KR102203945B1 - Electric Field Intensity Measuring Method of EMP Permeating Facility Area - Google Patents

Abstract

The method for measuring electric field strength inside a shielded room of the present invention includes the steps of setting a standardized frequency for a HEMP pulse or NNEMP pulse signal, setting a sampling time based on the sampling frequency, and dividing the time domain to be observed by the sampling time. Obtaining HEMP or NNEMP spectra for as many sample frequencies as the number of samples, installing a receiving antenna in a location adjacent to the outside of the shielding room and outside the transmitting antenna, and near-field transfer function for CW (Continuous Wave) sample frequency signals Measuring, and calculating the reflection coefficient and transmission coefficient of the entire shielding wall of the shielding room based on the reflection coefficient and transmission coefficient of the interface of the shielding wall of the shielding room, and using this to obtain the equivalent wave impedance of the wall surface, and The steps of obtaining a near wave impedance, converting a near field transfer function to a far field transfer function using the near wave impedance of the dipole transmission antenna and the equivalent wave impedance of the shielding wall, and the far distance in the HEMP or NNEMP spectrum for the sample frequency. And obtaining a spectrum of an electromagnetic field inside the shielded room by multiplying a transfer function, and obtaining a pulse signal in a time domain by inverse Fourier transform (IFFT) of the electromagnetic field spectrum inside the shielded room.

Description

Electric Field Intensity Measuring Method of EMP Permeating Facility Area}

The present invention relates to verifying the performance of a shielding facility by measuring an electromagnetic field inside a facility to be protected and to grasp the transient response of an electromagnetic field pulse inside the facility to be protected.

The prior art related to the present invention is disclosed in Korean Patent Application Publication No. 10-2015-0144949 (published on December 29, 2015). The above prior art replaces the location of the transmitting and receiving antennas so that the shielding effect can be measured even in a narrow space between the EMP protection facility and the external concrete structure, that is, unlike the existing shielding effect measuring method, the transmitting antenna is placed inside the facility and received. This is to analyze the shielding effect through the method of placing the antenna outside the facility. In order to achieve the above object, a transmission antenna is placed inside and a receiving antenna is placed outside to compare, measure and test the effect of shielding effect. .

In addition, the conventional steel plate welding shielding room can secure a shielding degree of 80dB or more by the panel assembly method, so it is sufficient to protect against the EMP effect, but it is expensive and requires a space between the reinforced concrete wall and the steel plate for measurement. will be. In the above conventional method, electromagnetic waves entering the external reception antenna are affected by not only electromagnetic waves transmitted inside the shielded room, but also various types of electromagnetic waves (broadcasting, mobile communication, instantaneous emission electromagnetic waves by sparks, etc.) directly radiated from the outside. It is difficult to measure the exact shielding degree.

In the prior art as described above, shielding costs are excessive, space costs are wasted, and measurement accuracy is also poor. Therefore, an object of the present invention is to measure the electric field inside the shielding room in the case of securing a shielding degree of 30dB ~ 40dB by constructing a shielding room by attaching a shielding sheet and film to the walls and windows of an existing building, and the value is shielded. It is to be able to judge whether the radiation resistance of the device installed inside the room is satisfied. To this end, the present invention is to provide a method for easily measuring the electric field strength inside a shielding room using a power source radiated from a short distance.

In order to achieve the above object, the method for measuring the electric field strength of the electromagnetic wave pulse penetrating into the shielded room of the present invention includes the steps of setting a standardized frequency for a HEMP pulse or an NNEMP pulse signal, and setting a sampling time based on the sampling frequency. Steps, obtaining a HEMP or NNEMP spectrum for the number of sample frequencies equal to the number of times the time domain to be observed is divided by the sampling time, and installing a receiving antenna in a location adjacent to the transmitting antenna and outside the shielding room and inside the shielded room, Measuring the near-field transfer function for the CW (Continuous Wave) sample frequency signal, and calculating the reflection coefficient and transmission coefficient of the entire shielding wall of the shielding room based on the reflection coefficient and transmission coefficient of the shielding wall interface of the shielding room, and using this Obtaining the equivalent wave impedance of the dipole transmission antenna, obtaining the near wave impedance of the dipole transmission antenna, and converting a near-field transfer function to a far-field transfer function using the near wave impedance of the dipole transmission antenna and the equivalent wave impedance of the shielding wall. Wow, Wah, and multiplying the HEMP or NNEMP spectrum for the sample frequency by the far-field transfer function to obtain a spectrum of the electromagnetic field inside the shielded room, and inverse Fourier transform (IFFT) the electromagnetic field spectrum inside the shielded room to convert the time domain into a pulse signal It is characterized in that made including the step of obtaining.

