KR101674139B1

KR101674139B1 - Broadband circularly polarized antenna using c-shaped slot

Info

Publication number: KR101674139B1
Application number: KR1020150124412A
Authority: KR
Inventors: 황금철; 권지나; 송찬미; 윤종헌; 윤주호; 이종민
Original assignee: 성균관대학교산학협력단
Priority date: 2015-09-02
Filing date: 2015-09-02
Publication date: 2016-11-08

Abstract

The present invention relates to a broadband circularly polarized antenna using a C-shaped slot, and more particularly, to a broadband circularly polarized antenna using a C-shaped slot, more particularly, a dielectric substrate, a ground plane formed on the dielectric substrate, a C-shaped slot formed on the ground plane, And a dielectric resonator formed on the ground plane so as to cover the slot, the dielectric resonator having a columnar structure having a speedron fractal shape as a bottom surface, and a wideband circular polarization The present invention relates to a broadband circularly polarized antenna using a C-shaped slot capable of realizing the characteristics of a circularly polarized antenna.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a broadband circular polarized antenna using a C-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadband circularly polarized antenna using a C-shaped slot, and more particularly, to a dielectric resonator of a speedrone fractal column structure and an antenna using a C-shaped slot.

An antenna is a conductor installed in the air for efficiently radiating electromagnetic waves to a space in order to achieve a communication purpose in wireless communication or for efficiently inducing an electromotive force by radio waves and for transmitting or receiving an electromagnetic wave to / to be.

Among these antennas, the microstrip patch antenna has characteristics of small size, light weight and thin shape, and can be mass-produced because it is easy to manufacture and is used in various communication fields.

However, since a microstrip patch antenna has a disadvantage of having a narrow impedance bandwidth of about 1 to 2%, it is difficult to realize a broadband circularly polarized antenna using such a microstrip patch element.

In contrast, a dielectric resonator antenna (hereinafter referred to as DRA) has advantages in that it can be realized with a wide bandwidth, ease of fabrication, simple structure, and small size as compared with the microstrip patch antenna, And thus it is widely utilized in the field of modern wireless communication systems because it has high efficiency and no surface wave caused by a conductor.

Circular polarization, on the other hand, has been actively studied for circularly polarized DRA because it mitigates multipath fading problem and is strong in communication environment where polarization distortion is a concern.

However, in the conventional circular polarization DRA design technique, when the circularly polarized wave is induced by using the single power feeding method, the axial ratio bandwidth is narrow to 3 to 4%, and when the dual feeding method is used, the axial ratio bandwidth is widened. However, It is accompanied by a drawback that it becomes somewhat complicated.

Therefore, it is necessary to develop a broadband circularly polarized antenna having a simple structure required in a modern wireless communication system while maintaining the advantages of a DRA antenna.

Korean Patent No. 10-0944968 entitled "Broadband circularly polarized antenna of speedron fractal structure" (published Mar. 3, 2010)

In order to solve the above problems, the present invention provides a dielectric resonator having a C-shaped slot formed on a ground plane and a Speedron fractal three-dimensional dielectric resonator placed on a ground plane to cover the slot, As well.

According to an aspect of the present invention, there is provided a broadband circularly polarized antenna using a C-shaped slot, including a dielectric substrate, a ground plane formed on the dielectric substrate, a C-shaped slot formed on the ground plane, A microstrip line formed on a lower surface of the dielectric substrate and serving as a feed line, and a dielectric resonator formed on the ground plane to cover the slot, the dielectric resonator having a columnar structure having a speedron fractal shape as a bottom surface .

The speedron fractal shape according to an embodiment of the present invention is formed by successively connecting right triangles having the same size of the first interior angle and a constant reduction ratio.

Also, the size of the first internal angle according to an embodiment of the present invention is 25 ° to 35 °.

The C-shaped slot according to an embodiment of the present invention is formed so as to be covered by a first right-angled triangular portion of a columnar dielectric resonator having the bottom surface of the Speedron fractal shape.

Also, the resonance frequency is reduced as the radius of the C-shaped slot increases according to an embodiment of the present invention.

Further, the radius of the C-shaped slot according to an embodiment of the present invention is determined by a size of the first internal angle, a height of the first right triangle, and a position of a center point of the C-shaped slot with respect to the dielectric resonator as fixed variables And a radius of the C-shaped slot is a variable, and is determined as a value when a frequency bandwidth representing a circular polarization characteristic is the maximum.

