KR20020019711A - Microstrip EMC cross dipole array wide-band antenna with circular polar ization - Google Patents

Abstract

PURPOSE: An electromagnetic coupled cross dipole array broadband circularly polarized wave antenna is provided to increase the bandwidth of frequency by employing a feeding microstrip line and an electromagnetic coupled cross dipole array device. CONSTITUTION: A substrate(10) has a ground surface(11) on a bottom and a dielectric constant(εr1). A T-junction microstrip line(21) having a plurality of rows is formed on the substrate(10) and branches into both sides(21b,21c) at a feeding point(21a). A dipole substrate(40) is formed on the microstrip line(21) and has a dielectric constant(εr2) different to the dielectric constant(εr1). A plurality of cross dipoles(30) having a plurality of rows are formed on the microstrip line(21) of the dipole substrate(40) and have a specific offset to each other.

Description

Microstrip EMC cross dipole array wide-band antenna with circular polarization

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetically coupled cross dipole array wideband circular polarization antenna, and more particularly, to an electromagnetically coupled cross dipole array having a wideband circular polarization characteristic. It relates to a polarized antenna.

With the rapid increase in mobile communication and satellite broadcasting using satellites, microstrip antennas are widely used as antennas in many wireless communication systems.

The conventional parabolic antenna for satellite broadcasting has a disadvantage that it is relatively affected by the external environment such as snow, rain, and wind, and thus, the planar antenna is being actively researched as an alternative.

The planar antenna consists of radiating elements, feeder nets, and active element circuits for high performance functions such as beam steering.

Radiating elements are generally arranged in quadrangular, circular, elliptical, etc. arrangements by waveguide slots.

As the feeding method, a coaxial or microstrip feeding method and a waveguide feeding method are used.

In the feeding method, linear polarization, circular polarization, elliptic polarization and inclined linear polarization can be performed according to the desired polarization characteristics and arrangement.

Among them, in the case of circular polarization, there are many printed antenna elements having circular polarization characteristics. However, when the microstrip is used, there is a big problem of having a narrow bandwidth at a high frequency band.

The present invention is to solve the above drawbacks, and to provide an electromagnetically coupled cross dipole array broadband circular polarization antenna having broadband circular polarization characteristics.

This invention is achieved by constructing and arraying a feed microstrip line and an electromagnetically coupled cross dipole radiation element to obtain broadband characteristics.

In order to achieve the above object, the present invention includes a substrate having a ground plane on the bottom surface and having a specific dielectric constant (ε _r1 ); A microstrip line formed on the substrate for feeding; It is characterized by consisting of a cross dipole placed on the microstripline, and formed on a cross substrate having another specific dielectric constant (ε _r2 ).

In still another aspect of the present invention, there is provided a substrate comprising: a substrate having a ground plane on a bottom surface and having a specific dielectric constant ε _r1 ; A plurality of T-junction microstrip lines formed on the substrate and branching from both sides of the feed point and the feed point; A dipole substrate having another specific dielectric constant lying on said microstrip line; The technical feature is that it consists of a plurality of rows of cross dipoles formed at positions on the plurality of rows of microstrip lines on the dipole substrate and having a specific offset from each other.

Figure 1a is an electromagnetic coupled cross dipole array broadband circular polarization of the present invention

Top view representing antenna,

1B is a broadband circular polarization of an electromagnetically coupled cross dipole array of the present invention.

Side view showing an antenna,

2 illustrates an electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention.

Indicating perspective,

3 shows the reflection and transmission characteristics calculated with the parameters given in Table 1;

graph,

4 is an electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention.

Graph showing calculated radiation pattern at frequency 12 GHz,

5 is an electromagnetic coupled cross dipole array broadband circular polarization antenna of the present invention.

Graph showing reflection and transmission characteristics according to offset change,

6 is an electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention.

A graph showing the radiant power as the offset changes,

7 illustrates an electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention.

A planar array of ten dipole elements,

8 is an electromagnetic coupled cross dipole array broadband circular polarization antenna of the present invention.

A graph showing the radiation pattern for a 10-element array,

9 shows an electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention.

Top view showing a T-junction microstrip line,

10 is an electromagnetic coupled cross dipole array broadband circular polarization antenna of the present invention.

Graph showing the reflection and transmission characteristics of the tee-junction power splitter

11 is an electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention.

Exploded perspective view showing a 20 element array of

12 is an electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention.

Reflection and transmission characteristics when the distance d between the elements is 8.0 mm

graph,

Figure 13 is an electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention.

The radiation pattern of Ex and Ey components with the change of the distance d between devices

Graphing,

14 is an electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention.

