CN105425051A - Broadband pulse electric field test probe - Google Patents

Abstract

The invention relates to a broadband pulsed electric field test probe, which comprises a metal shielding box, an electronic circuit board fixed in the metal shielding box, an antenna mounting seat welded on the electronic circuit board, and an extended The monopole cylindrical antenna outside the metal shielding box; the monopole cylindrical antenna is electrically insulated from the metal shielding box; the electronic circuit board is provided with a voltage follower and an electro-optical conversion circuit that are electrically connected in sequence, and the electro-optic conversion circuit includes a semiconductor laser and its drive. The circuit; the monopole cylindrical antenna is connected to the input end of the voltage follower, and the tail fiber of the semiconductor laser is connected to the external optical fiber link through the optical fiber adapter flange fixed on the metal shielding box. The object of the invention is to propose a broadband pulsed electric field test probe based on optical fiber transmission with wide frequency band, large range and strong anti-interference ability.

Description

A Broadband Pulse Electric Field Test Probe

technical field

The invention belongs to an electromagnetic field measuring device, in particular to a wide-band test probe used for measuring fast leading edge pulse electric field signals.

Background technique

The strong electromagnetic pulse generated by a nuclear explosion can couple energy into electronic equipment through cables or antennas, thereby causing damage to the electronic devices in them, resulting in functional failure or even damage to the equipment. The nuclear explosion electromagnetic pulse and its engineering protection technology have been widely concerned. The IEC Communication Committee (TC-77) listed it as a high-power electromagnetic environment that needs to be protected for civilian electronic equipment, electronic systems and devices. It has already been carried out at home and abroad. A lot of research work on nuclear electromagnetic pulse simulation and its effects. The pulse electric field measurement device mainly plays the following two roles in this field: to measure whether the electric field environment generated by the simulation device meets the predetermined technical indicators, whether it can be used for the anti-electromagnetic pulse test assessment and performance evaluation of the equipment; to obtain the electric field distribution of the test environment , The important parameters such as the internal coupling electric field of the tested system are used as the data basis for the verification and performance evaluation of weapons and equipment against nuclear electromagnetic pulses.

Pulse electric field signal measurement is a time-domain measurement. In order to truly reproduce the measured pulse waveform, the transfer function of the measurement probe should remain unchanged within the spectrum range of the measured signal. At the same time, the range coverage of the measuring probe needs to be large enough to meet the measurement requirements of the environmental electric field and coupling electric field. IEC6100-2-9 stipulates that the peak value of the NEMP waveform is 50KVm ^-1 , the leading edge is 2.5±0.5ns, and the half-maximum width (FWHM) is 23±5ns. According to this standard to carry out the construction of nuclear electromagnetic pulse simulator and effect research work, the frequency bandwidth of the measuring probe should be greater than 10k~500MHz, and the measuring range should cover 10~100kVm ^-1 .

Common frequency-domain electric field probes cannot be applied to pulse signal measurement; some broadband antennas that use cables to transmit signals, because of their poor anti-electromagnetic interference ability and short signal transmission distance, have great limitations in practical application (new dipole electric field Detector and measurement of space electric field [J], Zhu Min et al., Sensor Technology, April 2000, Volume 19, Issue 4); Wuhan Key Laboratory of Electromagnetic Compatibility National Defense Science and Technology developed a transient electromagnetic pulse transmitted by optical fiber Field tester (ZL200520097960.0), but it cannot be used to measure signals whose rise time is less than 2ns; the broadband electro-optic pulsed electric field measurement system (ZL01131849.X) developed by Northwest Institute of Nuclear Technology uses the principle of electro-optic effect of crystals, based on The optical waveguide modulator is integrated with a special antenna, and the signal is transmitted through the optical fiber. Its frequency response reaches 0.1Hz ~ 700MHz, but its measuring range is relatively small, about Vm ^-1 ~ KVm ^-1 , and the measuring device is not suitable for working Environmental requirements are high.