In the present invention configured as described above, by attaching the transmitting antenna to a wall or a glass window, there is an effect that it is easy to measure electromagnetic waves even in a shielded room inside a high-rise or dense building. In addition, since the present invention uses only one type of dipole antenna in the entire measurement band, there is an effect that it is not necessary to replace the antenna for each measurement band. In addition, the present invention has the effect of automating the entire process of data processing by modularizing all calculations for processing measurement data with software, and also has an effect that it is convenient to check the measurement results.

1 is a configuration diagram of a system for measuring electric field strength of an electromagnetic wave pulse penetrating into the shielded room of the present invention,
2 is a flowchart illustrating a method for measuring electric field strength of an electromagnetic wave pulse penetrating into a shielded room according to the present invention.

A method of measuring the electric field strength of an electromagnetic wave pulse penetrating into the shielding room of the present invention having the above object will be described on the basis of FIGS. 1 to 2 as follows.

1 is a block diagram of a system for measuring electric field strength of an electromagnetic wave pulse penetrating into a shielded room of the present invention. In Fig. 1, the electric field strength measurement system of the electromagnetic wave pulse penetrating into the shielded room according to the present invention generates a transmission power (Pt) and transmits it to a transmission (Tx) antenna through port 1 (Prt). A network analysis unit 100 that measures an electric field by receiving power from a receiving antenna and a second receiving antenna inside the shielded room, and a first receiving antenna (port 2) near the shielded room by copying the transmission power received from the network analysis unit. Gs: Pr1) and the dipole transmission (Tx) antenna 110 transmitted to the second reception antenna inside the shielded room, and the first reception antenna 120 installed outside the shielded room for measuring electromagnetic waves radiated from the transmission antenna. And, it is characterized in that it is composed of a second receiving antenna (port 3 Gs:Pr2) 130 for measuring after passing through the shielding wall the electromagnetic wave radiated by the transmitting antenna while moving the position inside the shielding room.

In the above, the receiving power P _r1 of the first receiving antenna near the shielding room and The received power P _r2 of the second receiving antenna inside the shielded room can be calculated as follows.

Where Pt is the transmission power [dBm], Lc is the cable loss [dB], Lw is the transmission loss [dB] of the wall of the shielded room, Lpath1, Lpath2 are the loss along the propagation path [dB], and Gt is the transmission antenna gain. [dB], and Gs is the gain of the first receiving antenna or the second receiving antenna [dB].

According to the link analysis result as described above, each parameter must be adjusted so that the power received through the reception antenna is equal to or greater than the reference reception sensitivity of the network analysis unit.

In addition, the transfer function S21 between port 1 and port 2, the transfer function S31 between port 1 and port 3, and the transfer function between port 2 and port 3 can obtain S32 , for example, between the port 2 and port 3 The transfer function S32 is the case of copying from port 2 and receiving from port 3.

In addition, in order to measure the long-distance shielding degree, the antenna of Port 1 should be as far away as possible from the facility, the Port 2 antenna should be placed near the shielded room, and the Port 3 antenna should be installed at the measurement location inside the shielding room. The shielding degree can be expressed as a transfer function, and the shielding degree of the long-distance measurement is S21/S31 .

In addition, in order to measure the short-distance shielding degree, if the transmit antenna is port 2 and the shielding degree is extracted by receiving at port 3, this S32 becomes the shielding degree, and this can be used as a transfer function.

2 is a flowchart illustrating a method of measuring the electric field strength of an electromagnetic wave pulse penetrating into the shielding room of the present invention. 2, the method of measuring the electric field strength of the electromagnetic wave pulse penetrating into the shielded room of the present invention includes the step of setting a standardized frequency for a HEMP pulse or an NNEMP pulse signal (S11), and setting a sampling time based on the sampling frequency. Step (S12), obtaining a HEMP or NNEMP spectrum for the number of sample frequencies divided by the sampling time by the time domain to be observed (S13), and a location adjacent to the transmitting antenna and the shielding room, and a receiving antenna inside the shielded room. Installing (S14), measuring a near-field transfer function for a CW (Continuous Wave) sample frequency signal (S15), and the entire shielding wall of the shielding room based on the reflection coefficient and transmission coefficient of the barrier wall interface of the shielding room. Obtaining the reflection coefficient and transmission coefficient of and using the same to obtain the equivalent wave impedance of the wall surface (S16), the step of obtaining the near wave impedance of the dipole transmission antenna (S17), and the near wave impedance of the dipole transmission antenna and the shielding wall surface Converting a short-range transfer function to a far-range transfer function using the equivalent wave impedance of (S18), and obtaining a spectrum of the electromagnetic field inside the shielded room by multiplying the HEMP or NNEMP spectrum for the sample frequency by the far-field transfer function (S19) And, inverse Fourier transform (IFFT) of the electromagnetic spectrum inside the shielding room to obtain a pulse signal in the time domain (S20).

