KR101727489B1 - An orthogonally polarized negative resonance crlh patch antenna - Google Patents

Abstract

The present invention relates to a new shaped pully-printed microstrip antenna having negative resonance and dual polarization, capable of realizing miniaturization. According to the present invention, a radiator is printed on a single layer substrate instead of a multilayer substrate. The negative resonance is resulted from a (composite right- and left-handed) CRLH structure of an interlock gap with a shape surrounded by a patch having a shorted ring while being capacitively coupled with the patch. According to the present invention, the antenna generates two orthogonal linearly polarized waves from one body including a coaxial power supply part to have a dual polarized wave characteristic. Moreover, the antenna is designed while being compared with a measurement result of a prototype antenna made by using a full-wave electromagnetic (EM) field simulation. Moreover, the antenna exhibits a gain of 4 dBi and efficiency of 78% in the negative resonance mode as an intermediate frequency of a downlink channel with a bandwidth of 200 MHz or higher having polarized wave isolation of 29 dB.

Description

[0001] The present invention relates to an orthogonal polarized negative resonance CRLH patch antenna,

The present invention relates to a CRLH patch antenna, and relates to an antenna having orthogonal polarizations and negative resonance characteristics.

Antennas in power generation in wireless communication systems are an indispensable constituent. In transmitting and receiving an RF signal, an antenna is an important factor that determines the quality of the overall communication. Among various types of antennas, microstrip antennas are widely used because they are inexpensive to fabricate together with a monopole antenna. Since the microstrip patch antenna was first introduced as a broadside radiation pattern due to half-wave resonance, its basic structure has been changed to a triangle or a circle in square form to satisfy band, beam pattern, gain, polarity, In the form of slots or loads, multiple stacks, coaxial feeds, line connections to apeture coupling.

Numerous methods are being developed to achieve multi-band, specific polarization, direction, miniaturization and weight reduction to meet the demand in communication channels, polarization, radiation angle, physical size, These technologies tend to be grouped recently due to the demands and issues in the wireless communications industry. For example, in the field of internal antennas for handset devices, the emitter on the substrate must have more than a single resonant path for multiple bands and must be fabricated with a mendering structure for miniaturization. As another example, in order to develop various functions in a wireless connection between transceivers, it is required that the antenna structure has the property of multiple polarizations. On the other hand, it is not desirable to have such a polarization characteristic and to have a large size. Therefore, the antenna should not be formed of a plurality of independent radiator structures but should be formed as a single body. There are two attempts to minimize the size of the antenna. Despite such efforts, however, the effect was negligible and there was a limit to reducing the size of the antenna. Because they rely on half-wavelength resonance in the frequency band of interest.

In recent years, metamaterials and their modified structures have been used as a solution to antenna enhancement and miniaturization. Among them, the structure based on CRLH (Composite Right- and Left-Handed) is composed of the phase lead of LH (left-handed) and the phase of RH (right-handed) due to non-linear dispersive curves Order resonance (ZOR) and negative resonance characteristics generated as a result of the sum of delays. The negative resonance and the ZOR are key to antenna miniaturization. Conventionally, mushroom array (Array of Mushroom), CSRR (Complimentary Split Ring Resonator) and the like have been used for achieving this purpose. However, an antenna using such a meta-material has only one polarization.

When an antenna is applied to the configuration of a repeater, a satellite communication, a base-station antenna, etc. in order to have RH half-wave resonance or metamaterial resonance, it will be required to have dual-polarization characteristics. To design an antenna with dual polarization characteristics to meet the demand for miniaturization, two different polarizations must be generated in a single emitter. Conventionally, there are several techniques related to dual-polarized microstrip patch antennas, but most of them use multilayers, which has the problem of increasing the volume of the antenna.

Disclosure of Invention Technical Problem [8] The present invention has been made in order to solve the problems of the related art as described above, and the radiator of the antenna is fabricated on a single- A composite right-and-left-handed (CRLH) structure of a circumferentially interlock gap is used while capacitively coupling to a patch having a shorted-ring so as to have a short- And to provide an orthogonally polarized negative resonant CRLH patch antenna that produces two linear polarized waves orthogonal to each other in a single body having coaxial feeds so as to have dual polarization characteristics do.