Also, the size of the first internal angle according to an embodiment of the present invention is 30 degrees, and the radius (r) of the C-shaped slot and the height (m ₁ ) of the first right triangle constituting the Speedron fractal shape And the ratio (r / m ₁ ) is 4.2 / 30 to 5.0 / 30.

At this time, the ratio (r / m ₁ ) is most preferably 4.6 / 30.

The present invention can realize broadband circular polarization characteristics while maintaining characteristics such as high efficiency and miniaturization due to the absence of surface current and conductor loss, which are advantages of DRA.

In addition, a broadband circularly polarized antenna can be realized without using a multilayer substrate to realize a wide band characteristic.

In addition, the characteristics of broadband circular polarization and reflection coefficient can be secured by using a simple power feeding method.

In addition, the present invention can be applied to various radio communication fields as a wideband circularly polarized antenna.

1 is a view for explaining a shape of a speedron fractal applied in the present invention.
2 is a perspective view of a wideband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention.
3 is a plan view of a broadband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention.
4 is a side view of a broadband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention.
5 is a photograph of a broadband circularly polarized antenna using a C-shaped slot manufactured based on the numerical values in Table 1.
FIG. 6 is a graph showing a simulation result for representing a reflection coefficient characteristic according to a size of a first internal angle? Of a broadband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention.
FIG. 7 is a graph showing a simulation result for representing an axial ratio characteristic according to a size of a first internal angle? Of a broadband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention.
FIG. 8 is a graph showing simulation results to show reflection coefficient characteristics according to a radius length of a C-shaped slot of a wideband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention.
FIG. 9 is a graph showing simulation results to show axial ratio characteristics according to a radius length of a C-shaped slot of a wide band circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention.
FIG. 10 is a diagram illustrating a wideband circularly polarized antenna using a C-shaped slot coupled with a dielectric resonator of a C-shaped slot and a Speedrone fractal column structure according to an embodiment of the present invention, an antenna having a C-shaped slot and a square- FIG. 7 is a graph showing a simulation result for comparing the reflection coefficient characteristics of FIG.
FIG. 11 is a graph showing a relationship between a broadband circularly polarized antenna using a C-shaped slot combined with a dielectric resonator having a C-shaped slot and a Speedron fractal column structure according to an embodiment of the present invention, an antenna having a C- In the graph of FIG.
12 is a graph comparing measured and simulated reflection coefficients of a wideband circular polarized antenna using a C-shaped slot according to an embodiment of the present invention.
FIG. 13 is a graph comparing simulation results with axial ratio and gain measurement results of a wideband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention.
FIG. 14 is a diagram illustrating a radiation pattern (a) at 5.25 GHz and a radiation pattern (b) at 5.55 GHz according to simulation and measurement results of a broadband circular polarization antenna using a C-shaped slot according to an embodiment of the present invention .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate a person skilled in the art to easily carry out the technical idea of the present invention. . In the drawings, the same reference numerals are used to designate the same or similar components throughout the drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining a shape of a speedron fractal applied in the present invention. Referring to FIG. 1, a fractal structure is a structure in which a certain unit shape is repeatedly bent repeatedly infinitely, and the fractal structure has properties of self-similarity and recursiveness.

On the other hand, a spidron is a geometrical structure in which isosceles triangles are mutually alternately joined to each other. In the antenna of the present invention, as shown in Iteration 1 of FIG. 1, an isosceles triangle having a base angle of? By connecting isosceles triangles whose base is γ, the result is a right triangle with two interior angles α and γ.

Here, a right triangle shown in Iteration 1 of FIG. 1 for forming a speedron fractal shape is defined as a first right triangle 10, and the first right triangle 10 has an isosceles Triangle and an isosceles triangle whose base angle is γ.

The first right triangle 10 has two interior angles formed on both sides with respect to the hypotenuse. An angle formed by the height of the first right triangle 10 and the hypotenuse is defined as the angle of the first right triangle 10 Is defined as a first internal angle alpha and an angle formed by the bottom surface of the first right triangle 10 and the hypotenuse is defined as a second internal angle? Of the first right triangle 10.