를 설정해야 하는 것이다. 이러한 표본화 주파수는 펄스가 포함한 주파수 스펙트럼 최대치(

)의 2배(Nyquist sampling theorem :

)로 설정한다. 이때 펄스가 포함한 주파수 스펙트럼 최대치(

)는 펄스 에너지의 99%까지(ex. : HEMP E1 복사성 펄스의 경우 60MHz, NNEMP hyper-band 신호의 경우 300MHz)가 포함된 주파수로 한다. In addition, the method of setting the maximum frequency as the sampling frequency for HEMP or NNEMP in the step S11 is the sampling frequency when FFT (Fast Fourier Transform) given EMP pulse in the time domain

Is to be set. This sampling frequency is the maximum of the frequency spectrum the pulse contains (

) Of Nyquist sampling theorem:

). At this time, the maximum value of the frequency spectrum (

) Is a frequency that includes up to 99% of the pulse energy (ex.: 60MHz for HEMP E1 radiated pulse, 300MHz for NNEMP hyper-band signal).

)은 표본화 주파수의 역수(

)로 하는 것이다. 즉 펄스에 의한 응답을 정확히 보기 위해서는 과도 응답이 모두 경과 할 때까지 보아야 하므로 입사 펄스의 수 배 이상을 전체 해석 시간(

)으로 설정해야 한다.In addition, the method of setting the sampling time based on the sampling frequency in step S12 is the sampling time (

) Is the reciprocal of the sampling frequency (

). In other words, in order to accurately see the response by the pulse, it is necessary to see it until all the transient response has elapsed. Therefore, the total analysis time (

) Should be set.

가 된다. 따라서 주파수 영역의 표본 주파수 개수도

개가 필요하다. 그런데, FFT는

까지의 데이터를 얻어야 하는데,

구간의 데이터는

구간의 데이터와 크기는 갖고 위상만 반대 부호이므로, 실제 측정에 필요한 데이터는

구간의 데이터만 있으면 되는 것이다. 즉, 주파수 영역에서의 측정 대역은

으로 주어지므로 상술한 펄스가 포함한 주파수 스펙트럼 최대치(

)까지로 설정하면 되는 것으로 이때 측정주파수 간격(

)은

으로 주어지는 것이다. At this time, the required time domain data is

Becomes. Therefore, the number of sampled frequencies in the frequency domain is also

I need a dog. By the way, FFT

I need to get the data up to,

The data in the section is

Since only the phase is the opposite sign with the data and size of the section, the data required for actual measurement

All you need is the data of the section. That is, the measurement band in the frequency domain is

Since it is given as the maximum value of the frequency spectrum included in the above-described pulse (

), and at this time, the measurement frequency interval (

)silver

It is given as.

, 최대 주파수

, 표본화 시간

, 표본 주파수 개수

및 전체 응답시간

를 이용하여 HEMP 또는 NNEMP신호를 FFT(Fast Fourier Transform)하여 스펙트럼 데이터를 얻을 수 있는 것이다.In addition, the step S13 includes the parameters described above,

, Maximum frequency

, Sampling time

, Number of sample frequencies

And total response time

It is possible to obtain spectrum data by FFT (Fast Fourier Transform) of the HEMP or NNEMP signal by using.

이고, 1에 해당되는 것이

이 된다. 앞서 설명한 바와 같이, 0.5(DC)를 중심으로 양쪽이 대칭임을 알 수 있는 것이다.Spectral data vs. When explaining the time domain waveform as an example, an example in which the pulse in the time domain is FFTed and expressed as a spectrum in the frequency domain are shown in Figures I to III below. At this time, DC component is equivalent to 0.5 of the normalized frequency, and 0 is equivalent to

And the equivalent of 1 is

Becomes. As described above, it can be seen that both sides are symmetric around 0.5 (DC).

[Figure I] HEMP E1 Pulse signal

[Figure II] NNEMP meso-band pulse signal

[Figure III] NNEMP hypo-band pulse signal

In addition, the transmission antenna fixing module installed on the exterior wall or glass window of the building applied to the present invention in step S14 has the following structure.