Contents of the invention

In order to solve the technical problems of poor anti-interference ability and small measuring range of existing frequency-domain electric field probes, the invention provides a broadband pulsed electric field test probe. The electric field test probe provided by the present invention is a broadband pulsed electric field test probe based on optical fiber transmission with wide frequency band, large range, and strong anti-interference ability. For measuring signals, the probe's -3dB bandwidth is 10k~550MHz, the range covers 10~100KVm ^-1 , and the linearity is good in its output dynamic range, which can be used for accurate measurement of electric field signals in nuclear electromagnetic pulse effect tests.

Technical solution of the present invention is:

A broadband pulsed electric field test probe, which is special in that it includes a metal shielding box 2, an electronic circuit board 1 fixed in the metal shielding box, an antenna mount 3 welded on the electronic circuit board 1, and fixed on the The monopole cylindrical antenna 4 in the antenna mount 3 and extending out of the metal shielding box; the monopole cylindrical antenna 4 is electrically insulated from the metal shielding box 2; the length of the monopole cylindrical antenna 4 is 6 mm to 66 mm The diameter of the metal shielding box 2 is greater than 2 times the length of the monopole cylindrical antenna 4; the electronic circuit board 1 is provided with a voltage follower and an electro-optical conversion circuit that are electrically connected in sequence, and the electro-optic conversion circuit includes a semiconductor laser and Its driving circuit; the monopole cylindrical antenna 4 is connected to the input end of the voltage follower, and the tail fiber of the semiconductor laser is connected to the external optical fiber link through the optical fiber adapter flange fixed on the metal shielding box 2 .

The above-mentioned semiconductor laser is a distributed feedback laser, and the drive circuit is a feedback-controlled stable power control drive circuit.

The above-mentioned voltage follower is composed of JFET input integrated operational amplifier OPA659, and its input impedance is greater than or equal to 10 ¹² Ω.

The above-mentioned monopole cylindrical antenna 4 is electrically insulated from the metal shielding box 2 through an insulating sleeve 5 .

The diameter of the above-mentioned monopole cylindrical antenna 4 is Φ2mm.

A capacitor C is also connected between the voltage follower and the electro-optical conversion circuit, and an inductor L is also connected between the semiconductor laser and the driving circuit.

The advantages of the present invention are:

1. The present invention has designed a monopole cylindrical electric small antenna with a frequency response greater than 1 Hz to 1.25 GHz, and adopts a JFET input integrated operational amplifier to form an impedance conversion circuit at the rear end of the antenna, and its input impedance up to 10 ¹² Ω (that is, the load impedance of the antenna ) ensures that the transfer function of the antenna has nothing to do with the frequency, and can realize the original waveform measurement of the time-domain signal of the pulsed electric field.

2. The probe circuit of the present invention adopts chip resistors and capacitors, high-speed integrated operational amplifiers and broadband semiconductor lasers, and its -3dB bandwidth reaches 10KHz to 550MHz, which can be used to accurately measure the nuclear electromagnetic pulse electric field signal specified in IEC6100-2-9; it is also applicable Pulse electric field measurement in the fields of lightning electromagnetic pulse, electromagnetic compatibility, high voltage technology and so on.

3. By optimizing the circuit design and reducing system noise, the present invention makes the dynamic range of the probe output reach 40dB; at the same time, because the probe is easy to replace and uses antennas of different sizes, its measuring range can cover 10Vm ^-1 ~ 100KVm ^-1 .

4. The present invention uses optical fiber to transmit signals, and has strong anti-interference ability; and the laser is driven by a constant power control circuit, and the system gain is stable, which is suitable for harsh outdoor working conditions.

5. The engineering design of the probe of the present invention has considered the following three points comprehensively: the disturbance of the probe to the measured field; the surface of the probe box is used as the reference ground plane of the monopole antenna, and its diameter should be greater than 2 times the length of the antenna; the probe should accommodate Enough power supply batteries to ensure the continuous working time of the probe. Through software simulation and practical application verification, the designed and developed electric field probe can ensure the authenticity of the measurement signal, and the continuous working time of the probe has reached 50 hours.

