KR101657871B1 - A planar type antenna apparatus for beamspace mimo system - Google Patents

Abstract

The antenna apparatus for a beam-space MIMO system according to the present invention includes a feed unit for supplying an RF signal, a reactance control unit for controlling a reactance value, an active unit connected to the feed unit through a feed point, An antenna element, at least one parasitic antenna element pair whose reactance value is controlled by a reactance controller, and a substrate on which a pair of active antenna elements and parasitic antenna elements are formed.
The antenna device for the beam-space MIMO system according to the present invention can obtain MIMO-level performance by using fewer RF stages than a conventional MIMO system by securing a plurality of radiation patterns with less interference within a limited space, It is possible to provide an antenna device capable of achieving miniaturization of the communication device.

Description

TECHNICAL FIELD [0001] The present invention relates to a planar antenna apparatus for a beam-space MIMO system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device, and more particularly, to an antenna device that secures a plurality of radiation patterns within a limited space to obtain a MIMO level performance with only a single RF circuit.

In general, a communication system based on a voice communication service uses a single input single output (SISO) system using only a single antenna element in narrow frequency band characteristics within a limited frequency range. However, a SISO system using a single antenna has a narrow band There was a great deal of difficulty in transmitting large amounts of data at high speed within a channel. Thus, a MIMO (Multiple Input Multiple Output) technique has emerged as a next generation wireless transmission technology that enables the data transmission / reception ratio to be transmitted with a lower error probability by independently driving each antenna using a plurality of antennas.

However, the MIMO technique that improves the data rate using a general array antenna increases the complexity of the hardware and increases the power consumption when the antenna is extended to improve the data rate. This is why it is difficult to expand the MIMO system considering the limited size and power consumption requirements of the mobile terminal.

Accordingly, a beam space MIMO (Beamspace MIMO) technique using an electronically steerable passive array radiator (ESPAR) has appeared. This is achieved by using an ESPAR antenna having a parasitic element disposed around an active element, This is to overcome the limitation of the system. In the conventional MIMO system, the data symbols are mapped to the respective antennas using the array antennas, so that the number of the antennas is increased to further increase the data rate, thereby mapping more data symbols. As the number of antennas increases, the system complexity increases greatly. On the other hand, in the case of the beam-space MIMO system, in order to increase the data transmission rate, the number of active elements connected to the RF stage is increased while the number of parasitic elements is increased while the number of parasitic elements is increased. The number of data symbols can be increased and the more data symbols can be mapped to more orthogonal basis patterns. Therefore, the system complexity problem can be greatly improved as compared with the conventional MIMO system because only one RF stage is used even if the device is extended to improve the data rate.

However, the beam-space MIMO system in which the disadvantages of the existing MIMO system are improved is implemented using a wire antenna having a three-dimensional structure such as a monopole antenna or a dipole antenna, and thus it is difficult to downsize it.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide MIMO-class performance with fewer RF stages than existing MIMO systems by securing a plurality of radiation patterns with less interference within a limited space, And it is an object of the present invention to provide an antenna device capable of realizing low power and achieving miniaturization of a communication device.

According to an aspect of the present invention, there is provided an antenna apparatus for a beam-space MIMO system, including a feeder for supplying an RF signal, a reactance controller for controlling a reactance value, And a substrate on which a pair of parasitic antenna elements and a pair of parasitic antenna elements are formed, the pair of parasitic antenna elements having reactance values controlled by a reactance controller, and a substrate on which a pair of parasitic antenna elements are formed .

