KR101043339B1 - Wide band antenna - Google Patents

Abstract

 There is provided a wideband antenna having a wide frequency band that can be used for a wireless local area network (WLAN), which can be manufactured in a small size and at a low cost. The broadband antenna according to the present invention includes a first antenna portion, a feed line, a second antenna portion, a connector connection portion and a stub grounded on one side thereof, and the frequency band is increased by being coupled with the stub and the first antenna portion or the second antenna portion. Can be.

Bow Tie Antenna, Resonance, Stub

Description

Wide band antenna

1 is a plan view of a conventional bow tie antenna.

2A and 2B are a plan view and a bottom view of a broadband antenna according to an embodiment of the present invention.

3 is a plan view of a broadband antenna according to another embodiment of the present invention.

4A is an equivalent circuit diagram of a broadband antenna according to the present invention, and FIG. 4B is a graph showing the frequency characteristics of the broadband antenna according to the present invention.

5 is a graph showing the return loss with respect to the frequency of the broadband antenna according to an embodiment of the present invention.

6 is a graph showing a gain with respect to the angle of the broadband antenna according to an embodiment of the present invention.

7A is a graph showing a two-dimensional E-plane radiation pattern of a broadband antenna according to an embodiment of the present invention, Figure 7b is a graph showing a three-dimensional E-plane radiation pattern of a broadband antenna according to an embodiment of the present invention to be.

8 is a graph showing the return loss with respect to the frequency of the broadband antenna according to another embodiment of the present invention.

(Explanation of symbols for the main parts of the drawing)

21, 31: first antenna unit

22a, 34a, 34b: second antenna portion

23, 32: feeder

24a, 24b, 36a, 36b: stubs

25a, 25b, 33a, 33b, 37: connector connection

35: balun

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wideband antenna, and more particularly, to a wideband antenna having a wide frequency band that can be used for a wireless local area network (WLAN) and being manufactured at a small size and at a low cost. .

Recently, due to the spread of the Internet and the rapid increase of multimedia data, the demand for high speed communication network is increasing. In particular, with the proliferation of portable computers and personal digital assistants (PDAs), there is an increasing interest in wireless local area networks as demands for connecting to a network are increased regardless of a place. Although the wireless local area network has a lower data rate than the wired local area network, the wireless local area network may have advantages such as mobility, portability, and simplicity, so that various services are provided in a wide frequency band through a wireless local area network in various applications. . An antenna, which is one of important components of a wireless local area network system, needs to have a wide frequency band to effectively provide such various services.

A bow tie antenna according to the related art will be described with reference to FIG. 1. In general, a bow tie antenna forms two triangular metal conductor patterns 11 and 12 in a bow tie shape and is supplied with voltage through feed lines 13 and 14 to form two triangular metal conductor patterns 11 and 12. It radiates in both directions and is known to have frequency broadband characteristics. However, the conventional bow tie antenna requires an infinitely large conductor pattern as a feed line (especially a ground voltage feed line), which makes it difficult to be used in an actual communication network system.

It is an object of the present invention to provide a wideband antenna that can be manufactured at a small size and at a low cost while having a wide frequency band that can be used for a wireless local area network (WLAN).

The broadband antenna according to an embodiment of the present invention for achieving the technical problem is a first antenna portion formed of a trapezoidal metal conductor on the first surface of the dielectric substrate, the first antenna on the first surface of the dielectric substrate A feed line connected to the center of the short side of the portion and formed of a metal conductor to supply a voltage to the first antenna portion, and a metal conductor above or below the portion where the feed line ends, spaced apart from the feed line on the first surface of the dielectric substrate; A first connector connection portion formed and a notch-shaped metal conductor formed on the second surface of the dielectric substrate so as not to overlap with the first antenna portion, the short side of the first antenna portion and the notch-shaped nipple A second antenna portion formed to face an additional portion, and a nipple of the second antenna portion opposed to the feed line on a second surface of the dielectric substrate; A balun formed of a metal conductor to be connected to the second connector; a second connector connection part formed of a metal conductor connected to a side of the dielectric substrate that is not connected to a corner of the second antenna part of the balun; and A second surface of the dielectric substrate includes a stub formed of a metal conductor to be connected to the second connector connection portion between the second antenna portion and the balun.