In order to form the speedrone fractal shape, a side constituting a part of the hypotenuse of the first right-angled triangle 10 among the two sides having the same length of the isosceles triangle having the base angle? In the first right-angled triangle 10 is set as a base An isosceles triangle having a base angle of? And an isosceles triangle having a base angle of? Are connected alternately to each other. As a result, a second right triangle 11 having two inner angles? And? Is connected to the first right triangle 10.

That is, the speedron fractal shape is formed by successively connecting right triangles having the same size of the first interior angle and a constant reduction ratio.

In the above manner, the speedrone fractal shape may be formed by sequentially combining the first right-angled triangle 10 to the n-th right-angled triangle, and each right-angled triangle may have a reduced scale or a length .

The speedron fractal shape shown in Iteration 3 of FIG. 1 is formed by successively connecting first right-angled triangles 10 to third right-angled triangles whose scales are reduced to a certain scale.

The speedron fractal shape shown in Iteration 7 of FIG. 1 is formed by successively connecting first right-angled triangles 10 to seventh right-angled triangles whose scales are reduced to a certain scale.

As a result, it is preferable that the speedron fractal shape is formed so that the reduction ratio of the right triangle constituting the speedron fractal shape is constant, and the right triangle of the same shape is formed by repeatedly joining at least twice .

1, the first internal angle of the right triangle is 30 degrees and the second internal angle is 60 degrees. In this case, the reduction ratio of the connected right triangle satisfies Equation 1 below.

[Equation 1]

(Where P _n is the height of the nth right triangle and P _n ₊₁ is the height of the (n + 1) th right triangle)

FIG. 2 is a perspective view of a broadband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention, FIG. 3 is a plan view of a broadband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention, 4 is a side view of a broadband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention.

Referring to the drawings, a broadband circular polarized antenna using a C-shaped slot according to the present invention has a ground plane 21 formed on a top surface of a dielectric substrate 24, Shaped slot (hereinafter referred to as " C-shaped slot ").

The C-shaped slot 22 may have a predetermined width W ₁ and may have a predetermined angle β with a predetermined radius r with respect to a center point. The C-shaped slot 22 may have a predetermined width W ₁ , Corresponds to the length from the center to the position including the width of the C-shaped slot 22.

On the lower surface of the dielectric substrate 24, a microstrip line 25 having a length L _s and a width W ₂ for performing a function as a feed line may be formed. The microstrip line 25 may preferably be a 50 OMEGA microstrip line.

The microstrip line 25 is preferably formed to penetrate a line extending vertically at a center point of the C-shaped slot 22, but is not limited thereto.

Here, the dielectric substrate 24 may be, for example, a RF-35 substrate or a PCB substrate such as glass epoxy (FR-4). In addition, a conventional dielectric substrate 24 known in the art may be used.

In addition, an SMA connector 23 may be attached to one side of the dielectric substrate 24 and connected to the microstrip line 25 and the ground plane 21.

The broadband circularly polarized antenna according to an embodiment of the present invention includes a columnar dielectric resonator 100 formed on the ground plane 21 so as to cover the C- .

The dielectric resonator 100 is formed on a ground plane 21 of a dielectric substrate 24 having a width of g _w and a height of g _h and a height of h and is formed on the ground plane 21 of the first variable resonator 100, the height of a right triangle (10), and m ₁ may have a pillar structure in which the speed Rhone fractal shape of size α of the first cabinet to the base. The dielectric resonator 100 preferably has a dielectric constant of 10 or more.

The bottom surface and the top surface of the dielectric resonator 100 are in the form of a speedron fractal as described above and a point at which the vertices of the first right triangle 10 and the second right triangle 11 meet is defined as the origin (0,0) The center point position of the C-shaped slot 22 with respect to the dielectric resonator 100 can be expressed by coordinates (a, b).

At this time, the C-shaped slot 22 is preferably formed to be covered by the first right-angled triangle 10 constituting the speedron fractal shape of the dielectric resonator 100.

Hereinafter, a broadband circularly polarized antenna using a C-shaped slot according to the present invention will be described in detail with reference to embodiments of the present invention. However, these examples are for illustrative purposes only, and the scope of the present invention is not limited to these examples.

