradual change transition transmission line stub is the outward extension of the input stub microstrip line at the connection part with the input port; the input section and the transition section form obtuse angle connection, and the input section and the output section form central symmetry; the two gradually-changed tightly-coupled 8.34dB directional couplers are cascaded to form a U shape, and the input port and the output port after the cascade are positioned on the outer side of the U shape.

4. The wideband multi-layer microstrip Butler beamforming network matrix device of claim 1 wherein said serpentine reference microstrip transmission line comprises in order from the input: a first U-shaped bend, a second U-shaped bend, a third U-shaped bend, a fourth U-shaped bend, a first right-angle bend, a second right-angle bend, a fifth U-shaped bend, a sixth U-shaped bend, a seventh U-shaped bend, a third right-angle bend, a fourth right-angle bend, an eighth U-shaped bend, a fifth right-angle bend and a sixth right-angle bend; the bending directions of the first right-angle bending and the second right-angle bending are opposite; the bending directions of the third right-angle bending and the fourth right-angle bending are opposite; the bending directions of the fifth right-angle bending and the sixth right-angle bending are opposite, and the length of the whole reference microstrip transmission line is

Wherein λ_gThe wavelength of the operating center frequency of the Butler matrix.

5. The device of any one of claims 1, 2, 3 or 4, wherein the port A of the first 90 ° 3dB broadband tightly-coupled directional coupler is connected with the port A of the first 180 ° 3dB broadband tightly-coupled directional coupler through a U-shaped bent microstrip line; the B port of the first 90-degree 3dB broadband tight coupling directional coupler is connected with the delta port of the second 180-degree 3dB broadband tight coupling directional coupler through a metalized via hole after passing through the transmission line cross point; the port A connecting microstrip line of the third 180-degree 3dB broadband tight coupling directional coupler is connected with a U-shaped bent microstrip line through a transmission line cross point and then is connected with the sigma port of the first 180-degree 3dB broadband tight coupling directional coupler through a metalized via hole; and the port B of the third 180-degree 3dB broadband tight coupling directional coupler is connected with the first section of microstrip line, then is connected with the second section of microstrip line through a metalized via hole, and then is connected with the sigma port of the second 180-degree 3dB broadband tight coupling directional coupler, and the first section and the second section of microstrip line form a U shape in a projection mode.

6. The device as claimed in any one of claims 1, 2, 3 or 4, wherein all external angles at the bends of the microstrip lines in the device are chamfered.

7. The broadband multilayer microstrip Butler beam forming network matrix device according to any one of claims 1, 2, 3 or 4, wherein the thickness of said first dielectric layer is 0.1-3 mm; the thickness of the second medium layer is 0.1-3 mm; the diameter of the metalized through hole is 0.1-1 mm.

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