Shows gain over frequency in array of 10 elements and 20 elements

graph.

<Explanation of symbols for the main parts of the drawings>

10 substrate 11 ground plane

20 microstrip line 21 tee-junction microstrip line

30: Electromagnetic Coupling (EMC) Cross Dipole

40: dipole substrate

An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1A and 1B are a plan view and a side view, respectively, of an electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention, and FIG. 2 is a perspective view of an electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention. A substrate 10 having a ground plane 11 on the surface and having a specific dielectric constant ε _r1 ; A microstrip line 20 formed on the substrate 10 for feeding; It is characterized by consisting of a cross dipole 30 which is placed on the microstrip line 20 and formed on the cross substrate 31 having another specific dielectric constant ε _r2 .

That is, a microstrip line 20 for feeding and an electromagnetic coupled cross dipole 30 for generating circular polarization with a dielectric interposed therebetween are configured.

The cross dipole 30 is positioned in an X shape with respect to the microstrip line 20, and the center of the cross dipole 30 is positioned at a predetermined offset with the center of the microstrip line 20. This is to ensure that the radio waves coming in and out of the antenna have a uniform current distribution.

Design parameters include the dipole length DL, the width DW, the angle A, the spacing DH between the feed microstrip line 20 and the cross dipole 30, the relative dielectric constant ε _r2 , and the like.

The design center frequency was 12 GHz, which is the frequency band for satellite broadcasting of Mugunghwa satellite.

The design parameters of the feed microstrip line 20 are fixed at the center frequency of 12 GHz for the width SW, the thickness SH of the substrate 10, and the dielectric constant ε _r1 so that the radiant power _exhibits optimal characteristics. Is used as a constant in the calculation for the design.

Calculation result

Figure 3 shows the reflection and transmission characteristics by the calculation results of the commercial software Ensemble and the FDTD method to which the moment method when calculating by applying the design parameters.

As shown in FIG. 3, the maximum radiation power is shown at 12 GHz, and the reflection characteristic is less than -20 dB in a wide frequency band, thereby satisfying the broadband characteristics.

The radiated powers calculated by Ensemble and FDTD method at 12 GHz were similar with 14.44% and 15.72% respectively.

4 is a diagram showing Ex and Ey components of a radiation pattern calculated by a given design parameter, and shows excellent circular polarization characteristics at a wide angle, and also shows that the cross polarization level in the front direction is about -58 dB. .

Characteristic change by offset

In the array of antennas, the spacing between the elements for adjusting the direction of propagation of the radio waves (d: FIG. 7) and the radiant power of each element to obtain a uniform current distribution of each antenna should be considered.

First, in order to make constant the radiated power radiated from each element (cross dipole: 30), the radiated power of the element near the input port of the feed microstrip line 20 is made smaller and the radiated power is gradually increased to minimize the reflection. Design so that uniform power is radiated.

To do this, it is common to investigate the characteristics of the devices while changing the dielectric constant (ε _r2 ), the height (DH), and the angle (A) of the dipole.

However, since the dielectric constant ε _r2 , the height, the angle of the cross dipole 30, and the like change, respectively, it is difficult to manufacture, the parameters of the feed microstrip line 20 remain constant in the present invention. The offset with respect to the center of the cross dipole 30 was changed, and the design which considered the ease of manufacture fully was performed.

5 and 6 show reflection and transmission characteristics and radiation power according to the change of the offset. When the cross dipole 30 is located at the center of the microstrip line 20, the radiation power is maximized to 14.44%, and the radiation power decreases gradually when it is moved to the left and right.

Therefore, when an array of radiation elements is to be arrayed, the efficiency of the antenna may be maximized by adjusting to generate uniform radiation power for each element by using the offset data of FIG. 6.

Design of Array Antenna

(10 element array)

7 is a plan view of 10 dipole arrays of the electromagnetically coupled cross dipole array broadband circular polarization antenna of the present invention, the substrate having a ground plane at the bottom and a specific dielectric constant ε _r1 ; A microstrip line 20 formed on the substrate for feeding; It is characterized by consisting of a plurality of cross dipoles 30 which are placed on the microstrip line 20, are formed on a substrate having a different specific dielectric constant ε _r2 , and are arranged at a predetermined offset from each other.

In the array antenna, the offset result of FIG. 6 is applied to generate uniform radiant power in each device.

In FIG. 7, d denotes an interval between elements (cross dipole 30), and offsets are arranged in a zigzag manner symmetrically from the input side to reduce mutual coupling between elements.

The offset value is the value when the design has about 6% radiation power for each device.

8 shows radiation patterns of Ex and Ey components calculated at the time of 10 element arrays. It can be seen that the Ex component and the Ey component of the main beam are almost identical, and thus the circular polarization is radiated. Also, the direction of the main beam is shifted by the change of the interval d between the elements.

