JP2011019021A - Reflect array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the degree of freedom in design by enlarging the phase variation range of a reflected wave when the structures of elements are changed within a predetermined period.SOLUTION: A reflect array is constituted of a plurality of array elements and a ground plate, wherein the plurality of array elements are configured to control the direction of scattered waves by controlling the phase thereof, and the array element consists of a main element and one or a plurality of sub-elements close to the main element.

Description

  The present invention relates to a reflect array. Specifically, the present invention relates to “application of reflected waves for improving radio wave environment”, “securing independent paths for the purpose of increasing transmission capacity using MIMO wireless communication” and “reflection of reflector antennas”. The present invention relates to a reflect array for use as a “mirror or primary radiator” and relates to a wideband reflect array capable of widening the range in which the phase of a scattered wave in an array element changes.

  Examples of conventional reflect arrays are disclosed in Non-Patent Document 1 and Non-Patent Document 2.

FIG. 1 shows the structure of an element constituting a conventional reflect array cited from Non-Patent Document 1. As shown in FIG. 1, a metal ground plate is provided on the back surface of a dielectric substrate having a relative dielectric constant ε _r , and such an element is a strip element having a width w and a length l provided on the surface of the dielectric substrate. It is constituted by.

  FIG. 2 shows the phase of the reflected wave with respect to the length l of the element (Reflection Phase) when the elements of FIG. It is a graph which shows.

Here, the width w of the device is "1.5mm", the thickness h of the substrate and "0.76mm", the dielectric constant epsilon _gamma is "2.5", the period L is "5mm" period D is “5 mm” and the design frequency f is “24 GHz”.

  From FIG. 2, it can be confirmed that the phase value of the reflected wave can be changed from “140 degrees” to “−180 degrees” by changing the element length from “1 mm” to “4.8 mm”.

  FIG. 2 shows that even if the length of the element is made smaller than “1 mm”, the change in the value of the phase of the reflected wave becomes small and it is difficult to make it larger than “140 degrees”.

  Further, since both the period D and the period L are set to “5 mm”, the length of the element cannot be set to “5 mm” or more. For this reason, the reflect array shown in FIG. 2 changes the phase of the reflected wave from “−180 degrees” to “180 degrees” when the element length is changed within this period. It was difficult to change by minutes.

D. Pilz and W.W. Menzel, “Full wave analysis of a planar reflector antenna”, Proc. Asia-Pacific Microwave Conference, 225-227, December 2-5, 1997 F. Venneri, G.M. Angilili and Di Massa, “Design of microstrip reflect array using data from isolated patch analysis”, IEEE Microwave and Optical Technology. 34, no. 6, September 20, 2002

  As described above, in the conventional reflect array, the change in the phase of the reflected wave when the dimension of the structure is changed within a predetermined period is changed from “180 degrees” to “−180 degrees”. It was difficult to change by “360 degrees”.

  On the other hand, the reflect array is generally designed using the structural parameters defined in FIG. 3 and (Equation 1).

Here, R _mn is the distance from the wave source to the mn th element, Φ _mn is the phase of the reflected wave from the mn th element,

は、リフレクトアレイの中心からｍｎ番目の素子までの位置ベクトルであり、

Is a position vector from the center of the reflect array to the mn th element,

は、リフレクトアレイのメインビームの方向に対する単位ベクトルである。

Is a unit vector for the direction of the main beam of the reflect array.

  The length of each element can be determined from the value of the phase of the reflected wave determined by (Equation 1) using FIG.

  Therefore, for example, if the value of the phase of the reflected wave cannot be obtained for any element length, as in “150 degrees” in FIG. 2, a reflect array having a phase in line with the theory cannot be configured. There was a problem.

  Therefore, the present invention has been made in view of the above-described problems, and increases the range in which the phase of the reflected wave changes when the structure of the element is changed within a predetermined period, thereby increasing the degree of freedom in design. It is an object of the present invention to provide a reflect array capable of increasing the height.

  A first feature of the present invention is a reflect array composed of a plurality of array elements and a ground plane, wherein the plurality of array elements controls the direction of the scattered waves by controlling the phase of the scattered waves. The array element is constituted by a main element and one or a plurality of sub-elements close to the main element.