According to another aspect of the present invention, there is provided a wideband antenna including a first antenna part formed of a trapezoidal metal conductor on one surface of a dielectric substrate and a metal conductor connected to a center of a short side of the first antenna part. A first branch having a feed line and a notch shape, the first branch having a notch shape and spaced apart from the first antenna portion and the feed line, the second branch having the notched shape A second antenna portion extending in parallel with the feed line and formed of a metal conductor on an upper portion of the feed line; a first branch having a notch shape is formed below the feed line and spaced apart from the first antenna portion and the feed line; The second branch is a third antenna portion extending in parallel with the feed line in the lower portion of the feed line is formed of a metal conductor, the second A connector connection part formed of a metal conductor to be connected to the second branch of the antenna part and the third antenna part, and a metal conductor between the branches of the second antenna part or the third antenna part, and one side is connected to the connector connection part Stub to be formed.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

2A and 2B, a broadband antenna according to an embodiment of the present invention will be described in detail. 2A is a plan view of a broadband antenna according to an embodiment of the present invention, and FIG. 2B is a bottom view of the broadband antenna according to an embodiment of the present invention.

The broadband antenna according to the embodiment of the present invention includes a first antenna unit 31, a feed line 32, a first connector connection unit 33, a second antenna unit 34, a balun 35, a stub 36 and And a second connector connection 37.

The first antenna portion 31 is formed of a trapezoidal metal conductor on one surface 30a of the dielectric substrate, and the second antenna portion 34 is notched on the other surface 30b of the dielectric substrate. The first antenna unit 31 is formed so as not to overlap the first antenna unit 31, and the notch-shaped stem 38 is formed at a center of the short side of the first antenna unit 31 so as to be spaced apart from each other. The two antenna section 34 constitutes a bow tie antenna. In addition, the first antenna unit 31 is not necessarily formed in a trapezoidal shape, but has a plurality of branches 31a, 31b, and 31c as shown in FIG. 2A, but may be formed in a trapezoidal shape as a whole. The two antenna unit 34 can also be formed in various shapes.

The feed line 32 is connected to the center of the short side of the first antenna unit 31 on one surface 30a of the dielectric substrate and is formed of a metal conductor to supply voltage to the first antenna unit 31, and a balun 35 ) Is formed on the other surface 30b of the dielectric substrate so as to be connected to the top portion 38 of the second antenna portion 34 with a metal conductor opposite to the feed line 32, and the top portion of the second antenna portion 34. The taper shape becomes narrower toward 38, thereby converting an unbalanced current mode into an equilibrium current mode. The balloon 35 is formed inside the second antenna parts 34a and 34b to reduce the size of the entire antenna.

The first connector connection part 33 may be spaced apart from the feed line 32 on one surface 30a of the dielectric substrate so as to be formed of a metal conductor on an upper portion of the end of the feed line 32 or one surface of the dielectric substrate. It is composed of a fourth connector connecting portion 33b which is spaced apart from the feed line 32 at 30a and is formed of a metal conductor vertically symmetrical to the third connector connecting portion 33a at the lower part of the end of the feed line 32, and the coaxial cable It is connected to the (coaxial) connector. The first connector connecting portion 33 is not required to include both the third connector connecting portion 33a and the fourth connector connecting portion 33b on one surface 30a of the dielectric substrate, but the third connector connecting portion 33a and the fourth connector connecting portion By having all of 33b, it is connected with a coaxial cable connector more efficiently.

The second connector connecting portion 37 is connected to the stubs 36a and 36b on the other side 30b of the dielectric substrate, and is not connected to the tops of the second antenna portions 34a and 34b of the balun 35. It is formed of a metal conductor so that it is connected to a coaxial connector.

