Short-wave duplexer

Abstract

The utility model discloses a short-wave duplexer, which at least comprises a low-pass filter, a high-pass filter, a first input port, a second input port and an output port, the output port outputs a synthesized power signal; a power signal with the frequency band of 5.9-9.9 MHz is input to the low-pass filter through the first input port; a power signal with the frequency band of 11.5-21.85 MHz is input to the high-pass filter through the second input port; the low-pass filter and the high-pass filter are connected through a star-shaped node; the low-pass filter is an elliptic function response low-pass filter, and the high-pass filter is an elliptic function response high-pass filter.

Description

Technical Field

[0001] The utility model belongs to the field of electronic information / radio frequency / high-power passive devices, and specifically relates to a short-wave duplexer. Background Art

[0002] A multiplexer (also called a frequency modulation multi-channel synthesizer) can synthesize the output power signals of multiple frequency transmitters without interfering with each other, and transmit them through a broadband antenna feeder system on the same tower. Using a multiplexer in a wireless transmission system can improve the utilization of tower top resources, improve transmission coverage, increase the reliability and scalability of the transmission system, and reduce the construction and maintenance costs of the entire system. A multiplexer used for synthesizing two channels is also called a duplexer.

[0003] According to different structural classifications, multiplexers can be divided into basic structural forms such as fixed impedance type (also known as bridge type), star point type, Manifold type (also known as generalized star type), phase sensitive type, and hybrid structures composed of basic structural units. Multiplexers with star point and Manifold structures are composed of multiple filters, one or more connection nodes, and connection hard feeds and accessories connecting the filters and nodes. The filters that constitute the star point and Manifold multiplexers can be bandpass filters, low-pass filters, and high-pass filters. Depending on the number of connected filters, the connection node or star node (StarPoint) can be a device with 3 ports, 4 ports or more ports. N-way star point and Manifold multiplexers contain N input ports and 1 output port. Compared with multiplexers with other structures, star point and Manifold structure multiplexers have the advantages of simple structure, low cost, and cabinet structure design.

[0004] Isolation is one of the important indicators of a multiplexer. It characterizes the degree of mutual influence between the input ports of the multiplexer, and the unit is dB. The lower the isolation index, the smaller the degree of mutual influence between the input ports of the multiplexer, and the better the index. Unlike the fixed impedance multiplexer, whose isolation is provided by the filter and coupler, the isolation of the star point and Manifold structure multiplexers is mainly provided by the filter. In order to meet the requirements of the multiplexer isolation index, the filter itself is required to have a greater out-of-band attenuation, that is, the filter needs to be steeper.

[0005] The out-of-band attenuation index of the filter is mainly determined by the following factors:

[0006] (1) Number of cavities. The more cavities or sections a filter has, the greater the out-of-band attenuation and the steeper the filter. However, the more cavities or sections a filter has, the greater the insertion loss of the filter, the lower the efficiency, and the higher the cost.

[0007] (2) Topological structure. Different filter topological structures correspond to different out-of-band attenuation indicators. Introducing cross-coupling between non-adjacent resonant cavities at appropriate locations can move part or all of the transmission zero points of the filter to a position with a limited frequency interval from the center frequency of the filter, which can effectively improve the out-of-band attenuation index of the filter.

[0008] (3) Passband bandwidth. Under the premise that other indicators are the same, the smaller the filter passband bandwidth, the narrower the relative bandwidth of the filter, the better the out-of-band attenuation index, but the filter insertion loss index will deteriorate accordingly.

[0009] The operating frequency range of shortwave communication is 2 to 32MHz, and it is widely used in various communication systems, including radio and television, military defense, and other communication networks. When the shortwave communication system contains transmitters with multiple operating frequencies and it is necessary to synthesize the output power signals of multiple transmitters working at different frequencies, it is necessary to design a multiplexer for the shortwave frequency band.

