KR20210146551A - Antenna using a ferrite core - Google Patents

Abstract

An antenna using a ferrite core is disclosed. In the disclosed antenna, a conductor is wound around a cylindrical ferrite core while repeating a step-like shape. The disclosed antenna can maintain a low antenna factor in an operating frequency band, and is suitable for measuring the shielding effectiveness of a small shielding facility due to its small size.

Description

Antenna using a ferrite core {ANTENNA USING A FERRITE CORE}

The following embodiments relate to an antenna using a ferrite core, and more specifically, to an antenna implemented by winding a conductor in a step shape on a cylindrical ferrite core.

An EMP (Electro Magnetic Pulse) attack is an attack that neutralizes the opponent's electronic equipment by using a powerful electromagnetic pulse. When a nuclear explosion occurs, electromagnetic waves and neutrons are generated, and gamma-ray photons, which are electromagnetic waves with strong energy generated at this time, diffuse into the atmosphere, generating powerful electromagnetic pulses. The electromagnetic pulse enters the electronic circuit and becomes a current. Because the energy of the EMP is so great, an overcurrent that the circuit cannot withstand flows, and this overcurrent destroys the electronic circuit, thereby destroying all electronic devices that operate as semiconductors, that is, communication equipment, Computers, vehicles, and computer networks are paralyzed.

When an EMP attack occurs, almost all military equipment is paralyzed, so the warfare capability is greatly reduced. Accordingly, interest in shielding facilities capable of shielding strong electromagnetic pulses caused by EMP attacks is increasing. However, it is difficult to precisely measure the shielding effect because the measuring antenna capable of measuring the shielding effect of the shielding facility has a large size.

The following embodiments aim to miniaturize a measuring antenna capable of measuring the shielding effect of a shielding facility.

According to the following embodiments, it is an object to miniaturize a loop antenna using a ferrite core.

According to an exemplary embodiment, an antenna including a cylindrical core made of a ferrite material, a conductor wound around the core, and a power supply port for feeding power to the conductor is disclosed.

Here, the conductor may be wound while being spaced apart from the core by a predetermined distance.

In addition, the conductor is wound by a first distance in a direction perpendicular to the longitudinal direction of the core, is wound by a second distance in the longitudinal direction of the core, and again by a first distance in a direction orthogonal to the longitudinal direction of the core. can be wound.

Also, the first distance may be shorter than the circumference of the core.

According to the following embodiments, it is possible to miniaturize a measuring antenna capable of measuring the shielding effect of the shielding facility.

According to the following embodiments, a loop antenna may be miniaturized using a ferrite core.

1 is a diagram illustrating the necessity of electromagnetic wave shielding.
Fig. 2 is a diagram showing the structure of an antenna according to an exemplary embodiment.
3 is a diagram illustrating an antenna factor according to a frequency of an antenna according to an exemplary embodiment.
Fig. 4 is a diagram showing the influence of a ferrite core according to frequency in an antenna according to an exemplary embodiment.
Fig. 5 is a diagram illustrating an EMP shielding effect measured using an antenna according to an exemplary embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating the necessity of electromagnetic wave shielding.

As shown in FIG. 1, EMP attacks affect a wide range of power/electronic devices and electronic systems such as national power transmission lines, communication networks, satellites and computer networks. Therefore, in order to preserve the warfare capability despite the enemy's attack, in order to block the effect of the EMP attack, the main facilities that can be the target of the enemy's attack must be equipped with an electromagnetic wave shielding facility.

However, since a huge cost is required to construct an electromagnetic wave shielding facility, most of the electromagnetic wave shielding facilities are built on a scale that is not sufficient to operate major electronic devices, and the inside of the shielding facility is generally cramped. Therefore, recently, rather than shielding all facilities operating electronic devices, research on small shielding facilities that protect only electronic devices has been focused.

In order to measure the shielding effectiveness (SE) of a small shielding facility, it is necessary to measure a magnetic field in a very low frequency band of several kHz, and for this, a fairly large loop antenna is often used. However, it is difficult to measure the performance of a small shielding facility using a large-sized loop antenna, and the measured shielding effect is often inaccurate.

To overcome this, various studies have been conducted to miniaturize the loop antenna, but in general, a complicated structure or an expensive manufacturing process is required, and when the antenna factor (AF) is high, the accuracy of magnetic field measurement is often poor. .

Fig. 2 is a diagram showing the structure of an antenna according to an exemplary embodiment.

Fig. 2 (a) is a side view of an antenna according to an exemplary embodiment.

