阅读说明：本技术 一种高频短波高抑制通信电路 (High-frequency short-wave high-suppression communication circuit ) 是由 谭灵杰 程福强 陈振权 于 2021-09-26 设计创作，主要内容包括：本发明提供了一种高频短波高抑制通信电路,包括依次连接的信号输入端口、功率放大电路、低通滤波电路、收发开关电路、定耦电路和天线,以及信号接收端口和控制端口；功率放大电路包括第一级功率放大电路、第二级功率放大电路、第三级功率放大电路和栅压开关驱动电路；定耦电路包括双芯线定耦模块和拉平校正模块；双芯线定耦模块包括双芯电缆WT6和双芯电缆WT7；拉平校正模块包括LC串联单元和LC并联单元；双芯电缆WT6和双芯电缆WT7的副电缆输入端分别通过LC串联单元和LC并联单元接地。该通信电路可实现高频短波信号的发送和接收功能,通过优化耦合平坦度来减少输出谐波,达到高抑制技术效果,提高运行稳定性和可靠性。(The invention provides a high-frequency short-wave high-suppression communication circuit which comprises a signal input port, a power amplification circuit, a low-pass filter circuit, a transceiving switch circuit, a fixed coupling circuit, an antenna, a signal receiving port and a control port, wherein the signal input port, the power amplification circuit, the low-pass filter circuit, the transceiving switch circuit, the fixed coupling circuit and the antenna are sequentially connected; the power amplification circuit comprises a first-stage power amplification circuit, a second-stage power amplification circuit, a third-stage power amplification circuit and a grid voltage switch driving circuit; the constant coupling circuit comprises a double-core wire constant coupling module and a leveling correction module; the two-core wire constant coupling module comprises a two-core cable WT6 and a two-core cable WT 7; the leveling correction module comprises an LC series unit and an LC parallel unit; the secondary cable input terminals of the two-core cable WT6 and the two-core cable WT7 are grounded through the LC series unit and the LC parallel unit, respectively. The communication circuit can realize the functions of transmitting and receiving high-frequency short-wave signals, reduce output harmonic waves by optimizing the coupling flatness, achieve the technical effect of high suppression, and improve the operation stability and reliability.)

1. A high-frequency short-wave high-suppression communication circuit is characterized in that: the device comprises a signal input port, a power amplifying circuit, a low-pass filter circuit, a transceiving switch circuit, a fixed coupling circuit, an antenna, a signal receiving port and a control port which are connected in sequence; the power amplifying circuit, the low-pass filter circuit, the transceiving switch circuit and the fixed coupling circuit are respectively connected with the control port; the signal receiving port is connected with the receiving and transmitting switch circuit;

the power amplification circuit comprises a first-stage power amplification circuit, a second-stage power amplification circuit, a third-stage power amplification circuit and a grid voltage switch driving circuit; the first-stage power amplification circuit comprises two stages of radio frequency module amplifiers connected in series; the second stage power amplification circuit comprises an LDMOS radio frequency tube VQ 3; the third stage of power amplifying circuit comprises a radio frequency tube VQ1 and a radio frequency tube VQ 2; the rear stage radio frequency module amplifier in the two stages of radio frequency module amplifiers is connected with an LDMOS radio frequency tube VQ3 through a transmission balun WT3, and the LDMOS radio frequency tube VQ3 is respectively connected with a radio frequency tube VQ1 and a radio frequency tube VQ2 through a transmission balun WT 9; the radio frequency tube VQ1 and the radio frequency tube VQ2 are also respectively connected with a low-pass filter circuit; the grid voltage switch driving circuit is respectively connected with the radio frequency tube VQ1, the radio frequency tube VQ2 and the LDMOS radio frequency tube VQ 3;

the constant coupling circuit comprises a double-core wire constant coupling module and a leveling correction module; the two-core wire fixed coupling module comprises a two-core cable WT6 and a two-core cable WT 7; the double-core cable WT6 and the double-core cable WT7 both consist of a main cable and an auxiliary cable; the input end of a main cable of the double-core cable WT6 is used for inputting signals, the output end of the main cable of the double-core cable WT6 is connected with the input end of the main cable of the double-core cable WT7, and the output end of the main cable of the double-core cable WT7 is used for outputting signals; the input end of the auxiliary cable of the double-core cable WT6 and the output end of the auxiliary cable of the double-core cable WT7 are respectively grounded; the leveling correction module comprises an LC series unit and an LC parallel unit; the output end of the auxiliary cable of the double-core cable WT6 and the input end of the auxiliary cable of the double-core cable WT7 are grounded through an LC series unit and an LC parallel unit which are connected in sequence respectively; the auxiliary cable output end of the two-core cable WT6 and the auxiliary cable input end of the two-core cable WT7 are also connected to the control port respectively.