Description of drawings

Figure 1 is an engineering structure diagram of the probe shielding box;

Fig. 2 is a structural block diagram of the probe circuit;

Fig. 3 is a probe circuit diagram;

Figure 4 is a frequency domain response diagram of the probe;

Figure 5 is the measurement sensitivity of the probe strong pulsed electric field (6mm length antenna);

Figure 6 shows the measurement sensitivity of the weak pulsed electric field of the probe (antenna with a length of 66mm);

Fig. 7 is a schematic diagram of probe work;

Reference signs are as follows: 1-electronic circuit board, 2-metal shielding box, 3-antenna mount, 4-monopole cylindrical antenna, 5-insulation kit, 6-electric field test probe, 7-optical fiber.

detailed description

Broadband pulsed electric field test probe, its electronic circuit board 1 is fixed in the metal shielding box 2, mainly including impedance conversion circuit and electro-optic conversion circuit; antenna mounting base 3 is welded on the electronic circuit board, monopole cylindrical antenna 4 is fixed on the In the antenna mounting base, and use the insulation kit 5 to maintain electrical insulation with the metal shielding box 2; the semiconductor laser is welded on the electronic circuit board 1, and the tail fiber of the semiconductor laser is connected to the outside through the optical fiber adapter flange fixed on the metal shielding box 2 Fiber link connection.

The pulse electric field probe adopts the monopole cylindrical antenna 4 as the signal receiving unit of the measuring device, which is processed by brass material, the design size is Φ2mm*L6mm～66mm, and the bottom end is equipped with a 5mm long thread for installation on the antenna mounting base 3. The measured electric field strength is proportional to the length of the monopole cylindrical antenna 4, and the antenna length can be changed within the design size range to meet the measurement requirements of electric field signals with different strengths.

The metal shielding box 2 is made of brass, and the built-in box cover is fixed by eight screws; the inside of the box body is designed with a mounting socket, which is convenient for fixing the electronic circuit board (1) by welding, and makes it electrically connected to the box body touch. The outer dimensions of the metal shielding box 2 are

The electronic circuit board 1 adopts JFET (junction field effect transistor) input integrated operational amplifier to form the signal processing circuit at the rear end of the antenna 4, which provides the high input impedance required for the antenna 4 to receive the original waveform signal, and also completes the sensor and electro-optical conversion circuit. Impedance matching. The JFET input integrated operational amplifier uses a junction field effect transistor as its input stage, and uses the electric field effect of the input loop to control the output loop current. It has high input impedance, small size, and good stability. In addition, the electronic circuit board 1 selects broadband discrete components, and performs wiring and soldering according to high-speed PCB manufacturing principles.

The electro-optical conversion circuit on the electronic circuit board 1 uses a semiconductor laser to convert the electrical signal into an optical signal, and the laser is a distributed feedback laser; the semiconductor laser is driven by a constant power control circuit.

Figure 1 is the engineering structure diagram of the probe shielding box; the structure of the electronic circuit board is shown in Figure 2, including a voltage follower, a capacitor C, a semiconductor laser, an inductor L, and a drive circuit that are electrically connected in sequence. The antenna mounting base 3 is welded on the electronic circuit board, the monopole cylindrical antenna 4 is fixed in the antenna mounting base by threads, and the monopole cylindrical antenna 4 is connected to the input end of the voltage follower.

The specific circuit is shown in Figure 3. The OPA659 integrated operational amplifier produced by TI is used as a voltage follower, its nominal bandwidth is 650MHz, and the input impedance is 10 ¹² Ω; the semiconductor laser LDM3S509-301 for analog signal transmission of Wuhan Telecom is used to complete the electro-optical conversion of the signal; the laser is stable The power drive circuit is a feedback control circuit, which uses the photodiode on the light-emitting surface of the laser to monitor the output optical power and feeds it back to the drive circuit. When the output optical power decreases, the drive current increases, and vice versa, and the optical output power is always kept at a constant value.