  In the first aspect of the present invention, the main element may be a dipole element, and the sub element may be a parasitic element.

  In the first feature of the present invention, the length of the sub element may be in the range of 0.6 to 0.95 times the length of the main element.

  As described above, according to the present invention, the range in which the phase of the reflected wave changes when the structure of the element is changed within a predetermined period can be increased, and the degree of freedom in design can be increased. A reflect array can be provided.

It is a figure which shows the structure of the element which comprises the conventional reflect array. It is a graph which shows the phase of the reflected wave with respect to the length of the element which comprises the conventional reflect array. It is a figure for demonstrating the design parameter of the conventional reflect array. It is a figure which shows the structure of the element which comprises the reflect array which concerns on the 1st Embodiment of this invention. It is a graph which shows the phase of the reflected wave with respect to the length of the element which comprises the reflect array which concerns on the 1st Embodiment of this invention. It is a figure which shows the characteristic of the phase of the reflected wave in the reflect array which concerns on the 1st Embodiment of this invention. It is a graph which shows the phase of the reflected wave with respect to the length of the element which comprises the reflect array which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structure of the reflect array which concerns on the 3rd Embodiment of this invention. It is a figure which shows the dimension of each element which comprises the reflect array which concerns on the 3rd Embodiment of this invention. It is a figure which shows the far scattering field of the reflect array which concerns on the 3rd Embodiment of this invention.

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

(First embodiment of the present invention)
FIG. 4A and FIG. 4B show the shapes of elements (array elements) constituting the reflect array according to the first embodiment of the present invention.

  As shown in FIGS. 1A and 1B, the elements constituting the conventional reflect array are composed of one strip element (dipole element), as shown in FIGS. 4A and 4B. In the element constituting the reflect array according to the present embodiment, the parasitic element 2 as the sub element is placed close to both sides of the strip element (dipole element) 1 as the main element.

  Here, the reflect array according to the present embodiment includes a plurality of array elements and a ground plane, and the plurality of array elements controls the direction of the scattered wave by controlling the phase of the scattered wave (reflected wave). Is configured to control.

  In addition, the parasitic element 2 which is a sub element may be one or plural. Further, the parasitic element 2 as a sub element may be a parasitic element (or a parasitic element).

  In general, when an element slightly shorter than the dipole element is brought close to a half-wavelength dipole element, a current is induced in the adjacent element like the Yagi-Uda antenna, and broadband characteristics and two-resonance characteristics can be obtained. And the characteristics of the reflection phase also change.

Figure 5 shows the phase of the reflected wave relative to the length l _m of the dipole elements constituting the reflectarray.

Here, the width w of the dipole elements is "1.5mm", the dielectric constant epsilon _gamma is "2.5", the period L is "5mm", the period D is "5mm", a design frequency f " 24 GHz ".

The length of the parasitic element 2 is 0.85 times the length l _m of the dipole elements 1. The length of the parasitic element 2 may be a length within 0.6 times to 0.95 times the length l _m of the dipole elements 1.

  In FIG. 5, the line C and the line D show the result of the reflect array according to the present embodiment, and the line A and the line B are for the case where the parasitic element is not brought close to the dipole element for comparison. The calculation results are shown.

  Here, the line C shows the characteristics of the case where the thickness h of the substrate is “0.76 mm”, and the line D shows the characteristics of the case where the thickness h of the substrate is “1.5 mm”. In the case of the line A and the line B, the thickness h of the substrate is “0.76 mm”.

FIG. 5 shows that when the length l _m of the dipole element 1 is “4.5 mm” or less, the inclination of the phase of the reflected wave becomes gentle when the substrate is thickened.

  In the case of the conventional dipole element alone, the phase value of the reflected wave hardly changes even when the element length is increased beyond “4.5 mm”. Then, the phase value of the reflected wave can be changed from “−360 degrees” to “−540 degrees” by “180 degrees” or more.

That is, the reflect array according to this embodiment, the length l _m of the dipole elements 1, from the "1mm", by varying in a range from "5mm" is a predetermined period, the reflected wave phase The changing range can be increased from “0 degree” to “−540 degrees”.