The stub 36 is formed of a metal conductor to be connected to the second connector connection portion 37 between the second antenna portion 34 and the balun 35 on the other side 30b of the dielectric substrate, and the second connector connection portion 37 The one side of the stub 36 is grounded by being connected to (). The stub 36 with one side grounded causes perturbation of the current distribution in the ground to have a finite ground size. Therefore, the size of the entire antenna can be reduced.

The stub 36 has an upper portion 34a and a balloon 35 of the second antenna portion 34 between the upper portion 34a of the second antenna portion 34 and the balloon 35 on the other side 30b of the dielectric substrate. And the lower portion 34b and the balloon 35 of the second antenna portion 34 between the lower portion 34b and the balloon 35 of the first stub 36a or the second antenna portion 34 which are formed to be spaced apart from each other. It is formed of a second stub (36b) formed spaced apart from each other and formed in the first stub (36a) in the vertical symmetry.

4A is an equivalent circuit diagram of a broadband antenna according to the present invention. The equivalent circuit illustrated in FIG. 4A may be described as having the following relationship with respect to a broadband antenna according to an embodiment of the present invention. L1, C1, and R1 correspond to the first antenna part 31 and the second antenna part 34, and L2, C2, and R2 correspond to the stub 36. Since one side of the stub 36 is grounded, the resonant circuit including L2, C2 and R2 is also grounded. Coupling coefficient M between L1 and L2 in FIG. 4A represents the radial coupling between the first antenna part 31 / the second antenna part 34 and the stub 36. Resistor R3 represents the resistance of an unshown RF signal source driving the first antenna portion 31 and the second antenna portion 34. R1, on the other hand, represents a non-radiation loss related to electromagnetic energy dissipation due to the finite conductivity of the actual conductors of the first antenna part 31 and the second antenna part 34. R2 represents the emission and radiation loss of the stub 36 and R4 represents the radiation loss of the first antenna portion 31 and the second antenna portion 34.

The equivalent circuit diagram of FIG. 4A is a schematic equivalent circuit diagram of a broadband antenna according to the present invention, which is shown only for the purpose of explaining the extension of the operating frequency band according to the coupling effect of the antenna. On the other hand, the use of equivalent circuit diagrams is common in antenna theory (Constantine A. Balanis, "Antenna Theory Analysis and Design", Second Edition, John Wiley & Sons, Inc. New York, Chichester, Brisbane, Toronto, Singapore, page 567, see Figure 11.15)

Referring to FIG. 4B, the interaction between the stub 36 having one side grounded and the first antenna unit 31 or the second antenna unit 34 will be described. 4b is a graph showing the frequency characteristics of a broadband antenna according to the present invention.

The stub 36 is affected by the input impedance due to the coupling impedance induced by coupling the stub 36 with the first antenna portion 31 or the second antenna portion 34 and the current distribution. In addition, antenna matching may be improved due to the above-described perturbation of the coupling impedance or current distribution, and radiation efficiency may be increased. For example, the reactance induced in the antenna through the coupling can offset the initial reactance of the antenna and thus increase the radiation efficiency. As shown in FIG. 4B, the coupling between the stub 36 and the first antenna unit 31 or the second antenna unit 34 does not occur because the stub 36 does not exist. It can be seen that the frequency band increases compared to the case. For example, “Coupling OFF” shown in FIG. 4B represents the ratio of RF power emitted by the circuit including R3 and L1, C1, R1 to RF power emitted by R4 in dB. As shown in FIG. 4B, assuming the loss at R1 is very small, the curve labeled “Coupling OFF” indicates that all power is transferred from R3 to R4 at the resonant frequency. In a wideband antenna, this indicates that all power transmitted from the signal source represented by R3 is emitted to the outer space represented by R4. That is, it indicates that all incident power is radiated and no power is returned to the signal source R3, so that the broadband antenna has high radiation efficiency near the resonance frequency.

On the other hand, the curve labeled “Coupling ON” in FIG. 4B shows that the frequency is expanded when the coupling effect occurs. That is, in the broadband antenna according to an embodiment of the present invention, by including a coupled resonant element such as the stubs (36a, 36b) in the antenna structure, it indicates that the antenna band can be extended with high radiation efficiency.

