US-12627067-B2 - Corner reflecting device and corner reflecting system

US12627067B2US 12627067 B2US12627067 B2US 12627067B2US-12627067-B2

Abstract

A corner reflecting device has at least one corner reflector. The reflector has a first right triangle plate, a second right triangle plate and a first isosceles right triangle plate, and a shape of the first right triangle plate is the same as a shape of the second right triangle plate, and is not an isosceles right triangle plate. A long leg of the second right triangle plate is connected with a long leg of the first right triangle plate. Two legs of the first isosceles right triangle plate are connected with a short leg of the first right triangle plate and a short leg of the second right triangle plate respectively. An intersection of the first right triangle plate, the second right triangle plate, and the first isosceles right triangle plate forms a leak hole.

Inventors

Chih-Chung Chung
Chun-Cheng Lin

Assignees

NATIONAL CENTRAL UNIVERSITY

Dates

Publication Date: 20260512
Application Date: 20240124
Priority Date: 20230605

Claims (13)

1 . A corner reflecting device comprising: at least one corner reflector, having: a first right triangle plate; a second right triangle plate, a shape thereof being the same as a shape of the first right triangle plate, one long leg of the second right triangle plate being connected with one long leg of the first right triangle plate; and a first isosceles right triangle plate, two legs thereof being connected with a short leg of the first right triangle plate and a short leg of the second right triangle plate respectively; wherein neither the first right triangle plate nor the second right triangle plate is an isosceles right triangle plate, an intersection of the long leg of the first right triangle plate, the long leg of the second right triangle plate, the short leg of the first right triangle plate, the short leg of the second right triangle plate, and the two legs of the first isosceles right triangle plate forming a leak hole.
2 . The corner reflecting device according to claim 1 , wherein the at least one corner reflector has two corner reflectors, which are disposed spaced apart from each other in a mutually inverted manner on the corner reflecting device, in order to let two hypotenuses of the two first isosceles right triangle plates be at two sides of the corner reflecting device, wherein the two sides correspond to each other and are on a same surface of the corner reflecting device.
3 . The corner reflecting device according to claim 2 further comprising: a carrier, having two hollow corner reflector accommodation slots on a surface thereof, in order to receive the two corner reflectors, wherein the two corner reflectors are firmly positioned at the carrier; wherein the surfaces of the two corner reflectors present a concave configuration compared with the carrier, in order to let the two leak holes of the two corner reflectors be disposed below the two hollow corner reflector accommodation slots of the carrier respectively.
4 . The corner reflecting device according to claim 3 , wherein the surface of the carrier is disposed a plurality of through holes, further comprising: a plurality of adjustable rods, penetrating through the plurality of through holes, each of the plurality of adjustable rods being located at a position on each of the plurality of through holes respectively, wherein an end of the adjustable rod to the position is defined as a first length, and another end of the other adjustable rod to the position is defined as a second length, a ratio being between the first length and the second length and varied, in order to let the corner reflecting device be placed horizontally on a hillside.
5 . The corner reflecting device according to claim 4 , wherein the carrier is a quadrilateral metal plate, the plurality of through holes being disposed at four corners of the surface of the carrier, the plurality of adjustable rods being composed of a plurality of threaded rods, a plurality of washers and a plurality of nuts.
6 . A corner reflecting system comprising: a plurality of corner reflecting devices, each of which being the same as the corner reflecting device according to claim 4 , the corner reflecting devices being disposed spaced apart on the hillside in a manner of at least one row or column.
7 . The corner reflecting system according to claim 6 , wherein the corner reflecting devices are disposed in the manner of at least one row, for the corner reflecting devices in the same row, a hypotenuse of the first right corner reflector of the corner reflector of one of the two adjacent corner reflecting devices facing the hypotenuse of the first right corner reflector of the other corner reflector of the other one of the two adjacent corner reflecting devices.
8 . The corner reflecting system according to claim 6 , wherein the corner reflecting devices are disposed in the manner of at least one column, for the corner reflecting devices in the same column, a spacing being between every two adjacent corner reflecting devices, and the spacing corresponding to an image resolution of a satellite.
9 . The corner reflecting system according to claim 6 , wherein the carrier is a quadrilateral metal plate, the plurality of through holes being disposed at four corners of the surface of the carrier, the plurality of adjustable rods being composed of a plurality of threaded rods, a plurality of washers and a plurality of nuts.
10 . The corner reflecting system according to claim 6 , wherein corresponding to a usage band of an incident radar wave of a Sentinel-1 satellite, a short leg of each of the first right triangle plate and the second right triangle plate being 21.6 cm, the long leg of each of the first right triangle plate and the second right triangle plate being 60 cm.
11 . The corner reflecting system according to claim 6 , wherein an incident radar wave of a satellite corresponds to an incident angle of the corner reflector, an effective aperture of the corner reflector being a hexagon or a rhombus.
12 . The corner reflecting device according to claim 1 , wherein the corner reflecting device corresponding to a usage band of an incident radar wave of a Sentinel-1 satellite, a short leg of each of the first right triangle plate and the second right triangle plate being 21.6 cm, the long leg of each of the first right triangle plate and the second right triangle plate being 60 cm.
13 . The corner reflecting device according to claim 1 , wherein an incident radar wave of a satellite corresponds to an incident angle of the corner reflector, an effective aperture of the corner reflector being a hexagon or a rhombus.

