JPS61242402A - Circular polarizing grating - Google Patents

Abstract

PURPOSE:To facilitate the manufacture of a circular polarizing grating and to reduce its weight by weaving metallic wires with longitudinal or lateral threads made of nonmetallic fiber and setting and molding synthetic resin in the fabric into the polarizing grating. CONSTITUTION:A polarizing grating G is provided on both sides of a foamed material U in the same grating direction and the foamed material U uses a material with a low dielectric constant close to 1.0 such as foamed polyurethane and foamed polystyrene. The polarizing grating G is manufacture by sandwiching one sheet of fabric which operates as a susceptance element to radio waves between two sheets N of fabric made of only nonmetallic fiber and setting and molding the synthetic resin material P in them. The internal fabric has flexibility, the polarizing grating is formed in an optional shape. The fabric C is formed by weaving longitudinal threads and latitudinal threads 2 made of nonmetallic fiber and latitudinal threads 3 made of metallic wires together. The threads 1 and 3 are woven regularly at intervals determined properly according to the wavelength of an object electromagnetic wave.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a circularly polarized grating made of a woven fabric that exhibits susceptance characteristics to radio waves.

[Prior Art] Conventionally, as this type of circularly polarized grating, there is one shown in FIG. 5, for example.

The conventional circularly polarized grating shown in the figure has two polarized gratings H,
The gratings are arranged in the circular waveguide T at appropriate intervals with their grating directions aligned.

The polarization grating H is constructed by punching out a metal plate in a grid shape or by stretching metal wires around a rigid frame.

In addition to this, a circular waveguide is not used as a circularly polarized wave grating.
Some are constructed by fixing each grid in space by some means, such as a frame.

However, these conventional circularly polarized gratings have the following problems.

[Problems to be Solved by the Invention] Conventional circularly polarized gratings require the provision of a polarized grating and a circular waveguide, and moreover, the polarized gratings are arranged at predetermined intervals within the circular waveguide. Therefore, there are problems in that the number of manufacturing steps is large, and assembly is time-consuming and expensive.

In addition, since the polarization grating and the circular waveguide each have their own weight,
There is a problem in that the weight increases as a whole.

Furthermore, because the conventional structure supports the polarization grating only at its periphery, the mechanical strength of the polarization grating is insufficient and it is difficult to maintain sufficient strength against external mechanical forces. It is. Furthermore, it is difficult to configure it into an arbitrary shape.

In addition, in conventional models, the polarization grating and circular waveguide are made of metal, so they often rust when used in harsh environments such as at sea, and require maintenance. There's a problem.

The present invention was made to solve these problems; it is easy to manufacture, can be formed at low cost, is lightweight, can be formed into any shape, and has sufficient mechanical strength. The purpose of this invention is to provide a circularly polarized grating with excellent environmental resistance.

[Means for Solving the Problems] The present invention relates to a circularly polarized grating, and as a means for solving the problems, it is characterized by having the following constituent requirements.

First, metal filaments (hereinafter referred to as metal filaments) are placed at predetermined intervals and woven into either the warp or weft of a woven fabric made of non-metallic fibers, making it more effective against radio waves. A woven fabric that becomes a susceptance element is formed.

Second, the woven fabric is cured and molded together with a synthetic resin to form a polarization grating.

Third, align the polarization gratings with their grating directions,
They are arranged at appropriate intervals, and a low dielectric constant material is inserted or filled between each polarization grating.

[Function] In the first constituent element above, metal filaments are woven at predetermined intervals into either the warp or weft of the woven fabric made of non-metallic fibers, thereby becoming a susceptance element for radio waves. That's what I do. Since this polarization grating is in the form of a woven fabric, it has flexibility and can be formed into any desired shape. Moreover, this woven fabric can be formed in the same process as for manufacturing a normal woven fabric.

Further, by hardening and molding the woven fabric using a synthetic resin material, it is possible to obtain a polarized wave grating that is lightweight and has a certain shape. In this case, since the metal wire is covered with a synthetic resin, it is possible to prevent the occurrence of rust and it can withstand use under adverse environments.

Furthermore, aligning the grating directions of the plurality of polarization gratings,
By arranging them at appropriate rtn intervals, a circularly polarized grating is constructed that converts linearly polarized waves into circularly polarized waves by a phase difference caused by the direction of the electric field component with respect to the grating.

In this case, by inserting or filling a low dielectric constant material between each polarization grating, the polarization grating spacing is kept constant over the entire surface of each polarization grating, and the entire circular polarization grating is made rigid. There is.

In this way, the present invention forms a polarization grating by hardening and molding a woven cloth-type susceptance element with a synthetic resin material, and then arranges a plurality of the susceptance elements at regular intervals with a low dielectric constant material interposed in a circular shape. Since it is composed of a polarization grating, the number of manufacturing steps is small, and each step is simple, so it can be manufactured at low cost.

[Example] Embodiments of the present invention will be described with reference to the drawings.

<Configuration of Example> Figures 1A-IC show the configuration of an example of the circularly polarized grating according to the present invention, and Figure 1A is a partially cutaway perspective view thereof.
51B is a partial sectional view thereof, and the tiSIC diagram is a partially enlarged perspective view of the woven fabric serving as the susceptance element used in the configuration of this embodiment.

