Miniaturized low-loss millimeter wave power division network based on LTCC technology

Abstract

The invention discloses a miniaturized low-loss millimeter wave power division network based on an LTCC (Low Temperature Co-Fired Ceramic) process, and belongs to the technical field of power distribution and synthesis in millimeter wave phased-array antennas. The millimeter wave power division network comprises a metal cavity; the LTCC substrate is positioned in the metal cavity, and a power division network circuit is printed in the substrate; and the radio frequency connector is fixed in the metal cavity and penetrates through the power division network circuit layer through a through hole formed in the LTCC substrate, so that input and output of signals are realized. According to the millimeter wave power division network, the technical advantages of the LTCC technology in the aspects of micromachining and three-dimensional integration are fully played, and the system integration level and the signal transmission performance of the millimeter wave power division network are improved by integrating the planar integration advantage of the strip line structure, the low transmission loss characteristic of the waveguide structure and the easy assembly and debugging characteristic of the microstrip structure; a vertical interconnection scheme of the power division network circuit and the radio frequency connector is adopted, the occupation of a traditional plane connection mode on the circuit space is broken through, and further optimization of the circuit size is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of power distribution and synthesis in millimeter-wave phased array antennas, and specifically relates to a high-density equal-power 1-in-16-out power distribution network applied to an antenna feeding system. Background Art

[0002] With the rapid development of wireless communication technologies in recent years, microwave components are tending towards multi-functionality; for example, the feeding system of an antenna is evolving from a single-channel to a multi-channel, from a single receiving or transmitting function to a transceiver integrated function, and the volume of the components is further reduced. This development trend has compelled the system design to adopt a three-dimensional integration scheme. In the three-dimensional integration technology scheme, the low-temperature co-fired ceramic (LTCC) technology has significant advantages in terms of electrical, thermal, and mechanical properties due to its unique material characteristics and advanced manufacturing processes.

[0003] For the research and development of millimeter-wave components, it is urgent to solve the technical problem of excessive transmission loss. Due to the strong radiation characteristics and weak bending ability of high-frequency signals, the signal strength and quality are significantly weakened as the frequency increases and the transmission path lengthens, which limits the transmission range and system reliability of wireless communication.

[0004] To meet the development requirements of millimeter-wave feeding systems, the power distribution network, which plays an important role in signal distribution, must develop in the direction of miniaturization and low loss.

[0005] In the millimeter-wave frequency band, there are mainly three forms of transmission line structures used as power distribution networks: waveguide form, microstrip form, and stripline form. Although the waveguide form power distribution network has advantages in terms of insertion loss and power capacity, its volume and weight are too large, and it is not easy to integrate with other planar circuits; the microstrip form power distribution network can achieve the effects of small volume, light weight, and easy debugging, but its disadvantage is the large radiation loss caused by the semi-open structure; while the stripline form power distribution network has the advantages of low radiation loss and easy integration with other planar circuits. However, its structural characteristics make it difficult to operate in terms of port installation and performance debugging of RF connectors. Therefore, for the feeding systems used in millimeter-wave phased array antennas, the power distribution networks made in the above situations cannot meet the development requirements. Summary of the Invention

[0006] The object of the present invention is to propose a miniaturized low-loss millimeter-wave power distribution network based on LTCC technology to address the technical contradiction problem of existing millimeter-wave power distribution networks in achieving low-loss characteristics and miniaturized design.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A miniaturized low-loss millimeter-wave power distribution network based on LTCC technology, comprising:

[0009] Metal cavity

[0010] LTCC substrate, which is located inside the metal cavity, and a power divider network circuit is printed in the LTCC substrate;

[0011] RF connector, which is fixed inside the metal cavity and penetrates through to the power divider network circuit layer through a through hole provided on the LTCC substrate to realize signal input and output.

[0012] Further, an insulating wafer is provided between the RF connector and the substrate.

[0013] Further, the type of the RF connector is an SSMP connector.