Parameter Value m ₁ 30 mm d 7 mm alpha 30 ° g _h 40 mm g _w 40 mm h 1.52 mm w _l 1 mm r 4.6 mm beta 23 ° (a, b) (10.4 mm, -3.4 mm) w ₂ 3.3 mm L _s 14.5 mm

For each variable shown in FIG. 2 to FIG. 4 and so on, for the fixed variable excluding some variable, the simulation was performed by applying the values in Table 1 above.

5 is a photograph of a broadband circularly polarized antenna using a C-shaped slot manufactured based on the numerical values in Table 1. Here, the dielectric substrate 24 uses an RF-35 substrate having a dielectric constant of 3.5 and a rust tangent of 0.0018, and the dielectric resonator 100 has a dielectric constant of 10.

FIG. 6 is a graph showing a simulation result to show a reflection coefficient characteristic according to the size of a first internal angle? Of a broadband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention. FIG. 5 is a graph showing a simulation result for representing an axial ratio characteristic according to a size of a first internal angle? Of a wideband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention.

In order to be able to operate as an antenna, it is preferable that the reflection coefficient is less than -10 dB, and when it exceeds -10 dB, the performance of the antenna is generally lowered. The antenna can be seen to exhibit circular polarization characteristics when the axial ratio is less than 3 dB in the frequency band where the reflection coefficient is less than -10 dB.

As shown in the figure, the reflection coefficient and the axial ratio change as the size of the first internal angle α changes. When the first internal angle α is 25 °, the reflection coefficient and the axial ratio change within the reflection coefficient bandwidth of -10 dB or less Single-band circular polarization occurs and its frequency band is around 5.4 GHz.

When the first internal angle alpha is 35 DEG, circularly polarized waves occur in two bands within a reflection coefficient bandwidth of -10 dB or less. As the size of the first internal angle alpha increases, the two bands exhibiting the axial ratio characteristics of 3 dB or less tend to move away from each other. When the first internal angle alpha is 30 degrees, the frequency bandwidth Was found to be the widest.

FIG. 8 is a graph showing a simulation result to show reflection coefficient characteristics according to a radius length of a C-shaped slot of a broadband circularly polarized antenna using a C-shaped slot according to an embodiment of the present invention. FIG. FIG. 5 is a graph illustrating simulation results for illustrating axial characteristics according to radius lengths of a C-shaped slot of a wideband circularly polarized antenna using a C-shaped slot according to an embodiment. FIG.

As can be seen, as the radius of the C-shaped slot 22 increases, the resonance frequency of the antenna tends to be lowered.

As shown, when the length of the radius of the C-shaped slot 22 changes, the reflection coefficient and the axial ratio change. When the radius of the C-shaped slot 22 is 4.2 mm, An axial ratio of less than 3 dB in the counting band occurs near both the 4.8 GHz and 5.7 GHz bands.

As the radius of the C-shaped slot 22 increases, the axial ratio ratios of the two 3 dB or less tend to approach each other. When the radius of the C-shaped slot 22 is 4.6 mm, the axial ratio bandwidth of 3 dB or less is the widest Respectively.

As described above, the above simulation is for determining the optimal radius of the C-shaped slot 22 exhibiting the maximum wideband circular polarization characteristic. Specifically, the radius of the C-shaped slot 22 is determined by the size of the first internal angle, The height of the right triangle 10 and the position of the center point of the C-shaped slot 22 with respect to the dielectric resonator 100 are fixed variables and the radius of the C-shaped slot 22 is changed as a variable A value less than 3 dB in the reflection coefficient bandwidth of -10 dB or less can be determined as the value when the axial ratio bandwidth is maximum.

The ratio of the radius r of the C-shaped slot 22 to the height m ₁ of the first right-angled triangle 10 constituting the speedrons fractal shape r / m ₁ ) is preferably from 4.2 / 30 to 5.0 / 30, and the ratio (r / m ₁ ) is most preferably 4.6 / 30.

FIG. 10 is a diagram illustrating a wideband circularly polarized antenna using a C-shaped slot coupled with a dielectric resonator of a C-shaped slot and a Speedrone fractal column structure according to an embodiment of the present invention, an antenna having a C-shaped slot and a square- FIG. 7 is a graph showing a simulation result for comparing the reflection coefficient characteristics of FIG.