Phase values of the reflected wave, the ratio r of the length l _p of the parasitic element 2 proximate the dipole elements 1 to the length l _m, and the value of the distance d between the dipole elements 1 and the parasitic element 2 It depends on.

In FIG. 6, the phase value of the reflected wave when the horizontal axis is d and the vertical axis is “r (= l _p / l _m )” is indicated by contour lines. In FIG. 6, the width w _m of the dipole element 1 is “1.0 mm”, the width w _m of the parasitic element 2 is “0.5 mm”, and the thickness h of the substrate is “0.76 mm”. The relative dielectric constant ε _γ is “2.5”, and the design frequency f is “24 GHz”.

  According to the reflect array according to this embodiment, the range in which the phase of the scattered wave changes in the array element is widened by bringing the sub element (parasitic element 2) close to the main element (dipole element 1). Can do.

(Second embodiment of the present invention)
Figure 7 shows a phase of the reflected wave relative to the length l _m of the dipole elements 1 constituting the reflect array according to this embodiment.

In FIG. 7, the period L and the period D are both “60 mm (about 0.41λ)”, the width w _m of the dipole element 1 is “12 mm”, and the width w _m of the parasitic element 2 is “6 mm”. The thickness h of the substrate is “10 mm”, the relative dielectric constant ε _r is “2.5”, and the distance d between the dipole element 1 and the parasitic element 2 is “3 mm”. The frequency f is “2.05 GHz”.

From Figure 7, also in case the reflect array according to this embodiment, the dipole elements 1 a length l _m from "5mm" to "55mm", by changing within a given period, the phase change of the reflected wave It can be seen that the range to be set can be “360 degrees” or more.

(Third embodiment of the present invention)
A reflect array according to a third embodiment of the present invention will be described with reference to FIGS.

  FIG. 8 is a reflect array using a dipole element 1 in the vicinity of a parasitic element 2 designed based on the phase of the reflected wave of the reflect array according to the second embodiment of the present invention.

  Here, as in the case of the second embodiment, the design frequency f is set to “2.05 GHz”. Based on the phase of each element determined by (Equation 1) and the phase of the reflected wave shown in FIG. The length of the element was determined.

In the case of a reflect array composed only of a conventional dipole element, when the length l _m of the dipole element 1 changes between about “3 mm” and about “4.5 mm”, the phase value of the reflected wave is It has changed more than “180 degrees”. The incident direction was (θ _i , φ _j ) = (0 °, 0 °), and the reflection direction was (θ _i , φ _j ) = (60 °, 0 °).

  FIG. 9 shows the dimension values of each element. FIG. 10 shows a far scattered field of the reflect array according to the present embodiment.

As shown in FIG. 10, a wave incident from an incident direction (θ _i , φ _j ) = (0 °, 0 °) is reflected in a desired reflection direction (θ _i , φ _j ) = (60 °, 0 °). The wave incident from the incident direction (θ _i , φ _j ) = (60 °, 0 °) is radiated in the desired reflection direction (θ _i , φ _j ) = (0 °, 0 °). It can be confirmed that the reversibility of communication is maintained.

  In this specification, the name “dipole element” is used for the central strip element, and the name “parasitic element” is used for the adjacent strip elements in accordance with the convention based on the operating principle of the Yagi-Uda antenna. .

  Although many papers have been published in which the reflect array as shown in FIG. 1 is called a “dipole array”, in reality, such elements are not supplied with power.

  Although the present invention has been described in detail using the above-described embodiment, it is obvious for those skilled in the art that the present invention is not limited to the embodiment described in the present specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

1. Dipole element 2. Parasitic element

Claims (3)

A reflect array including a plurality of array elements and a ground plane,
The plurality of array elements are configured to control the direction of the scattered wave by controlling the phase of the scattered wave,
The array element includes a main element and one or a plurality of sub elements adjacent to the main element. The main element is a dipole element,
The reflect array according to claim 1, wherein the sub-element is a parasitic element.   3. The reflect array according to claim 1, wherein the length of the sub element is in a range of 0.6 to 0.95 times the length of the main element.

Images