2. The high frequency short wave high rejection communication circuit of claim 1, wherein: the receiving and transmitting switch circuit comprises a diode VD211, a diode VD212 and a capacitor C212; the receiving and transmitting switch circuit is connected with a receiving and transmitting switch driving circuit;

the low-pass filter circuit is connected with the constant coupling circuit through a diode VD 211; the diode VD211 is also grounded through an inductor L211 and a capacitor C211 which are connected in series; the junction of the inductor L211 and the capacitor C211 is connected with the output end T of the transceiving switch driving circuit;

the low-pass filter circuit is also connected with a signal receiving port through a diode VD212 and a capacitor C212 which are connected in series; the junction of the diode VD212 and the capacitor C212 is grounded through an inductor L212 and a capacitor C213 which are connected in series; the junction of the inductor L212 and the capacitor C213 is connected to the input terminal R of the transmit-receive switch driving circuit.

3. The high frequency short wave high rejection communication circuit of claim 1, wherein: the LC series unit comprises an inductor L201 and a capacitor C203; the LC parallel unit comprises an inductor L202, an inductor L203, a capacitor C204 and a capacitor C205; the output end of the auxiliary cable of the double-core cable WT6 and the input end of the auxiliary cable of the double-core cable WT7 are grounded through an inductor L201, a capacitor C203 and an inductor L202 which are connected in sequence; the capacitor C204, the capacitor C205 and the inductor L203 are connected in series and then connected in parallel with the inductor L202.

4. The high frequency short wave high rejection communication circuit of claim 1, wherein: the leveling correction module further comprises a detection connection unit; the auxiliary cable output end of the two-core cable WT6 and the auxiliary cable input end of the two-core cable WT7 are connected to the control port through the detection connection unit respectively.

5. The high frequency short wave high rejection communication circuit of claim 4, wherein: the detection connecting unit comprises a diode VD201, a resistor R202, a capacitor C201 and a capacitor C202; the output end of the auxiliary cable of the double-core cable WT6 and the input end of the auxiliary cable of the double-core cable WT7 are respectively connected with the control port through a diode VD201 and a resistor R201 which are connected in series; the connection point of the diode VD201 and the resistor R201 is grounded through a capacitor C201; the control port is also connected to ground through a resistor R202 and a capacitor C202 connected in parallel.

6. The high frequency short wave high rejection communication circuit of claim 1, wherein: the leveling correction module connected with the output end of the auxiliary cable of the double-core cable WT6 is connected with the leveling correction module connected with the input end of the auxiliary cable of the double-core cable WT7, and the circuit topological structures are the same.

7. The high frequency short wave high rejection communication circuit of claim 1, wherein: the auxiliary cable input end of the two-core cable WT6 and the auxiliary cable output end of the two-core cable WT7 are respectively grounded through a resistor R203.

8. The high frequency short wave high suppression communication circuit of any one of claims 1 to 7, characterized by: in the power amplification circuit, two output ends of a transmission balun WT3 are connected with a capacitor C38; two output ends of the transmission balun WT3 are respectively connected with two input ends of an LDMOS radio frequency tube VQ3 through an inductor L21 and an inductor L27; two input ends of the LDMOS radio-frequency tube VQ3 are also connected with a resistor R65; an output end VG1 of the grid voltage switch driving circuit is respectively connected with two input ends of an LDMOS radio frequency tube VQ 3; two input ends of the LDMOS radio-frequency tube VQ3 are respectively connected with two output ends of the LDMOS radio-frequency tube VQ3 through a first RC series circuit; the power supply circuit is respectively connected with two output ends of the LDMOS radio frequency tube VQ3 through an inductor L26 and an inductor L29; two output ends of the LDMOS radio frequency tube VQ3 are respectively connected with an input end of a transmission balun WT9 through a first LC series circuit;