[0014] Further, the base 11 of the RF connector is fixed inside the metal cavity, an insulating wafer 3 is sleeved at the interface between the base of the RF connector and the wave pins, and the wave pins 12 of the RF connector penetrate through a through hole provided on the LTCC substrate to the power divider network circuit layer.

[0015] Further, the power divider network circuit is cascaded with strip line Wilkinson power dividers as basic units.

[0016] Further, the power divider network circuit includes a strip line circuit located inside the LTCC substrate and a microstrip line circuit exposed by laser cavity opening, and the wave pins of the RF connector are welded to the microstrip circuit.

[0017] Further, a metallized via hole array is symmetrically arranged on both sides of the conductive strip of the strip line circuit in a periodic and uniform distribution, and is connected to the bottom layer and the top layer of the LTCC substrate to form a waveguide-like structure, suppressing the dielectric radiation loss of the conductive strip.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The present invention gives full play to the technical advantages of the LTCC process in microfabrication and three-dimensional integration. By integrating the planar integration advantages of the strip line structure, the low transmission loss characteristics of the waveguide structure, and the easy assembly and debugging characteristics of the microstrip structure, the system integration degree and signal transmission performance of the millimeter-wave power divider network are improved. In addition, a vertical interconnection scheme between the power divider network circuit and the RF connector is adopted to break through the occupation of the circuit space by the traditional planar connection method, and further optimize the circuit size. Description of the Drawings

[0020] Figure 1 It is a sectional view (left) and a front view (right) of a miniaturized low-loss millimeter-wave power divider network based on the LTCC process according to the present invention;

[0021] Figure 2 is Figure 1 the partial enlarged view at position B in

[0022] Figure 3 is Figure 1 the partial enlarged view at position C in

[0023] Figure 4 is the three - dimensional disassembly view of the LTCC substrate of a miniaturized low - loss millimeter - wave power - dividing network based on LTCC technology according to the present invention;

[0024] Figure 5 is the performance test result of a miniaturized low - loss millimeter - wave power - dividing network based on LTCC technology according to the present invention, where (a) corresponds to the insertion loss and (b) corresponds to the voltage standing - wave ratio. Detailed implementation manners

[0025] For a clearer understanding of the technical features, objectives, and effects of the present invention, the detailed implementation manners of the present invention will now be described with reference to the accompanying drawings.

[0026] A miniaturized low - loss millimeter - wave power - dividing network based on LTCC technology includes an input port and 16 output ports. As Figure 1 shown, it includes a metal cavity 2, an LTCC substrate 4, a radio - frequency connector 1, and an insulating wafer 3. Among them, the bottom surface of the LTCC substrate is fixed in the metal cavity by welding, and a power - dividing network circuit is printed in the substrate. The radio - frequency connectors are arranged vertically, and their bases are welded in the mounting holes on the bottom wall of the metal cavity. The pins of the radio - frequency connectors penetrate through the through - holes reserved on the LTCC substrate to the power - dividing network circuit layer and are welded to the circuit layer to achieve signal input and output. Among them, the metal cavity 2 is used to support the whole structure, which is a hollow cuboid shape, and the bottom surface 41 of the LTCC substrate 4 is welded in the hollow position of the metal cavity 2. The power - dividing network has a total of 17 ports, where port1 is the signal input port and port2 - port17 are the signal output ports, and the distance between the output ports led out from the same branch line is 4.1 mm.

[0027] As Figure 2 shown, the base 11 of the SSMP radio - frequency connector is welded inside the bottom wall of the metal cavity 2. A polyimide insulating wafer 3 is sleeved at the interface between the base and the pin of the SSMP radio - frequency connector, and the pin 12 of the SSMP radio - frequency connector penetrates through the through - holes reserved on the LTCC substrate to the power - dividing network circuit layer.

[0028] As Figure 3As shown in the figure, the power distribution network circuit 5 includes a stripline circuit and a microstrip line circuit. The stripline circuit is located inside the LTCC substrate. Cavities are formed at the input / output ports of the stripline circuit by using the LTCC laser cavity opening process to form a microstrip circuit, which is welded to the wave pin 12 through a microstrip line circular pad. The microstrip line circuit is a stepped impedance matching circuit to cope with the impedance mismatch caused by the mutation of the transmission line.

