KR20080045831A - Micromini multi band antenna - Google Patents

Abstract

A micromini multi band antenna is provided to generate various resonance frequencies by controlling the resonance frequencies based on inductance of first and second connection units and capacitance of a third connection unit. A micromini multi band antenna(1) includes two or more radiation units(20). The radiation units supply zero order resonance. The radiation unit includes a zero order resonance circuit(114) and a radiator(111). The zero order resonance circuit is formed by a zero order resonance circuit operation principle. The radiator is connected to both ends of the zero order resonance circuit. The zero order resonance circuit includes a first transmission line(115), a second transmission line(116), and first to third connection units(117-119). The first connection unit is connected between the radiator and the first transmission line in series and has inductance. The second connection unit is connected between the radiator and the second transmission line in series and has inductance. The third connection unit is connected between the first transmission line and the second transmission line in series and has capacitance.

Description

Micromini multi band antenna

1 is a diagram showing the radiation characteristics of a conventional antenna.

2 is a view showing the structure of an antenna using a zero-order resonant circuit in accordance with the present invention.

Figure 3 shows the radiation characteristics of the antenna according to the invention.

The present invention relates to an antenna capable of frequency adjustment, and more particularly to an ultra-small multi-band antenna that implements multi-band using a metamaterial structure.

An antenna is an essential component of a wireless communication device for transmitting / receiving electromagnetic waves, and is configured to resonate with electromagnetic waves of a specific frequency and to transmit / receive electromagnetic waves of that frequency. Resonance generally means that the impedance of the circuit is imaginary at a specific frequency, and in practice, refers to a phenomenon in which the S11 parameter, which is the reflection coefficient of the circuit, decreases rapidly at a specific frequency.

Conventional antennas have a resonant structure in primary mode. That is, the conventional antenna has an electrical length of λ / 2 with respect to the wavelength λ corresponding to the desired frequency and is composed of a conductor (transmission line) having one end open or shorted. As a result, electromagnetic waves guided along the conductive wire form standing waves in the conductive wire, and resonance occurs. The antenna having such a first mode resonant structure is determined by the electrical length of the antenna entirely dependent on the resonant frequency, so that the size of the antenna changes according to the resonant frequency, and in particular, the antenna becomes larger as the desired resonant frequency is lowered.

In order to solve this disadvantage, a monopole antenna having an electrical length of λ / 4 has been proposed by forming an antenna on a ground plane, and in order to further reduce the size of the monopole antenna, a complex such as a helix shape and a meander shape are proposed. An antenna having a shape has been proposed. However, the proposed antennas still do not escape the limit of size depending on the resonant frequency, and as the antenna becomes smaller, its shape becomes more complicated to form a fixed length antenna in a narrow space. In addition, as the shape of the antenna becomes more complicated, there is a difficulty in maintaining the performance of the antenna, such as the influence of coupling between the conductors formed increases.

In addition, a method of increasing the effective electrical length of an antenna by adding a dielectric having a high dielectric constant has been proposed, but this is undesirable because it requires additional costs for manufacturing and adding a dielectric constant.

Applicant of the present invention found that the metamaterial theory can be used to solve the above-mentioned problems of the prior art, and the patent application No. 10-2006-0084866 "Ultra-small multi-band antenna using metamaterial" and patent application No. 10-2006-0091526 filed "An antenna capable of adjusting the resonant frequency using a metamaterial and a device including the same". The contents of these applications are included herein.

Metamaterial refers to a material or electromagnetic structure that is artificially designed to have special electromagnetic properties that are not generally found in nature. In general, and in this specification, metamaterial refers to a dielectric material ( By negative permittivity and permeability both negative materials or electromagnetic structures.

Such materials are also called Double Negative (DGN) materials in the sense of having two negative parameters. In addition, metamaterials have a negative reflection coefficient due to their negative dielectric constant and permeability, and thus are also called NRI (Negative Refractive Index) materials. Metamaterial was first studied by Soviet physicist V. Veselago in 1967, but more than 30 years later, a concrete implementation method has been studied and application has been attempted.