On the other hand, in the broadband antenna according to another embodiment of the present invention to be described later, the stubs 24a and 24b play the same role as the stubs 36a and 36b of one embodiment.

The resonant frequency coupled with the stub 36 and the first antenna portion 31 or the second antenna portion 34 occurs within the frequency band radiated by the first antenna portion 31 or the second antenna portion 34. The length of the stub 36 is preferably about 1/4 of the resonance frequency.

The stub 36 does not have to include both the first stub 36a and the second stub 36b on the other side 30b of the dielectric substrate, but includes both the first stub 36a and the second stub 36b. As a result, the coupling with the first antenna unit 31 or the second antenna unit 34 may be more effectively generated, and the frequency band may further increase. And the stub 36 is preferably formed in parallel with the feed line (32).

The broadband antenna according to an embodiment of the present invention further includes a balun 35 and a stub 36 in addition to the first antenna part 31 and the second antenna part 34 to reduce the overall size of the antenna and its structure. It can be made simple and at low cost. In addition, due to the coupling between the stub 36 and the first antenna unit 31 or the second antenna unit 34, a wider frequency band may be provided.

5 is a graph showing the return loss with respect to the frequency of the broadband antenna according to an embodiment of the present invention. As shown in FIG. 5, the broadband antenna according to the exemplary embodiment of the present invention shows that the frequency band of the 10 dB return loss is 4.37 GHz to 6.37 GHz (32%). Therefore, the broadband antenna according to the embodiment of the present invention is suitable for the IEEE 802.11a standard that defines the frequency band of a wireless local area network (WLAN), so that the wireless local area network Can be applied to

FIG. 6 is a graph showing a gain for an angle of a broadband antenna according to an embodiment of the present invention. As shown in FIG. 6, it can be seen that the broadband gain according to an embodiment of the present invention has a maximum gain of 2 dBi. .

FIG. 7A is a graph illustrating a two-dimensional E-plane radiation pattern of a broadband antenna according to an embodiment of the present invention. As shown in FIG. 7A, a broadband antenna according to an embodiment of the present invention in two dimensions is provided in a specific direction. It can be seen that there is no orientation for. FIG. 7B is a graph showing a three-dimensional E-plane radiation pattern of a broadband antenna according to an embodiment of the present invention. As shown in FIG. 7B, the broadband antenna according to an embodiment of the present invention may be specified in three dimensions. It can be seen that there is no directionality to the direction.

A broadband antenna according to another embodiment of the present invention will be described with reference to FIG. 3. 3 is a plan view of a broadband antenna according to another embodiment of the present invention.

According to another embodiment of the present invention, a broadband antenna includes a connector connection part 25 including a first antenna part 21, a feed line 23, a connection part 25a, and a connection part 25b, a second antenna part 22a, and a third antenna part. 22b and the stub 24.

The first antenna portion 21 is formed of a trapezoidal metal conductor on one surface 20 of the dielectric substrate, and the second antenna portion 22a has a notch shaped first branch on one surface 20 of the dielectric substrate ( A branch is spaced apart from the first antenna portion 21 and the feed line 23, and is formed on the feed line 23, and the second branch of the notch shape extends in parallel with the feed line 23 on the feed line 23. Formed of metal conductors. The third antenna portion 22b has a notch-shaped first branch formed on one surface 20 of the dielectric substrate and spaced apart from the first antenna portion 21 and the feed line 23, and is formed below the feed line 23. The second branch of the notch shape is formed of a metal conductor under the feed line 23 so as to extend in parallel with the feed line 23, and the first antenna portion 21, the second antenna portion 22a, and the third antenna portion 22b as a whole constitutes a bow tie antenna. The first antenna unit 21 is not necessarily formed in a trapezoidal shape, but has a plurality of branches 21a, 21b, and 21c as shown in FIG. 3, but may be formed in a trapezoidal shape as a whole. The second antenna portion 22a and the third antenna portion 22b can also be formed in various shapes.