[0010] For the demand for inter-frequency power synthesis in the shortwave band, the existing solution is to use a broadband power synthesizer to synthesize two power signals of different frequencies. The biggest problem with this solution is that the synthesis efficiency of the synthesizer will be very low. For example, using a ferrite broadband power synthesizer to achieve two 1kW inter-frequency power synthesis, the power loss on the matching load will reach 1kW, which means that half of the total input power will be lost; and when the amplitudes (power sizes) of the two input powers are different, this loss will be even greater. In other words, using this method for inter-frequency synthesis, not counting the insertion loss of the synthesizer itself, the insertion loss of the entire system is at least 3dB. This solution can also be used as an alternative in low-power systems, but it is not suitable for high-power occasions. Utility Model Content

[0011] Purpose of the utility model: To solve the problem that the existing duplexer cannot meet the demand for high-power synthesis of different frequencies in the shortwave frequency band, the utility model proposes a shortwave duplexer, which is composed of a low-pass filter and a high-pass filter to realize the synthesis of two high-power signals of different frequencies. Technical solution: A shortwave duplexer, comprising at least 1 low-pass filter, 1 high-pass filter, a first input port, a second input port and an output port; the output port outputs the synthesized power signal;

[0012] A power signal with a frequency band of 5.9 to 9.9 MHz is input to the low-pass filter through the first input port;

[0013] A power signal with a frequency band of 11.5 to 21.85 MHz is input to the high-pass filter through the second input port;

[0014] The low-pass filter and the high-pass filter are connected via a star node; the low-pass filter is an elliptic function response low-pass filter, and the high-pass filter is an elliptic function response high-pass filter.

[0015] Furthermore, the first input port, the second input port and the output port are all DIN 7 / 16 (F) ports.

[0016] Furthermore, the isolation between the first input port and the second input port is not less than 30 dB.

[0017] Furthermore, the out-of-band attenuation of the low-pass filter at 11.5 MHz is greater than 35 dB.

[0018] Furthermore, the out-of-band attenuation of the high-pass filter at 9.9 MHz is greater than 35 dB.

[0019] Furthermore, the low-pass filter is a 7th-order elliptic function response low-pass filter, and the high-pass filter is a 7th-order elliptic function response high-pass filter.

[0020] Furthermore, the inductance elements constituting the 7th-order elliptic function response low-pass filter and the 7th-order elliptic function response high-pass filter are winding inductors, and each winding inductor is supported by a bracket made of bakelite strips.

[0021] Furthermore, the capacitive elements constituting the 7th-order elliptic function response low-pass filter and the 7th-order elliptic function response high-pass filter are composed of a capacitor group in which a plurality of chip capacitors are connected in parallel.

[0022] Furthermore, the chip capacitor is a chip high-Q ceramic capacitor.

[0023] Furthermore, the winding inductor is wound by a pure copper wire with a diameter of φ4 mm.

[0024] Beneficial effects: Compared with the prior art, the utility model has the following advantages:

[0025] (1) The short-wave duplexer proposed in the utility model is mainly composed of a low-pass filter and a high-pass filter. The low-frequency band (5.9-9.9MHz) power signal passes through the low-pass filter, and the high-frequency band (11.5-21.85MHz) power signal passes through the high-pass filter. The two frequency band power signals are synthesized and output at the output port of the duplexer. That is to say, the operating frequency of the short-wave duplexer proposed in the utility model meets the requirements of 5.9-9.9 / 11.5-21.85MHz, and the interval between the two operating frequency bands is only 1.6MHz;

[0026] (2) Both the low-pass filter and the high-pass filter of the utility model adopt a 7th-order elliptic function response, and the filter has an excellent out-of-band attenuation index, meeting the index requirements of the duplexer isolation;

[0027] (3) The low-pass filter and high-pass filter of the utility model are composed of separate components, and the capacitors in the duplexer all use a capacitor group with multiple capacitors connected in parallel, which greatly improves the current carrying characteristics and power capacity of the capacitors;

