An antenna duplexer

Abstract

The utility model relates to the technical field of antenna communication, specifically disclose a kind of antenna diplexer, including PCB board and impedance matching circuit, the two sides of the PCB board are respectively equipped with SMD device, circuit layout area is equipped in the board body of the PCB board, the impedance matching circuit is welded in the circuit layout area, the H end and L end of the impedance matching circuit are connected with the SMD device located in two sides, the S end of the impedance matching circuit is connected with the common port of antenna. The present antenna diplexer has about 30dB isolation between its L port and H port, to meet the practical application in most cases. The port of the present antenna diplexer is frequency-selective, to achieve the effect of distributing power according to situation.

Description

Technical Field

[0001] This utility model relates to the field of antenna communication technology, and in particular to an antenna duplexer. Background Technology

[0002] An antenna duplexer is a 3-port microwave device used for frequency multiplexing. The two ports are typically named L and H (L representing the low-frequency band and H representing the high-frequency band), and are multiplexed to a third port S (S stands for sum). The bandwidths of H and L are separate, and their signals can coexist on the S port without interference.

[0003] Currently, the traditional impedance matching principle is used to match the L and H terminals of the duplexer to the input port S. This allows the reactance of the low-pass filter to compensate for the high-pass filter. Ideally, low-frequency signal power on port L is transmitted to the common port S, while all high-frequency signal power on port H is transmitted to the same port S. However, in reality, signal separation is not perfect, and a certain degree of crosstalk must be tolerated between L and H. Therefore, some power may leak to the wrong ports, affecting the allocated signal power. Utility Model Content

[0004] The purpose of this invention is to provide an antenna duplexer to solve the problems encountered in the background art.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows:

[0006] An antenna duplexer includes a PCB board and an impedance matching circuit. SMD devices are mounted on both sides of the PCB board. A circuit layout area is provided in the body of the PCB board. The impedance matching circuit is soldered in the circuit layout area. The H-terminal and L-terminal of the impedance matching circuit are connected to the SMD devices located on both sides. The S-terminal of the impedance matching circuit is connected to the common port of the antenna.

[0007] In the above scheme, the impedance matching circuit includes an upper line and a lower line. The two ends of the upper line and the two ends of the lower line are connected by connecting lines to form a frame-shaped series circuit. The connecting lines on both sides are connected to the SMD devices on each side through PCB lines. Capacitors and inductors are alternately connected in series between the upper line and the lower line.

[0008] As a preferred embodiment, the linewidths of both the upper and lower lines are greater than the linewidth of the connecting lines, and the linewidth of the capacitor element is greater than the linewidth of the connecting lines. In practice, the capacitor element is an adjustable capacitor or a high-frequency SMD ceramic capacitor; the inductor element is a high-Q SMD inductor.

[0009] In the above solution, the SMD device is fixed to both sides of the PCB board by solder pads, and the solder pads are connected to the connecting lines. As a preferred embodiment, the solder pads are located in the middle of both sides of the PCB board. Grounding holes are provided on the surface of the PCB board.

[0010] In the above scheme, the capacitor element includes a first capacitor and a second capacitor, and the inductor element includes a first inductor and a second inductor. One side pin of the first capacitor is connected to the lower circuit, and the other side pin of the first capacitor is connected to the first inductor. The first inductor and the second inductor are connected in series in the upper circuit with a gap. One side pin of the second capacitor is connected to the lower circuit, and the other side pin of the second capacitor is connected to the second inductor.

[0011] In the above scheme, a high-resistance wire is also connected between the upper circuit and the lower circuit. The lower part of the upper circuit and the upper part of the lower circuit are each provided with a reserved connector, and a reserved position for components is provided between the two reserved connectors.