According to an aspect of the present invention, there is provided an orthogonally polarized negative resonant CRLH patch antenna,

Board; A radiator disposed on the substrate and including a CRLH (Composite Right-and-Left-Handed) structure; A first power feeder installed at a lower portion of the radiator; And a second feeding part provided coaxially with the first feeding part at a lower part of the radiator, wherein the CRLH structure is formed by a plurality of concave and convex shapes including an interlock gap, And may be capacitively coupled to the radiator as a structure.

In addition, the substrate may be a 1-layer substrate.

In addition, the radiator and the CRLH structure are each square, and the CRLH structure may be included in the radiator upper surface.

The interlock gap may be 2 mm.

In addition, the radiator may include eight vias at the center and corners of each plane, and the radius of each via may be 0.5 mm.

The first feeder and the second feeder are spaced apart from each other at a right angle from the center of the radiator, and the polarizations generated by the first feeder and the second feeder may be orthogonal to each other.

The distance between the first feeding part and the second feeding part may be 5 mm from the center of the radiator.

By using a single body having one coaxial feeding part, the present invention can be miniaturized as compared with a conventional case in which feeding parts are provided in each layer using multi-layers.

(CRLH) structure of a circumferentially interlock gap while capacitively coupling to a patch having a shorted-ring. It is possible to fabricate a high performance and high efficiency antenna by using two orthogonal linear polarizations in one body having resonance of a coaxial feeder and coaxial feeders.

The antenna according to the present invention exhibited 5 dBi gain and 78% efficiency in the negative resonance mode at the intermediate frequency of the downlink channel of bandwidth above 20 MHz with 29 dB polarization isolation.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Figure 1 shows a single polarized CRLH patch antenna.
Figure 2 shows the parameters of a single polarization CRLH patch antenna, -1 ^st resonance and ZOR phenomenon.
Figure 3 shows the associated measurements for a dual polarized CRLH patch antenna.
Figure 4 shows the fabricated dual polarization CRLH patch antenna and associated measurements.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments will be described in detail below with reference to the accompanying drawings.

The following examples are provided to aid in a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, this is merely an example and the present invention is not limited thereto.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intention or custom of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification. The terms used in the detailed description are intended only to describe embodiments of the invention and should in no way be limiting. Unless specifically stated otherwise, the singular form of a term includes plural forms of meaning. In this description, the expressions "comprising" or "comprising" are intended to indicate certain features, numbers, steps, operations, elements, parts or combinations thereof, Should not be construed to preclude the presence or possibility of other features, numbers, steps, operations, elements, portions or combinations thereof.

It is also to be understood that the terms first, second, etc. may be used to describe various components, but the components are not limited by the terms, and the terms may be used to distinguish one component from another .

Hereinafter, exemplary embodiments of an orthogonally polarized negative resonant CRLH patch antenna according to the present invention will be described in detail with reference to the accompanying drawings.

- CRLH antenna with negative resonant mode characteristics

Figure 1 shows a single polarized CRLH patch antenna. More specifically, FIG. 1 (a) is a top view of an antenna, and FIG. 1 (b) is a side view of an antenna.

The microstrip antenna of FIG. 1 is intended to have negative resonance and ZOR (zero order resonance) characteristics, which capacitively couples to a patch having a shorted-ring, ) Is a composite right- and left-handed (CRLH) structure by an interlock gap. 1 (a) and 1 (b), the antenna according to the present invention has a coaxial feed and a single-layer substrate for a low-profile structure . Unlike the traditional half-wavelengths based on antennas with feed lines and multilayer structures for single or dual polarization characteristics, the -1st resonant mode of the antenna according to the invention is used to generate linear polarization and broadside radiation patterns Will be selected. Although ZOR produces a monopole radiation pattern that is irrelevant to the purposes of the present invention, it is necessary in the design process. This is because the -1st resonance in the CRLH antenna according to the present invention involves ZOR. In order to fabricate an antenna applicable to base-station components or the like having a smaller size and low-profile advantage, the volume of the radiator for one of the bands in the range of 1.7 GHz to 2.5 GHz is 5 x 5 x 1 cm ³ or less. In the 2.37 GHz band with a bandwidth of 40 MHz or more, it has a gain of 3dBi or more and efficiency of 70% or more. This means that the -1 st resonance mode should be generated at 2.37 GHz. The antenna design according to the present invention is performed through the following parameter study to overcome the problem of low gain and low efficiency in negative resonance at the opportunity cost of ZOR and positive resonance relaxation.