two output ends of the transmission balun WT9 are connected in series through a capacitor C15, a capacitor C223 and a capacitor C16; the junction of the capacitor C15 and the capacitor C223 is connected with the G pole of the radio frequency tube VQ1 through a resistor R10; the junction of the capacitor C16 and the capacitor C223 is connected with the G pole of the radio frequency tube VQ2 through a resistor R11; an output end VG2 of the grid voltage switch driving circuit is respectively connected with a G pole of the radio frequency tube VQ1 and a G pole of the radio frequency tube VQ2 through a series resistor circuit; the series resistance circuit is grounded through the RC parallel circuit I; the G pole of the radio frequency tube VQ1 is connected with the D pole of the radio frequency tube VQ1 through a second RC series circuit; the G pole of the radio frequency tube VQ2 is connected with the D pole of the radio frequency tube VQ2 through a RC series circuit III; the D pole of the radio frequency tube VQ1 is connected with a power supply circuit through an inductor L2; the D pole of the radio frequency tube VQ2 is connected with a power supply circuit through an inductor L7; the D pole of the radio frequency tube VQ1 is connected with the input end I of the transmission balun WT2 through an inductor L22; the D pole of the radio frequency tube VQ2 is connected with the second input end of the transmission balun WT2 through an inductor L23; a capacitor C71 is connected between the first input end and the second input end of the transmission balun WT 2; the S pole of the radio frequency tube VQ1 and the S pole of the radio frequency tube VQ2 are respectively grounded.

9. The high frequency short wave high suppression communication circuit of any one of claims 1 to 7, characterized by: the low-pass filter circuit comprises a plurality of low-pass filter branches for realizing low-pass filtering of signals in different frequency bands; each low-pass filtering branch circuit is connected between the power amplifying circuit and the transceiving switch circuit through a radio frequency switch with one more selection.

10. The high frequency short wave high rejection communication circuit of claim 9, wherein: the one-from-many radio frequency switch comprises a diode VD39, a diode VD40, an inductor L78 and a capacitor C162; each low-pass filtering branch comprises an LC parallel filtering circuit I, an LC parallel filtering circuit II and an LC parallel filtering circuit III which are connected in sequence;

the output end of the power amplifying circuit is connected with the first LC parallel filter circuit of each low-pass filter branch circuit through a diode VD 39; the LC parallel filter circuit III of each low-pass filter branch is respectively connected with the transceiving switch circuit through a diode VD40 and is connected with the control port through an inductor L178; the control port is connected to ground through a capacitor C162.

Technical Field

The invention relates to the technical field of high-frequency communication, in particular to a high-frequency short-wave high-suppression communication circuit.

Background

The working frequency of the high-frequency communication circuit is generally 2-30 MHz, and the high-frequency communication circuit is used for remote speech communication between an airplane and the ground or between the airplane and other airplanes and is a main communication means for high-latitude area and remote communication. The high frequency communication circuit generally includes a power amplifying circuit, a filter circuit, a constant coupling circuit, and the like.

In order to meet the gain requirement of the high-frequency communication circuit, the power amplification circuit can adopt a multi-stage amplification structure, and the control device outputs the adjustment parameters of amplification of each stage to achieve accurate and stable power amplification effect. The constant coupling circuit is used for detecting the output power so as to realize feedback regulation of the regulation parameter of the power amplification circuit according to the output power and realize the stability of the transmission output of the communication circuit. However, the performance of the existing constant-coupling circuit is not ideal, and the constant-coupling circuit formed by combining the double-core cables is generally used for narrow bands; coupling flatness is poor in multiple frequency application occasions; when the standing wave performance of the ultra-short wave antenna is poor, the output power fluctuation is large, the stable work of a power amplifying circuit is not facilitated, the output harmonic waves are increased, and the stability and the reliability of the operation of a high-frequency communication circuit are influenced.

Disclosure of Invention

In order to overcome the defects and shortcomings in the prior art, the invention aims to provide a high-frequency short-wave high-suppression communication circuit; the communication circuit can realize the functions of transmitting and receiving high-frequency short-wave signals, reduce output harmonic waves by optimizing the coupling flatness, achieve the technical effect of high suppression, and improve the stability and reliability of the operation of the communication circuit.

