Small short-wave strong electromagnetic suppression circuit with surge detection

Abstract

The invention relates to a small short-wave strong electromagnetic suppression circuit with a surge detection function. The small short-wave strong electromagnetic suppression circuit comprises a transient protection circuit, a sampling circuit, a photoelectric coupling circuit, a direct-current feed circuit and an alternating-current coupling circuit, the transient protection circuit adopts a gas discharge tube to perform strong electromagnetic pulse protection; the sampling circuit consists of a current sampling transformer and a rectifier diode, and is used for rectifying and sampling the strong electromagnetic pulse current and providing a trigger signal for the photoelectric coupling circuit; the photoelectric coupling circuit is composed of a capacitor, a current-limiting resistor and an optocoupler, high-resistance isolation of the transient protection path and the short-wave signal path is achieved, and short-wave signal transmitting and receiving are not affected. The direct current feed circuit adopts an MOS tube switch to complete on-off of current, and the follow current problem of a gas discharge tube is solved; the alternating-current coupling circuit completes short-wave signal transmission and has an attenuation effect on low-frequency interference. The problem of strong electromagnetic pulse interference at the radio frequency front end of a short-wave radio station with a direct-current feed function is solved, and a strong electromagnetic pulse detection function is provided for the short-wave radio station.

Description

Technical Field

[0001] The invention belongs to the technical field of strong electromagnetic pulse protection and relates to a small short-wave strong electromagnetic suppression circuit with surge detection. Background Art

[0002] As an important part of the shortwave communication system, the RF front end is easily damaged by strong electromagnetic pulse interference such as lightning. Therefore, it is necessary to install a strong electromagnetic suppression circuit on the shortwave RF front end to improve the electromagnetic protection capability of the shortwave communication system.

[0003] Most shortwave radio stations require DC power supply, so the strong electromagnetic suppression circuit is also required to have the function of DC power supply. The transient protection of strong electromagnetic pulses such as lightning mainly uses gas discharge tubes, which have the advantages of small size, large flow rate, small capacitance, and fast response. However, there is a continuous current phenomenon after the gas discharge tube is triggered and turned on. The continuous current voltage can be checked in the manual and is generally 12V.

[0004] One difficulty in designing strong electromagnetic protection for RF channels with feeding functions is the selection of protection schemes. The classic design is to use a gas discharge tube plus a varistor. This method requires multiple varistors to be connected in parallel, which is relatively large. Another common method is to connect multiple discharge tubes in series, but as the feeding voltage continues to increase, the number of series stages will increase, the volume and residual voltage will also increase, and multiple stages of decoupling in the later stage will be required, which will further increase the volume. In addition, the current short-wave suppressor circuits do not have the function of strong electromagnetic pulse detection. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and propose a small shortwave strong electromagnetic suppression circuit with surge detection, which, on the one hand, solves the problem of strong electromagnetic pulse interference of the RF front end of a shortwave radio station with a DC feeding function, and on the other hand, provides a strong electromagnetic pulse detection function for the shortwave radio station, and has the advantages of miniaturization and no risk of continuous current.

[0006] The technical solution of the present invention is: a small short-wave strong electromagnetic suppression circuit with surge detection, including a transient protection circuit, a sampling circuit, a photoelectric coupling circuit, a DC feeding circuit, and an AC coupling circuit;

[0007] Transient protection circuit, using gas discharge tube for strong electromagnetic pulse protection;

[0008] The sampling circuit is used to rectify and sample the strong electromagnetic pulse current and provide a trigger signal for the photoelectric coupling circuit;

[0009] Photoelectric coupling circuit to achieve high-impedance isolation between transient protection path and short-wave signal path to avoid affecting short-wave signal transmission and reception;

[0010] The DC feed circuit completes the on-off control of the current and solves the problem of continuous current in the gas discharge tube;

[0011] AC coupling circuit completes short-wave signal transmission and attenuates low-frequency interference.

[0012] Furthermore, the transient protection circuit is composed of a single or multiple gas discharge tubes G1 connected in parallel, and is used to protect against lightning pulses with a large flow rate of 10kA at the us level.

[0013] Furthermore, the sampling circuit includes a rectifier bridge composed of a current sampling transformer T1 and rectifier diodes D1~D4; one end of the primary side of the current sampling transformer T1 is connected to the RF input terminal IN, and the other end is connected to the gas discharge tube, the secondary side of the current sampling transformer T1 is connected to the upper and lower ends of the rectifier bridge, and the left and right ends of the rectifier bridge are connected to the two ends of the capacitor in the photoelectric coupling circuit, so as to realize sampling after rectification of the strong electromagnetic pulse current and provide a trigger signal for the photoelectric coupling circuit.

