KR20080006415A - Antenna being in structure of photonic band gap - Google Patents

Abstract

An antenna having a photonic band gap structure is provided to improve a signal reception/transmission efficiency of the antenna by enhancing a front/back ratio and an isolation of the antenna. An antenna having a photonic band gap structure includes a metal layer(110), plural conductive pins(114), and an EMI(ElectroMagnetic Interference) shielding plate(116). Radiating elements are implemented on the metal layer. The conductive pins are fixed to be vertical to an edge of the metal layer. The EMI shielding plate is supported on the conductive pin and shields an electromagnetic signal which is diffracted under the metal layer. When the metal layer has a polygonal shape, the EMI shielding plate is arranged on one of the metal layers. A frequency band of the shielded electromagnetic signal is determined by a width of the EMI shielding plate, a spacing between the conductive pins, and a height of the conductive pin.

Description

Antenna being in structure of photonic band gap

1 illustrates a typical antenna shape and radiation pattern.

2 is a diagram illustrating a photon bandgap structure used in a general antenna.

Figure 3 is an exploded perspective view showing the form of the antenna of the photon bandgap structure in accordance with an embodiment of the present invention and a radiation pattern of radio waves.

4 is a diagram simulating a form in which propagation of a specific frequency is blocked on the antenna of the photon bandgap structure according to an embodiment of the present invention.

FIG. 5 is a graph illustrating a comparison of specific frequency bands blocked on an antenna having a photon bandgap structure according to an exemplary embodiment of the present invention. FIG.

Figure 6 is a perspective view showing the shape of the antenna implemented using the full conductor structure.

7 is a view showing the shape of a conventional antenna, a graph of a cutoff frequency band and a graph measuring a radiation pattern.

8 is a diagram showing the shape of the antenna of the photon bandgap structure according to an embodiment of the present invention, a graph of a cutoff frequency band and a graph measuring a radiation pattern.

<Explanation of symbols for main parts of drawing>

100: antenna of the photon bandgap structure according to the present invention

110: metal layer 112: radiating element

114: conductive pin 116: radio shield

120: dielectric layer 140: ground layer

142: feed line

The present invention relates to an antenna structure used in the RF communication module.

Currently, mobile communication terminals such as mobile phones, smart phones, personal digital assistants (PDAs), and radio frequency identification (RFID) devices are widely used, and various electronic devices are embedded and these electronic devices are mounted on a printed circuit board (PCB). It is common to form an integrated module.

In such a communication module, an antenna for converting a transmitted / received signal into an electrical signal and a signal in the air is necessary.

That is, the antenna is a device for converting the electrical signal expressed in voltage / current and the electromagnetic wave expressed in the electric field / magnetic field to interwork with the change of the electromagnetic field outside the antenna and the electrical signal on the wire inside the antenna.

There are many different types of antennas, such as dipole antennas, monopole antennas, microstrip antennas (also called "patch antennas"), horn antennas, and parabolic. Examples include antennas, helical antennas, slot antennas, and the like.

In particular, in the case of a communication module having a multi-layered structure such as a low temperature co-fired ceramic (LTCC) substrate, a printed antenna is used. The printed antenna is a resonator type antenna. ) And a traveling wave antenna.

FIG. 1 is a diagram illustrating a shape and a radiation pattern of a general antenna 10, and FIG. 2 is a diagram illustrating a photon bandgap structure 24 used in a general antenna.

Referring to FIG. 1, a simplified form of a general substrate printed antenna 10 is shown, which comprises a radiator over a substrate layer (usually a lamination structure of a metal thin film layer, a dielectric layer, and a ground layer) 12. 14) is formed.

A feeding line and a feeding slot are formed (not shown) inside the substrate layer 12 to supply current, and the current forms electromagnetic energy to excite the current to the radiating element 14.

When current is excited, the radiating element 14 is excited to radiate electromagnetic waves to the outside.

At this time, the direction of the electromagnetic wave is changed according to the type of the radiating element 14, for example, if the radiating element 14 is provided in the form of a patch, the main radiation in the upper side of the antenna, that is, the z axis in the spatial coordinates Is done.

