REFLECTARRAY AND DESIGN METHOD

• US 20150022414A1
• Filed: 12/03/2012
• Published: 01/22/2015
• Est. Priority Date: 02/29/2012
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Maruyama, Tamami, Oda, Yasuhiro, Kayama, Hidetoshi, Tran, Ngoc Hao, Shen, Jiyun
• Granted Patent: US 9,620,864 B2
• Time in Patent Office: Days
• US Class Current: 343/836
• CPC Class Codes: G06F 30/392 Floor-planning or layout, e.g. partitioning or placement
• CPC Class Codes: H01Q 15/008 said selective devices having Sievenpipers' mushroom elements
• CPC Class Codes: H01Q 15/0086 said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials
• CPC Class Codes: H01Q 15/14 Reflecting surfaces; Equivalent structures electromagnetic shields H01Q1/526
• CPC Class Codes: H01Q 15/148 with means for varying the reflecting properties H01Q15/147 takes precedence
• CPC Class Codes: H01Q 19/185 wherein the surfaces are plane
• CPC Class Codes: H01Q 3/46 Active lenses or reflecting arrays

Abstract

A method of designing a reflectarray including a substrate having a surface perpendicular to a predetermined axis, wherein elements are disposed on the substrate. The method obtains a reflection phase of the elements as a function of a design parameter such as element spacing, when a radio wave enters the arranged elements, and stores a relationship between the reflection phase and the design parameter in a memory. Here, the design parameter is equally set for the elements. The method repeatedly determines, for each of the elements, the design parameter of a specific element in accordance with the relationship. The function of the design parameter has a range of almost 360 degrees with respect to a range of the design parameter. The reflection phase is the continuous function of the element spacing such that two resonant points occur at which the reflection phase becomes zero.

Claims

1. A design method of designing a reflectarray, the reflectarray being such that a plurality of elements are disposed on a substrate having a surface which is perpendicular to a predetermined axis, wherein the reflectarray reflects an incident wave in a desired direction, the design method comprising:

a step of obtaining a reflection phase of the elements as a function of a design parameter, when a radio wave enters the elements which are arranged, and a storing a relationship between the reflection phase and the design parameter in a memory, wherein any of the design parameter among a size of element spacing, a size of a patch of the element, and a size of a gap between the patches of the neighboring elements is equally set for the elements; and

a step of repeatedly determining, for each of the elements, the design parameter of a specific element in accordance with the relationship, so that the specific element among the elements reflects the incident wave with a specific reflection phase among a plurality of reflection phases,

wherein the function of the design parameter has a range which is substantially equal to 360 degrees with respect to a predetermined numerical range of the design parameter,

wherein the reflection phase is the continuously varying function with respect to the element spacing, and

wherein the function of the design parameter is the continuous function (which indicates a two resonance characteristic) such that two resonant points (the element spacing which causes resonance) occur at which the reflection phase becomes zero.

2. The design method according to claim 1,

wherein each of the elements has a element structure, wherein the element structure includes, at least a patch and a ground plate, and

wherein a length of a gap between the patches of the neighboring elements is equal to a length of a gap between the patches of the different neighboring elements.

4. A reflectarray which is designed by the design method according to claim 1,

wherein a control angle of a reflected wave that operates for a phase of an oblique incident wave is different from a control angle of a reflected wave that operates for a phase of a front incident wave.

9. A MIMO communication system that performs MIMO-based communication by generating multiple paths by using the reflectarray according to claim 1.

3. A reflectarray that utilizes mushroom-like structures,

wherein, if structures based on arrays of the mushroom-like structures, which include a distance between vias of the mushroom-like structure;

element spacing; and

a distance between gaps, are used as a parameter for a wave that enters the reflectarray from a predetermine angle other than 0 degrees while an electric field is in parallel with a plane of incidence, there are at least two structures with which a reflection phase becomes zero, and

wherein a range of the reflection phase is 360 degrees.

5. The reflectarray according to claim 3,

wherein a reflected wave with respect to an oblique incident wave and a reflected wave with respect to a front incident wave are directed in a same direction.

10. A MIMO communication system,

wherein the reflectarray according to claim 5 causes a plurality of radio waves entering from a plurality of incident directions to reflect in a same direction, so that a communication terminal that receives the radio wave which is reflected by the reflectarray is able to communicate in a multi-path environment.

6. A reflectarray that includes a plurality of elements,

wherein, when a k-th element among the plurality of elements reflects an incident wave, a reflection phase of a reflected wave takes different values φ

_kn (n=1, . . . , N) depending on N types of incident angles θ

_in,

wherein, when a radio wave enters the reflectarray with an incident angle θ

_im;

when each of the elements reflects the radio wave with the corresponding reflection phase φ

_km; and

when the reflected wave is reflected by the reflectarray with a reflection angle θ

_rm;

the incident angle θ

_im, the reflection angle θ

_rm, and a control angle A_m satisfy a predetermined functional relationship (m=1, . . . , N),

wherein, when a radio wave enters the reflectarray with the incident angle θ

_iw;

when each of the elements reflect the radio wave with the corresponding reflection phases φ

_kw; and

when the reflected wave is reflected by the reflectarray with a reflection angle θ

_rw;

the incident angle θ

_iw, the reflection angle θ

_rw, and a control angle A_W satisfy the predetermined functional relationship (w=1, . . . , N), and

wherein the A_m and the A_w take values which are different from each other.

7. The reflectarray according to claim 6,

wherein the reflection angle θ

_rm for the case in which the radio wave enters with the incident angle θ

_im and the reflection angle θ

_rw for the case in which the radio wave enters with the incident angle θ

_iw are same values.

8. The reflectarray according to claim 6,

wherein, when an incident angle of a radio wave is denoted by θ

_i, a reflection angle of the radio wave is denoted by θ

_r, and a control angle is denoted by A, the predetermined functional relationship is represented by

θ

_r=arcsin [sin(θ

_i)+sin(A)].