[0014] Furthermore, the photoelectric coupling circuit includes a capacitor C1, a current limiting resistor R0 and an optical coupler V1; the DC feeding circuit includes a MOS tube M1, a voltage regulator tube Z1, an inductor L1 and resistors R1, R2, R3;

[0015] One end of the optocoupler V1 input diode is connected to the current limiting resistor R0, and the other end is connected to the capacitor C1. The collector of the optocoupler V1 output transistor is connected to the S pole of the MOS tube in the DC feeding circuit, and the emitter of the optocoupler output transistor is connected to the anode of the voltage regulator tube Z1 in the DC feeding circuit.

[0016] The voltage regulator Z1 is connected in parallel to both ends of the MOS tube GS to ensure that the voltage at the GS end of the MOS tube is within the working range; the inductor L1 is connected to the D pole of the MOS tube to prevent surge current from entering the subsequent circuit; the resistor R1 is connected to the S pole of the MOS tube, and the S pole is connected to the receiver output terminal OUT; one end of the resistor R2 is connected to the resistor R1, and the other end is grounded; one end of the resistor R3 is connected to the G pole of the MOS tube, and the other end is connected to the resistor R2; when a strong electromagnetic pulse triggers the gas discharge tube, the MOS tube automatically cuts off the DC feed path to prevent the gas discharge tube from continuing current.

[0017] Furthermore, the AC coupling circuit is composed of a capacitor C2, one end of the capacitor C2 is connected to the RF input terminal IN, and the other end is connected to the receiver output terminal OUT.

[0018] Furthermore, the resistance values ​​of resistors R1 and R2 must be selected to ensure that |U GS |≥|U GS(off) |,U GS(off) is the voltage threshold value of the GS terminal of the MOS tube, U GS is the GS terminal voltage of MOS tube M1, that is, the voltage divided by resistor R1, UGS =U dc *R 1 / (R 1 +R 2 ), U dc is the DC feed voltage;

[0019] The resistor R3 is set to 90-110 ohms to prevent the G pole of the MOS tube from oscillating.

[0020] Furthermore, the voltage of the voltage regulator tube Z1 is greater than the voltage threshold value of the GS terminal of the MOS tube and is within the normal working voltage range of the GS terminal.

[0021] Furthermore, the selection of the inductor L1 is based on the breakdown current I between the MOS tube DS DS and the breakdown voltage of the gas discharge tube V BR Confirm: V BR =L1*(dI DS / dt).

[0022] Furthermore, the selection principle of capacitor C1 and current limiting resistor R0 is:

[0023] When the lightning electromagnetic pulse reaches the RF input terminal IN, assuming that the primary-to-secondary turns ratio of the current sampling transformer T1 is 1:N, the primary current i 1 , secondary current i 2 , then i 2 =i 1 / N;i 2 After being rectified by the D1~D4 rectifier bridge, the capacitance is C 1 The capacitor C1 is quickly charged, and the charging resistor is the parasitic resistance R of the secondary side of the current sampling transformer T1. ESR , charging time τ = R ESR *C 1 , the charging voltage is U C1 =[∫i 2 *dt] / C 1 , the optocoupler input current is i F =U C1 / R 0 ;

[0024] The selection of capacitor value C1 and current limiting resistor R0 should ensure that i F Within the allowable range of the optocoupler input current, the optocoupler input diode works, and after the optocoupler output triode is turned on, the GS end of the MOS tube is short-circuited, the DS end of the MOS tube is disconnected, and the DC feed voltage is disconnected.

[0025] Furthermore, the selection principle of capacitor C2 is to ensure that the capacitor impedance is as low as possible and the equivalent resistance ESR is as small as possible at 2 MHz.