In order to achieve the purpose, the invention is realized by the following technical scheme: a high-frequency short-wave high-suppression communication circuit is characterized in that: the device comprises a signal input port, a power amplifying circuit, a low-pass filter circuit, a transceiving switch circuit, a fixed coupling circuit, an antenna, a signal receiving port and a control port which are connected in sequence; the power amplifying circuit, the low-pass filter circuit, the transceiving switch circuit and the fixed coupling circuit are respectively connected with the control port; the signal receiving port is connected with the receiving and transmitting switch circuit;

the power amplification circuit comprises a first-stage power amplification circuit, a second-stage power amplification circuit, a third-stage power amplification circuit and a grid voltage switch driving circuit; the first-stage power amplification circuit comprises two stages of radio frequency module amplifiers connected in series; the second stage power amplification circuit comprises an LDMOS radio frequency tube VQ 3; the third stage of power amplifying circuit comprises a radio frequency tube VQ1 and a radio frequency tube VQ 2; the rear stage radio frequency module amplifier in the two stages of radio frequency module amplifiers is connected with an LDMOS radio frequency tube VQ3 through a transmission balun WT3, and the LDMOS radio frequency tube VQ3 is respectively connected with a radio frequency tube VQ1 and a radio frequency tube VQ2 through a transmission balun WT 9; the radio frequency tube VQ1 and the radio frequency tube VQ2 are also respectively connected with a low-pass filter circuit; the grid voltage switch driving circuit is respectively connected with the radio frequency tube VQ1, the radio frequency tube VQ2 and the LDMOS radio frequency tube VQ 3;

the constant coupling circuit comprises a double-core wire constant coupling module and a leveling correction module; the two-core wire fixed coupling module comprises a two-core cable WT6 and a two-core cable WT 7; the double-core cable WT6 and the double-core cable WT7 both consist of a main cable and an auxiliary cable; the main cable and the auxiliary cable are insulated from each other; the input end of a main cable of the double-core cable WT6 is used for inputting signals, the output end of the main cable of the double-core cable WT6 is connected with the input end of the main cable of the double-core cable WT7, and the output end of the main cable of the double-core cable WT7 is used for outputting signals; the input end of the auxiliary cable of the double-core cable WT6 and the output end of the auxiliary cable of the double-core cable WT7 are respectively grounded; the leveling correction module comprises an LC series unit and an LC parallel unit; the output end of the auxiliary cable of the double-core cable WT6 and the input end of the auxiliary cable of the double-core cable WT7 are grounded through an LC series unit and an LC parallel unit which are connected in sequence respectively; the auxiliary cable output end of the two-core cable WT6 and the auxiliary cable input end of the two-core cable WT7 are also connected to the control port respectively.

The communication circuit can realize the functions of sending and receiving high-frequency short-wave signals; the power amplification circuit can realize the power amplification function of the input signal; the low-pass filter circuit can filter out harmonic out-of-band frequency signals of the signals; the receiving/transmitting switching circuit can realize the switching of receiving/transmitting functions; the constant coupling circuit can realize the power detection function and output VF and VR. The working principle of the communication circuit is as follows: when the signal is transmitted, the signal input port is used as an excitation port, and after the signal is processed by the power amplification circuit and the through filter circuit, the signal is transmitted to the antenna by the transceiving switch circuit through the fixed coupling circuit to be output; when receiving signals, the receiving and transmitting switch circuit is communicated with the signal receiving port to realize signal receiving.

The fixed coupling circuit couples signals by adopting a double-core cable and processes the signals by combining a leveling correction module, so that the technical problem that the amplitude-frequency characteristic of a coupling port signal is uneven when the output signal is detected due to the fact that the difference between the maximum frequency and the minimum frequency of 2-30 MHz high-frequency signals is dozens of times can be solved; the leveling correction module of the constant coupling circuit can perform leveling correction processing on the signal waveform obtained by coupling through an internal inductor and capacitor combination network, LC parallel connection and LC series connection modes, so that the coupled waveform is oblique and smooth. Compared with the traditional constant coupling circuit with the coupling flatness of only 10dB, the constant coupling circuit can enable the coupling flatness to be less than 1dB, and ensures that the power fluctuation is reduced under the condition of poor standing wave of the ultra-short wave antenna, and the stability of the power amplification circuit is improved, so that the output harmonic wave is reduced, the technical effect of high suppression is achieved, and the stability and the reliability of the operation of the communication circuit are improved.

Preferably, the transceiving switch circuit comprises a diode VD211, a diode VD212, a capacitor C212; the receiving and transmitting switch circuit is connected with a receiving and transmitting switch driving circuit;

the low-pass filter circuit is connected with the constant coupling circuit through a diode VD 211; the diode VD211 is also grounded through an inductor L211 and a capacitor C211 which are connected in series; the junction of the inductor L211 and the capacitor C211 is connected with the output end T of the transceiving switch driving circuit;

the low-pass filter circuit is also connected with a signal receiving port through a diode VD212 and a capacitor C212 which are connected in series; the junction of the diode VD212 and the capacitor C212 is grounded through an inductor L212 and a capacitor C213 which are connected in series; the junction of the inductor L212 and the capacitor C213 is connected to the input terminal R of the transmit-receive switch driving circuit.