An antenna according to an exemplary embodiment includes a core 220 , a conductor 230 , and a feeding port 240 . The core 220 of the antenna is made of a ferrite material, and has a cylindrical shape. The interior 210 of the ferrite core 220 may be an empty space. The conductor 230 may be wound around a core 220 made of a ferrite material to form a loop antenna. The feeding port 240 may be connected to the conductor 230 surrounding the ferrite core 220 to feed the loop antenna.

According to one side, the conductor 230 may be wound while being spaced apart from the ferrite core 220 by a predetermined distance.

2B is a diagram illustrating a conductor wound around a core.

The conductor is shaped like a very thin tape and its width is 'w'. According to one side, the conductor may be wound by a first distance in a direction orthogonal to the longitudinal direction of the core. Thereafter, the conductor may be rotated 90 degrees and wound a second distance in the longitudinal direction of the core. In addition, thereafter, it may be wound by a first distance in a direction orthogonal to the longitudinal direction of the core by rotating 90 degrees in the opposite direction again. Here, the first distance is shorter than the circumference of the core, and when the conductor is wound by only the first distance, it is shorter than the length of the circumference spaced apart from the ferrite core by a predetermined distance. Therefore, if the conductor is wound by a first distance in a direction orthogonal to the longitudinal direction of the core and then wound again in the longitudinal direction of the core, the conductor takes a step-like shape as shown in (b) of FIG. repeated and wound up.

Exemplary design parameters of the antenna shown in FIG. 2 are shown in the table below.

은 페라이트 코어의 내부 직경이고,

는 페라이트 코어의 외부 직경이다.

는 권선된 도체가 형성한 원의 지름이고,

권선된 도체 사이의 간격이다.

는 도체의 폭이고,

는 페라이트 코어의 길이 또는 높이이고,

는 도체가 페라이트 코어에 권선된 횟수이다.here,

is the inner diameter of the ferrite core,

is the outer diameter of the ferrite core.

is the diameter of the circle formed by the wound conductor,

It is the spacing between the wound conductors.

is the width of the conductor,

is the length or height of the ferrite core,

is the number of times the conductor is wound on the ferrite core.

3 is a diagram illustrating an antenna factor according to a frequency of an antenna according to an exemplary embodiment.

3A is a diagram illustrating an experimental environment for measuring an antenna factor. In FIG. 3A , two reference antennas Ant. 1 and Ant. 2 are used to measure the antenna factor of the third antenna Ant. 3 . In this case, the antenna factor of the third antenna Ant. 3 may be defined as in Equation 1 below.

[Equation 1]

,

및

는 각 안테나들간의 S 파라미터이다.Here, i is an index indicating the third antenna (Ant. 3), and l and n are indexes indicating the reference antennas (Ant. 1, Ant. 2).

,

and

is the S parameter between each antenna.

는 하기 수학식 2와 같이 정의되고,

는 하기 수학식 3과 같이 정의된다.here,

is defined as in Equation 2 below,

is defined as in Equation 3 below.

[Equation 2]

는 두 레퍼런스 안테나(Ant. 1, Ant. 2) 간의 거리이고,

와

는 각각 두 레퍼런스 안테나(Ant. 1, Ant. 2)의 반지름이다.here,

is the distance between the two reference antennas (Ant. 1, Ant. 2),

Wow

are the radii of the two reference antennas (Ant. 1, Ant. 2), respectively.

[Equation 3]

는 측정 주파수를 나타내고,

는 자유공간의 파수(wave number)로, 파장의 역수를 나타낸다.

는 자유공간에서의 투자율을 의미하며,

는 안테나의 부하 임피던스를 나타낸다.here,

represents the measurement frequency,

is the wave number of free space, and represents the reciprocal of the wavelength.

is the permeability in free space,

is the load impedance of the antenna.

3B is a diagram comparing a theoretical antenna factor and an antenna factor calculated through simulation. In (b) of FIG. 3 , the horizontal axis represents the frequency, and the vertical axis represents the antenna factor. A solid line is a diagram illustrating an antenna factor measured using the manufactured antenna, and a thin dotted line is a theoretical value of the antenna factor. A thick dotted line indicates an antenna value calculated through simulation.

Referring to FIG. 3B , the antenna factor measured using the manufactured antenna is close to the antenna factor calculated through simulation in all measured frequency bands.

Fig. 4 is a diagram showing the influence of a ferrite core according to frequency in an antenna according to an exemplary embodiment.