[0026] The beneficial effects of the present invention compared with the prior art are:

[0027] (1) The short-wave strong electromagnetic suppression circuit of the present invention can be used for a radio frequency path with a DC feeding function, and adopts pulse sampling and path control to prevent the gas discharge tube from continuing current. Compared with the traditional anti-following current solution, the circuit has a smaller volume, faster response, and is more reliable;

[0028] (2) The short-wave strong electromagnetic suppression circuit of the present invention has a surge detection signal terminal, which can be used for electromagnetic perception detection, strong electromagnetic early warning, etc.;

[0029] (3) When the short-wave strong electromagnetic suppression circuit of the present invention is used for lightning electromagnetic pulse protection, the residual voltage is lower and the response time is faster;

[0030] (4) The shortwave strong electromagnetic suppression circuit of the present invention can be widely used in the RF front end of each shortwave radio station equipped with a feeding function. It has the functions of large feeding voltage, small size, light weight, no freewheeling and surge detection, and can greatly enhance the strong electromagnetic pulse perception and protection capabilities of the shortwave communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of a small short-wave strong electromagnetic suppression circuit with surge detection according to the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] Example 1

[0034] like Figure 1 As shown, the present invention proposes a small short-wave strong electromagnetic suppression circuit with surge detection, which includes five parts: transient protection circuit, sampling circuit, photoelectric coupling circuit, DC feeding circuit and AC coupling circuit. Among them:

[0035] Transient protection circuit, using gas discharge tube for strong electromagnetic pulse protection;

[0036] The sampling circuit is composed of a current sampling transformer and a rectifier diode connected in sequence, and is used to rectify and sample the strong electromagnetic pulse current and provide a trigger signal for the photoelectric coupling circuit;

[0037] The photoelectric coupling circuit is composed of a capacitor, a current-limiting resistor and an optical coupler connected in sequence to achieve high-impedance isolation between the transient protection path and the short-wave signal path to avoid affecting the transmission and reception of short-wave signals;

[0038] The DC feed circuit uses MOS tube switches to complete the current on and off, solving the problem of continuous current in the gas discharge tube;

[0039] The AC coupling circuit, composed of capacitors, is used to complete short-wave signal transmission and attenuate low-frequency interference.

[0040] The transient protection circuit is composed of a gas discharge tube G1, which can be connected in parallel alone or in multiples, and is mainly used to protect against lightning pulses with a large flow rate of 10kA at the us level.

[0041] The sampling circuit includes a rectifier bridge composed of a current sampling transformer T1 and rectifier diodes D1 to D4. One end of the primary side of the current sampling transformer T1 is connected to the radio frequency input terminal IN, and the other end is connected to the gas discharge tube G1. The secondary side of the current sampling transformer T1 is connected to the upper and lower ends of the rectifier bridge. The left and right ends of the rectifier bridge are connected to the capacitor C1 in the photoelectric coupling circuit to achieve sampling after rectification of the strong electromagnetic pulse current and provide a trigger signal for the photoelectric coupling circuit.

[0042] The photoelectric coupling circuit includes a capacitor C1, a current limiting resistor R0 and an optical coupler V1, one end of the input diode of the optical coupler V1 is connected to the current limiting resistor R0, and the other end is connected to the capacitor C1, the collector of the output transistor of the optical coupler V1, that is, the 3rd pin, is connected to the S end of the MOS tube in the DC feeding circuit, and the emitter of the optical coupler output transistor, that is, the 5th pin, is connected to the anode of the voltage regulator tube Z1 in the DC feeding circuit. The photoelectric coupling circuit realizes high-resistance isolation between the transient protection path and the short-wave signal path to avoid affecting the transmission of the short-wave signal.

[0043] The DC feeding circuit includes a MOS tube M1, a voltage regulator tube Z1, an inductor L1, and resistors R1, R2, and R3. The voltage regulator tube Z1 is connected in parallel to both ends of the MOS tube GS to ensure that the voltage at the MOS tube GS end is within the working range. The inductor L1 is connected to the drain D of the MOS tube to prevent surge current from entering the subsequent circuit. The resistor R1 is connected to the source S of the MOS tube, and the source S is connected to the receiver output end OUT; one end of the resistor R2 is connected to the resistor R1, and the other end is grounded; one end of the resistor R3 is connected to the gate G of the MOS tube, and the other end is connected to the resistor R2. When a strong electromagnetic pulse triggers the gas discharge tube, the MOS tube automatically cuts off the DC feeding path to prevent the gas discharge tube from continuing current. Among them, the MOS tube M1 is preferably a P MOS tube.

[0044] The AC coupling circuit is composed of a capacitor C2, one end of which is connected to the radio frequency input terminal IN and the other end is connected to the receiver output terminal OUT, and is used to complete short-wave signal transmission and attenuate low-frequency interference.