The transceiving switch circuit can stably and reliably realize the switching of the signal receiving and transmitting functions.

Preferably, the LC series unit comprises an inductance L201 and a capacitance C203; the LC parallel unit comprises an inductor L202, an inductor L203, a capacitor C204 and a capacitor C205; the output end of the auxiliary cable of the double-core cable WT6 and the input end of the auxiliary cable of the double-core cable WT7 are grounded through an inductor L201, a capacitor C203 and an inductor L202 which are connected in sequence; the capacitor C204, the capacitor C205 and the inductor L203 are connected in series and then connected in parallel with the inductor L202.

Preferably, the leveling correction module further comprises a detection connection unit; the auxiliary cable output end of the two-core cable WT6 and the auxiliary cable input end of the two-core cable WT7 are connected to the control port through the detection connection unit respectively.

Preferably, the detection connection unit comprises a diode VD201, a resistor R202, a capacitor C201 and a capacitor C202; the output end of the auxiliary cable of the double-core cable WT6 and the input end of the auxiliary cable of the double-core cable WT7 are respectively connected with the control port through a diode VD201 and a resistor R201 which are connected in series; the connection point of the diode VD201 and the resistor R201 is grounded through a capacitor C201; the control port is also connected to ground through a resistor R202 and a capacitor C202 connected in parallel. The detection connection unit can stably and reliably transmit the signal after the leveling correction to the control port.

Preferably, the leveling correction module connected to the output end of the secondary cable of the two-core cable WT6 is the same as the leveling correction module connected to the input end of the secondary cable of the two-core cable WT7 in circuit topology.

Preferably, the secondary cable input end of the two-core cable WT6 and the secondary cable output end of the two-core cable WT7 are grounded through a resistor R203 respectively.

Preferably, in the power amplification circuit, two output ends of the transmission balun WT3 are connected with a capacitor C38; two output ends of the transmission balun WT3 are respectively connected with two input ends of an LDMOS radio frequency tube VQ3 through an inductor L21 and an inductor L27; two input ends of the LDMOS radio-frequency tube VQ3 are also connected with a resistor R65; an output end VG1 of the grid voltage switch driving circuit is respectively connected with two input ends of an LDMOS radio frequency tube VQ 3; two input ends of the LDMOS radio-frequency tube VQ3 are respectively connected with two output ends of the LDMOS radio-frequency tube VQ3 through a first RC series circuit; the power supply circuit is respectively connected with two output ends of the LDMOS radio frequency tube VQ3 through an inductor L26 and an inductor L29; two output ends of the LDMOS radio frequency tube VQ3 are respectively connected with an input end of a transmission balun WT9 through a first LC series circuit;

two output ends of the transmission balun WT9 are connected in series through a capacitor C15, a capacitor C223 and a capacitor C16; the junction of the capacitor C15 and the capacitor C223 is connected with the G pole of the radio frequency tube VQ1 through a resistor R10; the junction of the capacitor C16 and the capacitor C223 is connected with the G pole of the radio frequency tube VQ2 through a resistor R11; an output end VG2 of the grid voltage switch driving circuit is respectively connected with a G pole of the radio frequency tube VQ1 and a G pole of the radio frequency tube VQ2 through a series resistor circuit; the series resistance circuit is grounded through the RC parallel circuit I; the G pole of the radio frequency tube VQ1 is connected with the D pole of the radio frequency tube VQ1 through a second RC series circuit; the G pole of the radio frequency tube VQ2 is connected with the D pole of the radio frequency tube VQ2 through a RC series circuit III; the D pole of the radio frequency tube VQ1 is connected with a power supply circuit through an inductor L2; the D pole of the radio frequency tube VQ2 is connected with a power supply circuit through an inductor L7; the D pole of the radio frequency tube VQ1 is connected with the input end I of the transmission balun WT2 through an inductor L22; the D pole of the radio frequency tube VQ2 is connected with the second input end of the transmission balun WT2 through an inductor L23; a capacitor C71 is connected between the first input end and the second input end of the transmission balun WT 2; the S pole of the radio frequency tube VQ1 and the S pole of the radio frequency tube VQ2 are respectively grounded.

The power amplification circuit can realize a power amplification function of an input signal. The gate voltage switch driving circuit can adopt the prior art.