Due to the above characteristics, in the metamaterial, electromagnetic waves are transmitted by the left hand law rather than following Fleming's right hand law. That is, the phase propagation direction (phase velocity direction) and the energy propagation direction (group velocity direction) of the electromagnetic wave are reversed, and the signal passing through the metamaterial has a negative phase delay. Accordingly, metamaterials are sometimes referred to as left-handed materials (LHMs). In addition, in the metamaterial, the relationship between β (phase constant) and ω (frequency) is nonlinear, and its characteristic curve is also present on the left half of the coordinate plane. Due to such nonlinear characteristics, the metamaterial has a small phase difference according to frequency, so that a wideband circuit can be realized. Since the phase change is not proportional to the length of the transmission line, a small circuit can be realized.

It is possible to implement a zero order resonator (ZOR) using this metamaterial. An example of a zero-order resonator implementation using metamaterials is disclosed in U.S. Application No. 11 / 092,143 to Itoh et al. Unlike the conventional resonant structure, the zero order resonator has a resonant frequency determined regardless of the electrical length of the resonant structure. The zero order resonator has substantially the same resonant structure as the LC resonant circuit, so that the inductance and capacitance of the inductor and capacitor included in the circuit determine the resonant frequency. Therefore, the resonant frequency can be changed by adjusting the inductance and capacitance, and the size of the antenna does not increase even if the resonant frequency is lowered.

However, referring to the antenna shown in FIG. 1 of Patent Application No. 10-2006-0084866 "Subminiature Multi-Band Antenna Using Metamaterial" patented by the present applicant, the antenna is implemented using a zero-order resonant circuit. While there is an advantage that can be made very small regardless of frequency, there is a problem that the bandwidth is narrow, it is difficult to have a multi-band structure.

That is, as shown in Figure 1, when using a conventional antenna, there is no method for producing a micro-antenna that causes zero-order resonance at the same time in the reception band of GPS and Bluetooth. Therefore, a user has to give up transmission and reception of any one band and have a problem of communicating using only one specific band frequency.

The present invention devised to solve the above problems is to provide an antenna structure capable of resonating in multiple bands in a micro-antenna using a metamaterial structure.

The present invention for achieving the above object is a multi-band antenna comprising two or more radiators, the radiator provides a micro multi-band antenna that provides zero-order resonance.

The radiating unit may include: a 0th order resonant circuit constituting a 0th order resonant circuit by the 0th order resonant circuit operation principle; It includes a radiator connected to both ends of the zero-order resonant circuit.

Preferably, the zero-order resonant circuit comprises: a first transmission line; A second transmission line; A first connection portion connected in series between the radiator and the first transmission line and having an inductance; A second connection portion connected in series between the radiator and the second transmission line and having an inductance; And a third connection portion connected in series between the first transmission line and the second transmission line and having capacitance.

The present invention also provides a wireless communication device including the ultra-small multi-band antenna.

In order to fully understand the present invention, the advantages of the operability of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

2 is a view showing the structure of an antenna using a zero-order resonant circuit according to the present invention.

Referring to FIG. 2, the antenna 1 according to the present invention includes a feed coaxial line 10 that transmits a feed signal, a first radiator 20 that provides a first resonance frequency, and a second resonance frequency. The second radiating part 30 and the ground plane 40 are included.

In more detail, a feed portion 11 is formed at a portion where the feed coaxial line 10, the first radiating portion 20, and the second radiating portion 30 are electrically connected to each other. The radiator 111 of the first radiator 20 and the second radiator 30 is configured, and a zero-order resonant circuit 114 is configured at the end of the radiator 111. First and second connection parts 117 and 118 connected to the radiator 111 are provided at both ends of the zeroth order resonant circuit 114, and a third connection part 119 is formed at the center of the zeroth order resonant circuit 114. exist. The zero-order resonant circuit 114 includes a first transmission line 115, a second transmission line 116, and first and second connection portions 117 and 118 with the third connection portion 119 as the center. do. The first and second connectors 117 and 118 may have a structure having an inductor element or an inductance component, and the third connector 119 may have a structure having a capacitor element or a capacitance.