The frequency response of the probe is shown in Figure 4. In the 10k-550MHz frequency band, the probe gain drops less than 3dB. The antenna with a total length of 6mm is selected, the sensitivity of the probe is 8.36×10 ^-9 W/Vm ^-1 , the highest measurable pulse intensity is greater than 12kVm ^-1 , and as shown in Figure 5, the response linearity of the strong pulse field of the probe is good; the selected total length is With a 66mm antenna, the probe sensitivity is 12.5×10 ^-6 W/Vm ^-1 , the lowest measurable pulse intensity is less than 10Vm ^-1 , and as shown in Figure 6, the probe has a good response linearity to weak pulse fields.

The working process of the probe is:

As shown in Figure 7, the electric field test probe 6 is placed in the environment of the electromagnetic field E to be measured, and an antenna with an appropriate length is selected according to the estimated electric field strength (the larger the field strength, the shorter the antenna), and the direction of the antenna is kept parallel to the direction of the electric field; Single-mode optical fiber 7 with a wavelength of 1310nm, connect the probe to the analog signal optical receiver, and use an oscilloscope to monitor the output of the optical receiver. The optical receiver can be OPC5505 from Tektronix. The analog bandwidth of the oscilloscope should be greater than 1GHz, and the sampling rate should be greater than 5Gbit/ s.

When the pulse electric field is generated, the oscilloscope will record the data and waveform, and the calculation method of the pulse electric field strength is:

Pulse electric field intensity = oscilloscope reading (V)/[optical receiver photoelectric conversion efficiency (V/W) × pulse electric field test probe sensitivity (W/Vm ^-1 )]

The probe has been used in nuclear electromagnetic pulse, lightning electromagnetic pulse, and pulse electric field measurement work in high voltage fields.

Claims (6)

1. A broadband pulsed electric field test probe is characterized in that: comprise metal shielding box (2), be fixed on the electronic circuit board (1) in the metal shielding box, be welded on the antenna mount on the electronic circuit board (1) (3), the monopole cylindrical antenna (4) that is fixed in the antenna mount (3) by threads and stretches out of the metal shielding box; insulation; the length range of the monopole cylindrical antenna (4) is 6 mm to 66 mm; the diameter of the metal shielding box (2) is greater than twice the length of the monopole cylindrical antenna (4); the electronic circuit board (1) A voltage follower and an electro-optical conversion circuit electrically connected in sequence are provided on it, the electro-optic conversion circuit includes a semiconductor laser and its drive circuit; the monopole cylindrical antenna (4) is connected to the input end of the voltage follower, and the semiconductor laser The pigtail is connected to the external optical fiber link through the optical fiber adapter flange fixed on the metal shielding box (2). 2. The broadband pulsed electric field test probe according to claim 1, characterized in that: the semiconductor laser is a distributed feedback laser, and the drive circuit is a feedback-controlled stable power control drive circuit. 3. The broadband pulsed electric field test probe according to claim 1 or 2, wherein the voltage follower is composed of a JFET input integrated operational amplifier OPA659, and its input impedance is greater than or equal to 10 ¹² Ω. 4. The broadband pulsed electric field test probe according to claim 3, characterized in that: the monopole cylindrical antenna (4) is electrically insulated from the metal shielding box (2) through an insulating sleeve (5). 5. The broadband pulsed electric field test probe according to claim 4, characterized in that: the diameter of the monopole cylindrical antenna (4) is Φ2mm. 6. The broadband pulsed electric field test probe according to claim 5, characterized in that: a capacitor C is also connected between the voltage follower and the electro-optical conversion circuit, and an inductor is also connected between the semiconductor laser and the driving circuit L.