[0012] Compared with existing technologies, the advantages of this invention are: this antenna duplexer has approximately 30dB of isolation between its L and H ports, meeting the needs of most practical applications. The ports of this antenna duplexer are frequency-selective to achieve power distribution as needed. This antenna duplexer has a simple structure, utilizes impedance matching principles, matches the two ports of the duplexer to the input port S, and uses the reactance of the low-pass filter to compensate for the reactance of the high-pass filter. Attached Figure Description

[0013] The disclosure of this utility model is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this utility model. In the drawings, the same reference numerals are used to refer to the same parts. Wherein:

[0014] Figure 1 This is a schematic diagram of the structure of this utility model;

[0015] Figure 2 This is a comparison diagram of frequency and isolation when the present invention is applied;

[0016] The diagram labels are as follows: 1-PCB board; 11-Grounding hole; 12-Circuit layout area; 13-Component reserved position; 2-SMD component; 21-Pad; 3-Impedance matching circuit; 30-High resistance line; 31-Upper line; 32-Lower line; 33-Connecting line; 34-PCB line; 35-First capacitor; 36-First inductor; 37-Second capacitor; 38-Second inductor; 39-Reserved connector. Detailed Implementation

[0017] To make the technical means, creative features, achieved objectives and effects of this utility model easier to understand, the utility model will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of this utility model, and therefore only show the relevant components of this utility model.

[0018] Based on the technical solution of this utility model, without changing the essential spirit of this utility model, those skilled in the art can propose various interchangeable structural methods and implementation methods. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative descriptions of the technical solution of this utility model, and should not be regarded as the entirety of this utility model or as a limitation or restriction of the technical solution of this utility model.

[0019] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0020] Example 1, as Figure 1 As shown, an antenna duplexer includes a PCB board 1 and an impedance matching circuit 3. SMD devices 2 are mounted on both sides of the PCB board 1. A circuit layout area 12 is provided in the body of the PCB board 1. The impedance matching circuit 3 is soldered in the circuit layout area 12. The H terminal and L terminal of the impedance matching circuit 3 are connected to the SMD devices 2 located on both sides. The S terminal at the bottom of the impedance matching circuit 3 is connected to the common port of the antenna.

[0021] This antenna duplexer has approximately 30dB of isolation between its L and H ports to meet the needs of most practical applications. The ports of this antenna duplexer are frequency-selective to achieve power distribution as needed. This antenna duplexer has a simple structure and uses impedance matching principles, matching the two ports of the duplexer to the input port S, with the reactance of the low-pass filter compensating for the reactance of the high-pass filter.

[0022] The impedance matching circuit 3 includes an upper line 31 and a lower line 32. The two ends of the upper line 31 and the two ends of the lower line 32 are connected by connecting lines 33 to form a frame-shaped series circuit. The connecting lines 33 on both sides are connected to the SMD devices 2 on each side through PCB lines 34. Capacitors and inductors are alternately connected in series between the upper line 31 and the lower line 32.

[0023] The main function of a low-pass filter is to allow signals within a set low-frequency cutoff frequency range above 10MHz to pass through with almost no loss, while significantly attenuating signals above the cutoff frequency. By properly designing the values ​​of inductors and capacitors, a high impedance is created for high-frequency signals, thereby suppressing their transmission and preventing them from entering the receiving or transmitting link, ensuring effective isolation from the high-pass band. Conversely, a high-pass filter allows signals within a set high-frequency cutoff frequency range below 1.0GHz to pass through, effectively suppressing signals below the cutoff frequency. By creating a high impedance for low-frequency signals, it prevents low-frequency signals from entering the high-frequency signal path, ensuring the normal operation of the duplexer and achieving separate transmission of signals in different frequency bands.

[0024] As a preferred embodiment, the line widths of both the upper line 31 and the lower line 32 are greater than the line width of the connecting line 33, and the line width of the capacitor element is also greater than the line width of the connecting line 33. In implementation, adjustable capacitors or high-frequency SMD ceramic capacitors (such as the Murata GJM series or AVX Accu-P series) are used as capacitors, and high-Q SMD inductors are used to ensure low ESR and high Q values, replacing the capacitors.

[0025] SMD device 2 is fixed to both sides of PCB board 1 by solder pads 21. The solder pads 21 are connected to the connecting line 33 to achieve effective connection. As a preferred embodiment, the solder pads 21 are located in the middle of both sides of PCB board 1 for easy installation on the antenna. Grounding holes 11 are provided on the surface of PCB board 1 to prevent short circuits.