As can be seen from the side view and the front view, the transmission antenna is a structure that is attached to a glass window or a wall surface using a detachable pad using a dipole antenna.

In addition, the receiving antenna moving module installed inside the facility applied to the present invention in step S14 is for moving the receiving antenna to each measurement position and has the following structure.

As can be seen from the above, the receiving antenna has a structure in which a slider fastened to the H-beam rail under the antenna port to measure radio waves while moving inside the facility can move along the rail.

를 설정하고,

개(

)의 표본 주파수에 대하여 송신 안테나와 수신 안테나 장치를 이용하여 근거리 전달함수

를 측정하는 것이다.In addition, in order to measure the near-field transfer function in step S15, the sampling frequency

And set

dog(

For the sample frequency of ), a short-range transfer function using a transmitting antenna and a receiving antenna device

Is to measure.

In addition, in step S16, a method of obtaining the equivalent wave impedance of the shielding wall by using the reflection coefficient and the transmission coefficient of the entire shielding wall can be obtained by the following process. The model for obtaining the total reflection coefficient and transmission coefficient by repeating the reflection and transmission of the electromagnetic wave radiated from the antenna at the barrier wall interface is shown in Figure IV below.

Figure IV Continuous reflection and transmission model

In Figure IV, medium a is air (free space) and medium b is a shielding wall. Electromagnetic waves incident from a to b are reflected at the interface (a|b) and some are transmitted inside the shielding wall. The transmitted electromagnetic wave is attenuated and propagated to the opposite boundary (b|a), and then some of it is transmitted and some of it is reflected back to the boundary (a|b), and then the transmission and reflection are continued again. . At this time, the total reflection coefficient is the sum of all electric fields propagating from the interface (a|b) to the a side divided by the incident wave, and the total transmission coefficient is the sum of all the electric fields that pass through the interface (a|b) and propagating to the b side as an incident wave. It becomes something divided. These are expressed as formulas as follows.

Total transmission coefficient:

Shielding degree:

Total reflection coefficient:

Return loss:

Each parameter used in the above equation is as follows.

* Interface reflection coefficient

* Interface transmission coefficient

, Propagation constant of medium b:

,

진공 중의 유전율 및 벽면의 유전율

Permittivity in vacuum and permittivity of wall

진공 중의 투자율

Permeability in vacuum

벽면의 도전율

Electrical conductivity of the wall

는 각각 입사파와 차폐벽의 파동 임피던스이며,

는 차폐벽의 두께를 나타낸 것이다. 상기와 같은 방법으로 구한 전체 반사 계수와 투과 계수를 이용하여 차폐벽면의 등가 임피던스 Ｚw를 NRW(Nicolson-Ross-Weir Method)에 의하여 구할 수 있는 것이다. here,

Is the incident wave and the wave impedance of the shielding wall, respectively,

Represents the thickness of the barrier wall. By using the total reflection coefficient and transmission coefficient obtained by the above method, the equivalent impedance xw of the shielding wall can be obtained by NRW (Nicolson-Ross-Weir Method).

In addition, the method of extracting the wave impedance of the dipole transmission antenna in step S17 is given by the following equation (a).

... 식(a)

... Equation (a)

방향에 대하여When describing the wave impedance in detail, the electromagnetic field of a dipole antenna is expressed using a polar coordinate system,

Against the direction

Is calculated as, and each parameter expressed in the above equation is as follows.

극 좌표계(spherical coordinate)의 좌표

Coordinates in the spherical coordinate system

자유공간 파동임피던스

Free space wave impedance

파수(wave number,

)

Wave number,

)

다이폴 커넥터 인가 전류

Dipole connector applied current

다이폴 중심으로부터 관측위치와의 거리

Distance from the center of the dipole to the observation position

다이폴의 길이임.

This is the length of the dipole.

)로부터 원거리 전달함수(

)를 얻는 식은 다음 식(b)와 같다. 여기에서 상기 S15, S16 단계에서 구한 벽면의 등가 파동 임피던스와 다이폴 송신 안테나의 근거리 파동 임피던스가 아래 수식(b)에 포함되는 것이다.In addition, in step S18, the short-range transfer function is first measured in order to convert it into a far-range transfer function based on the short-range transfer function inside the shielded room. This is done by using the network analysis unit to radiate radio waves from port 2 (first receiving antenna) and measuring the reception level at port 3 (second receiving antenna) as described in FIG. 1, and measuring the ratio S32. The near-field transfer function obtained from these measurement data (

) To the long-distance transfer function (

) Is given in Equation (b) below. Here, the equivalent wave impedance of the wall and the near wave impedance of the dipole transmission antenna obtained in steps S15 and S16 are included in Equation (b) below.