In addition, if the radiating element 14 is provided in the form of a tapered slot, the chef is made to the side that the slot is open, that is, one side corresponding to the x-axis or y-side on the spatial coordinates.

In addition, when the radiating element 14 has a dipole shape, a conductor having two different poles is formed to have a length 1/2 of a corresponding frequency band, thereby enabling omnidirectional radiation.

However, these antennas, electromagnetic waves are also emitted to the back of the substrate layer by the radio wave diffraction phenomenon at the end of the substrate.

Referring to FIG. 1, the antenna has radiation patterns such as a main lobe B1, side lobes B2 on both sides, and a back lobe B3 on the rear side, and a back lobe B3 due to a diffraction phenomenon. It can be seen that the measurement is large.

The antenna used in the communication module must meet the following requirements in order to provide high quality communication. First, the antenna must be able to receive a signal having a strength above an appropriate level, and second, a signal-to-noise ratio above an appropriate level. Should have Third, it must be able to cope with multi-path transmission / reception environment caused by reflected waves, etc. Fourth, the front / back ratio and isolation between lobes should be good.

In particular, the fourth requirement is an important parameter for determining the performance of the antenna, and suppressing the occurrence of backlobe as much as possible can improve the front-to-back ratio and isolation.

In the case of a patch antenna, a photon bandgap (PBG) structure 26 is also used to improve the isolation between the patches 24 on the substrate 22, as shown in FIG. The main purpose of suppressing the propagation interference between the patches is to significantly reduce the effect of preventing back lobes from occurring.

In addition, the conventional photon bandgap structure has a disadvantage in that the arrangement is complicated, the gap size is large, and the radio wave shielding effect is not good. In addition, the conventional photon bandgap structure is difficult to manufacture in the process, and there is a limit in minimizing the size of the antenna because a certain interval must be secured for each device.

The present invention provides an antenna in which the front / rear ratio and isolation are improved by suppressing a back lobe phenomenon.

In addition, the present invention provides an antenna having a photon bandgap structure, which is easy to manufacture and can be implemented in a small size, and has excellent radio wave shielding effect in suppressing a back lobe phenomenon.

The antenna of the photon bandgap structure according to the present invention comprises a metal layer mounted with a radiating element; A plurality of conductive pins fixed perpendicularly to an outer portion of the metal layer; And a radio wave shielding plate mounted on the conductive pin and shielding radio waves diffracted to the bottom surface of the metal layer.

In addition, in the antenna of the photon bandgap structure according to the present invention, the frequency band of the shielded radio wave is determined by at least one of a width of the radio wave shield plate, a gap between the conductive pins, and a height of the conductive pins.

In addition, the conductive pin and the wave shielding plate provided in the antenna of the photon bandgap structure according to the present invention are disposed opposite to each other of the main lobe of the radiating element.

Hereinafter, an antenna having a photon bandgap structure according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is an exploded perspective view showing the form of the antenna 100 of the photon bandgap structure according to an embodiment of the present invention and a diagram showing the radiation pattern of radio waves.

Referring to FIG. 3, the antenna 100 having a photon bandgap structure according to the present invention includes a ground layer 140, a dielectric layer 120, a metal layer 110, photon bandgap elements 114 and 116, and a radiating element 112. The photon bandgap elements 114 and 116 according to the present invention are provided to shield the radiation pattern of the back lobe and may be provided in various kinds of antennas.

For example, the photon bandgap structure according to the present invention may be applied to a dipole antenna, a monopole antenna, a microstrip antenna, a patch antenna, a horn antenna, a parabolic antenna, a helical antenna, and a slot antenna.

In the embodiment of the present invention, the radiation element 112 is to be provided as a ± 45 ° dual polarization radiation element.

The ground layer 140 has a feed line 142 is formed from one side end to the center portion, the feed line 142 emits energy by forming an electromagnetic field when a current is supplied.

In general, as a method for transmitting or receiving a signal from the metal layer 110 located at the foremost of the antenna 100, the power supply line 142 is connected through an electricity supply line to directly supply a current and a power supply line. There is an indirect feeding method in which 142 forms an electromagnetic field and transfers electromagnetic energy, and the antenna 100 according to the present invention uses the direct feeding method.

The metal layer 110 is made of a metal material, for example, a metal material such as copper may be used.