[0026] Example 2, based on Example 1, includes a capacitor element comprising a first capacitor 35 and a second capacitor 37, and an inductor element comprising a first inductor 36 and a second inductor 38. One side pin of the first capacitor 35 is connected to the lower circuit 32, and the other side pin of the first capacitor 35 is connected to the first inductor 36. The first inductor 36 and the second inductor 38 are connected in series at intervals on the upper circuit 31. One side pin of the second capacitor 37 is connected to the lower circuit 32, and the other side pin of the second capacitor 37 is connected to the second inductor 38.

[0027] The first capacitor 35 is C1, and the second capacitor 37 is C2. Adjustable capacitors with a capacitance of 6pF and an accuracy of ±1% can be used to ensure low ESR and high Q value. The first inductor 36 is L1, and the second inductor 38 is L2. High-Q SMD inductors are selected. PCB board 1 uses an FR4 board with a DK value of 4 to reduce losses and lower the overall cost of the duplexer.

[0028] In terms of circuit connections, one pin of capacitor C1 is connected to the common port via a wide copper foil trace, and the other pin is connected to one end of inductor L1. The other end of inductor L1 is then connected to one pin of capacitor C2, forming a regular and compact circuit layout. Both ends are connected to SMD device 2 (female) via pad 21, and the external thread assembly allows the duplexer to be effectively connected to the antenna to be used.

[0029] Starting from the common port, capacitor C1, inductor L1, capacitor C2, inductor L2 are arranged in sequence, with capacitors and inductors connected alternately. One end of each capacitor is connected to the output terminal of the previous stage inductor, and the other end is connected to the input terminal of the next stage inductor. In the actual PCB layout, the surface-mount inductors and capacitors are precisely placed in designated positions according to calculated parameters, and the leads of the capacitors and inductors are interconnected through copper traces to form a complete circuit path.

[0030] As a preferred embodiment, a high-impedance line 30 is also connected between the upper line 31 and the lower line 32 to match impedance, absorb energy, and prevent signal reflection from causing waveform distortion. The lower part of the upper line 31 and the upper part of the lower line 32 are each provided with a reserved connector 39. A component reserved position 13 is provided between the two reserved connectors 39. This component reserved position 13 is used to install other capacitor components, and for each additional capacitor component, an additional reactance is added.

[0031] The common port (ANT) trace of the lower line 32 uses a wider copper foil trace (continuous 50Ω microstrip line), avoids right-angle traces, and uses arcs or 45° bevels to reduce reflection.

[0032] For capacitor C1, one pin is directly connected to the ANT trace (wide copper foil), and the other pin is connected to L1. Minimize the trace length from C1 to L1 to reduce parasitic inductance.

[0033] Connection of inductor L1 and capacitor C2: The traces of inductor L1 and capacitor C2 should be as short as possible to avoid introducing additional parasitic capacitance. SMD devices in 0402 or 0603 packages can be used to reduce the influence of distributed parameters.

[0034] In addition, regarding grounding and shielding, ensure a good grounding plane to avoid resonance interference, and add a shielding cover (such as a metal cavity) if necessary to reduce radiation coupling.

[0035] Please see Figure 2 A Butterworth high-pass filter with a cutoff frequency of 100MHz and a characteristic impedance of 50Ω was simulated, and the results were plotted.

[0036] Based on embodiments 1-2, the impedance matching circuit 3 in this duplexer constitutes a filter with a specific resonant frequency. For a 10MHz-1.0GHz duplexer, by precisely designing the values ​​of the inductor and capacitor, the LC filter of the receiving channel presents low impedance in the receiving frequency band (e.g., around 10MHz), resulting in minimal attenuation of the received signal and allowing the signal in this band to pass smoothly to the receiver; while in the transmitting frequency band (e.g., around 1.0GHz), the LC filter of the transmitting channel presents high impedance, greatly attenuating the transmitted signal and preventing it from entering the receiver, thereby achieving initial separation of the received and transmitted signals in terms of frequency.

[0037] In signal isolation, this antenna duplexer utilizes the characteristics of an LC network to prevent transmitted signals from leaking into the receiving channel and to prevent the received signal from being interfered with by the transmitted signal. During transmission, the LC network of the transmitting channel effectively transmits the transmitted signal to the antenna, while simultaneously controlling the reception.