..식(b)

..Expression (b)

The following parameters shown above are all functions of frequency.

자유공간 파동 임피던스와 벽면 파동 임피던스의 비,

The ratio of the free space wave impedance to the wall wave impedance,

다이폴 안테나의 근거리 복사장의 파동 임피던스와 벽면 파동 임피던스의 비,

The ratio of the wave impedance of the near-field radiation of the dipole to the wave impedance of the wall,

벽면의 등가 임피던스(벽면의 재질 및 구조에 따라 다르며, 측정 혹은 모델링에 의하여 산출),

Equivalent impedance of the wall (depending on the material and structure of the wall, calculated by measurement or modeling),

벽면의 감쇠 정수(벽면의 재질 및 구조에 따라 다르며, 측정 혹은 모델링에 의하여 산출),

Wall attenuation constant (depending on the material and structure of the wall, calculated by measurement or modeling),

벽면의 두께임.

This is the thickness of the wall.

In addition, in the step S19, the spectrum of the electromagnetic field penetrating into the facility can be obtained by multiplying the long-range transfer function obtained by converting the short-range transfer function for the sample frequency by the HEMP or NNEMP spectrum obtained in the step S13.

In addition, in step S20, a pulse shape in the time domain can be obtained by performing an inverse Fourier transform (IFFT) of the electromagnetic spectrum penetrating into the facility obtained in step S19.

100: network analysis unit, 110: dipole transmission antenna,
120: first receiving antenna, 130: second receiving antenna

Claims (7)

delete delete In the method of measuring the electric field strength inside the shielded room when HEMP or NNEMP pulse waves penetrate into the shielded room,
The method of measuring the electric field strength inside the shielded room when the pulse wave penetrates into the shielded room,
Setting a standardized frequency for the HEMP pulse or the NNEMP pulse signal (S11);
Setting a sampling time based on the sampling frequency (S12);
Obtaining an HEMP or NNEMP spectrum for the number of sample frequencies obtained by dividing the time domain to be observed by the sampling time (S13);
Installing a receiving antenna in a location adjacent to the transmitting antenna and outside the shielding room and inside the shielding room (S14);
Measuring a short-range transfer function with respect to the sample frequency (S15);
Calculating the reflection coefficient and transmission coefficient of the entire shielding wall of the shielding room based on the reflection coefficient and transmission coefficient of the shielding wall interface of the shielding room, and using the same to obtain the equivalent wave impedance of the wall (S16);
Obtaining a near wave impedance of the dipole transmission antenna (S17);
Converting a short-range transfer function into a far-range transfer function using the short-range wave impedance of the dipole transmission antenna and the equivalent wave impedance of the shielding wall (S18);
Multiplying the HEMP or NNEMP spectrum for the sample frequency by the far-field transfer function to obtain a spectrum of the electromagnetic field inside the shielded room (S19);
And inverse Fourier transform (IFFT) of the electromagnetic field spectrum inside the shielded room to obtain a pulse signal in the time domain (S20).The electric field inside the shielded room when the pulse wave penetrates into the shielded room. Method of measuring strength.
The method of claim 3,
The step of setting the maximum frequency as the sampling frequency for the HEMP pulse or NNEMP pulse signal (S11) is the maximum frequency spectrum included in the pulse (

A method of measuring electric field strength inside a shielded room when a pulse wave penetrates into the shielded room, characterized in that it is set to 2 times of ) .
The method of claim 3,
The total transmission coefficient T of the shielding wall in step S16 is,

ego
The total reflection coefficient (ρ) of the shielding wall is

A method for measuring electric field strength inside a shielded room when a pulse wave penetrates into the shielded room, characterized in that.
Where the interface reflection coefficient is

ego
The interface transmission coefficient is

ego,
Propagation constant of medium b:

,

Permittivity in vacuum and permittivity of walls,

Permeability in vacuum,

The conductivity of the shielding wall,

Is the incident wave and the wave impedance of the shielding wall, respectively,

Is the thickness of the barrier wall.
The method of claim 3,
The receiving antenna,
A method of measuring electric field strength inside a shielded room when a pulse wave penetrates into the shielded room, characterized in that the slider fastened to the H-beam rail under the antenna port can move along the rail.
The method of claim 3,
In the step S16, the equivalent impedance of the wall is,
A method for measuring electric field strength inside a shielded room when a pulse wave penetrates into the shielded room, characterized in that it can be obtained by the NRW method (Nicolson-Ross-Weir Method) using the reflection coefficient and transmission coefficient of the entire shielding wall.

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