Preferably, the low-pass filtering circuit comprises a plurality of low-pass filtering branches for realizing low-pass filtering of signals in different frequency bands; each low-pass filtering branch circuit is connected between the power amplifying circuit and the transceiving switch circuit through a radio frequency switch with one more selection.

Preferably, the one-out-of-multiple radio frequency switch comprises a diode VD39, a diode VD40, an inductor L78 and a capacitor C162; each low-pass filtering branch comprises an LC parallel filtering circuit I, an LC parallel filtering circuit II and an LC parallel filtering circuit III which are connected in sequence;

the output end of the power amplifying circuit is connected with the first LC parallel filter circuit of each low-pass filter branch circuit through a diode VD 39; the LC parallel filter circuit III of each low-pass filter branch is respectively connected with the transceiving switch circuit through a diode VD40 and is connected with the control port through an inductor L178; the control port is connected to ground through a capacitor C162. Each low-pass filtering branch can realize low-pass filtering of signals in different frequency bands, filters out harmonic out-of-band frequency signals of the signals and eliminates interference.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. the communication circuit can realize the functions of sending and receiving high-frequency short-wave signals, and has stable and reliable operation;

2. the leveling correction module of the communication circuit can level and correct the signal waveform obtained by coupling through an internal inductor and capacitor combination network, LC parallel connection and LC series connection modes, so that the coupled waveform is oblique and smooth; the coupling flatness can be less than 1dB, the power fluctuation is reduced under the condition of ensuring the ultra-short wave antenna standing wave difference, and the stability of the power amplifying circuit is improved, so that the output harmonic wave is reduced, the technical effect of high inhibition is achieved, and the stability and the reliability of the operation of the communication circuit are improved;

3. in the communication circuit, the transceiving switch circuit can stably and reliably realize the switching of the signal receiving and transmitting functions.

Drawings

FIG. 1 is a schematic block diagram of a high frequency short wave high rejection communication circuit of the present invention;

FIG. 2 is a schematic block diagram of the implementation of the high-frequency short-wave high-rejection communication circuit of the invention in a frequency band of 2-30 MHz;

FIG. 3 is a schematic circuit diagram of a transmit-receive switch circuit in the high-frequency short-wave high-rejection communication circuit according to the present invention;

FIG. 4 is a schematic circuit diagram of a constant coupling circuit in the high frequency short wave high suppression communication circuit according to the present invention;

FIG. 5 is a schematic circuit diagram of a power amplifier circuit in the high frequency short wave high rejection communication circuit of the present invention;

fig. 6 is a schematic circuit diagram of a low-pass filter circuit in the high-frequency short-wave high-suppression communication circuit according to the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Examples

As shown in fig. 1 to fig. 6, the high-frequency short-wave high-rejection communication circuit of the present embodiment includes a signal input port, a power amplifying circuit, a low-pass filter circuit, a transceiver switch circuit, a fixed-coupler circuit, an antenna, a signal receiving port, and a control port, which are connected in sequence; the power amplifying circuit, the low-pass filter circuit, the transceiving switch circuit and the fixed coupling circuit are respectively connected with the control port; the signal receiving port is connected with the receiving and transmitting switch circuit.

The communication circuit can realize the functions of sending and receiving high-frequency short-wave signals; the power amplification circuit can realize the power amplification function of the input signal; the low-pass filter circuit can filter out harmonic out-of-band frequency signals of the signals; the receiving/transmitting switching circuit can realize the switching of receiving/transmitting functions; the constant coupling circuit can realize the power detection function and output VF and VR. The working principle of the communication circuit is as follows: when the signal is transmitted, the signal input port is used as an excitation port, and after the signal is processed by the power amplification circuit and the through filter circuit, the signal is transmitted to the antenna by the transceiving switch circuit through the fixed coupling circuit to be output; when receiving signals, the receiving and transmitting switch circuit is communicated with the signal receiving port to realize signal receiving.

The power amplification circuit comprises a first-stage power amplification circuit, a second-stage power amplification circuit, a third-stage power amplification circuit and a grid voltage switch driving circuit; the first-stage power amplification circuit comprises two stages of radio frequency module amplifiers which are connected in series; the second stage power amplification circuit comprises an LDMOS radio frequency tube VQ 3; the third stage of power amplifying circuit comprises a radio frequency tube VQ1 and a radio frequency tube VQ 2; the rear stage radio frequency module amplifier in the two stages of radio frequency module amplifiers is connected with an LDMOS radio frequency tube VQ3 through a transmission balun WT3, and the LDMOS radio frequency tube VQ3 is respectively connected with a radio frequency tube VQ1 and a radio frequency tube VQ2 through a transmission balun WT 9; the radio frequency tube VQ1 and the radio frequency tube VQ2 are also respectively connected with a low-pass filter circuit; the grid voltage switch driving circuit is respectively connected with the radio frequency tube VQ1, the radio frequency tube VQ2 and the LDMOS radio frequency tube VQ 3.