FIG. 11 is a graph showing a relationship between a broadband circularly polarized antenna using a C-shaped slot combined with a dielectric resonator having a C-shaped slot and a Speedron fractal column structure according to an embodiment of the present invention, an antenna having a C- In the graph of FIG.

As shown in the figure, a broadband circularly polarized antenna using a C-shaped slot in which a C-shaped slot 22 according to an embodiment of the present invention is coupled with a dielectric resonator of a Speedron fractal column structure has a bandwidth And that the bandwidth representing the axial ratio of 3 dB or less is wider than that of the C-shaped slot 22 and the square-column dielectric resonator.

This can further improve the bandwidth that exhibits a reflection coefficient of less than -10 dB and an axial ratio of less than 3 dB, that is, a bandwidth that exhibits a circular polarization characteristic, as compared with a dielectric resonator of a pillar-type columnar structure. .

12 is a graph comparing measured and simulated reflection coefficients of a broadband circularly polarized antenna according to an embodiment of the present invention. As shown, the measured bandwidth of the reflection coefficient of less than -10 dB was 4.32-6.30 GHz (37.29%), and the simulation result was 4.25-6.09 GHz (35.59%). As a result, Are significantly coincident with each other.

FIG. 13 is a graph comparing simulation results with measurement results of the axial ratio and gain of a wideband circularly polarized antenna according to an embodiment of the present invention. As shown, the measured axial bandwidth of less than 3 dB is 5.13-5.76 GHz (11.57%), and the simulation result is 4.98-5.73 GHz (14.01%). The gain within the axial bandwidth of less than 3 dB was measured from 2.20 dBic to 3.16 dBic, and the measurement results and the simulation results are generally in agreement.

FIG. 14 is a graph showing a simulation result at a frequency of 5.25 GHz and a radiation pattern (a) according to a measurement result, a simulation pattern at 5.55 GHz and a radiation pattern according to a measurement result b).

Referring to FIG. 14, it can be seen that the measurement results and the simulation results are substantially in agreement, and the broadband circularly polarized antenna using the C-shaped slot according to the embodiment of the present invention has a + z axis direction (LHCP) antenna with directivity characteristics, and the difference between the left polarization (LHCP) and the postal wave (RHCP) in the + z axis direction (θ = 0 °) is more than 17 dB. It can be confirmed that it is implemented.

It has been confirmed that the antenna according to the above embodiment is applicable to the 5.2 GHz WLAN application, and it can be utilized in various wireless communication fields by adjusting the physical size of the antenna.

As described above, an optimal embodiment has been disclosed in the drawings and specification. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

10: first right triangle
11: second right triangle
21: Ground plane
22: C-shaped slot
23: SMA connector
24: dielectric substrate
25: Microstrip line
100: dielectric resonator

Claims

A dielectric substrate;
A ground plane formed on an upper surface of the dielectric substrate;
A C-shaped slot formed on the ground plane;
A microstrip line formed on a lower surface of the dielectric substrate and serving as a feed line; And
And a dielectric resonator formed on the ground plane so as to cover the slot, the pole resonator having a columnar structure having a speedron fractal shape as a bottom surface.

The method according to claim 1,
Wherein the fastron fractal shape is formed by sequentially connecting right triangles having the same size of the first internal angle and a constant reduction ratio.

3. The method of claim 2,
Wherein the first internal angle is between 25 ° and 35 °.

3. The method of claim 2,
Wherein the C-shaped slot is formed so as to be covered by a first right-angled triangular portion of a columnar dielectric resonator having the bottom surface of the Speedron fractal shape.

3. The method of claim 2,
And the resonance frequency is lowered as the radius of the C-shaped slot increases.

5. The method of claim 4,
The radius of the C-
The first right angled triangle, the C-shaped slot, and the center point of the dielectric resonator,
Wherein a radius of the C-shaped slot is a variable, and a value of a frequency bandwidth showing a circular polarization characteristic is determined as a maximum value.

3. The method of claim 2,
The size of the first internal angle is 30 [deg.],
Wherein the ratio (r / m ₁ ) of the radius (r) of the C-shaped slot to the height (m ₁ ) of the first right-angled triangle constituting the speedrone fractal shape is 4.2 / 30 to 5.0 / Broadband circularly polarized antenna using slot.

8. The method of claim 7,
Wherein the ratio (r / m ₁ ) is 4.6 / 30.