Since the antenna 1 according to the present invention uses the zero-order resonant circuit 114, a non-resonant (zero-order) resonant circuit may be configured as described above, and the resonant frequency f1 of the low frequency band in the zero-order resonant circuit is described. ) Is formed. The low frequency band resonant frequency f1 in the antenna 1 according to the present invention is formed only by the structure of the zero-order resonant circuit 114, and is independent of the length of the radiator 111, and thus is dependent on the physical length of the antenna. It is possible to realize a miniature antenna that can resonate in a desired frequency band regardless. In particular, since the resonance frequency of the antenna is adjusted by the inductor value of the first and second connectors 117 and 118 or the capacitor value of the third connector 119, various resonance frequencies may be generated using the same antenna structure. have.

In particular, in the case of the present invention, by connecting a plurality of radiating portions in parallel, by adjusting the frequency of the zero-order resonant in each of the deflector, it is possible to cause zero-order resonance in the multiple frequency band at the same time. That is, although two radiators are shown in FIG. 2, two or more radiators may be connected in parallel to generate zero-order resonance in multiple bands.

On the other hand, since radiation is not performed in the zero-order resonant circuit, even if additional resonant circuits are arranged adjacently, the resonant frequency does not change significantly. By using this property, independent adjustment of each resonant frequency is possible. For example, the inductor has a value of 71 nH for GPS and 29 nH for Bluetooth, but 68 nH and 30 nH may be used for the multi-band antenna of the present invention, respectively. That is, since the plurality of zero-order resonant circuits 114 do not interfere with each other, the resonant frequency may be adjusted by using an inductor or a capacitor having substantially the same value as when a single zero-order resonant circuit 114 is formed.

Since not only the resonance frequency but also the radiation gain do not significantly affect each other, as shown in FIG. 2, it is possible to easily implement a multi-band antenna by connecting the respective resonance antennas in parallel.

Broadband characteristics can also be easily achieved by adjusting each resonant frequency to adjacent frequencies.

3 is a diagram showing the radiation characteristics of the antenna according to the present invention.

Referring to FIG. 3, unlike the conventional FIG. 1, since a single antenna may be used to simultaneously generate resonance in a GPS band and a Bluetooth band, an ultra-small multi-band antenna may be implemented. The application field of the antenna is not limited thereto, but the low frequency band resonant frequency f1 operates at the T-DMB, and the high frequency band resonant frequency f2 can be variously adjusted, such as L-band and mobile communication band, as necessary. Because of this, the field of application is very wide.

Meanwhile, as described above, when two or more radiators of the present invention are used in combination, a micro multi-band antenna resonating in two or more multi bands may be implemented.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. . Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

The present invention provides an antenna structure capable of resonating in multiple bands in a micro-antenna using a metamaterial structure.

Claims (4)

A multiband antenna comprising two or more radiators, Wherein said radiating portion provides zero order resonance. The method of claim 1, The radiating part, A zeroth order resonant circuit constituting a zeroth order resonant circuit by the zeroth order resonant circuit operation principle; Ultra small multi-band antenna including a radiator connected to both ends of the zero-order resonant circuit. The method of claim 2, The zero-order resonant circuit, A first transmission line; A second transmission line; A first connection portion connected in series between the radiator and the first transmission line and having an inductance; A second connection portion connected in series between the radiator and the second transmission line and having an inductance; And And a third connection portion connected in series between said first transmission line and said second transmission line and having capacitance. 4. A wireless communication device comprising the micro multiband antenna of any one of claims 1 to 3.

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