[0029] As Figure 4 shown in the figure, by using the punching and filling microfabrication technology of the LTCC process, an array of metallized vias 6 evenly distributed periodically is arranged on both sides of the conductive strip of the power distribution network circuit 5, which is connected to the bottom layer 41 and the top layer 42 of the substrate to form a waveguide-like structure.

[0030] In actual use, port1 - port17 are connected to other functional components in different connection ways according to actual needs.

[0031] In the embodiment of the miniaturized low-loss millimeter-wave power distribution network of the present invention, it operates in the frequency range of 30 GHz to 40 GHz. As Figure 5 shown in the figure, in the case of a relatively long transmission line, its insertion loss is less than 26 dB, and the voltage standing wave ratio is as low as 1.5.

[0032] In summary, the present invention adopts a vertical interconnection scheme between the power distribution network circuit and the RF connector. The signal output direction is perpendicular to the circuit plane, and the conversion from the planar power distribution circuit to the space is completed without increasing the planar area, which is beneficial to the integration of the power distribution network in the third dimension of space; the SSMP connector adopted has a very small diameter and can support the high-density arrangement of ports; the power distribution network circuit is based on the LTCC process, integrating the technical advantages of three transmission lines, realizing the high integration and low-loss characteristics of the millimeter-wave power distribution network; an insulating wafer is arranged at the interface between the base and the wave pin of the connector, which can prevent the short-circuit fault caused by excessive solder infiltration into the wave pin area during the base welding process and improve the assembly yield; this power distribution network has the advantages of low loss, miniaturization and easy assembly.

[0033] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "bottom", "top", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the present invention is usually placed during use. It is only for the convenience of describing the present invention and is a simplified description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0034] In the description of the invention, it should also be noted that, unless otherwise clearly specified and defined, the terms "arranged", "connected", and "sheathed" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection. It may be a mechanical connection or an electrical connection.

Claims

1. A miniaturized and low-loss millimeter-wave power distribution network based on LTCC technology, characterized in that Comprising: A metal cavity; An LTCC substrate, which is located inside the metal cavity, and a power splitting network circuit is printed in the LTCC substrate; A radio frequency connector, which is fixed inside the metal cavity and penetrates through to the power splitting network circuit layer through a through hole provided on the LTCC substrate.

2. The miniaturized low-loss millimeter-wave power dividing network based on LTCC technology according to claim 1, wherein An insulating wafer is provided between the radio frequency connector and the substrate.

3. The miniaturized low-loss millimeter-wave power dividing network based on the LTCC process according to claim 1, wherein The type of the radio frequency connector is an SSMP connector.

4. The miniaturized low-loss millimeter-wave power distribution network based on LTCC technology according to claim 1, characterized in that, The base of the radio frequency connector is fixed inside the metal cavity, an insulating wafer is sleeved at the interface between the base of the radio frequency connector and the wave pin, and the wave pin of the radio frequency connector penetrates through a through hole provided on the LTCC substrate to the power splitting network circuit layer.

5. The miniaturized low-loss millimeter-wave power division network based on the LTCC process according to claim 1, wherein The power splitting network circuit is formed by cascading basic units of stripline Wilkinson power dividers.

6. The miniaturized low-loss millimeter-wave power splitting network based on LTCC technology according to claim 1, wherein The power splitting network circuit includes a stripline circuit located inside the LTCC substrate and a microstrip line circuit exposed by laser cavity opening, and the wave pin of the radio frequency connector is welded to the microstrip circuit.

7. The miniaturized low-loss millimeter-wave power dividing network based on LTCC technology according to claim 1, characterized in that, Metallized via hole arrays which are symmetrically arranged on both sides of the conductive strip of the stripline circuit and are uniformly distributed periodically are connected to the bottom layer and the top layer of the LTCC substrate to form a waveguide-like structure.

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