The feed line 23 is connected to the center of the short side of the first antenna unit 21 on one surface 20 of the dielectric substrate and formed of a metal conductor to supply voltage to the first antenna unit 21, and the connector connection unit 25. Is formed of a metal conductor spaced apart from the feed line 23 on one surface 20 of the dielectric substrate so as to be connected to a second branch of the second antenna portion 22a and the third antenna portion 22b, and is a coaxial connector. Connected with.

The stub 24 is spaced apart from the second antenna portion 22a and the third antenna portion 22b between the branches of the second antenna portion 22a or the third antenna portion 22b on one surface 20 of the dielectric substrate. And a side of the stub 24 is grounded by being formed of a metal conductor and connected to the connector connection portion 25. The stub 24, which has one side grounded, causes perturbation of the current distribution in the ground to have a finite ground size. This reduces the size of the entire antenna.

The stub 24 is the first stub 24a or the first spaced apart from the second antenna portion 22a formed between the first and second branches of the second antenna portion 22a on one surface 20 of the dielectric substrate. A third stub 24b is formed between the first and second branches of the third antenna portion 22b and is spaced apart from the third antenna portion 22b, and is formed of a second stub 24b that is symmetrically formed on the first stub 24a.

A broadband antenna according to another embodiment of the present invention has the following relationship with FIG. 4A. L1, C1, and R1 correspond to the first to third antenna units 21, 22a, and 22b, and L2, C2, and R2 correspond to the stub 24. Since one side of the stub 24 is grounded, the resonant circuit including L2, C2 and R2 is also grounded. The coupling coefficient M between L1 and L2 in FIG. 4A represents the radial coupling between the first first to third antenna parts 21, 22a, 22b and the stub 36. Resistor R3 represents the resistance of an unshown RF signal source that drives the first through third antenna portions 21, 22a, 22b. R1, on the other hand, represents a non-radiation loss related to electromagnetic energy dissipation due to finite conductivity of the actual conductors of the first to third antenna units 21, 22a and 22b. R2 represents the emission and radiation loss of the stub 24, and R4 represents the radiation loss of the first to third antenna units 21, 22a and 22b.

Referring to FIG. 4B, the interaction between the stub 24 having one side grounded and the first to third antenna units 21, 22a, and 22b will be described.

The stub 24 is affected by the input impedance due to the coupling impedance induced by coupling the stub 24 and the first to third antenna units 21, 22a, and 22b and the perturbation of the current distribution. In addition, antenna matching may be improved due to the above-mentioned perturbation of the coupling impedance or current distribution, and radiation efficiency may be increased. For example, the reactance induced in the antenna through the coupling can offset the initial reactance of the antenna and thus increase the radiation efficiency. As a result, as shown in FIG. 4B, when the coupling occurs between the stub 24 and the first to third antenna units 21, 22a, and 22b, the coupling does not occur because the stub 24 does not exist. It can be seen that the frequency band increases compared to the case where it is not.

The resonance frequency coupled with the stub 24 and the first to third antenna parts 21, 22a, and 22b is within a frequency band radiated by the first to third antenna parts 21, 22a, and 22b. And the length of the stubs 24a and 24b is preferably about 1/4 of the resonance frequency.

The stubs 24a and 24b do not have to have both the first stub 24a and the second stub 24b on one surface 20 of the dielectric substrate, but the first stub 24a and the second stub 24b are not provided. The coupling with the first to third antenna units 21, 22a, and 22b can be more effectively generated, and the frequency band can be further increased. The stub 24 is preferably formed in parallel with the feed line 23.

The broadband antenna according to another embodiment of the present invention is not formed on the other surface of the dielectric substrate, all metal conductor patterns are formed only on one surface 20 of the dielectric substrate, and the first to third antenna portions 21 and 22a. In addition to the stub 24, the size of the entire antenna can be reduced and its structure can be simplified and manufactured at low cost. In addition, due to the coupling between the stub 24 and the first to third antenna units 21, 22a, and 22b, a wider frequency band may be provided.