In addition, in the antenna apparatus for a beam-space MIMO system according to an embodiment of the present invention, the active antenna element adjusts a radiation pattern in a direction perpendicular to the substrate, and the pair of parasitic antenna elements radiate in a direction And the at least one pair of parasitic antenna elements may be formed symmetrically with respect to each other around the active antenna element, the active antenna element and the parasitic antenna element may have a flat plate shape, and the active antenna element and the parasitic antenna element The active antenna element and the parasitic antenna element may be formed by opening a part of the upper surface or the lower surface of the substrate, and the active antenna element and the parasitic antenna element may be formed on the upper surface or the lower surface of the substrate, A round microstrip Antenna may be a (microstrip patch antenna), may be at least one of the parasitic antenna elements of each of the parasitic antenna element pair is "L" shaped slot antenna type (slot antenna).

The technique disclosed in the present invention can have the following effects. It is to be understood, however, that the scope of the disclosed technology is not to be construed as limited thereby, as it is not meant to imply that a particular embodiment should include all of the following effects or only the following effects.

The antenna device for the beam-space MIMO system according to the present invention can obtain MIMO-level performance by using fewer RF stages than a conventional MIMO system by securing a plurality of radiation patterns with less interference within a limited space, It is possible to provide an antenna device capable of achieving miniaturization of the communication device.

1 illustrates an antenna apparatus for a beam-space MIMO system according to an embodiment of the present invention.
FIG. 2 is a diagram showing an arrangement of antenna elements and a current distribution diagram in an antenna device for a beam-space MIMO system according to an embodiment of the present invention.
FIG. 3 illustrates S-parameter characteristics for an antenna apparatus for a beam-space MIMO system according to an embodiment of the present invention.
FIGS. 4 and 5 show a log scale of an embodiment in which various radiation patterns are formed by an antenna device for a beam space MIMO system according to an embodiment of the present invention.
Figure 6 shows a portion of the embodiment of Figure 4 on a linear scale.
FIG. 7 shows an embodiment of radiation pattern formation when a weight is added to an RF signal.
FIG. 8 illustrates an ESPAR antenna having three elements as a conventional ESPAR antenna.

For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprise", "having", and the like are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as meaning consistent with meaning in the context of the relevant art and are not to be construed as ideal or overly formal in meaning unless expressly defined in the present application .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

MIMO techniques for improving data rate using a general array antenna are already well known. In the conventional MIMO technology, when the antenna is extended, the RF stage also increases, thereby increasing hardware complexity and power consumption. This problem is a major disadvantage in mobile terminals with limited power. Therefore, it is difficult to extend the MIMO system to improve the transmission rate. However, data usage on mobile handsets is steadily increasing and demands faster speeds. Recently, a beam space MIMO (Beamspace MIMO) technique using an electronically steerable passive array radiator (ESPAR) has emerged in order to overcome the drawbacks of a conventional MIMO system using a linear array antenna. This is to overcome the limitation of the existing MIMO system by using the ESPAR antenna having a parasitic element disposed around the active element. In the conventional MIMO system, the data symbols are mapped to the respective antennas using the array antennas, so that the number of the antennas is increased to further increase the data rate, thereby mapping more data symbols. As the number of antennas increases, the system complexity increases greatly. On the other hand, in the case of the beam-space MIMO system, in order to increase the data transmission rate, the number of active elements connected to the RF stage is increased while the number of parasitic elements is increased while the number of parasitic elements is increased. The number of data symbols can be increased and the more data symbols can be mapped to more orthogonal basis patterns. Therefore, the system complexity problem can be greatly improved as compared with the conventional MIMO system because only one RF stage is used even if the device is extended to improve the data rate.

However, the beam-space MIMO system, which improves the disadvantages of the existing MIMO system, is implemented using a wire antenna having a three-dimensional structure such as a monopole antenna and a dipole antenna. FIG. An example of a beam-space MIMO system is shown.

Specifically, in the beam-space MIMO system 800 of FIG. 8, the RF signal is supplied from the feeder 820 to the active antenna 810, and the reactance controllers 821 and 822 feed the RF signals to the respective parasitic antennas 811 and 812, The reactance value of the reactance is controlled. In this case, a single feed is performed by the feeder 820 to the active antenna 810, whereby induction currents are generated in the parasitic antennas 811 and 812, and the reactance values of the parasitic antennas 811 and 812 The beam steering is achieved through the modification. Accordingly, even if a single feeding is possible, it is possible to extend to a plurality of antenna elements, so that the system complexity may not increase greatly even if the elements are expanded to improve the data rate.