Figure 4 (a) is a view showing the influence of the ferrite core according to the frequency. In FIG. 4A , the horizontal axis represents frequency, and the vertical axis represents an antenna factor. The blue solid line indicates the simulated value of the antenna factor when there is a ferrite core, and the blue dotted line indicates the measured value of the antenna factor when the ferrite core is present. In addition, a red solid line indicates a simulated value of an antenna factor when there is no ferrite core, and a red dotted line indicates an actual measured value of the antenna factor when a ferrite core is not present.

Referring to FIG. 4A , the measured antenna factor value represents a value similar to the simulation value. It can be seen that the case in which the ferrite core is present has a smaller antenna factor compared to the case in which the ferrite core is not provided, and the low-end frequency band antenna factor can be reduced by using the ferrite core.

4B illustrates an antenna factor according to a change in an incident angle. In FIG. 4A , the horizontal axis represents an incident angle of an incident radio wave, and the vertical axis represents an antenna factor. In addition, a solid line indicates a simulated value when a ferrite core is present, a dotted line indicates a simulated value when a ferrite core is not present, and a star (*) indicates an actual measured value when a ferrite core is present.

Referring to (b) of FIG. 4 , when there is a ferrite core, the simulated value and the actual measured value show similar trends. In addition, it can be seen that the antenna factor is about 4 dB lower in the case where the ferrite core is present than in the case where the ferrite core is not present. Accordingly, it can be seen that the manufactured antenna shows a stable antenna factor despite the change in the angle of incidence, and maintains the antenna factor at a low value despite the small antenna.

Fig. 5 is a diagram illustrating an EMP shielding effect measured using an antenna according to an exemplary embodiment.

Figure 5 (a) shows the experimental environment in which the EMP shielding effect was measured. A frequency source and a detector are placed with the shielding member shown in gray interposed therebetween. The frequency source and detector emit/sense electromagnetic waves using a 0.3m-sized loop antenna. Each loop antenna is spaced 0.3m from the shielding member. The measured shielding effect may be defined by Equation 4 below.

[Equation 4]

는 차폐 효과를 나타내며, 단위는 dB이다.

은 수신 안테나가 차폐 부재 없이 자유공간에 위치한 경우의 수신 전압을 나타내고,

는 차폐 부재가 안테나 사이에 위치하는 경우에 수신 전압을 나타낸다.In Equation 4,

represents the shielding effect, and the unit is dB.

represents the receiving voltage when the receiving antenna is located in free space without a shielding member,

denotes the received voltage when the shielding member is positioned between the antennas.

5 (b) is a diagram illustrating a shielding effectiveness (SE: Shielding Effectiveness) measured using the manufactured antenna. In (b) of FIG. 5 , the horizontal axis represents the frequency, and the vertical axis represents the measured shielding effect. The graph expressed by connecting the circle (o) indicates the measured value for the horizontal polarization, and the graph expressed by connecting the X(x) indicates the measured value for the vertical polarization.

The average shielding effectiveness over the entire frequency range is approximately 5.19 dB for horizontal polarization and 14.14 dB for vertical polarization. In the range of 10 kHz to 3 MHz, the average shielding effectiveness is 26.9 dB for horizontal polarization and 17.2 dB for vertical polarization.

Referring to FIG. 5 , it can be seen that the proposed antenna can suppress the antenna factor to a low level while minimizing the size of the loop antenna, and thus is suitable for measuring the shielding effect of an enclosure made of a shielding member.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and available to those skilled in the art of computer software. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floppy disks. - includes magneto-optical media, and hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

As described above, although the embodiments have been described with reference to the limited embodiments and drawings, various modifications and variations are possible from the above description by those skilled in the art. For example, the described techniques are performed in an order different from the described method, and/or the described components of the system, structure, apparatus, circuit, etc. are combined or combined in a different form than the described method, or other components Or substituted or substituted by equivalents may achieve an appropriate result.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

210: inside of the ferrite core
220: ferrite core
230: conductor
240: power supply port

Claims (4)

A cylinder-shaped core made of a ferrite material;
a conductor wound around the core; and
a feed port that feeds the conductor
An antenna comprising a. According to claim 1,
The conductor is wound at a predetermined distance from the core and spaced apart from each other. According to claim 1,
The conductor is wound by a first distance in a direction orthogonal to the longitudinal direction of the core,
wound by a second distance in the longitudinal direction of the core;
An antenna wound by a first distance again in a direction orthogonal to the longitudinal direction of the core. According to claim 1,
wherein the first distance is a length shorter than the circumference of the core.

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