The dielectric layer 120 insulates the ground layer 140 and the metal layer 110, and the feed line 142 of the ground layer 140 passes through a via hole (not shown) of the dielectric layer 120. It is electrically connected to the radiating element 112.

The photon bandgap elements 114 and 116 include a plurality of conductive pins 114 arranged in a straight line on the upper surface of the metal layer 110 and a radio wave shield plate 116 fixed on the conductive pins 114. 114) have the same height and are arranged at regular intervals.

The conductive pins 114 are fixed perpendicularly to the outer portion of the metal layer 110, and the radio wave shielding plate 116 is supported on the conductive pins 114 and propagated to the bottom surface of the metal layer 110. Shield.

The conductive pin 114 and the wave shield plate 116 are formed of a conductor in the same manner as the metal layer 110.

First, the "photon band gap phenomenon" will be described.

Photonic Band Gap (PBG) theory is a technology that controls the movement of electrons in semiconductor technology, and it is an electronic band gap that exists between the conduction band and the valence band. ) Creates a potential by the regular arrangement of atoms or molecules that make up a substance.

In other words, the periodic arrangement of dielectrics acting as potentials for electromagnetic waves creates a band gap for electromagnetic waves, similar to the concept of electronic band gaps, which means that electromagnetic waves with a specific wavelength can be selectively passed or prevented from proceeding. do.

The Maxwell's equation for electromagnetic waves in a three-dimensional periodic array array is

▽ × [1 / ε (r) × ▽ × H (r)] = W ² / C ² × H (r)

In Equation 1, the photonic crystal unit grid vector Ri coincides with the periodic dielectric function ε (r) = ε (r + Ri) for (i = 1, 2, 3 for 3 dimensions). In this case, applying the Bloch-Floquet theory, the solution of the equation can be selected in the form of H (r) = eik · xHn, k (r) with eigenvalues ωn (k), where Hn, k is a periodic envelope function (periodic envelope). satisfies the function).

FIG. 4 is a diagram illustrating a form in which propagation of a specific frequency is blocked on the antenna 100 having a photonic bandgap structure according to an embodiment of the present invention, and FIG. 5 is an antenna having a photon bandgap structure according to an embodiment of the present invention. A graph showing a comparison of specific frequency bands blocked on 100.

Referring to FIG. 4, the photon bandgap elements 114 and 116 including the conductive pin 114 and the radio wave shielding plate 116 have a width of the radio wave shielding plate 116, a gap between the conductive pins 114, and a conductive pin. Shielding the radio wave of a specific frequency band by a variable such as the height of the 114, for example, the width of the radio shield plate 116 is 20mm, the spacing between the conductive pins 114 is 35mm, conductive pin 114 If the height of 20 mm, radio waves of about 2 GHz to 2.5 GHz (-10 dB reference bandwidth) are shielded.

That is, it can be seen that the radio wave in the Z-axis direction is shielded by the photon bandgap element among the three-dimensional electromagnetic field planes of the E, H, and Z axes.

As the radio wave radiated backward is shielded, the utilization efficiency of the radio wave is increased, which means that the antenna 100 according to the present invention can be used as a base station and a repeater antenna as well as a Wi-Bro terminal.

In addition, referring to FIG. 5, three measurement lines are illustrated, where the x-axis is a frequency (GHz) and the y-axis is a field strength (dB) of a vector field.

The measuring line "D1" is a radio wave measuring line when a structure for guiding radio waves from the radiating element 112 is not formed on the metal layer 110.

According to the measurement line "D1", it can be seen that the radio wave is not shielded in any frequency band and the radio wave passes evenly.

6 is a perspective view showing the shape of the antenna 30 implemented using the full conductor structure.

The antenna 30 shown in FIG. 6 is similar in shape to the antenna 100 according to the present invention, but the PEC (Perfect Conductor) structure (plate conductor plate) 36 is vertical on the metal layer 32. Formed, and the radio wave shielding plate 34 is coupled to the PEC structure 36 is different.

The measurement line "D3" is a measurement line in which the propagation of the antenna 30 by the PEC (Perfect Electric Conductor) structure 36 of FIG. 6 is guided, and a slight shielding effect at a high band frequency. Was measured, but the effect is slight.