Specifically, in the power amplification circuit, a capacitor C38 is connected to two output terminals of the transmission balun WT 3; two output ends of the transmission balun WT3 are respectively connected with two input ends of an LDMOS radio frequency tube VQ3 through an inductor L21 and an inductor L27; two input ends of the LDMOS radio-frequency tube VQ3 are also connected with a resistor R65; an output end VG1 of the grid voltage switch driving circuit is respectively connected with two input ends of an LDMOS radio frequency tube VQ 3; two input ends of the LDMOS radio-frequency tube VQ3 are respectively connected with two output ends of the LDMOS radio-frequency tube VQ3 through a first RC series circuit; the power supply circuit is respectively connected with two output ends of the LDMOS radio frequency tube VQ3 through an inductor L26 and an inductor L29; two output ends of the LDMOS radio frequency tube VQ3 are respectively connected with an input end of a transmission balun WT9 through an LC series circuit I.

Two output ends of the transmission balun WT9 are connected in series through a capacitor C15, a capacitor C223 and a capacitor C16; the junction of the capacitor C15 and the capacitor C223 is connected with the G pole of the radio frequency tube VQ1 through a resistor R10; the junction of the capacitor C16 and the capacitor C223 is connected with the G pole of the radio frequency tube VQ2 through a resistor R11; an output end VG2 of the grid voltage switch driving circuit is respectively connected with a G pole of the radio frequency tube VQ1 and a G pole of the radio frequency tube VQ2 through a series resistor circuit; the series resistance circuit is grounded through the RC parallel circuit I; the G pole of the radio frequency tube VQ1 is connected with the D pole of the radio frequency tube VQ1 through a second RC series circuit; the G pole of the radio frequency tube VQ2 is connected with the D pole of the radio frequency tube VQ2 through a RC series circuit III; the D pole of the radio frequency tube VQ1 is connected with a power supply circuit through an inductor L2; the D pole of the radio frequency tube VQ2 is connected with a power supply circuit through an inductor L7; the D pole of the radio frequency tube VQ1 is connected with the input end I of the transmission balun WT2 through an inductor L22; the D pole of the radio frequency tube VQ2 is connected with the second input end of the transmission balun WT2 through an inductor L23; a capacitor C71 is connected between the first input end and the second input end of the transmission balun WT 2; the S pole of the radio frequency tube VQ1 and the S pole of the radio frequency tube VQ2 are respectively grounded.

The power amplification circuit can realize the power amplification function of the input signal. The gate voltage switch driving circuit can adopt the prior art.

The low-pass filter circuit comprises a plurality of low-pass filter branches for realizing low-pass filtering of signals in different frequency bands; each low-pass filtering branch circuit is connected between the power amplifying circuit and the transceiving switch circuit through a radio frequency switch with one more selection.

When the communication circuit is applied to a frequency band of 2-30 MHz, the frequency band division of the low-pass filtering branch preferably adopts the scheme shown in FIG. 2, and the filtering effect of signals in different frequency bands can be improved. The one-out-of-multiple radio frequency switch comprises a diode VD39, a diode VD40, an inductor L78 and a capacitor C162; each low-pass filtering branch comprises an LC parallel filtering circuit I, an LC parallel filtering circuit II and an LC parallel filtering circuit III which are connected in sequence;

the output end of the power amplifying circuit is connected with the first LC parallel filter circuit of each low-pass filter branch circuit through a diode VD 39; the LC parallel filter circuit III of each low-pass filter branch is respectively connected with the transceiving switch circuit through a diode VD40 and is connected with the control port through an inductor L178; the control port is connected to ground through a capacitor C162. Each low-pass filtering branch can realize low-pass filtering of signals in different frequency bands, filters out harmonic out-of-band frequency signals of the signals and eliminates interference.

The transceiving switch circuit comprises a diode VD211, a diode VD212 and a capacitor C212; the receiving and transmitting switch circuit is connected with a receiving and transmitting switch driving circuit; the low-pass filter circuit is connected with the constant coupling circuit through a diode VD 211; the diode VD211 is also grounded through an inductor L211 and a capacitor C211 which are connected in series; the junction of the inductor L211 and the capacitor C211 is connected with the output end T of the transceiving switch driving circuit.

