WO2017043946A1

WO2017043946A1 - Reflective cell-array antenna having miniaturised structure

Info

Publication number: WO2017043946A1
Application number: PCT/KR2016/010267
Authority: WO
Inventors: 김동호; 박장순
Original assignee: 세종대학교산학협력단
Priority date: 2015-09-11
Filing date: 2016-09-12
Publication date: 2017-03-16
Also published as: KR20170031527A; KR101751123B1

Abstract

A reflective cell-array antenna having a miniaturised structure is disclosed. The disclosed antenna comprises: a feed radiator that is fed with and radiates an RF signal; a cell-array that is spaced apart, at an arbitrary distance, from the feed radiator and in which a plurality of unit cells are arrayed; and further comprises a control unit that controls the capacitance or inductance of a variable reactive element, wherein variable reactive elements are coupled to one or more cells of the unit cells. According to the disclosed antenna, a reflective cell-array antenna having a miniaturised structure can be designed to be usable in a low frequency band.

Description

Miniaturized Reflective Cell Array Antenna

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective cell array antenna, and more particularly, to a reflective cell array antenna that can be used in a low frequency band by miniaturizing its structure.

Reflective cell array antenna is an antenna consisting of a feed radiator and a cell array that radiate an RF signal, and is used in many fields due to its high gain and simple structural features.

On the other hand, the next generation mobile communication services are required to provide a variety of data services at a faster speed, and as one of the methods for accommodating them, there is a demand for a method to more actively use the band below 6GHz.

Reflective cell array antennas are antennas with various advantages, but the feed emitter and the cell array must be spaced at about 10 times the wavelength of the operating frequency, and the separation distance between the cell array and the feed emitter is low enough to increase with a lower operating frequency. In the frequency band, there is a problem in that the reflective cell array antenna cannot be implemented with a miniaturized structure.

In order to reduce the structure of the reflective cell array antenna, an array antenna having a folded structure and the like has been proposed, but there has been a limitation in miniaturizing the antenna of the low frequency band with such a structure.

For this reason, the conventional reflective cell array antenna is mainly used only at high frequencies of 10 ~ 20 GHz or more, and there is a problem that cannot be used due to size problems in the low frequency band.

The present invention is to solve the above-mentioned problems of the prior art, and proposes a miniaturized reflective cell array antenna that can be used in a frequency band of 6 GHz or less.

In order to achieve the above object, according to an embodiment of the present invention, a feeding radiator for receiving and radiating an RF signal; And a cell array in which a plurality of unit cells are arranged to be spaced apart from the feeding radiator at a predetermined distance, wherein at least some of the unit cells are coupled to a variable reactive element and adjust capacitance or inductance of the variable reactive element. There is provided a reflective cell array antenna further comprising:

The distance between the feed radiator and the cell array is set to 1.5 lambda or less.

The variable reactive device includes a varactor diode, and the controller controls a voltage applied to the varactor diode.

The variable reactive element includes a chip capacitor.

The control unit adjusts the reflection phases of the plurality of unit cells such that the direct wave radiated directly from the feed radiator and the reflected waves reflected through the plurality of unit cells undergo constructive interference at a predetermined wavefront.

The reflection phase of the unit cells located at (m, n) of the cell array is set as in the following equation.

In the above equation, f is frequency, c is the speed of electromagnetic waves, l _mn is the distance from the feed emitter to the unit cell located at (m, n), and r _mn is the unit cell located at (m, n). The distance to a particular wavefront, d is the distance from the feed radiator to the predefined specific wavefront, q is any integer, m, n is the index of the position of the unit cells in the cell array,

Means phase,

Is the phase delayed by the distance d,

Is the phase delayed by the distance lmn,

Is the phase that is delayed due to the distance r _mn ,

Means the reflection phase.

According to another aspect of the invention, the feeding radiator for feeding and radiating the RF signal; And a cell array in which a plurality of unit cells are arranged and spaced apart from the feeding radiator at a predetermined distance, wherein a distance between the feeding radiator and the cell array is set to 1.5 lambda or less, and reflects at least one of the plurality of unit cells. There is provided a reflective cell array antenna further comprising means for adjusting the phase.