[0045] like Figure 1 When the short-wave strong electromagnetic suppression circuit works normally, the DC feed voltage is set to U dc , the GS terminal voltage U of MOS tube M1 GS That is, R1 resistor divider voltage, U GS =U dc *R1 / (R 1 +R 2 ). The resistance values ​​of resistors R1 and R2 should be selected to ensure that |U GS |≥|U GS(off) |,U GS(off) It is the voltage threshold value of the MOS tube GS terminal, which can make the two ends of the MOS tube DS conductive, so as to output the feeding DC signal from the receiver output terminal OUT to the RF input terminal IN.

[0046] The voltage regulator Z1 is connected in parallel to the GS terminal of the MOS tube. The voltage of the voltage regulator Z1 should be greater than the voltage threshold value of the GS terminal of the MOS tube and within the normal working voltage range of the GS terminal.

[0047] The resistor R3 is set to 90-110 ohms to prevent the G pole of the MOS tube from oscillating.

[0048] Inductor L1 blocks lightning current. The selection of inductor L1 is based on the breakdown current I between MOS tube DS. DS and the breakdown voltage of the gas discharge tube V BR To determine, that is, V BR =L1*(dI DS / dt).

[0049] The shortwave signal is transmitted bidirectionally through the capacitor C2 in the AC coupling circuit. The principle of selecting the capacitor value should ensure that the capacitor impedance is very low at 2MHz, and the capacitor with a small ESR should be selected as much as possible. The equivalent resistance ESR of capacitor C2 generates heat loss and forms insertion loss. Assuming that the shortwave transmission power is P and the shortwave working impedance is R (50Ω), according to The maximum working voltage of the short-wave strong electromagnetic pulse suppression circuit can be obtained according to The effective current of the short-wave strong electromagnetic pulse suppression circuit can be obtained. If the effective current and the equivalent resistance ESR of capacitor C2 are known, the heat loss can be obtained.

[0050] During normal operation, the DC breakdown voltage of the gas discharge tube should be greater than both the DC feed voltage and the maximum short-wave signal operating voltage to prevent it from being falsely triggered by the DC feed and short-wave signal.

[0051] When the lightning electromagnetic pulse reaches the IN terminal, assuming that the primary-to-secondary turns ratio of the current sampling transformer T1 is 1:N, the primary current i 1 , secondary current i 2 , then i 2 =i 1 / N.i 2 After being rectified by the D1~D4 rectifier bridge, the capacitance is C 1 The capacitor C1 is quickly charged, and the charging resistor is the parasitic resistance R of the secondary side of the current sampling transformer T1. ESR , charging time τ = RESR *C 1 Since the parasitic resistance is very small, the charging process is very fast. The charging voltage is U C1 =[∫i 2 *dt] / C 1 The current at the optocoupler input is i F =U C1 / R 0 The capacitance values ​​C1 and R0 should be selected to ensure that i F Within the allowable range of the optocoupler input current, the optocoupler input diode works, and after the optocoupler output triode is turned on, the GS end of the MOS tube is short-circuited, the DS end of the MOS tube is disconnected, and the DC feed voltage is disconnected.

[0052] Inductor L1 blocks the lightning current, and the lightning current is completely discharged by gas discharge tube G1. After the discharge, since the DC power supply has been disconnected, the gas discharge tube has no continuous current phenomenon and quickly returns to the off state. The sampling circuit is not triggered by lightning current, the optocoupler does not work, the MOS tube returns to the closed state, and the DC power supply is restored.

[0053] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0054] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A small short-wave strong electromagnetic suppression circuit with surge detection, characterized in that: Including transient protection circuit, sampling circuit, photoelectric coupling circuit, DC feeding circuit, AC coupling circuit; Transient protection circuit, using gas discharge tube for strong electromagnetic pulse protection; The sampling circuit is used to rectify and sample the strong electromagnetic pulse current and provide a trigger signal for the photoelectric coupling circuit; Photoelectric coupling circuit to achieve high-impedance isolation between transient protection path and short-wave signal path to avoid affecting short-wave signal transmission and reception; The DC feed circuit completes the on-off control of the current and solves the problem of continuous current in the gas discharge tube; AC coupling circuit completes short-wave signal transmission and attenuates low-frequency interference.

2. A small short-wave strong electromagnetic suppression circuit with surge detection according to claim 1, characterized in that: The transient protection circuit is composed of a single or multiple gas discharge tubes G1 connected in parallel, and is used to protect against lightning pulses with a large flow rate of 10kA at the us level.