However, in the beam-space MIMO system 800 having the conventional ESPAR antenna, as shown in FIG. 8, the ESPAR antenna having a monopole antenna element or the dipole antenna element can be realized. However, since the conventional ESPAR antenna is implemented as a wire antenna such as a monopole or a dipole antenna, the conventional ESPAR antenna has a three-dimensional structure, so that it is difficult to miniaturize the conventional ESPAR antenna.

1, an antenna apparatus 100 for use in a beam space MIMO system includes a feeder 120 for supplying an RF signal, a parasitic antenna element 111 (Not shown) for controlling the reactance values 121 to 128 of the reactance elements 118 to 118, an active antenna element 110 connected to the feed part through a feed point and supplied with RF signals from the feed part, At least one pair of parasitic antenna elements 111 to 118 whose reactance values are controlled, and a substrate 101 on which active antenna elements and parasitic antenna element pairs are formed.

In the antenna device 100 according to the embodiment of the present invention, an RF signal is supplied to the active antenna element 110 through the feeding point 102, and the active antenna element 110 applies an RF signal to the active antenna element 110 in a direction The radiation pattern is adjusted and the radiation patterns in the azimuth direction with respect to the substrate 101 are adjusted as the reactances 121 to 128 of the parasitic antenna elements 111 to 118 are controlled. Thus, the radiation patterns are adjusted by the antenna elements 110 to 118 formed in a two-dimensional flat plate shape on the substrate 101, so that a large number of radiation patterns with low interference in the plane of 0.5? 0.5 (?: Transmission signal wavelength) .

FIG. 1 illustrates an antenna device 100 for a beam-space MIMO system in accordance with an embodiment of the present invention. In this embodiment, the antenna size is 62.5 x 62.5 x 0.87 mm, the resonance frequency of the design target is 2.4 GHz, and a circular microstrip circular patch antenna is formed on the Teflon substrate as the active antenna element. And four or eight pairs of "L" shaped slot antennas 111 to 118 as parasitic antenna elements are formed around one circular microstrip patch antenna 110 .

Here, each slot antenna pair 111, 115, 112 and 116, 113 and 117, 114 and 118 are formed symmetrically with respect to one circular microstrip patch antenna 110 as a center. The circular microstrip patch antenna 110 is provided with a feed point 102 through which the RF signal is supplied from the feeder 120. Each of the "L" shaped slot antennas 111 to 118 is connected to a reactance control unit (not shown) so that the values of the reactances 121 to 128 can be controlled. The azimuth angle azimuth ) Direction can be adjusted.

That is, the radiation pattern in the vertical direction is adjusted by the circular microstrip patch antenna 110 which is the active antenna element and the radiation pattern in the horizontal direction is adjusted by the "L" shaped slot antennas 111 to 118 which are parasitic antenna elements So that the desired radiation pattern can be obtained without increasing the system complexity.

FIG. 2 shows the arrangement of antenna elements and the current distribution diagram in the antenna device according to the present embodiment. That is, on the substrate, a circular microstrip patch antenna 110, which is an active antenna element, and slot antennas 111 to 118, which are "L" shaped parasitic antenna elements, are formed two- Quot; L "-shaped slot antenna pairs 111, 115, 112 and 116, 113 and 117, 114 and 118, which are parasitic antenna elements, are arranged symmetrically with respect to the microstrip patch antenna 110 . Referring to the current distribution diagram in FIG. 2, it is assumed that the current flows through the one circular microstrip patch antenna 110 corresponding to the active antenna element through which the RF signal is supplied through the feed point 102 and the "L" The current distribution in the active antenna element in which power is supplied is determined in accordance with the RF signal to be fed and also in the parasitic antenna element in which power is not supplied thereto It can be seen that the induction current is generated, which is controlled according to the reactance value of the parasitic antenna element, so that it is possible to adjust the radiation pattern according to the control of the current distribution.

