KR100757090B1 - Multi-band monopole antena - Google Patents

Abstract

A multi-band monopole antenna is provided to obtain omni-direction by not concentrating reflection of electromagnetic waves on a specific direction and to obtain a multi-band characteristic by controlling the length of slits. A multi-band monopole antenna includes a main radiator(11), a feeding unit(14), a parasitic radiator, a ground plane, a first slit(12), a second slit(13), and a third slit. The main radiator(11) and the feeding unit(14) are formed on one side of a substrate(15). The parasitic radiator and the ground plane are formed on the other plane of the substrate(15). The first slit(12) is formed on the main radiator(11). The second slit(13) is I-shaped, and is formed on the main radiator(11). The third slit is I-shaped, and is formed on the parasitic radiator. The ground plane is separated from the parasitic radiator by a predetermined gap.

Description

Multiband Monopole Antenna {MULTI-BAND MONOPOLE ANTENA}

1 illustrates a top and side view of a monopole antenna in accordance with one embodiment of the present invention.

2 is a plan view illustrating a bottom surface of a monopole antenna according to an embodiment of the present invention.

3 is a graph showing a change in return loss characteristic according to the length of the third slit in the monopole antenna according to an embodiment of the present invention.

4 is a graph showing a change in return loss characteristic according to a change in a parameter of a monopole antenna according to an embodiment of the present invention.

5A through 5F are graphs illustrating an antenna radiation pattern according to an embodiment of the present invention.

6 is a graph showing the gain of a monopole antenna according to an embodiment of the present invention.

<Description of Drawing>

11 Main copy 12 First slit

13 2nd slit 14 Feeder

15 substrate 21 parasitic radiant

22 Third slit 23 Ground plane

The present invention relates to a multiband monopole antenna.

With the rapid development of analog and digital communication technology in the world, various kinds of mobile communication services such as cellular, personal communication system (PCS), global system for mobile communication (GSM), personal handy system (PHS) and satellites In Korea, cellular, PCS and CT-2 are commercially available or commercially available. In addition, digital cordless systems (DCS), universal mobile telecommunications systems (UMTS), WiBro and WLAN are currently in use or commercially available.

In addition, SDR (Software Defined Radio) technology is being researched and developed worldwide as a next-generation based technology that can provide solutions for system integration in an era of multi-standard, multi-band, and multi-service. SDR technology can process from baseband to RF / IF signals using reconfigurable components such as high-speed digital signal processing and field programmable gate arrays (FPGAs). In order to construct a system that can be flexibly applied to various wireless mobile communication environments, the SDR technology that enables continuous communication by downloading the object-oriented structure software on an open terminal hardware platform enables various communication systems in the mobile communication market. It is a new system that can simultaneously provide multiple standards, multiple processing frequencies and multiple mobile communication services that unite communication systems.

In particular, SDR technology in the United States began with the need to build a single system that enables continuous communication anywhere, anytime in military operations. The existing communication equipment is capable of communicating by using the military communication infrastructure in the operating frequency band in a specific region, and has a disadvantage in that it cannot receive a command to perform operations when it leaves the service area or the military network is damaged. Therefore, the military needed to develop a system capable of continuous communication and flexibly adapting to changes in communication technology. In the US Department of Defense, SPEAKeasy was launched in 1995 as a system development project that can change service specifications and execute hardware independent operation by changing application programs based on hardware platforms that perform common functions. The investment has expanded and the JTRS project has begun to define object-oriented infrastructure.

  Similarly, in 1994, SDR technology initiatives have been taking place in Europe in various forms. Furthermore, SDR technology is now being considered as a next-generation technology that can provide economic benefits as well as military purposes, which has begun to attract the attention of companies, and research is already underway at universities and various research institutes around the world. Based on this, the SDR communication system is expected to be applicable to not only base stations but also personal portable terminal systems. Therefore, in the antenna field, a multiband antenna suitable for the use of an SDR system has been researched and developed.

 Currently, multiband antennas have various types of bandwidths, such as broadband antennas that can cover all frequencies used by various mobile communication services, reconfigurable antennas using on / off signals such as chip diodes, and antennas using multiple resonances. Multiband antennas are under development.

It is an object of the present invention to provide a multiband monopole antenna that can include the frequency of use of various mobile communication services.

A multi-band monopole antenna according to an aspect of the present invention is a dielectric substrate, a main radiation body formed on one surface of the dielectric substrate and having a Γ-shaped first slit and an I-shaped second slit, and a strip connected to the main radiator. And a parasitic radiator formed on the other surface of the dielectric substrate and having an I-shaped third slit, and a ground plane formed at regular intervals from the parasitic radiator on the other surface of the dielectric substrate.