According to embodiments of the present invention, a reflective cell array antenna having a miniaturized structure may be designed to be used in a frequency band of 6 GHz or less.

1 is a conceptual diagram illustrating a structure of a reflective cell array antenna according to an embodiment of the present invention.

2 and 3 are views showing the structure of a feed radiator of a reflective cell array antenna according to an embodiment of the present invention.

4 is a diagram illustrating an operation structure of a reflective cell array antenna according to an exemplary embodiment of the present invention.

5 is a view for explaining an analysis method in a conventional reflective cell array antenna.

6 illustrates a structure of a cell array in a reflective cell array antenna according to an embodiment of the present invention.

7 is an example illustrating a coupling structure of a variable capacitive element in a reflective cell array antenna according to an embodiment of the present invention.

8 is an example showing a coupling structure of a variable capacitive element in a reflective cell array antenna according to another embodiment of the present invention.

9 is a conceptual diagram illustrating a reflection phase adjustment method according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, it includes not only "directly connected" but also "indirectly connected" with another member in between. .

In addition, when a part is said to "include" a certain component, it means that it may further include other components, without excluding the other components unless otherwise stated.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a reflective cell array antenna according to an embodiment of the present invention includes a feed radiator 10, a cell array 20, a substrate 30, and a controller 40.

The feeding radiator 10 receives a feeding signal and functions to radiate an RF signal to the outside or to receive an RF signal from the outside. According to the exemplary embodiment of the present invention, the feeding radiator 10 may be a radiator having an omnidirectional radiation pattern, but is not limited thereto.

In one example, a emitter, such as a dipole emitter, a monopole emitter, may be used as the feed emitter 10.

A portion of the signal emitted by the feed radiator 10 is directed to the cell array 20, and the signal directed to the cell array 20 is reflected at the cell array 20. Accordingly, the signal radiated from the feed radiator 10 may be classified into a direct wave radiated directly and a wave reflected from the cell array 20.

The cell array 20 is provided below the feed radiator 10, and the cell array 20 is formed on the substrate 30. The cell array 20 refers to a structure in which a plurality of unit cells of a metal material are arranged. The arrangement structure of the unit cells constituting the cell array 20 may be variously set, and the arrangement structure may be determined based on required radiation characteristics. The unit cell may be in a non-powered state that is not connected to ground and power feeding.

In one example, the array structure may be a structure in which a plurality of unit cells are arranged periodically, or may be a structure in which a plurality of unit cells are arranged aperiodically. Not only the arrangement structure of the unit cells but also the shape of the unit cell may affect the overall radiation pattern. The shape of the unit cell will be described in detail with reference to the separate drawings.

The cell array 20 is formed on the substrate 30, and the substrate 30 is made of a dielectric material.

Although not shown, a ground plane electrically connected to the ground may be coupled to the lower portion of the substrate 30.

The feed radiator 10 and the cell array 20 are spaced apart by an arbitrary distance, and as described in the prior art, the general reflective cell array antenna is spaced about 10 times the wavelength of the operating frequency.

The separation of the feed radiator 10 by about 10 times the wavelength length is because the wave reflected from the cell array 20 is analyzed based on a far field.

When the reflected wave is analyzed based on the near field, the analysis becomes very complicated, which makes it difficult to design the structure of the cell array based on the near field.

Therefore, the conventional reflective cell array antenna has a large size due to the separation distance between the feed radiator 10 and the cell array 20, and has a problem that it is virtually difficult to use in a low frequency band having a large wavelength length. .

The present invention proposes a reflective cell array having a structure capable of reducing the distance between the feed radiator 10 and the cell array 20 without analyzing the cell array structure by the near field.

According to one embodiment of the present invention, the separation distance between the feed radiator 10 and the cell array 20 is set to a distance of 1.5λ or less. Here, λ means a wavelength length corresponding to the operating frequency of the antenna. The present invention proposes a cell array 20 and a controller 40 in which a proper gain can be obtained while the distance between the cell array 20 and the feed radiator 10 is significantly reduced.