The low-pass filter circuit is also connected with a signal receiving port through a diode VD212 and a capacitor C212 which are connected in series; the junction of the diode VD212 and the capacitor C212 is grounded through an inductor L212 and a capacitor C213 which are connected in series; the junction of the inductor L212 and the capacitor C213 is connected to the input terminal R of the transmit-receive switch driving circuit. The transceiving switch circuit can stably and reliably realize the switching of signal receiving and transmitting functions. The transceiver switch driving circuit may employ the prior art.

The constant coupling circuit comprises a double-core wire constant coupling module and a leveling correction module; the two-core wire constant coupling module comprises a two-core cable WT6 and a two-core cable WT 7; the double-core cable WT6 and the double-core cable WT7 both consist of a main cable and an auxiliary cable; the main cable and the auxiliary cable are insulated from each other; the input end of a main cable of the double-core cable WT6 is used for inputting signals, the output end of the main cable of the double-core cable WT6 is connected with the input end of the main cable of the double-core cable WT7, and the output end of the main cable of the double-core cable WT7 is used for outputting signals; the input end of the auxiliary cable of the double-core cable WT6 and the output end of the auxiliary cable of the double-core cable WT7 are respectively grounded; the leveling correction module comprises an LC series unit and an LC parallel unit; the output end of the auxiliary cable of the double-core cable WT6 and the input end of the auxiliary cable of the double-core cable WT7 are grounded through an LC series unit and an LC parallel unit which are connected in sequence respectively; the auxiliary cable output end of the two-core cable WT6 and the auxiliary cable input end of the two-core cable WT7 are also connected to the control port respectively.

The leveling correction module connected with the output end of the auxiliary cable of the double-core cable WT6 is connected with the leveling correction module connected with the input end of the auxiliary cable of the double-core cable WT7, and the circuit topological structures are the same. The LC series unit comprises an inductor L201 and a capacitor C203; the LC parallel unit comprises an inductor L202, an inductor L203, a capacitor C204 and a capacitor C205; the output end of the auxiliary cable of the double-core cable WT6 and the input end of the auxiliary cable of the double-core cable WT7 are grounded through an inductor L201, a capacitor C203 and an inductor L202 which are connected in sequence; the capacitor C204, the capacitor C205 and the inductor L203 are connected in series and then connected in parallel with the inductor L202.

The leveling correction module also comprises a detection connection unit; the auxiliary cable output end of the two-core cable WT6 and the auxiliary cable input end of the two-core cable WT7 are connected to the control port through the detection connection unit respectively. The following scheme is preferably adopted for the detection connecting unit: the device comprises a diode VD201, a resistor R202, a capacitor C201 and a capacitor C202; the output end of the auxiliary cable of the double-core cable WT6 and the input end of the auxiliary cable of the double-core cable WT7 are respectively connected with the control port through a diode VD201 and a resistor R201 which are connected in series; the connection point of the diode VD201 and the resistor R201 is grounded through a capacitor C201; the control port is also connected to ground through a resistor R202 and a capacitor C202 connected in parallel. The detection connection unit can stably and reliably transmit the signal after the leveling correction to the control port. The control port is connected with the control device to feed back and control the power amplification circuit according to the detection power signal output by the constant coupling circuit.

The auxiliary cable input end of the two-core cable WT6 and the auxiliary cable output end of the two-core cable WT7 are grounded through a resistor R203 respectively.

The fixed coupling circuit adopts a double-core cable to couple signals and combines a leveling correction module to process, so that the technical problem that the amplitude-frequency characteristic of a coupling port signal is uneven when the maximum frequency and the minimum frequency of a 2-30 MHz high-frequency signal are different by dozens of times when the output signal is detected can be solved; the leveling correction module of the constant coupling circuit can perform leveling correction processing on the signal waveform obtained by coupling through an internal inductor and capacitor combination network, LC parallel connection and LC series connection modes, so that the coupled waveform is oblique and smooth. Compared with the traditional constant coupling circuit with the coupling flatness of only 10dB, the constant coupling circuit can enable the coupling flatness to be less than 1dB, and ensures that the power fluctuation is reduced under the condition of poor standing wave of the ultra-short wave antenna, and the stability of the power amplification circuit is improved, so that the output harmonic wave is reduced, the technical effect of high suppression is achieved, and the stability and the reliability of the operation of the communication circuit are improved.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.