3 is a graph illustrating a result of measurement of S parameters for the antenna apparatus according to the present embodiment. In this embodiment, as described above, the antenna size is 62.5 x 62.5 x 0.87 mm, and the resonance frequency of the design target is 2.4 GHz. Referring to FIG. 3, it can be seen that resonance occurs at 2.4 GHz, which is the design target in the present embodiment, and it can be seen that it has good radiation characteristics.

FIGS. 4 and 5 illustrate an embodiment in which various radiation patterns are formed by the antenna device according to the present embodiment in a log scale.

Specifically, in this embodiment, eight radiation patterns are formed, and the reactance values 121 through 128 of the slot antennas 111 through 118, which are parasitic antenna elements, are adjusted to form each radiation pattern. The values of the inductance L, the capacitance C and the resistance component R of the slot antennas 111 through 118 for adjusting the reactance values of the slot antennas 111 through 118 in the present embodiment are shown in Tables 1 - Table 8 shows the results.

pattern Slot antenna R [Ω] L [nH] C [pF] pattern 1 111 10 4 10 112 One 0 One 113 One 0 One 114 One 0 One 115 One 0 One 116 One 0 One 117 One 0 One 118 One 0 One

pattern Slot antenna R [Ω] L [nH] C [pF] pattern 2 111 One 0 One 112 One 0 One 113 100 60 One 114 One 0 One 115 One 0 One 116 One 0 One 117 One 0 One 118 One 0 One

pattern Slot antenna R [Ω] L [nH] C [pF] pattern 3 111 One 0 One 112 One 0 One 113 One 0 One 114 One 0 One 115 100 60 One 116 One 0 One 117 One 0 One 118 One 0 One

pattern Slot antenna R [Ω] L [nH] C [pF] pattern 4 111 One 0 One 112 One 0 One 113 One 0 One 114 One 0 One 115 One 0 One 116 One 0 One 117 10 40 10 118 One 0 One

pattern Slot antenna R [Ω] L [nH] C [pF] pattern 5 111 One 0 5 112 One 0 One 113 One 0 One 114 One 0 One 115 One 0 One 116 One 0 One 117 One 0 One 118 One 0 One

pattern Slot antenna R [Ω] L [nH] C [pF] pattern 6 111 One 0 One 112 One 0 One 113 One 0 5 114 One 0 One 115 One 0 One 116 One 0 One 117 One 0 One 118 One 0 One

pattern Slot antenna R [Ω] L [nH] C [pF] pattern 7 111 One 0 One 112 One 0 One 113 One 0 One 114 One 0 One 115 One 0 5 116 One 0 One 117 One 0 One 118 One 0 One

pattern Slot antenna R [Ω] L [nH] C [pF] pattern 8 111 One 0 One 112 One 0 One 113 One 0 One 114 One 0 One 115 One 0 One 116 One 0 One 117 One 8 One 118 One 0 One

As shown in Tables 1 to 8, in order to form a beam pattern in a specific direction, the reactance of a slot antenna corresponding to a specific parasitic antenna element is adjusted differently from the reactance of slot antennas corresponding to other parasitic antenna elements. This makes it possible to control the vertical and horizontal directions of the beam pattern.

That is, from the radiation pattern shown in FIGS. 4 and 5 and the resistance R, inductance L, and capacitance C for the slot antennas 111 to 118 shown in Tables 1 to 8, It can be seen that it is possible to form a desired radiation pattern by adjusting the reactance values 121 to 128 of the slot antennas 111 to 118 so that interference can be generated within a limited space by feeding only one active antenna element 110 It is possible to form a small number of radiation patterns, thereby reducing the complexity and the power consumption of the system, thereby achieving miniaturization of the communication equipment.