Figure 2 shows the parameters of a single polarization CRLH patch antenna, -1 ^st resonance and ZOR phenomenon. More specifically, FIG. 2 (a) shows S ₁₁ according to the change of i_l. FIG. 2 (c) shows S ₁₁ as the number of fingers changes from 8 vias. 2 (d) and 2 (e) show S ₁₁ according to a target band. FIG. 2 (f) shows an E-field and a monopole beam pattern at ZOR. FIG. 2 (g) shows the E-field and broadside beam patterns in the -1 ^st resonance mode.

Each of the parameter sweeps in FIG. 2 is a structure performed for an equivalent CRLH circuit including a capacitor and an inductor to generate negative resonance and ZOR (a CR of 0.35 pF from the center patch and an LR of 31.80 nH, A CL of 0.06 pF by a capacitive gap, and a LL of 11.5 nH by a shorted ring. The gap is a circumferentially symmetrical interlocked structure (n_f pairs of fingers on each of the four sides, and the length of each finger is i_l). This is for balance between miniaturization and orthogonal polarization and is formed with 3.5 x 3.5 x 0.317 cm ³ of vias of the structure on a substrate with Er = 2.2 to have negative resonance characteristics at 1.85 GHz. In Fig. 2 (a), n_f = 3, i_l changes from 0.8 mm to 2 mm, and as CL increases, the negative resonance frequency and the ZOR frequency change downward and this tendency is changed from n_f to 3 4 vias and i_l = 2 in Fig. 2 (b). In Fig. 2 (c), the other parameter sweep shows that the change in negative resonance characteristics, which occurs when n_f changes from 3 to 5 and i_l = 2 mm and 8 vias, is the most desirable Do. Therefore, as can be seen from Figs. 2 (d) and 2 (e) measured under the condition of 8 vias with n_f = 5, i_l = 2 mm, r_w = 1.8 mm and v_dia = 0.5 mm, the center frequency and bandwidth are 2.37 GHz and 40 MHz. In FIG. 2 (f) a ZOR characteristic with an in-phase E-field in the structure and a monopolar far-field pattern in the structure is disclosed, below which FIG. 2 (g) A negative resonance mode characteristic of a miniaturized antenna with electric field characteristics such as a broadside beam pattern and a +1 ^st resonance is disclosed. The antenna has a gain of 3.9 dBi or more, an efficiency of 75% or more, and a linear polarization characteristic.

The effect of reducing the antenna size in the method according to the present invention is not the same as that of the unit cell in the ZOR antenna including the periodic unit cell and the negative resonance structure according to the present invention is not smaller than the RH half wavelength, It is of the order of magnitude necessary to generate dual polarization characteristics. The single polarization corresponds to the x-axis of the Cartesian coordinate system in Fig.

-One ^st  Dual Polarized Antenna with Resonant Characteristics

Hereinafter, a negative resonant CRLH microstrip antenna having dual polarization characteristics is designed and its characteristics are measured. First, the design is performed by an EM field simulator.

Figure 3 shows a dual polarized CRLH patch antenna and associated measurements. More specifically, Fig. 3 (a) is a top view of a three-dimensional structure. Fig. 3 (b) shows the relationship between f2_d and the -1 ^st resonance mode. Fig. 3 (c) and Fig. 4 (d) show S ₁₁ and S ₂₁ in the -1 ^st resonance mode. Figs. 3 (e) and 3 (f) show the excitation at the first feeding part for the x-axis polarized wave and the second feeding part for the y-axis polarized wave, respectively (E-field and beam pattern) .