[0028] (4) The two different-frequency power signals synthesized by the short-wave duplexer proposed in the utility model do not require amplitude and phase requirements, and the two input ports have at least 20dB isolation, and the duplexer insertion loss is not greater than 0.5dB; since no filter is ideal, a transition band needs to be set between the filters of the two frequency bands. The narrower the transition band, the higher the requirement for the filter's out-of-band attenuation. The two frequency bands of the short-wave duplexer proposed in the utility model are 5.9-9.9MHz and 11.5-21.85MHz, respectively, and the transition band is only 9.9-11.5MHz. The duplexer cannot input signals within the transition band;

[0029] (5) The technical indicators of the shortwave duplexer proposed in the utility model include: operating frequency: 5.9~9.9 / 11.5~21.85MHz; rated power: 2×2kW average power; reflection loss ≥20dB; insertion loss ≤0.5dB; isolation ≥30dB. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the appearance of a short-wave duplexer disclosed in the utility model;

[0031] Figure 2 This is the result of Chebyshev low-pass computer simulation;

[0032] Figure 3 This is a graph of Chebyshev Qualcomm computer simulation results;

[0033] Figure 4 This is the simulation result diagram of the 7th-order elliptic function duplexer;

[0034] Figure 5 This is a schematic diagram of the internal structure of a shortwave duplexer disclosed in the utility model;

[0035] Figure 6 The circuit schematic diagram of the low-pass and high-pass filters of the 7th-order elliptic function. DETAILED DESCRIPTION

[0036] The technical solution of the utility model is now further described in conjunction with the accompanying drawings and embodiments.

[0037] like Figure 1 and Figure 5As shown, this embodiment proposes a short-wave duplexer, which mainly includes: a low-pass filter, a high-pass filter, a star node connecting the low-pass filter and the high-pass filter, and two input ports (P in1 , P in2 ), 1 output port P out , coaxial cables and other connecting wires. 2 input ports (P in1 , P in2 ) and 1 output port P out All are DIN 7 / 16 (F) ports. The outer conductor of the port is directly mounted on the housing 1 of the shortwave duplexer. The inner conductor of the port is connected to the low-pass filter and the high-pass filter through a wire. The housing of the shortwave duplexer is made of aluminum alloy and is subjected to conductive oxidation treatment.

[0038] The power signal of the low frequency band (5.9-9.9MHz) passes through the low-pass filter, and the power signal of the high frequency band (11.5-21.85MHz) passes through the high-pass filter. The power signals of the two frequency bands are synthesized and output at the output port of the duplexer. In other words, the short-wave duplexer of this embodiment has two working frequency bands, 5.9-9.9MHz and 11.5-21.85MHz, respectively. The transition band width between the two working frequency bands is only 1.6MHz, which is relatively narrow. The isolation between the two input ports of the short-wave duplexer is required to be no less than 30dB, and a 5dB redundancy is reserved for the short-wave duplexer. The out-of-band attenuation of the low-pass and high-pass filters at the corresponding frequency positions must reach at least 35dB. That is to say, for a low-pass filter with a passband of 5.9 to 9.9 MHz, the out-of-band attenuation at 11.5 MHz must be greater than 35 dB; similarly, for a high-pass filter with a passband of 11.5 to 21.85 MHz, the out-of-band attenuation at 9.9 MHz must also be greater than 35 dB.

[0039] The low-pass filter and high-pass filter can adopt the Chebyshev response structure. The low-pass filter and high-pass filter need at least 13 sections. The computer simulation results of the 13-section Chebyshev low-pass and high-pass filters are as follows: Figure 2 and Figure 3 As shown in Figure 13, the Chebyshev low-pass and high-pass filters contain 13 capacitors and inductors. There are too many components, making it difficult to implement the filter, and the loss of the filter will be relatively large.