According to a preferred embodiment of the present invention, the controller 40 performs a control operation for adjusting the reflection phase of the reflected wave reflected from the cell array. Detailed control operations performed by the controller 40 will be described in detail with reference to the separate drawings.

2 and 3 are views illustrating a structure of a feeding radiator of a reflective cell array antenna according to an embodiment of the present invention, and FIG. 2 is a view illustrating an upper surface of the feeding radiator around a substrate. Is a view showing the lower surface of the feed radiator around the substrate.

2 and 3, a radiator 210 for radiating an RF signal is formed on an upper portion of the substrate 200, and a feeder for providing a feed signal to the radiator 210 is formed below the substrate 200. The structure 220 is formed.

Referring to FIG. 2, the radiator 210 is a dipole emitter that includes a first element 211 and a second element 212. Of course, the dipole emitter is just one example of the feed emitter of the present invention and various kinds of emitters may be used. Dipole emitters have an omnidirectional radiation pattern.

The first element 211 of the dipole emitter is provided with a feed signal and the second element 212 is electrically connected to ground. The first element 211 is connected to the feed structure 220 to receive a feed signal.

For example, the first element 211 may be connected to the feed structure 220 through a via hole to receive a feed signal.

Referring to FIG. 4, the radiation signal emitted from the feed radiator 10 includes a direct wave 131 directly radiated to the outside. The radiation signal also includes a reflected wave 130 reflected from the cell array 20.

As a result, in the reflective cell array antenna, the direct wave 131 and the reflected wave 130 together constitute a radiation signal, and the overall radiation pattern is determined according to how the direct wave 131 and the reflected wave 130 overlap each other. .

The beam direction and phase of the reflected wave 130 vary according to the structure of the cell array 20. In the present invention, the reflected wave 130 adjusts the reflected phase through the control unit 40 so that the feed radiator 10 and the cell array ( 20) Provides a reflective cell array antenna that can be secured even when the distance is close.

5 is a view for explaining an analysis method of a conventional reflective cell array antenna.

Referring to FIG. 5, the relationship between the feed radiator 10 and the unit cells constituting the cell array is interpreted based on the far field, and the incident wave is interpreted in the far region of the TE mode or the TM mode using the reversible characteristics of the antenna. do.

Since the cell array is designed by such an analysis method, the cell array of the conventional reflective cell array antenna generally has a periodic structure and the shape of the cell array is also generally uniform.

However, there is a problem in that a cell array having a periodic and uniform structure cannot secure an appropriate gain radiation pattern when the feed emitter 10 is located within one wavelength.

6 is a diagram illustrating the structure of a cell array in a reflective cell array antenna according to an embodiment of the present invention.

Referring to FIG. 6, a plurality of unit cells are arranged on the substrate 30, and the unit cells 600, 601, and 602 have various shapes. Since the unit cells 600, 601, and 602 have various forms, the arrangement structure of the unit cells is aperiodic.

The feed radiator 10 emits RF signals to various types of unit cells 600, 601, and 602 arranged on the substrate 30. In this case, the feeding radiator 10 emits a signal at an angle corresponding to a desired beam direction, and as described above, the direct wave directly emitted and the reflected wave reflected from the unit cells together form a radiation signal.

Since the feed radiator 10 emits a signal at a predetermined angle, the radiation signal forms a wavefront having a predetermined angle.

In FIG. 6, the unit cells have various shapes in order to secure desired reflection phase characteristics. However, the desired reflection phase characteristic may not be secured only by the change of the shape of the unit cell, and the intended reflection phase characteristic may not be secured due to processing error.

According to a preferred embodiment of the present invention, the variable reactive element is coupled to the unit cell, and the controller 40 controls the reflection phase characteristic of each unit cell by changing the capacitance of the variable reactive element. Here, the variable reactive device refers to a device capable of varying the capacitance or inductance of the device.

7 is an example illustrating a coupling structure of a variable reactive element in a reflective cell array antenna according to an embodiment of the present invention.

Referring to FIG. 7, the variable reactive device 700 is coupled to connect two specific unit cells. That is, the unit cells and the variable reactive element 700 are coupled in series.