In order to make the above-mentioned negative resonant antenna have orthogonal polarization characteristics, the structure needs two feeds, as can be seen in Fig. 3 (a). The first feeding portion (port 1) and the second feeding portion (port 2) generate polarized waves in the x-axis direction and the y-axis direction, respectively. According to the test of Fig. 3 (b), the two feed portions should be located at offset points 5 mm away from the center of the antenna. S ₁₁ and S ₂₂ are defined as the return loss of the first feeder and the second feeder, respectively. The isolation between polarizations is defined as S ₂₁ and S ₁₂ . Figure 3 (c) and (d) from the -1 ^st-mode resonance frequency is a first feeding part and a lower than -10dB in both the second feeding part | S ₁₁ | And | S ₂₂ |. In addition, the orthogonal polarization has an isolation of 30 dB or more. As shown in FIG. 3 (e), when the antenna is fed from the first feeder, the LH half-wavelength field is generated along the x-axis, the gain in the x-axis direction is more than 3dBi, ≪ / RTI > In Fig. 3 (f), the mirror effect in the y-axis direction can be confirmed by the second feeding part.

Figure 4 shows the fabricated dual polarization CRLH patch antenna and associated measurements. More specifically, Fig. 4 (a) is a photograph of a front portion and a rear portion of the manufactured antenna. 4 (b) and 4 (c) show S ₁₁ and S ₂₁ in the -1 ^st resonance mode. 4 (d) and 4 (e) show the excitation at the first feeding part for generating the x-axis polarized wave and the second feeding part for generating the y-axis polarized wave, respectively (E-field and beam pattern).

Fig. 4 (a) is a photograph of the manufactured double resonance resonant antenna. For fabrication, the SMA connector used in the fabrication of the first feeder and the second feeder is attached to the backside of the substrate, and Taconic TLY-5 is used as a single layer substrate (Er = 2.2 and 0.317 cm thick). As shown in FIGS. 4 (b) and 4 (c), the fabricated antenna exhibits a return loss of less than -10 dB and a polarization isolation of 25 dB or more, Almost the same result, but there is a difference in that the negative resonance characteristic is increased by 0.5 GHz and the bandwidth is widened to 35 MHz. This is due to technical deficiencies such as soldering, precise alignment failure, and errors in the material itself. However, although the EM field simulation result is slightly different, the frequency band of the antenna can be applied to a downlink channel of 1.7 GHz to 2.5 GHz. Radiation characteristic of the antenna (radiation characteristic) is -1 is measured at a resonance frequency of the ^st sound, the resonant frequency of the -1 ^st Well are each 2.37GHz and 2.36GHz in the first feeding portion and second feeding portion. The maximum gain and efficiency of the antenna can be achieved by more than 4 dBi (5 dBi) and 75% (78%), respectively. The radiation pattern has a broadside characteristic as a design for the polarized wave in the x-axis direction (Fig. 4 (d)) and the y-axis direction polarized wave (Fig. 4 (e)). This represents dual polarization from a single body of a negative resonant CRLH antenna with a single layer structure.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, . Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the scope of the appended claims, as well as the appended claims.

Claims (7)

Board;
A radiator disposed on the substrate and including a CRLH (Composite Right-and-Left-Handed) structure;
A coaxial first power feeder installed below the radiator;
And a coaxial secondary power feeder disposed at a lower portion of the radiator at a predetermined distance from the first power feeder,
Wherein the CRLH structure is capacitively coupled to the radiator in a structure surrounded by a repeating surface having irregularities including interlock gaps. ≪ RTI ID = 0.0 > 11. < / RTI >
The method according to claim 1,
Wherein the substrate is a single-layer (1-layer) substrate.
The method according to claim 1,
The radiator and the CRLH structure are each square,
Wherein the CRLH structure is included in the upper surface of the radiator.
The method according to claim 1,
Wherein the interlock gap is determined according to the design and is between 0.8 mm and 2 mm.
The method according to claim 1,
Wherein the radiator includes respective vias at the center and corners of each plane. ≪ RTI ID = 0.0 > 11. < / RTI >
The method according to claim 1,
Wherein the first feeder and the second feeder are spaced from each other at a right angle from the center of the radiator,
Wherein the polarized waves generated by the first and second feeders are orthogonal to each other.
The method according to claim 6,
Wherein the spacing distance between the first feeding part and the second feeding part from the center of the radiator is determined according to the design and is 5 mm each, and the orthogonally polarized negative resonant CRLH patch antenna.

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