On the other hand, the measurement line "D2" is a measurement of the radio wave when the photon bandgap element 112 according to the present invention, it can be seen that the frequency of about 2.16 GHz band is effectively blocked as described above. .

And, looking at the radiation pattern of the antenna 100 of the present invention shown in Figure 3, it can be seen that the back lobe radiation is significantly reduced compared to the general antenna 10 shown in FIG.

It can be seen that the photon bandgap elements 114 and 116 shown in FIG. 3 are formed as two parts facing each other on both sides of the main lobe (array of radiating elements). The type of antenna and the shape of the radiating element 112 are shown. As a matter of course, the shape and arrangement of the photon bandgap elements 114 and 116 may be different.

For example, when the main lobe of the radiating element 112 is directed only to the upper surface of the metal layer 110, the photon bandgap elements 114 and 116 are disposed in an RF fence surrounding all of the radiating element 112. It could be.

In addition, it is advantageous for the photon bandgap elements 114 and 116 to be located adjacent to the ends of the metal layer 110 to shield back lobe radiation.

7 is a graph measuring a shape of a conventional antenna, a graph of a cutoff frequency band, and a radiation pattern, and FIG. 8 is a graph of a shape of an antenna having a photon bandgap structure, a cutoff frequency band, and a radiation pattern according to an embodiment of the present invention. It is a graph measured.

In the graphs illustrated in FIGS. 7 and 8, the x-axis represents frequency (GHz) and the y-axis represents magnitude (dB) of the S parameter.

7 (a) and 8 (a), the antennas 10 and 100 each include radiating elements 14 and 112 connected to the feed lines 16 and 142 on a metal layer. The antenna 100 according to the present invention (Fig. 8 (a) Figure) 100 can be seen that the photon band gap elements 114, 116 are further provided, Fig. 6 (b) and Fig. 7 (b) Comparing the drawings, it can be seen that the radiating element radiates radio waves by resonating the frequency in the band of about 2.16 GHz.

However, while the radio wave number of about -12.94 dB is conventionally measured, the radio wave number of about -22.17 dB is measured according to the antenna according to the present invention.

This means that unnecessary radiation generated to the rear of the antenna is effectively removed, thereby improving sensitivity to the signal.

In addition, when comparing FIG. 7C and FIG. 8C, the propagation graph shown in FIG. 8 is more distorted in a circle than in FIG. 7, and the back lobe radiation is shielded. This means that the concentration of radio waves directed toward the main lobe is improved.

Although the present invention has been described above with reference to the embodiments, these are only examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains may have an abnormality within the scope not departing from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not illustrated. For example, each component specifically shown in the embodiment of the present invention can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

According to the antenna of the photon bandgap structure according to the present invention, the antenna efficiency is improved by improving the front / rear ratio and isolation, and it is possible to provide an antenna capable of stably transmitting and receiving signals with less power.

In addition, according to the present invention, by combining a variable such as the width, spacing, height, etc. of the photon bandgap structure, it is possible to easily select the frequency band of the radio wave to be blocked, and can also form a photon bandgap structure by a simple process It is effective to manufacture high performance antennas with minimum cost and time.

Claims (6)

A metal layer on which the radiating element is mounted; A plurality of conductive pins fixed perpendicularly to an outer portion of the metal layer; And And a radio shielding plate mounted on the conductive pin and shielding radio waves diffracted to the bottom surface of the metal layer. The method of claim 1, And the conductive pins and the wave shielding plate are disposed on at least one surface of the metal layer when the metal layer has a polygonal shape. The method of claim 1, And a frequency band of the shielded radio wave is determined by at least one of a width of the radio wave shield plate, a gap between the conductive pins, and a height of the conductive pins. The method of claim 1, wherein the radiating element An antenna having a photonic bandgap structure, characterized in that provided on the metal layer protruding or patch-shaped. The method of claim 1, wherein the conductive pin and the wave shield plate The photonic bandgap structure antenna, characterized in that disposed adjacent to the surface end of the metal layer. The method of claim 1, wherein the conductive pin and the wave shield plate An antenna having a photonic bandgap structure, which is disposed to face each other on both sides of the main lobe of the radiating element.

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