When the distance d was 8.0 mm, the beam was facing in the front direction, and when d was changed by ± 0.5 mm, the direction of the main beam moved by about ± 8 °. Due to the mutual coupling between the elements, it can be seen that the direction of the beam is directed to the front when the distance d between the elements is 8.0 mm which is slightly smaller than λ _g / 2.

Feeding structure

In order to design a 20-element array antenna, as shown in FIG. 9, a T-junction was applied because the input wave input from port 1 should be divided by -3 dB into port 2 and port 3. A quarter-wave matching transformer was used to match each port to 50 Ω.

FIG. 10 shows the reflection and transmission characteristics of a T-junction power splitter with a quarter-wave matching transformer.

Frequency bands with a reflection coefficient of less than -20 dB range from 10.77 to 12.72 GHz with a bandwidth of about 2 GHz and S21 and S31 at -12.13 dB and -3.18 dB at 12 GHz, respectively. have.

20-element array

Fig. 11 is a perspective view showing the structure of an antenna in which 20 EMC cross dipole elements are arranged with a dielectric interposed over the designed microstrip tee-junction power splitter feed line, having a ground plane 11 at the bottom and a specific dielectric. A substrate 10 having a constant ε _r1 ; A plurality of T-junction microstrip lines 21 formed on the substrate and branching from a feed point 21a to both sides 21b and 21c at the feed point 21a; A dipole substrate (40) having another specific dielectric constant lying on the microstrip line (21); It is composed of a plurality of rows of cross dipoles 30 formed at positions on the plurality of rows of microstrip lines 21 on the dipole substrate 40 and having a specific offset from each other.

The feed point 21a may be preferably fed at intervals of 1 / 4λ at both ends of the terminal.

12 shows the reflection and transmission characteristics of a 20-element array antenna when the distance d between the elements is 8.0 mm. At 12 GHz, radiated power was calculated to be about 73%.

FIG. 13 shows the radiation pattern of Ex and Ey components according to the change of the interval d between devices.

As in the 10-element array antenna described above, it can be seen that the direction of the beam changes as d changes. However, when d = 8.0 mm, the angle with 3 dB beam width is -18 ° to 20 ° and the axis ratio is about 1 dB, which shows excellent circular polarization characteristics.

14 shows the calculated gains of the 10- and 20-element array antennas. The gains of the 10- and 20-element array antennas at 12 GHz are 2.3 dB, 7.6 dBi and 9.9 dBi, respectively, with peak values at 12 GHz, and the gains are gradually decreasing as the frequency changes.

As described above, the present invention is designed and arrayed by an antenna composed of a feed microstrip line and an electromagnetically coupled cross dipole radiation element in order to obtain broadband and excellent circular polarization characteristics. The invention has an effect of gain of 7.6 dBi and 9.9 dBi at the design frequency of 12 GHz, respectively.

Claims (7)

A substrate having a ground plane on the bottom surface and having a specific dielectric constant ε _r1 ; A microstrip line formed on the substrate for feeding; And an electromagnetic coupling cross dipole array wideband circular polarization antenna disposed on the microstripline and formed on a cross substrate having a different dielectric constant (ε _r2 ). The wideband circular polarization antenna of claim 1, wherein the center of the cross dipole is positioned at a predetermined offset from the center of the microstrip line. A substrate having a ground plane on the bottom surface and having a specific dielectric constant ε _r1 ; A microstrip line formed on the substrate for feeding; Electromagnetically coupled cross dipole array broadband circle, characterized in that it consists of a plurality of cross dipoles placed on the microstripline, formed on a substrate having a different specific dielectric constant (ε _r2 ) and arranged at a predetermined offset from each other. Polarized antennas. A substrate having a ground plane on the bottom surface and having a specific dielectric constant ε _r1 ; A plurality of T-junction microstrip lines formed on the substrate and branching from both sides of the feed point and the feed point; A dipole substrate having another specific dielectric constant lying on said microstrip line; And a plurality of cross dipoles having a specific offset from each other and formed at positions on a plurality of rows of microstrip lines on the dipole substrate. 5. The wideband circular polarization of the electromagnetic coupling cross dipole array according to claim 4, wherein the feed point uses a quarter-wave matching transformer having a quarter wavelength and having a thickness of two stages. antenna. 5. The broadband circular polarization antenna of claim 4, wherein the spacing between the tee junction microstrip lines branching to both sides is formed to match the wavelength of the input wave. 5. The broadband circular polarization antenna of claim 4, wherein the feed point feeds at intervals of 1/4 lambda at a terminal end of the antenna.