Embodiments of a multiband monopole antenna according to the present invention may have one or more of the following features. For example, the main and parasitic radiators may be rectangular. The dielectric substrate may be formed by any one of FR-4, epoxy, Duroid, Teflon, bakelite, high resistance silicon, glass, alumina, LTCC and air form. Can be. It is preferable that the ground plane does not overlap with the main radiator.

The main and parasitic radiators are characterized by improving the return loss characteristics in the frequency bands of 0.88-0.96 GHz, 1.71-2.50 GHz, and 5.15-5.85 GHz. The size of the main radiator is 25 mm x 28 mm, the size of the parasitic radiator. May be 17 mm x 23 mm, and the spacing between the parasitic radiator and the ground plane is 2 mm. The width of the feed part may be 3 mm, the length of the first slit may be 45 mm, the length of the second slit may be 16 mm, and the length of the third slit may be 16 mm. In addition, the dielectric substrate may use an FR-4 substrate having a thickness of 1.6 mm and a relative dielectric constant of 4.4.

Hereinafter, an embodiment of a multi-band monopole antenna according to the present invention will be described in detail with reference to the accompanying drawings, and in the following description with reference to the accompanying drawings, the same or corresponding components are given the same reference numerals and duplicated thereto. The description will be omitted.

1 is a plan view and a side view of an antenna according to an embodiment of the present invention, Figure 2 is a rear view thereof.

1 and 2, in a multi-band monopole antenna according to an exemplary embodiment of the present invention, a main radiator 11 and a power feeding unit 14 are formed on one surface of a substrate 15, and a parasitic surface is formed on the other surface of the substrate. The radiator 21 and the ground plane 23 are formed. In the main radiator 11, a first slit 12 having a Γ shape and a second slit 13 having an I shape are formed, and a third slit 22 having an I shape is formed in the parasitic radiator 21. have. In addition, the ground plane 23 is spaced apart from the parasitic radiator 21 by a predetermined interval d.

Multiband monopole antenna according to an embodiment of the present invention having such a configuration can adjust the resonant frequency band of the lowest frequency band by adjusting the length of the first slit 12 having a Γ shape, having an I shape By adjusting the length of the second slit 13, the impedance matching characteristic of the highest frequency band can be obtained. And since the resonance of the intermediate band is added by adjusting the length of the I-shaped third slit 22 formed in the parasitic radiator 21, the antenna according to the present embodiment can obtain the multi-band characteristics. Therefore, the resonance characteristics and the impedance characteristics may be adjusted by adjusting the lengths of the first slit 12, the second slit 13, and the third slit 22.

The dielectric substrate 15 is made of a nonconductive material having a predetermined ε _r and a thickness h. As the dielectric substrate 15, FR-4 which is relatively inexpensive can be used. Of course, the dielectric substrate 15 is not limited thereto, and may be one of epoxy, duroid, Teflon, bakelite, high resistance silicon, glass, alumina, LTCC, and air form. You can choose either one. The dielectric substrate according to the present embodiment used a FR-4 substrate having a size of 35 × 50 (mm), a dielectric constant of 4.4, and a thickness of 1.6 mm.

The main radiator 11 formed on one surface of the dielectric substrate 15 has a longitudinal shape of W _p × L _p size. One side of the main copy member 11 is provided with a power feeding portion 14. In addition, the first slit 12 having a Γ shape formed on the main radiation body 11 extends from one side of the main radiation body 11 along the inside of the main radiation body 11. The first slit 12 is bent twice at an angle of 90 degrees. In addition, the I-shaped second slit 13 extends in a straight line with a constant length S ₁ on one side of the main radiation body 11. By adjusting the length Γ _L of the first slit 12, the resonant frequency band may be adjusted in the 920 MHz band corresponding to the center frequency band of GSM. In the present embodiment, the length Γ _L of the first slit 12 is 45 mm, and the length S ₁ of the second slit is 16 mm.

The power feeding portion 14 has a fine width W _f and extends between the start points of the first slit 12 and the second slit 13 and extends to the end of the substrate 15. By forming the feed section 14 into a micro patch structure having a fine width W _f , it is possible to achieve a lighter weight and a smaller size of the antenna. In the present Example, the width W _f of the power supply part 14 was 3 mm.

