Corner reflector and method for fabricating same

Patent metadata

Field	Value
Publication number	US-2018019521-A1
Application number	US-201615549857-A
Country	US
Kind code	A1
Filing date	Feb 17, 2016
Priority date	Feb 23, 2015
Publication date	Jan 18, 2018
Grant date	—

Abstract

A corner reflector includes annular balloons, which, when gas is supplied to the inside, annularly expand, and radio wave reflective films each developed to a plane by the expansion of the annular balloons. The three annular balloons are provided so as to be orthogonal to each other in the expansion. A constraint fabric wound around each annular balloon is provided. The constraint fabric includes an inner peripheral side fabric portion located on the side of a virtual central axis of the annular balloon and extending in the annular direction around the virtual central axis, and an outer peripheral side fabric portion located on the side opposite to the virtual central axis and extending in the annular direction. The elongation degree of the outer peripheral side fabric portion in the annular direction is higher than the elongation degree of the inner peripheral side fabric portion in the annular direction.

First claim

1 . A corner reflector reflecting a radio wave, the corner reflector comprising:
three annular balloons each of which has flexibility and airtightness, and, when gas is supplied to an inside thereof, expands in an annular shape extending in an annular direction around a virtual central axis due to gas pressure; and radio wave reflective films each of which includes an outer peripheral edge portion attached to the annular balloon so as to be developed to a plane due to the expansion of the annular balloon, wherein the three annular balloons are provided so as to be orthogonal to each other in the expansion, the corner reflector further comprises a constraint fabric wound around each of the annular balloons in a winding direction orthogonal to the annular direction, the constraint fabric supports surface pressure from the annular balloon in an expansion state where the annular balloon annularly expand, to thereby restrict expansion of the annular balloon, the constraint fabric includes an inner peripheral side fabric portion which is located on a side of the virtual central axis of the annular balloon and which extends in the annular direction in the expansion state, and an outer peripheral side fabric portion which is located on a side opposite to the virtual central axis and which extends in the annular direction in the expansion state, and concerning an elongation degree representing an elongation characteristic of the constraint fabric, the elongation degree of the outer peripheral side fabric portion in the annular direction is higher than the elongation degree of the inner peripheral side fabric portion in the annular direction.

2 . The corner reflector according to claim 1 , wherein the constraint fabric is formed by warp fiber threads and weft fiber threads which are woven with each other, and in the expansion state, the warp fiber threads each extend in the annular direction and the weft fiber thread each extend in a direction crossing the annular direction, and
concerning an elongation degree representing an elongation characteristic of each of the warp fiber threads, the elongation degree of each of the warp fiber thread forming the outer peripheral side fabric portion is higher than the elongation degree of each of the warp fiber thread forming the inner peripheral side fabric portion.

3 . The corner reflector according to claim 1 , wherein the constraint fabric is formed by warp fiber threads and weft fiber threads which are woven with each other, and in the expansion state, the warp fiber threads each extend in the annular direction and the weft fiber thread each extend in a direction crossing the annular direction, and
a weaving density of the warp fiber threads forming the outer peripheral side fabric portion is lower than a weaving density of the warp fiber threads forming the inner peripheral side fabric portion.

4 . The corner reflector according to claim 2 , wherein
the weft fiber threads include a first fiber thread and a second fiber thread, concerning an elongation degree representing an elongation characteristic of each of the weft fiber threads, the elongation degree of the second fiber thread is lower than the elongation degree of the first fiber thread, strength of the second fiber thread is higher than strength of the first fiber thread, and in the expansion state, the second fiber threads are arranged in the annular direction such that a density of the second fiber threads is less than a density of the first fiber threads.

5 . A method for fabricating a corner reflector reflecting a radio wave comprising the steps of:
(A) preparing a balloon which has expanded in a cylindrical shape by supply of gas to an inside thereof, and a constraint fabric, (B) winding the constraint fabric wound around the cylindrical balloon, (C) joining axial direction end portions of the cylindrical balloon around which the constraint fabric is wound, to each other to transform the balloon into an annular balloon extending in an annular direction around a virtual central axis; and (D) joining end portions of the constraint fabric in the annular direction of the annular balloon, fabricating the annular balloons of which number is three, by the steps (A), (B), (C), and (D), the method comprising the steps of: (E) assembling the three annular balloons to each other so that planes including annular shapes of the three annular balloons are orthogonal to each other, (F) attaching a radio wave reflective film to an inner side of each of the annular balloons to form a corner reflector, and (G) removing the gas from the inside of the annular balloons to deflate the annular balloons, wherein the constraint fabric supports surface pressure from the annular balloon in an expansion state where the annular balloon extends in the annular direction around the virtual central axis and annularly expand, to thereby restrict expansion of the annular balloon, the constraint fabric includes an inner peripheral side fabric portion which is located on a side of the virtual central axis of the annular balloon and which extends in the annular direction in the expansion state, and an outer peripheral side fabric portion which is located on a side opposite to the virtual central axis and which extends in the annular direction in the expansion state, and concerning an elongation degree representing an elongation characteristic of the constraint fabric, the elongation degree of the outer peripheral side fabric portion in the annular direction is higher than the elongation degree of the inner peripheral side fabric portion in the annular direction.

6 . The corner reflector according to claim 3 , wherein
the weft fiber threads include a first fiber thread and a second fiber thread, concerning an elongation degree representing an elongation characteristic of each of the weft fiber threads, the elongation degree of the second fiber thread is lower than the elongation degree of the first fiber thread, strength of the second fiber thread is higher than strength of the first fiber thread, and in the expansion state, the second fiber threads are arranged in the annular direction such that a density of the second fiber threads is less than a density of the first fiber threads.

Assignees

• Ihi Aerospace Co Ltd
• Seiren Co Ltd

Inventors

• Mori Mamoru
• Kataoka Hisanao
• Sakagawa Sachiyo
• Takagi Susumu

Classifications

• H01Q15/20 Primary

  Collapsible reflectors · CPC title

• F41H11/02 Primary

  Anti-aircraft or anti-guided missile {or anti-torpedo} defence installations or systems (cartridges or missiles for producing smoke or for dispensing radar chaff or infrared material F42B5/15, F42B12/48, F42B12/70; {informative reference: details of radar or sonar systems G01S7/00; jamming or electronic countermeasures G01S7/38, G01S7/495, H04K3/00}) · CPC title

• F41J2/00

  Reflecting targets, e.g. radar-reflector targets; Active targets transmitting electromagnetic {or acoustic} waves · CPC title