As a result of simulation of the broadband antenna according to another embodiment of the present invention, it can be seen that the frequency band of 10 dB return loss is 7.0 GHz (33%) at 5.07 GHz. Therefore, the broadband antenna according to another embodiment of the present invention also conforms to the IEEE 802.11a standard that defines the frequency band of a wireless local area network (WLAN), so that the wireless local area network Can be applied to

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

According to the present invention made as described above, it is possible to provide a wideband antenna having a wide frequency band that can be used in a wireless local area network (WLAN), which can be manufactured in a small size and low cost.

Claims (10)

 A first antenna unit formed of a trapezoidal metal conductor on a first surface of the dielectric substrate; A feed line connected to a center of a short side of the first antenna unit on a first surface of the dielectric substrate and formed of a metal conductor to supply a voltage to the first antenna unit; A first connector connection part formed on the first surface of the dielectric substrate, the first connector connecting part being spaced apart from the feed line and formed of a metal conductor on an upper portion or a lower portion of the portion where the feed line ends; The second antenna is formed on the second surface of the dielectric substrate so as not to overlap the first antenna portion with a notch-shaped metal conductor, and the short side of the first antenna portion and the notch-shaped vertex face each other. part; A balun formed of a metal conductor on a second surface of the dielectric substrate so as to be connected to a top of the second antenna unit opposite the feed line; A second connector connection part formed on a second surface of the dielectric substrate, the second connector part being formed of a metal conductor connected to a side not connected to a corner part of the second antenna part of the balun; And And a stub formed on the second side of the dielectric substrate, the metal conductor being connected to the second connector connection portion between the second antenna portion and the balun.  The method of claim 1, The balun is a wideband antenna, characterized in that formed in a taper (taper) shape that becomes narrower toward the top of the second antenna portion.  The method of claim 1, The stub is formed between the upper portion of the second antenna portion and the balun, the upper portion of the second antenna portion and the first stub or the lower portion of the second antenna portion between the balun and the lower portion of the second antenna portion. And a second stub formed to be spaced apart from the balun, respectively, and formed to be symmetrical to the first stub.  The method of claim 1, The stub is a broadband antenna, characterized in that formed in parallel with the feed line.  The method of claim 1, The length of the stub is a broadband antenna, characterized in that 1/4 of the wavelength of the frequency at which the stub is coupled and resonated with the first antenna portion or the second antenna portion.  The method of claim 1, The first connector connecting portion is spaced apart from the feed line and the third connector connecting portion formed on the upper portion of the end of the feed line or spaced apart from the feed line and the third connector connecting portion is formed symmetrically in the lower portion of the end And a fourth connector connection portion.  A first antenna unit formed of a trapezoidal metal conductor on one surface of the dielectric substrate; A feed line connected to a center of a short side of the first antenna unit and formed of a metal conductor to supply a voltage to the first antenna unit; A notch-shaped first branch is formed above the feed line and spaced apart from the first antenna unit and the feed line, and the second branch of the notched shape extends in parallel with the feed line on the feed line and extends into the metal conductor. A second antenna unit formed; The first branch of the notch shape is formed below the feed line and spaced apart from the first antenna portion and the feed line, the second branch of the notch shape is formed in a metal conductor extending in parallel with the feed line in the lower portion of the feed line 3 antenna section; A connector connecting portion formed of a metal conductor to be connected to the second branch of the second antenna portion and the third antenna portion; And Broadband antenna comprising a stub formed of a metal conductor between the branches of the second antenna portion or the third antenna portion, one side is connected to the connector connection portion.  The method of claim 7, wherein The stub is formed between the first and second branches of the first antenna and the second branch of the second antenna portion, or between the first and second branches of the third antenna portion and the third antenna portion. And a second stub which is formed to be spaced apart from the second stub and is symmetrically formed on the first stub.  The method of claim 7, wherein The stub is a broadband antenna, characterized in that formed in parallel with the feed line.  The method of claim 7, wherein The length of the stub is a broadband antenna, characterized in that 1/4 of the wavelength of the frequency at which the stub is coupled and resonated with the first antenna to the third antenna.

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