The parasitic radiator 21 formed on the back surface of the substrate 15 has an inverted U-shape as a whole with an I-shaped third slit 22 formed on a rectangular conductor. The parasitic radiator 21 has a width W _b and a height L _b . The parasitic radiators 21 are spaced apart from the ground plane 23 by d. By adjusting the length of the third slit 22 of the parasitic radiator 21, resonance having an intermediate band frequency can be added. In this embodiment, the parasitic radiator 21 has a size of 17 × 23 mm.

The ground plane 23 is formed on a part of the bottom surface of the dielectric substrate 15 at regular intervals from the parasitic radiator 21. The ground plane 23 is formed so as not to overlap with the main radiator 11, that is, the main radiator 11 and the ground plane 23 do not overlap when the antenna is viewed from the front. Therefore, electromagnetic waves radiated by the main radiator 11 can be emitted without being shielded by the ground plane 23, thereby obtaining omnidirectional radiation characteristics similar to those of a general monopole antenna.

The dimensions of the antennas discussed above are summarized in Table 1 below. As the dielectric substrate 15, a FR-4 substrate having a size of 35 × 50 (mm), a dielectric constant of 4.4, and a thickness of 1.6 mm was used.

[Table 1] Antenna dimension unit: mm

W _p L _p W _b L _b 25 28 17 23 Γ _L S ₁ S ₂ d 45 16 16 2

3 is a graph showing a measurement of return loss for each frequency according to the change in length of the third slit 22 having an I shape of the parasitic radiator 21.

Here, the reflection loss refers to the loss caused by the reflection of the power input to the input terminal and represents the value of the reflection coefficient S11 in dB. Return loss is used as an indicator of how well the impedance matching at the input stage is done. Referring to FIG. 3, when the length of the third slit 22 is changed from 12 mm to 16 mm by 2 mm intervals, the reflection loss characteristic of the multi-band monopole antenna according to the exemplary embodiment of the present invention is shown. It can be seen that by changing the length of the third slit 22, resonance is formed at 2.1 GHz, thereby improving bandwidth characteristics in the reference 1.7 to 2.5 GHz band with a return loss of -10 dB or less. In particular, when the length of the third slit 22 is formed to 16 mm, it can be seen that the reflection loss is reduced the most in the 1.7 to 2.5 GHz band, thereby improving impedance matching.

Figure 4 is a graph showing the measurement of the return loss for each frequency with or without each configuration in a multi-band monopole antenna according to an embodiment of the present invention.

4 shows the frequency range for each communication system. That is, GSM (0.88 ~ 0.96GHz) corresponding to low frequency band, DCS (1.71 ~ 1.88GHz), UMTS (1.91 ~ 2.17GHz), WiBro (2.30 ~ 2.39GHz) and 2.4GHz WLAN 2.40 ~ 2.50) is indicated on the x-axis. In addition, 5.2 / 5.8 GHz WLAN (5.15 to 5.85 GHz) corresponding to the high frequency band is displayed.

As can be seen in FIG. 4, in the case of a monopole antenna having a simple rectangular patch (dotted line display), the impedance matching characteristic is not good because the return loss is large except for 2.6 to 2.9 GHz based on -10 dB. Can be. However, in the case of an antenna having only a main radiator 11 having a Γ-shaped first slit 12 and an I-shaped second slit 13 on one surface of the dielectric substrate 15 (dotted dotted line), a simple square Compared to the monopole antenna, the return loss is reduced in the low frequency band of 0.86-0.98 GHz and the high frequency band of 4.72 GHz to 6.61 GHz, thereby improving impedance matching characteristics. In the case of the antenna according to the present embodiment (solid line display), the reflection loss is reduced in the low frequency band 0.86-0.98 GHz, the intermediate frequency band 1.7-2.6 GHz, and the high frequency band 4.72 GHz to 6.61 GHz, thereby improving impedance matching characteristics. It can be seen that. Therefore, multi-resonant and multi-band monopole antennas can be obtained by forming the first radiator 11 having the first slit 12 and the second slit 13, and the parasitic radiator 21 having the third slit 22. have.

5A to 5F are diagrams illustrating radiation patterns according to frequencies of antennas according to an embodiment of the present invention. 5A-5F, the dotted line represents the E (x-z) plane and the solid line represents the H (x-y) plane.

Referring to FIG. 5A, it can be seen that the multi-band monopole antenna according to an embodiment of the present invention exhibits omnidirectional characteristics similar to a general monopole antenna at 0.92 GHz, which is the center frequency of GSM.

Referring to FIG. 5B, the multi-band monopole antenna according to the embodiment of the present invention exhibits omnidirectional characteristics at 1.80 GHz, which is the center frequency of the DCS.

Referring to FIG. 5C, the multi-band monopole antenna according to an embodiment of the present invention exhibits omnidirectional characteristics at 2.05 GHz, which is the center frequency of UMTS.