Here, the variable reactive device 700 may include a varactor diode, a variable chip capacitor, and a variable chip inductor.

For example, when the converter diode is used as a variable reactive element, the controller 40 may adjust the capacitance of the varactor diode by adjusting the voltage applied to the varactor diode.

As shown in FIG. 7, at least some of the unit cells may be electrically connected to a ground plane formed under the substrate 30.

8 is an example illustrating a coupling structure of a variable reactive element in a reflective cell array antenna according to another embodiment of the present invention.

Referring to FIG. 8, the variable reactive device 800 is connected to each unit cell. One end of the variable reactive device 800 may be connected to the unit cell, and the other end thereof may be connected to the ground plane. That is, in the example shown in FIG. 8, the variable reactive elements 800 have a structure in which they are connected in parallel. In this case, at least a part of the unit cell may be connected to the ground plane.

As shown in FIG. 7 and FIG. 8, the variable reactive element may be connected in series or parallel to the unit cell, and the controller 40 may adjust the capacitance or inductance of the variable reactive element to ultimately adjust the reflection phase. .

Hereinafter, a method of adjusting a reflection phase in a cell array that can secure an appropriate gain even when the feed emitter is close to the cell array within a distance of one wavelength will be described.

9 is a conceptual diagram illustrating a reflection phase adjusting method according to an embodiment of the present invention.

Referring to FIG. 9, the feed radiator 10 emits a direct wave d having a predetermined direction. In addition, the feed radiator 10 emits an RF signal toward the cell array, and reflecting waves r _m1 , r _m2 , r _mn and r _mN are reflected through the cell array.

According to the present invention, the direct wave d radiated from the feed radiator 10 and the reflected wave r _m1 , r _m2 , r _mn , r _mN reflected from the unit cell of the cell array have the same phase to reinforce each other between the direct wave and the reflected wave The reflection phase of each unit cell is adjusted to cause interference.

The specific wavefront 900 can be defined by the direct wave d and the reflected waves r _m1 , r _m2 , r _mn , r _mN , and preferably the direct wave d and the reflected wave r at the wavefront 900. _m1 , r _m2 , r _mn , r _mN ) have the same phase so that the reflection phase is adjusted so that constructive interference occurs.

Phase delay from radiating feed radiator to reaching unit cell at (m, n) in cell array

Is expressed by Equation 1 below.

In Equation 1, r _mn denotes a distance from a unit cell located at (m, n) to a wavefront, and m, n denotes an index of a position of unit cells in a cell array.

Referring to FIG. 9, a distance difference between unit cells (for example, n and n-1 th unit cells) adjacent to each other in the y direction may be

Since there is a relationship between and, the following relationship is established. Here, θ means the angle between the plane perpendicular to the cell array and the direct wave.

The phase of the reflection coefficient of the unit cell at (m, n) in the cell array

, The phase delayed by the distance l _mn

, The phase delayed by the distance r _mn

In this case, the total phase delay until the electromagnetic wave emitted from the feed antenna is reflected by the unit cell to the desired wavefront can be expressed as Equation 3 below.

The relationship that the constructive interference between the direct wave and the reflected waves from the unit cells at the specific wavefront defined is as shown in Equation 4 below.

In Equation 4 above,

Denotes a phase delayed by the distance d. The reflection phase in each unit cell for constructive interference between the reflected waves and the direct wave at a specific wavefront defined may be defined as in Equation 5 below.

According to a preferred embodiment of the present invention, it is possible to provide a good gain even if the distance between the feed emitter and the cell array is reduced within one wavelength distance by adjusting the reflection phase of each unit cell as shown in Equation 5 below.

As described above, the adjustment of the reflection phase may be performed by adjusting the size and shape of the unit cell or adjusting the capacitance or inductance of the variable reactive element connected to the unit cell.

The reflection phase adjustment described above may be achieved by changing the shape and size of the unit cells forming the cell array. For example, in the cell array structure shown in FIG. 6, the antenna may be designed to adjust the reflection phase as shown in Equation 5 by changing the shape and size of each unit cell constituting the cell array.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be.

Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is represented by the following claims, and it should be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present invention.

Claims

A feeding radiator configured to receive and radiate an RF signal;

It includes a cell array spaced apart from the feeding radiator at an arbitrary distance and a plurality of unit cells are arranged,

And a control unit coupled to at least some of the unit cells, and configured to adjust capacitance or inductance of the variable reactive element.
The method of claim 1,

And the distance between the feed radiator and the cell array is set to 1.5 lambda or less.
The method of claim 1,

The variable reactive device includes a varactor diode, and the controller controls the voltage applied to the varactor diode.
The method of claim 1,

And the variable reactive element comprises a chip capacitor.
The method of claim 1,

The control unit adjusts the reflection phase of the plurality of unit cells such that the direct wave radiated directly from the feed radiator and the reflected waves reflected through the plurality of unit cells undergo constructive interference at a predetermined wavefront. Cell array antenna.
The method of claim 5,

And a reflection phase of unit cells located at (m, n) of the cell array is set as in the following equation.

In the above equation, f is frequency, c is the speed of electromagnetic waves, l mn is the distance from the feed emitter to the unit cell located at (m, n), and r mn is the unit cell located at (m, n). The distance to a particular wavefront, d is the distance from the feed radiator to the predefined specific wavefront, q is any integer, m, n is the index of the position of the unit cells in the cell array,
Means phase,
Is the phase delayed by the distance d,
Is the phase delayed by the distance l mn ,
Is the phase that is delayed due to the distance r mn ,
Is the reflection phase.
A feeding radiator configured to receive and radiate an RF signal;

It includes a cell array spaced apart from the feeding radiator at an arbitrary distance and a plurality of unit cells are arranged,

And a distance between the feed radiator and the cell array is set to 1.5 lambda or less, and further comprising means for adjusting a reflection phase of at least one of the plurality of unit cells.
The method of claim 7, wherein

Means for adjusting the reflection phase,

And a variable reactive element coupled to at least a portion of the plurality of unit cells, and a control unit configured to adjust capacitance or inductance of the variable reactive element.
The method of claim 8,

The variable reactive device includes a varactor diode, and the control unit adjusts a voltage applied to the varactor diode.
The method of claim 8,

The control unit adjusts the reflection phase of the plurality of unit cells such that the direct wave radiated directly from the feed radiator and the reflected waves reflected through the plurality of unit cells undergo constructive interference at a predetermined wavefront. Cell array antenna.
The method of claim 10,

And a reflection phase of unit cells located at (m, n) of the cell array is set as in the following equation.

In the above equation, f is frequency, c is the speed of electromagnetic waves, l mn is the distance from the feed emitter to the unit cell located at (m, n), and r mn is the unit cell located at (m, n). The distance to a particular wavefront, d is the distance from the feed radiator to the predefined specific wavefront, q is any integer, m, n is the index of the position of the unit cells in the cell array, Means phase,
Is the phase delayed by the distance d,
Is the phase delayed by the distance l mn ,
Is the phase that is delayed due to the distance r mn ,
Is the reflection phase.
A feeding radiator configured to receive and radiate an RF signal;

It includes a cell array spaced apart from the feeding radiator at an arbitrary distance and a plurality of unit cells are arranged,

The size and shape of each of the unit cells of the cell array are set such that the direct wave radiated directly from the feed radiator and the reflected waves reflected through the plurality of unit cells have a reflection phase in which constructive interference occurs at a predetermined wavefront in advance. Reflective cell array antenna, characterized in that.
The method of claim 12,

And a reflection phase of unit cells located at (m, n) of the cell array is set as in the following equation.

In the above equation, f is frequency, c is the speed of electromagnetic waves, l mn is the distance from the feed emitter to the unit cell located at (m, n), and r mn is the unit cell located at (m, n). The distance to a particular wavefront, d is the distance from the feed radiator to the predefined specific wavefront, q is any integer, m, n is the index of the position of the unit cells in the cell array,
Means phase,
Is the phase delayed by the distance d,
Is the phase delayed by the distance l mn ,
; Means a phase delay due to the distance r mn,
Is the reflection phase.