A dielectric waveguide diplexer structure

Abstract

The application discloses a medium waveguide diplexer structure and relates to the technical field of communication. The diplexer comprises a three-port circulator, a transmitting medium waveguide filter and a receiving medium waveguide filter. The circulator has a first port, a second port and a third port; the input end of the transmitting medium waveguide filter is used for connecting a transmitter, and the output end is connected with the first port of the circulator; the input end of the receiving medium waveguide filter is connected with the third port of the circulator, and the output end is used for connecting a receiver; and the second port of the circulator is used for connecting an antenna. The circulator is configured to enable the signal input from the first port to be output from the second port and enable the signal input from the second port to be output from the third port. The application introduces the circulator, thereby helping to reduce the requirement on the suppression performance of the medium waveguide filter, facilitating to reduce the design and manufacturing difficulty and the overall size of the medium waveguide diplexer.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and more specifically to a dielectric waveguide duplexer structure for frequency division duplex systems. Background Technology

[0002] In mobile communication systems, Frequency Division Duplex (FDD) mode requires the transmit and receive signals to be isolated via the same antenna. A common technical solution in existing waveguide duplexers is to directly connect the transmit and receive filters to the antenna through a common port. For example, Chinese patent CN103531868A discloses a substrate-integrated waveguide duplexer where the transmit and receive filter channels are combined and split at the common port via a dual-mode common resonant cavity. Another example is Chinese patent CN217361869U, which discloses a debug-free waveguide duplexer that has a high-frequency channel, a low-frequency channel, and a common channel within a housing, connecting the transmit and receive channels to the common channel via a three-way cavity. Yet another example is Chinese patent CN200986960Y, which discloses a coupling structure between filters and a common port, using a common resonator to connect multiple filters to the common port.

[0003] In the aforementioned existing technical solutions, the transmitting and receiving filters are directly connected at a common port. The impedances of the two filters at this common port interfere with each other, often requiring additional impedance matching design and occupying a large space. Furthermore, since isolation between the transmitted and received signals mainly relies on the out-of-band suppression characteristics of the filters themselves, the suppression requirements are high, making the design and manufacturing of dielectric waveguide filters more difficult. In addition, existing waveguide duplexers involve processes such as silver layer stripping during commissioning, making it difficult to control passive intermodulation parameters in production. Summary of the Invention

[0004] Purpose of the invention: The present invention aims to provide a dielectric waveguide duplexer structure to solve the problems of high filter suppression requirements, difficulty in passive intermodulation control, and large space occupation for port matching in the prior art.

[0005] Technical Solution: A dielectric waveguide duplexer structure includes a three-port circulator, a transmitting dielectric waveguide filter, a receiving dielectric waveguide filter, and an antenna interface. The circulator has a first port, a second port, and a third port for unidirectional circular signal transmission. The input of the transmitting dielectric waveguide filter is connected to a transmitter, and its output is connected to the first port of the circulator. The input of the receiving dielectric waveguide filter is connected to the third port of the circulator, and its output is connected to a receiver. The antenna interface is connected to the second port of the circulator for connecting an antenna. The circulator is configured such that a signal input from the first port can be output from the second port, and a signal input from the second port can be output from the third port.

[0006] Furthermore, the transmitting and receiving dielectric waveguide filters are integrated with the circulator into a modular structure via a printed circuit board (PCB). In one assembly method, the transmitting and receiving dielectric waveguide filters are soldered to the same side surface of the PCB. In another assembly method, the transmitting and receiving dielectric waveguide filters are soldered to different side surfaces of the PCB to further reduce the planar footprint of the module.

[0007] Furthermore, a low-intermodulation circulator can be used to reduce the passive intermodulation performance of the system.

[0008] Furthermore, the transmitting dielectric waveguide filter and / or the receiving dielectric waveguide filter may be a stripline waveguide filter or a dielectric-filled waveguide filter based on a dielectric resonator.

[0009] Furthermore, the isolation between the first port and the third port of the circulator, and between the third port and the first port, is configured to be greater than or equal to 20dB.

[0010] Furthermore, signal connections can be established between the output of the transmitting medium waveguide filter and the first port of the circulator, and between the input of the receiving medium waveguide filter and the third port of the circulator, via microstrip lines or coplanar waveguide transmission lines.

[0011] Furthermore, a ground layer and a signal wiring layer are provided on the printed circuit board, and the ports of the circulator, as well as the ports of the transmitting medium waveguide filter and the receiving medium waveguide filter, are electrically connected to the signal wiring layer on the printed circuit board by soldering.

[0012] Furthermore, the operating frequency bands of the transmitting medium waveguide filter and the receiving medium waveguide filter correspond to the transmitting frequency band and the receiving frequency band, respectively, and the two frequency bands are different.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. By introducing a circulator, the transmitted and received signals are isolated using the circulator's inherent isolation characteristics. This helps reduce the suppression requirement of the dielectric waveguide filter by more than 20dB, thereby reducing the filter order and making it easier to shrink the filter size.