3. A small short-wave strong electromagnetic suppression circuit with surge detection according to claim 1, characterized in that: The sampling circuit includes a rectifier bridge composed of a current sampling transformer T1 and rectifier diodes D1 to D4; one end of the primary side of the current sampling transformer T1 is connected to the radio frequency input terminal IN, and the other end is connected to the gas discharge tube, the secondary side of the current sampling transformer T1 is connected to the upper and lower ends of the rectifier bridge, and the left and right ends of the rectifier bridge are connected to the two ends of the capacitor in the photoelectric coupling circuit, so as to realize sampling after rectification of the strong electromagnetic pulse current and provide a trigger signal for the photoelectric coupling circuit.

4. A small short-wave strong electromagnetic suppression circuit with surge detection according to claim 3, characterized in that: The photoelectric coupling circuit includes a capacitor C1, a current limiting resistor R0 and an optical coupler V1; the DC feeding circuit includes a MOS tube M1, a voltage regulator tube Z1, an inductor L1 and resistors R1, R2 and R3; One end of the optocoupler V1 input diode is connected to the current limiting resistor R0, and the other end is connected to the capacitor C1. The collector of the optocoupler V1 output transistor is connected to the S pole of the MOS tube in the DC feeding circuit, and the emitter of the optocoupler output transistor is connected to the anode of the voltage regulator tube Z1 in the DC feeding circuit. The voltage regulator Z1 is connected in parallel to both ends of the MOS tube GS to ensure that the voltage at the GS end of the MOS tube is within the working range; the inductor L1 is connected to the D pole of the MOS tube to prevent surge current from entering the subsequent circuit; the resistor R1 is connected to the S pole of the MOS tube, and the S pole is connected to the receiver output terminal OUT; one end of the resistor R2 is connected to the resistor R1, and the other end is grounded; one end of the resistor R3 is connected to the G pole of the MOS tube, and the other end is connected to the resistor R2; when a strong electromagnetic pulse triggers the gas discharge tube, the MOS tube automatically cuts off the DC feed path to prevent the gas discharge tube from continuing current.

5. A small short-wave strong electromagnetic suppression circuit with surge detection according to claim 1, characterized in that: The AC coupling circuit is composed of a capacitor C2, one end of the capacitor C2 is connected to the radio frequency input terminal IN, and the other end is connected to the receiver output terminal OUT.

6. A small short-wave strong electromagnetic suppression circuit with surge detection according to claim 4, characterized in that: The resistance values ​​of resistors R1 and R2 must be selected to ensure that |U GS |≥|U GS(off) |,U GS(off) is the voltage threshold value of the GS terminal of the MOS tube, U GS is the GS terminal voltage of MOS tube M1, that is, the voltage divided by resistor R1, U GS =U dc *R1 / (R1+R2), U dc is the DC feed voltage; The resistor R3 is set to 90-110 ohms to prevent the G pole of the MOS tube from oscillating.

7. A small short-wave strong electromagnetic suppression circuit with surge detection according to claim 4, characterized in that: The voltage of the voltage regulator tube Z1 is greater than the voltage threshold value of the GS terminal of the MOS tube and is within the normal working voltage range of the GS terminal.

8. A small short-wave strong electromagnetic suppression circuit with surge detection according to claim 4, characterized in that: The selection of inductor L1 is based on the breakdown current I between MOS tube DS DS and the breakdown voltage of the gas discharge tube V BR Confirm: V BR =L1*(dI DS / dt).

9. A small short-wave strong electromagnetic suppression circuit with surge detection according to claim 4, characterized in that: The selection principle of capacitor C1 and current limiting resistor R0 is: When the lightning electromagnetic pulse reaches the RF input terminal IN, assuming that the primary-secondary turns ratio of the current sampling transformer T1 is 1:N, the primary current is i1, and the secondary current is i2, then i2 = i1 / N; i2 is rectified by the D1-D4 rectifier bridge and quickly charged by the capacitor C1 with a capacitance of C1. The charging resistor is the parasitic resistance R of the secondary side of the current sampling transformer T1. ESR , charging time τ = R ESR *C1, charging voltage is U C1 =[∫i2*dt] / C1, the current at the optocoupler input is i F =U C1 / R0; The selection of capacitor value C1 and current limiting resistor R0 should ensure that i F Within the allowable range of the optocoupler input current, the optocoupler input diode works, and after the optocoupler output triode is turned on, the GS end of the MOS tube is short-circuited, the DS end of the MOS tube is disconnected, and the DC feed voltage is disconnected.

10. A small short-wave strong electromagnetic suppression circuit with surge detection according to claim 5, characterized in that: The selection principle of capacitor C2 is: to ensure that the capacitor impedance is as low as possible at 2MHz and the equivalent resistance ESR is as small as possible.

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