Referring to FIG. 5D, the multi-band monopole antenna according to an embodiment of the present invention exhibits omnidirectional characteristics at 2.33 GHz, which is the center frequency of WiBro.

Referring to FIG. 5E, the multi-band monopole antenna according to an embodiment of the present invention exhibits omnidirectional characteristics at 2.45 GHz, which is a center frequency of a 2.4 GHz WLAN.

Referring to FIG. 5F, a multiband monopole antenna according to an embodiment of the present invention exhibits omnidirectional characteristics at 5.50 GHz, which is a center frequency of 5.2 / 5.8 GHZ WLAN.

Accordingly, as can be seen through FIGS. 5A to 5F, the multi-band monopole antenna according to the embodiment of the present invention has a low frequency band of 0.88-0.96 GHz, an intermediate frequency band of 1.71-2.50 GHz, and a high frequency of 5.15-5.85 GHz. It can be seen that it exhibits omnidirectional similarity to the monopole antenna with respect to the band.

6 is a graph illustrating a measurement of gain with respect to the frequency of an antenna according to an embodiment of the present invention.

Here, the gain is an index indicating how much the reflection shape is concentrated in a specific direction compared to an isotropic antenna in which electromagnetic waves are reflected in all directions. Referring to FIG. 6, in the low frequency band of 0.88-0.96 GHz corresponding to the frequency band of GSM, the gain of the antenna has a gain change of 1.13 dBi from 0.47 dBi to 1.54 dBi. In the intermediate frequency band of 1.70 to 2.50 GHz, corresponding to the frequency bands of DCS, UMTS, WiBro, and 2.4 GHz WLAN, the maximum gain is 2.01 dBi, which has a gain variation characteristic of less than 1.02 dBi. In addition, in the high frequency band of 4.72 to 6.61 GHz, which corresponds to the frequency band of 5.2 / 5.8 GHz, the maximum gain is 3.74 dBi and has a gain change characteristic of about 1.76 dBi.

Therefore, in the multi-band monopole antenna according to the embodiment of the present invention, reflection of electromagnetic waves is not concentrated in a specific direction in the low frequency band of 0.88-0.96 GHz, the intermediate frequency band of 1.71-2.50 GHz, and the high frequency band of 5.15-5.85 GHz. It can be seen that it exhibits omnidirectional similar to the monopole antenna.

Although the embodiments of the present invention have been described above, various changes and modifications of the present invention should also be construed as falling within the scope of the present invention as long as the technical idea of the present invention is realized.

The present invention can provide a multi-band monopole antenna that can include the frequency of use of various mobile communication services.

Claims (14)

A dielectric substrate; A main radiator formed on one surface of the dielectric substrate and having a first slit having a Γ shape and a second slit having an I shape; A feed unit having a strip shape connected to the main copy body; A parasitic radiator formed on the other surface of the dielectric substrate and having a third slit of an I shape; And a ground plane formed at a predetermined distance from the parasitic radiator on the other side of the dielectric substrate. The method of claim 1, The main radiator and the parasitic radiator are rectangular. The method of claim 1, The dielectric substrate is a multi-band monopole antenna, characterized in that the FR-4 substrate. The method of claim 1, The dielectric substrate is any one of epoxy, duroid, Teflon, bakelite, high resistance silicon, glass, alumina, LTCC, and air form. antenna. The method of claim 1, And the ground plane does not overlap the main radiation body. The method of claim 1, The main radiator and the parasitic radiator are characterized in that the return loss characteristic is improved in the frequency band of 0.88 ~ 0.96 GHz, 1.71 ~ 2.50 GHz, and 5.15 ~ 5.85 GHz. The method of claim 6, Multi-band monopole antenna, characterized in that the size of the main radiator is 25mm × 28mm. The method of claim 6, The parasitic radiator has a size of 17 mm × 23 mm multi-band monopole antenna. The method of claim 6, And the spacing between the parasitic radiator and the ground plane is 2 mm. The method of claim 6, The width of the feed portion is a multi-band monopole antenna, characterized in that 3mm. The method of claim 6, The length of the first slit is a multi-band monopole antenna, characterized in that 45mm. The method of claim 6, The length of the second slit is a multi-band monopole antenna, characterized in that 16mm. The method of claim 6, The length of the third slit is a multi-band monopole antenna, characterized in that 16mm. The method of claim 6, The dielectric substrate is a multi-band monopole antenna, characterized in that the FR-4 substrate having a thickness of 1.6mm and a dielectric constant of 4.4.

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