[0038] The receiving channel presents high impedance to reduce the coupling of the transmitted signal to the receiving channel. During reception, the LC network of the receiving channel efficiently transmits the received signal to the receiver, while presenting high impedance to the transmitting channel to prevent the received signal from being absorbed or interfered with by the circuitry of the transmitting channel.

[0039] In impedance matching, this antenna duplexer also needs to achieve impedance matching between the antenna, transmitter, and receiver. By properly designing the parameters of the LC network, good impedance matching is achieved between the transmitting and receiving channels and the antenna, as well as the corresponding transmitter and receiver, within the operating frequency range. This ensures that signal reflection is minimized during transmission, improving signal transmission efficiency and reducing signal distortion and power loss.

[0040] With functions such as frequency selection, signal isolation, and impedance matching, the 10MHz-1.0GHz antenna duplexer can effectively separate and combine transmit and receive signals of different frequencies, ensuring the normal operation of both the transmitting and receiving ends in the communication system and improving the system's performance and reliability.

[0041] Additionally, during implementation, the low-pass filter was simulated with a start-cutoff frequency of 100MHz and tested on a network analyzer. Since the characteristic impedance should be matched to 50Ω, the simulation was run and the results plotted using the integrated tools in the QUCS filter synthesis tool.

[0042] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. An antenna duplexer, characterized in that: The circuit includes a PCB board (1) and an impedance matching circuit (3). SMD devices (2) are mounted on both sides of the PCB board (1). A circuit layout area (12) is provided in the body of the PCB board (1). The impedance matching circuit (3) is soldered in the circuit layout area (12). The H and L terminals of the impedance matching circuit (3) are connected to the SMD devices (2) located on both sides. The S terminal of the impedance matching circuit (3) is connected to the common port of the antenna.

2. The antenna duplexer according to claim 1, characterized in that: The impedance matching circuit (3) includes an upper line (31) and a lower line (32). The two ends of the upper line (31) and the two ends of the lower line (32) are connected by connecting lines (33) to form a frame-shaped series circuit. The connecting lines (33) on both sides are connected to the SMD devices (2) on each side through PCB lines (34). Capacitors and inductors are alternately connected in series between the upper line (31) and the lower line (32).

3. An antenna duplexer according to claim 2, characterized in that: The SMD device (2) is fixed on both sides of the PCB board (1) by pads (21), and the pads (21) are connected to the connecting line (33).

4. An antenna duplexer according to claim 3, characterized in that: The pads (21) are located in the middle of both sides of the PCB board (1).

5. An antenna duplexer according to claim 2, characterized in that: The capacitor element includes a first capacitor (35) and a second capacitor (37), and the inductor element includes a first inductor (36) and a second inductor (38). One side pin of the first capacitor (35) is connected to the lower line (32), and the other side pin of the first capacitor (35) is connected to the first inductor (36). The first inductor (36) and the second inductor (38) are connected in series on the upper line (31) at intervals. One side pin of the second capacitor (37) is connected to the lower line (32), and the other side pin of the second capacitor (37) is connected to the second inductor (38).

6. An antenna duplexer according to claim 5, characterized in that: A high-resistance line (30) is also connected between the upper line (31) and the lower line (32).

7. An antenna duplexer according to claim 5, characterized in that: The lower part of the upper line (31) and the upper part of the lower line (32) are respectively provided with reserved connectors (39), and there is a reserved position (13) for components between the two reserved connectors (39).

8. An antenna duplexer according to claim 1, characterized in that: The PCB board (1) has a grounding hole (11) on its surface.

9. An antenna duplexer according to claim 5, characterized in that: The line width of the upper line (31) and the line width of the lower line (32) are both greater than the line width of the connecting line (33), and the line width of the capacitor element is greater than the line width of the connecting line (33).

10. An antenna duplexer according to claim 2, characterized in that: The capacitor element is an adjustable capacitor or a high-frequency SMD ceramic capacitor; the inductor element is a high-Q SMD inductor.

Images