Communications: radio wave antennas – Antennas – Mesh – woven – braided or multiple strip
Patent
1999-05-18
2000-11-28
Wong, Don
Communications: radio wave antennas
Antennas
Mesh, woven, braided or multiple strip
343912, 343915, 343DIG2, H01Q 136
Patent
active
061541850
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a reflecting material for an antenna using triaxial woven fabrics, and more particularly, to a reflecting material for an antenna usable in frequency bands as high as 20-60 GHz.
2. Description of the Related Art
With expansions of the communications market and the broadcasting field, such as mobile communications and digital broadcasting of TV, etc through artificial satellites, the antenna has increasingly been scaled up and enhanced in terms of power.
In recent years, there has been developed an antenna involving the use of triaxial woven fabrics as a reflecting material and utilizing the characteristics of the triaxial woven fabrics.
The followings are the reasons therefor:
The triaxial woven fabrics have a light weight and a high rigidity, and are easy to scale up as well as being high in terms of accuracy of dimension and configuration thereof.
The triaxial woven fabrics can be designed so that a coefficient of thermal expansion is approximately zero to 0 with a single-layered structure, and exhibits an excellent dimensional stability. triaxial woven fabrics have opening holes and a flexibility thereof to absorb vibrations and an impacts, and are therefore strong against an impact load when launching.
A simple structure of a support member of a reflection surface may suffice.
A forming process can be simplified, and a stabilized quality and a decrease in costs can be attained.
Under such circumstances, there is a demand for the reflecting material of the triaxial woven fabrics which is usable for high frequency micro- and milli-waves through which a much larger quantity of information can be transmitted.
There has hitherto been, however, no antenna-oriented reflecting material using the triaxial woven fabrics, which is usable for frequency bands as high as 20-60 GHz.
It is a primary object of the present invention to provide an antenna-oriented reflecting material using triaxial woven fabrics which is usable for frequency bands as high as 20-60 GHz.
SUMMARY OF THE INVENTION
To accomplish the object described above, the present inventors have discussed that it is feasible to manufacture a reflecting material usable for high frequency bands without spoiling advantages of triaxial woven fabrics by controlling mainly a construction, a volume resistivity and a mass per unit length of the triaxial woven fabrics.
Namely, the present invention is, with an antenna reflecting material being composed of single-layered triaxial woven fabrics, characterized such that the relationship between a reflection ratio and a frequency of radio waves is varied by using as a parameter at least one of a construction, a volume resistivity, a mass per unit length and a fiber density of the triaxial woven fabrics, and each parameter is set so that the reflection ratio falls within an allowable reflection ratio range in a predetermined frequency band.
Namely, one, two or three or all four of the parameters may be changed. construction, the volume resistivity and the mass per unit length, and the fiber density may also be conceived important.
A number-of-filaments and a sizing content may also be added as parameters. The number-of-filaments is a factor pertaining to a thickness of the woven fabrics, and bears a proportional relationship with the mass per unit length if a diameter of the single fiber itself is the same. If the diameter of the single fiber itself is different, the number-of-filaments becomes an independent parameter. Further, the sizing content normally assumes a level within a range on the order of 3%, and is defined as an incidental parameter.
The setting of each of those parameters is determined by a composite model reflection ratio .GAMMA. obtained from a sum of a first reflection ratio .GAMMA.s based on a surface resistance of the triaxial woven fabrics and a second reflection ratio .GAMMA.p based on opening holes of the triaxial woven fabrics.
An influence by the weave opening holes is small in a low frequency
REFERENCES:
patent: 3874422 (1975-04-01), Dow
patent: 4438173 (1984-03-01), Trost
patent: 4868580 (1989-09-01), Wade
patent: 5168005 (1992-12-01), Keating et al.
patent: 5686930 (1997-11-01), Brydon
patent: 5702993 (1997-12-01), Kubomura et al.
Nguyen Hoang
Sakase-Adtech Co., Ltd.
Wong Don
LandOfFree
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