[0014] 2. Since the order of the filter can be reduced and the insertion loss of the circulator is low, it helps to reduce the overall insertion loss of the duplexer.

[0015] 3. When a low intermodulation circulator is used, the isolation effect of its antenna port helps to reduce the passive intermodulation performance requirements of the transmit filter, and makes it easier to reduce the manufacturing difficulty of the dielectric waveguide filter.

[0016] 4. The introduction of circulators simplifies the design of common ports, facilitates port matching, and helps reduce the size space occupied by port matching.

[0017] 5. While keeping the insertion loss constant, reducing the filter order to achieve size reduction helps to further compress the size of individual dielectric resonators, thereby reducing the overall size and cost of dielectric waveguide duplexers. Attached Figure Description

[0018] Figure 1 This is an isometric view of the present invention.

[0019] Figure 2 This is the front view of the present invention.

[0020] Reference numerals: three-port circulator 10, transmitting medium waveguide filter 20, receiving medium waveguide filter 30, first port 11, second port 12, third port 13, printed circuit board 50. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 Reference Figure 1 and Figure 2 This embodiment provides a dielectric waveguide duplexer structure. The duplexer includes a three-port circulator 10, a transmitting dielectric waveguide filter 20, a receiving dielectric waveguide filter 30, and an antenna interface.

[0023] Circulator 10 is a three-port non-reciprocal device with a first port 11, a second port 12, and a third port 13. Circulator 10 is configured to achieve unidirectional ring transmission of signals, meaning that an RF signal input from the first port 11 can only be output from the second port 12, and an RF signal input from the second port 12 can only be output from the third port 13. Circulator 10 has inherent isolation between the first port 11 and the third port 13, and between the third port 13 and the first port 11, with an isolation level preferably greater than or equal to 20 dB.

[0024] The transmitting dielectric waveguide filter 20 is a bandpass filter implemented based on a dielectric waveguide structure, and its operating frequency band corresponds to the transmission frequency band of the communication system. The transmitting dielectric waveguide filter 20 has one input terminal and one output terminal. Its input terminal is used to connect to a transmitter (not shown) to receive the radio frequency signal output by the transmitter. Its output terminal is connected to the first port 11 of the circulator 10 to send the filtered transmission signal into the circulator 10.

[0025] The receiving dielectric waveguide filter 30 is also a bandpass filter based on a dielectric waveguide structure. Its operating frequency band corresponds to the receiving frequency band of the communication system, which is different from the operating frequency band of the transmitting dielectric waveguide filter 20. The receiving dielectric waveguide filter 30 has one input terminal and one output terminal. Its input terminal is connected to the third port 13 of the circulator 10 for receiving the radio frequency signal received by the antenna from the circulator 10. Its output terminal is used to connect to a receiver (not shown) to output the filtered received signal to the receiver.

[0026] The antenna interface is connected to the second port 12 of the circulator 10. The antenna interface is used to connect an external antenna (not shown) to enable the transmission and reception of radio frequency signals.

[0027] In this embodiment, the transmitting medium waveguide filter 20 and the receiving medium waveguide filter 30 are integrated with the circulator 10 into a modular structure via a printed circuit board (PCB) 50. Specifically, the circulator 10, the transmitting medium waveguide filter 20, and the receiving medium waveguide filter 30 are respectively mounted on the PCB 50. The PCB 50 has a ground layer and a signal routing layer. Each port of the circulator 10 (first port 11, second port 12, and third port 13) and each port of the transmitting medium waveguide filter 20 and the receiving medium waveguide filter 30 are electrically connected to the signal routing layer on the PCB 50 by soldering.

[0028] The output of the transmitting dielectric waveguide filter 20 is connected to the first port 11 of the circulator 10 via a microstrip line or a coplanar waveguide transmission line on the printed circuit board 50. Similarly, the input of the receiving dielectric waveguide filter 30 is also connected to the third port 13 of the circulator 10 via a microstrip line or a coplanar waveguide transmission line on the printed circuit board 50.

[0029] In this embodiment, the transmitting dielectric waveguide filter 20 and the receiving dielectric waveguide filter 30 can be stripline waveguide filters or dielectric-filled waveguide filters based on dielectric resonators. The specific structural form can be selected according to the operating frequency band and performance requirements.

[0030] The working process of this embodiment is as follows: In the transmission link, the radio frequency signal output by the transmitter is bandpass filtered by the transmitting medium waveguide filter 20 and then input from the first port 11 of the circulator 10. Due to the unidirectional transmission characteristic of the circulator 10, the signal is output from the second port 12 and transmitted to the antenna via the antenna interface, where it is radiated outwards.

[0031] In the receiving link, the radio frequency signal received by the antenna is transmitted to the second port 12 of the circulator 10 via the antenna interface. Due to the unidirectional transmission characteristic of the circulator 10, the signal is output from the third port 13 and enters the receiving medium waveguide filter 30 for bandpass filtering, and then output to the receiver for processing.