FIG. 6 shows a part of the embodiment of FIG. 4 on a linear scale. Specifically, the radiation patterns of pattern 1 and pattern 2 of FIG. 4 are shown on a linear scale. In other words, pattern 1 and pattern 2 in FIG. 6 represent radiation patterns of pattern 1 and pattern 2 in FIG. 4 on a linear scale, so that the point where radiation pattern formation is easily controllable is displayed visually prominently.

Fig. 7 shows an embodiment of the radiation pattern formation in the case where a weight is added to the RF signal. That is, FIG. 7 shows a case in which a weight is added to a base pattern, and it is possible to form a radiation pattern having not only a radiation pattern is formed in only one specific direction according to a weight value, will be. That is, it is possible to easily steer the beam in a desired direction by forming a radiation pattern having directivity in various directions at the same time by one active antenna element supplied with such an RF signal and the parasitic antenna element around the active antenna element.

Meanwhile, in the antenna device 100 for the beam-space MIMO system according to an embodiment of the present invention, the active antenna element 110 and the parasitic antenna elements 111 to 118 have a flat plate shape. Accordingly, the active antenna element 110 and the parasitic antenna elements 111 to 118 may be formed on either the upper surface or the lower surface of the substrate, or may be formed on the upper surface of the substrate or all of the lower surface of the substrate, Or may be formed on the upper and lower surfaces of the substrate, respectively. In addition, the active antenna element 110 and the parasitic antenna elements 111 to 118 may be formed by opening a part of a top surface or a bottom surface of the substrate. For example, it may be formed by exposing a copper foil surface inside the resin insulating layer by removing a part of the resin insulating layer formed on the upper surface or the lower surface of the substrate 101.

The antenna device for a beam-space MIMO system according to an embodiment of the present invention has a plurality of radiation patterns with less interference within a limited space, thereby achieving MIMO-grade performance It is possible to realize a low complexity and a low power, thereby achieving the miniaturization of the communication device.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. The codes and code segments constituting the computer program may be easily deduced by those skilled in the art. Such a computer program is stored in a computer readable storage medium, readable and executed by a computer, thereby realizing an embodiment of the present invention. As the storage medium of the computer program, a magnetic recording medium, an optical recording medium, or the like can be included.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (9)

1. An antenna apparatus for a beam-space MIMO system,
A feeding part for feeding an RF signal;
A reactance controller for controlling a reactance value;
An active antenna element connected to the power feeder through a feed point and supplied with the RF signal from the feeder;
At least one pair of parasitic antenna elements whose reactance value is controlled by the reactance controller; And
And a substrate on which the active antenna element and the parasitic antenna element pair are formed,
Wherein the active antenna element adjusts a radiation pattern in a direction perpendicular to the substrate and the parasitic antenna element pair adjusts a radiation pattern in a horizontal direction with respect to the substrate to form a plurality of radiation patterns / RTI > antenna system for a beam-space MIMO system. delete The method according to claim 1,
Wherein the at least one pair of parasitic antenna elements are symmetrically symmetrical about the active antenna element, respectively. The method according to claim 1,
Wherein the active antenna element and the parasitic antenna element have a planar shape. The method according to claim 1,
Wherein the active antenna element and the parasitic antenna element are formed only on an upper surface or a lower surface of the substrate or on an upper surface and a lower surface of the substrate, respectively. The method according to claim 1,
Wherein the active antenna element and the parasitic antenna element are formed by opening a portion of an upper surface or a lower surface of the substrate. The method according to claim 1,
Wherein the active antenna element is a circular microstrip patch antenna. ≪ RTI ID = 0.0 > 8. < / RTI > The method according to claim 1,
Wherein each parasitic antenna element of the at least one parasitic antenna element pair is an "L" shaped slot antenna. 9. A beam space MIMO system, comprising an antenna arrangement according to any one of the preceding claims.

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