[0040] Therefore, compared to the low-pass and high-pass filters of the Chebyshev response, the present embodiment adopts elliptic function low-pass and high-pass filters, which can effectively improve the out-of-band attenuation index of the filter by moving part of the transmission zero point of the filter from infinity in the frequency domain to a position finitely far from the filter passband. To put it another way, in order to achieve the same out-of-band attenuation index requirements, the number of inductor and capacitor elements contained in the elliptic function response filter will be smaller. In this way, the filter will be easier to implement and the loss of the filter will be smaller. Through computer simulation, it can be seen that the low-pass and high-pass filters of the 7th-order elliptic function can achieve the above-mentioned out-of-band attenuation requirements. The simulation results are as follows. Figure 4 shown. Figure 6 The circuit schematic of the low-pass and high-pass filters of the 7th-order elliptic function is shown.

[0041] The power capacity of the shortwave duplexer is required to be greater than 2×2kW average power, and the overall insertion loss is required to be no greater than 0.5dB. This power level and loss level are relatively high. Therefore, the inductor and capacitor components in the low-pass filter and high-pass filter in the shortwave duplexer proposed in this embodiment cannot use ordinary chip inductors and capacitors, but need to use high-voltage, high-current, and high-Q value inductor components and capacitor components. Figure 5 As shown, the short-wave duplexer proposed in this embodiment adopts a winding inductor 2, and the wire is made of pure copper with a diameter of φ4mm. The connection points at both ends of each winding inductor 2 adopt an adjustable fixture structure to facilitate the adjustment of the inductance. The inductor is supported by a bracket made of bakelite strips. The capacitors in the low-pass and high-pass filters are both chip-type high-Q ceramic capacitors, and each capacitor of the filter is composed of a capacitor group 4 of multiple chip capacitors connected in parallel. The inductor and capacitor elements are connected by a φ4mm pure copper wire.

Claims

1. A shortwave duplexer, characterized in that: At least one low-pass filter, one high-pass filter, a first input port, a second input port and an output port; the output port outputs the synthesized power signal; A power signal with a frequency band of 5.9 to 9.9 MHz is input to the low-pass filter through the first input port; A power signal with a frequency band of 11.5 to 21.85 MHz is input to the high-pass filter through the second input port; The low-pass filter and the high-pass filter are connected via a star node; the low-pass filter is an elliptic function response low-pass filter, and the high-pass filter is an elliptic function response high-pass filter.

2. A shortwave duplexer according to claim 1, characterized in that: The first input port, the second input port and the output port are all DIN 7 / 16 (F) ports.

3. The shortwave duplexer according to claim 1, characterized in that: The isolation between the first input port and the second input port is not less than 30 dB.

4. The shortwave duplexer according to claim 1, characterized in that: The out-of-band attenuation of the low-pass filter at the 11.5 MHz position is greater than 35 dB.

5. The shortwave duplexer according to claim 1, characterized in that: The out-of-band attenuation of the high-pass filter at 9.9 MHz is greater than 35 dB.

6. The shortwave duplexer according to claim 1, characterized in that: The low-pass filter is a 7th-order elliptic function response low-pass filter, and the high-pass filter is a 7th-order elliptic function response high-pass filter.

7. The shortwave duplexer according to claim 6, characterized in that: The inductance components constituting the 7th-order elliptic function response low-pass filter and the 7th-order elliptic function response high-pass filter are winding inductors, and each winding inductor is supported by a bracket consisting of bakelite strips.

8. The shortwave duplexer according to claim 6, characterized in that: The capacitor elements constituting the 7th-order elliptic function response low-pass filter and the 7th-order elliptic function response high-pass filter are composed of a capacitor group in which a plurality of chip capacitors are connected in parallel.

9. The shortwave duplexer according to claim 8, characterized in that: The chip capacitor is a chip high-Q ceramic capacitor.

10. The shortwave duplexer according to claim 7, characterized in that: The winding inductor is obtained by winding a pure copper wire with a diameter of φ4mm.

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