[0032] During this process, the transmitted and received signals are isolated through the isolation characteristics of the circulator 10. The isolation between the first port 11 and the third port 13 of the circulator 10, and between the third port 13 and the first port 11, is greater than or equal to 20dB. As a result, the out-of-band suppression required by the transmitting medium waveguide filter 20 and the receiving medium waveguide filter 30 can be reduced accordingly.

[0033] Example 2 The difference between this embodiment and Embodiment 1 lies in the different assembly methods of the transmitting medium waveguide filter 20 and the receiving medium waveguide filter 30 on the printed circuit board 50.

[0034] In this embodiment, the transmitting medium waveguide filter 20 and the receiving medium waveguide filter 30 are soldered to different side surfaces of the printed circuit board 50. Specifically, the transmitting medium waveguide filter 20 is mounted on the first surface (e.g., the front surface) of the printed circuit board 50, and the receiving medium waveguide filter 30 is mounted on the second surface (e.g., the back surface) of the printed circuit board 50. The mounting position of the circulator 10 can be selected to be located on the front or back surface of the printed circuit board 50 according to the actual layout requirements.

[0035] By adopting a double-sided assembly method, the projection areas of the transmitting medium waveguide filter 20 and the receiving medium waveguide filter 30 on the printed circuit board 50 can partially or completely overlap, which helps to further reduce the overall planar area occupied by the module and facilitates its application in space-constrained scenarios.

[0036] The other structures, connections, and working processes in this embodiment are the same as in Embodiment 1, and will not be repeated here.

[0037] Example 3 The difference between this embodiment and Embodiment 1 is that the circulator 10 uses a low intermodulation circulator.

[0038] The low-intermodulation circulator improves its passive intermodulation performance by optimizing the internal ferrite material formulation, improving the magnetic circuit design, and employing a low-intermodulation welding process. In this embodiment, since the second port 12 of the circulator 10 is connected to the antenna interface, the transmitted signal power at the antenna port is relatively high, which easily generates passive intermodulation products inside the circulator. With the low-intermodulation circulator, the passive intermodulation level generated by the circulator 10 itself is lower. Simultaneously, the isolation between the antenna port (second port 12) and the transmit port (first port 11), as well as between the circulator 10 and the receive port (third port 13), helps suppress the transmission of passive intermodulation products to the transmit and receive links.

[0039] The other structures, connections, and working processes in this embodiment are the same as in Embodiment 1, and will not be repeated here.

[0040] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A dielectric waveguide duplexer structure, characterized in that, include: A three-port circulator, having a first port, a second port, and a third port, is used to achieve unidirectional ring transmission of signals; A transmitting medium waveguide filter, the input of which is connected to a transmitter, and the output of which is connected to the first port of the circulator; A receiving medium waveguide filter, the input of which is connected to the third port of the circulator, and the output of which is used to connect to a receiver; An antenna interface is connected to the second port of the circulator for connecting an antenna; The circulator is configured such that a signal input from a first port can be output from a second port, and a signal input from a second port can be output from a third port.

2. The dielectric waveguide duplexer structure according to claim 1, characterized in that, The transmitting medium waveguide filter and the receiving medium waveguide filter are integrated with the circulator into a modular structure via a printed circuit board.

3. The dielectric waveguide duplexer structure according to claim 1, characterized in that, The transmitting medium waveguide filter and the receiving medium waveguide filter are respectively soldered to the same side surface of the printed circuit board.

4. The dielectric waveguide duplexer structure according to claim 1, characterized in that, The transmitting medium waveguide filter and the receiving medium waveguide filter are respectively soldered to different side surfaces of the printed circuit board.

5. The dielectric waveguide duplexer structure according to claim 1, characterized in that, The circulator is a low intermodulation circulator.

6. The dielectric waveguide duplexer structure according to claim 1, characterized in that, The transmitting dielectric waveguide filter and / or the receiving dielectric waveguide filter are stripline waveguide filters or dielectric-filled waveguide filters based on dielectric resonators.

7. The dielectric waveguide duplexer structure according to claim 1, characterized in that, The isolation between the first port and the third port of the circulator, and between the third port and the first port, is greater than or equal to 20 dB.

8. The dielectric waveguide duplexer structure according to claim 1, characterized in that, The output of the transmitting medium waveguide filter is connected to the first port of the circulator, and the input of the receiving medium waveguide filter is connected to the third port of the circulator via a microstrip line or a coplanar waveguide transmission line.

9. The dielectric waveguide duplexer structure according to claim 1, characterized in that, The printed circuit board is provided with a ground layer and a signal wiring layer. The ports of the circulator, as well as the ports of the transmitting medium waveguide filter and the receiving medium waveguide filter, are electrically connected to the signal wiring layer on the printed circuit board by soldering.

10. A dielectric waveguide duplexer structure according to any one of claims 1 to 9, characterized in that, The transmitting medium waveguide filter and the receiving medium waveguide filter operate at different frequency bands, corresponding to the transmitting frequency band and the receiving frequency band, respectively.

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