CN-122000656-A - Low-cost high-performance hybrid integrated coaxial line directional coupler and radio frequency module

CN122000656ACN 122000656 ACN122000656 ACN 122000656ACN-122000656-A

Abstract

The invention provides a hybrid integrated coaxial line directional coupler with low cost and high performance and a radio frequency module. The mixed integration scheme of the single-layer double-sided printed circuit board and the metal cavity is adopted, so that the number and cost of assembly accessories are greatly reduced. Meanwhile, the single-layer double-sided printed circuit board is matched with the metal cavity body to form an effect similar to a coaxial coupling line, so that radiation loss is effectively restrained, field distribution is improved, and the insertion loss, coupling flatness and isolation performance of the coupler are improved. And (3) hollowing out part of medium in the middle of a transmission line on the circuit board, and performing phase compensation on a transmission signal of the coupling line, so that the excellent performances of the directional coupler in the coupling degree, return loss, insertion loss and isolation degree are further realized. Under the condition of ensuring the performance of the device, the medium between the transmission line and the ground is reserved, and the physical stability of the device is improved.

Inventors

LU YONGQING
SHEN GUANGXIU
LI JIAQI
QIN SHUYANG
HAN YE

Assignees

南京邮电大学

Dates

Publication Date: 20260508
Application Date: 20260410

Claims (7)

1. The low-cost high-performance hybrid integrated coaxial line directional coupler is characterized by comprising an input port, a straight-through port, a coupling port, an isolation port and n sections of coupling line units which are sequentially and tightly connected along the horizontal symmetrical axis direction, wherein n is an integer and is more than or equal to 2; The coupling line unit comprises a first metal shell, a first circuit board and a second metal shell which are sequentially connected from top to bottom to form a metal-circuit board-metal sandwich structure, wherein the first circuit board is a single-layer double-sided printed circuit board which is symmetrical about a y axis and comprises a ground I, a first medium area, a first transmission line, a second medium area, a second transmission line, a third medium area and a ground II which are sequentially connected through the medium area; the upper part of the first transmission line of the first section of coupling line unit is connected with the coupling port, the upper part of the second transmission line is connected with the input port, the lower part of the first transmission line of the nth section of coupling line unit is connected with the isolation port, and the lower part of the second transmission line is connected with the through port.
2. The hybrid integrated coaxial directional coupler of claim 1, wherein the first circuit board is simultaneously double-sided metal wiring, an upper metal layer, a dielectric region and a lower metal layer are sequentially arranged from top to bottom, copper is removed from the upper metal layer and the lower metal layer at the first dielectric region, the second dielectric region and the third dielectric region, all the dielectric is reserved in the first dielectric region and the third dielectric region, the dielectric in the middle is reserved in the second dielectric region, and the rest of the dielectric is hollowed out.
3. The low-cost high-performance hybrid integrated coaxial line directional coupler according to claim 2, wherein the first metal shell is of a cuboid metal structure, a first rectangular groove is milled at the bottom of the first metal shell, the first rectangular groove is attached to an upper metal layer of the first circuit board, the second metal shell is of a cuboid metal structure, a second rectangular groove is milled at the top of the second metal shell, and the second rectangular groove is attached to a lower metal layer of the first circuit board.
4. The hybrid integrated coaxial line directional coupler of claim 1, wherein the first transmission line and the second transmission line are copper plated on the side near each other to form a coupled line structure.
5. The low-cost high-performance hybrid integrated coaxial line directional coupler according to claim 1, wherein metal through holes are uniformly distributed on the surfaces of the ground I and the ground II, and the ground structure is communicated up and down.
6. The hybrid integrated coaxial line directional coupler of claim 1, wherein the input port, the pass-through port, the coupling port, and the isolation port are all single transmission line structures.
7. A radio frequency module comprising a low cost high performance hybrid integrated coaxial line directional coupler according to any one of claims 1 to 6.

Description

Low-cost high-performance hybrid integrated coaxial line directional coupler and radio frequency module Technical Field The invention belongs to the technical field of radio frequency microwave circuits, and particularly relates to a low-cost high-performance hybrid integrated coaxial line directional coupler and a radio frequency module. Background The coupler is used as a core passive device, and is widely applied to the fields of communication, radar, measurement and control and the like by virtue of directional coupling, power sampling, energy distribution and isolation functions. The coupler is used for realizing the monitoring of transmitting power, the detection of standing wave ratio and fault location in a 5G/6G base station, guaranteeing the communication quality, isolating an uplink and a downlink through high directivity in a satellite communication system, reducing signal distortion, protecting a sensitive receiving device and supporting target detection in a phased array radar T/R assembly, precisely separating incident waves and reflected waves in a vector network analyzer and other instruments, guaranteeing the measurement accuracy, adapting to extreme environments in special scenes such as aerospace and the like, providing high-reliability passive device support, and being a key support of a high-end radio frequency microwave system. Currently, most of integrated directional couplers are of multi-layer circuit board structures. For the circuit to be realized by using the coupled line structure, if the left-right coupling structure of the single-sided metal wiring of the single-layer circuit board is adopted, the traditional design method is limited, and the directional coupler is difficult to achieve wide frequency band and high performance. If the upper and lower coupling structures of the double-sided metal wiring of the single-layer circuit board are adopted, the electric field is more distributed in the dielectric plate due to the fact that the two coupling lines are located on two sides of the dielectric, and larger dielectric loss is caused. If the number of layers of the circuit board is increased, a coupling structure is formed on different circuit boards, and a through hole is formed by hollowing out the medium of the middle circuit board of the coupling structure, so that the production cost is doubled, and the method is mostly applied to the field with small frequency bandwidth range. For the directional coupler of the broadband, a micro-coaxial process is adopted at present, but the process has extremely high production cost, and the isolation and coupling performance are reduced when the frequency bandwidth is widened. The patent with publication number CN109149044A discloses a dielectric integrated suspension line coupler based on a multi-inner layer structure, which uses double-sided metal wires to excavate most of dielectric through a third circuit board and a fifth circuit board to form a coupling structure, and a fourth circuit board forms a through hole to integrally form a broadside coupling structure. The scheme realizes that the return loss and the isolation of the coupler are better than 23dB in the frequency range from 2GHz to 5GHz, and reduces the dielectric loss. But the hollowing is aimed at two circuit boards instead of a single-layer circuit board, and the frequency multiplication is only 2.5 times, and in addition, the scheme adopts seven layers of circuit boards, so that the cost is high. The patent with publication number CN115000664A discloses a common mode suppressed dielectric integrated suspension parallel strip line differential coupler, wherein two layers of metal conductors of a traditional double-sided parallel strip line are respectively arranged on a metal layer G5 and a metal layer G6, and meanwhile, most of dielectric is excavated by a dielectric substrate to reduce metal loss, and stubs corresponding to the layers G5 and G6 are connected by metallized through holes to form the differential coupler. But the metal layer G5 and the metal layer G6 are of differential coupler structures, and the transmission lines are mutually contacted and mutually independent and inconsistent with the transmission lines of the directional coupler. The research on the effect of medium excavation is not aimed at a directional coupler, and excessive excavation of the medium can affect the physical stability of the coupler. The patent with the publication number of CN120691080A discloses a quadrature directional coupler based on a micro-coaxial technology, and the ultra-wideband directional coupler realizes impedance matching through a coaxial structure, and the scheme realizes the technical effects of 4dB of coupling degree, 15dB of return loss, 10dB of directivity, wide working frequency band and small size. However, the micro-coaxial technology adopted by the patent has higher cost, and the support bar has larger influence on the directivity, return loss and coupling