Description

BACKGROUND Technical Field The present disclosure is related to a corner reflecting device and a corner reflecting system, which simplifies the installation process in order to let the corner reflecting device be directly laid flat on a hillside, and designs the length ratios of the corner reflector in order to adapt the incident angle directions of the incident radar waves of various satellites, further that, the area is decreased and the reflection amount of the reflected radar wave is increased, and the measurement accuracy is improved. Related Art A corner reflector is a device that reflects radar waves and is usually constructed by three isosceles triangle plates that are mutually perpendicular and intersected. It is called echo reflector (also known as trihedral corner reflector). Moreover, there is another corner reflector (also called dihedral corner reflector) assembled by two plates perpendicular to each other, and has higher reflection efficiency under the condition of the same area. This kind of corner reflector may have a higher overlap to the incident direction of the incident radar wave, so as to maintain accuracy. Compared with the aforesaid dihedral corner reflector, the trihedral corner reflector has a larger error range to be used. According to the present technical literatures, the length of the hypotenuse of the trihedral corner reflector (i.e., the length of the hypotenuse of the isosceles right triangle plate) is usually suggested set to be 1.5 meters, in order to approach the purposes of saving cost and better efficiency. In other words, increasing the length of the trihedral corner reflector is to improve performance, but the disadvantage that comes with it is an oversized volume, which causes the problems of performance improvements being out of proportional costs; on the other hand, if the condition is vice versa, the performance may be insufficient. Traditional large corner reflectors are expensive and large. Therefore, some literatures discuss the possibility of micro corner reflectors replacing large corner reflectors. At last, the conclusion is that although the reflection amount of the micro corner reflector is as low as hardly identifying the differences between noise signals and reflection signals. A special arrangement can still solve the problem, that is, the reflection signals of the micro corner reflector can be found. Simply speaking, the prior micro corner reflector still has the disadvantage of less performance. With respect to FIG. 1A, FIG. 1B and FIG. 1C, which illustrate a schematic 3-D view of a prior corner reflector in different angles, a schematic view shows an effective aperture of the prior corner reflector and an equivalent view of reflected radar waves of the prior corner reflector. As shown in FIG. 1A, a prior corner reflector 1 is constructed by three isosceles right triangle plates 11a, 11b, 11c, which are perpendicularly connected to each other for each pair, and made of radiation-reflective materials. For the aspect of usage, each connecting point of each pair of the three isosceles right triangle plates 11a, 11b, 11c is lower than the horizontal plane. That is, compared with the horizontal plane, the three isosceles right triangle plates 11a, 11b, 11c form a structure that is a concave configuration, which is lower than the horizontal plane, as shown in the left figure, left corner reflector, of FIG. 1A. If rotating the left figure toward the horizontal plane, a 3-D view of the corner reflector 1 will be shown in the right figure, right corner reflector, of FIG. 1A. As shown in FIG. 1B, the effective aperture of the prior corner reflector 1 is hexagonal, and the area of the effective aperture Aeffec is a2/2√{square root over (3)}, wherein a is the length of the corner reflector 1. By the left figure of FIG. 1C, the corner reflector 1 will have three times of reflection for the incident radar wave IW from a satellite, and therefore the reflected radar wave RW is produced. After the reflected radar wave RW is expanded to a straight line, equivalently, the reflected radar wave RW can be regarded as the equivalent radar wave RW′ in the middle figure of FIG. 1C. That is to say, the incident radar wave IW passes through the corner reflector 1 and the virtual corner reflector 1′ to generate the equivalent radar wave RW′. The virtual corner reflector 1′ is produced by mirroring the corner reflector 1, as shown in the right figure of FIG. 1C. The effective aperture Aeffect is equivalent to the overlapped portion of the corner reflector 1 and the virtual corner reflector 1′. Further, a corresponding radar cross section (RCS) is RCSreflector=(4⁢π⁢Aeffec2)/λ2, and the logarithm expression is RCSdb=10 log RCSreflector, where λ is the radar wavelength. Overall, the corner reflector 1 in FIG. 1A is the aforesaid large corner reflector, which has the disadvantages of a large volume and higher manufacturing cost. On the other hand, the possibility that the reflection