As shown in FIGS. 1A and 1B, the circularly polarized wave grating of this embodiment is constructed by bonding polarized wave gratings G to both sides of a foamable material U with their grating directions aligned.

As the foamable material U, a low dielectric constant material having a dielectric constant close to 1.0 is used, such as foamed polyurethane or foamed polystyrene. This foamable material U is made by bonding a polarization grating to a pre-foamed material, as well as fixing each polarization grating with a jig and then filling or injecting raw materials for the foamable material and a solvent to foam the material. It may be formed by

As shown in FIG. 1B, the polarization grating G has one woven fabric C that serves as a susceptance element for radio waves, and a woven fabric consisting only of two nonmetallic fibers (hereinafter referred to as nonmetallic woven fabric). These are sandwiched between N and then hardened and molded with a synthetic resin material P.

As the synthetic resin material P, for example, polyester resin, epoxy resin, acrylic resin, etc. are used.

The molding using the synthetic resin P can be made into any desired shape because the internal woven fabric has flexibility.

As shown in FIG. 1C, the woven fabric C that constitutes the polarization grating G and serves as a susceptance element is a mixture of warp threads L and weft threads 2 made of non-metallic fa fibers and warp threads 3 made of metal filaments. It is formed by The warp threads 1 and 3 are regularly woven at intervals determined appropriately depending on the wavelength of the target electromagnetic waves.

That is, in this embodiment, two warp threads 1 and one warp thread 3 are arranged.

The warp 1 and weft 2 and the non-metallic woven fabric N are manufactured using non-metallic fibers that can be fixed to the synthetic resin material P. Note that it is preferable that the warp threads 1 and weft threads 2 be firmly fixed. Therefore, the warp threads 1 and weft threads 2 should be selected appropriately in relation to the resin used. For example, for the resins listed above, glass m#I may be used I can do it.

On the other hand, the metal filaments used in the construction of the woven fabric C are as follows:
Metal wire such as aluminum or copper, or type 1 or 2
A combination of two or more metal wires twisted together, metal fibers, or carbon fibers can be used. Therefore, in this specification, the term "metal wire" is used not only to mean metal in the narrow sense but also to include things made of conductors such as carbon.

<Effects of Examples> Next, let's talk about the effect of the circularly polarized grating of this example.

This will be explained with reference to FIGS. 2 and 3 and using a theoretical model.

The following theory is based on “Broadband C1rcular Po1
arjsera ”by A, J, LAI↑Z, M
,A.

Marconi review project
This is a quotation from Ond Quarter, 1989.

As shown in FIG. 2, gratings Kl and 2 made of conductive wires such as metal wires are placed at a distance apart, and the polarization direction of the gratings Kl and 2 is θ. Consider a case where a linearly polarized electric field E is vertically incident from the Z-axis direction.

In this case, if the magnitude of the electric field is E, its X component Ex
, Fm minute EV becomes Eg = E cogθ E and = E 5ine , respectively.

Since the electric field perpendicular to the grating is known to be unaffected by the grating, the only change in the electric field component E is a phase change proportional to the propagation distance.

On the other hand, in circuit theory, the influence of the lattice on the electric field parallel to the lattice is assumed to be al conductive susceptance +# kh
-f L Jf Kanjima < 4L f! MIJ't
D 111 drunken world wavelength λ0. It can be expressed as a first equation as a function of the diameter d of the filament W and the lattice spacing a.

In the tree theory model, two lattices are used, so the equivalent circuit has susceptance B at both ends of the transmission line of length.
It becomes a form in which the are connected. For convenience, each end of the circuit has a length! By adding an L/2 transmission line, the circuit shown in FIG. 3 is obtained.

From the figure, it can be seen that the equivalent circuit of the polarization conversion grating consists of a cascade connection in which each circuit a is a unit. - Next, find the scattering matrix S of one circuit a.

Four-terminal constant F for a circuit with only susceptance B.

teeth.

1''(-3B?), and by converting this, the scattering matrix Sg is obtained as shown in the second equation.

8. “(j斐ㅅ)32j,B(,?,/A2:jB
() (2) Furthermore, since the transmission line connected before and after the susceptance B only provides a phase change, the scattering matrix S of the circuit a becomes a linear expression.

S = exp(-jφ) Sqexpc
−jφ ) “(X ψ) (3) Since the scattering matrix defines the incident electric field and reflected electric field at the input and output terminals, as shown in Figure 3, if we take the incident electric field and reflected electric field, we obtain the linear equation The relationship holds true.

Era-Y & +ZE12
(4) EoxZEX+YEI2
(5) E2+=YE22+ZErb
(8) Eo=ZE22+Yerb
(7) In the above formulas 4 to 7,
It is clear from FIG. 3 that Ell Snow E22 E12''E21. Also, if the output terminals are matched.

Erb+=.

Therefore, by substituting these conditions into the above-mentioned equations 4 to 7 and rearranging them, a linear relationship is obtained.

Era/Ex =YEL+Z2/(1-Y2)]
(8) Eo / Ex = Z2/ (1-Y2)
(9) Furthermore, if the input end is also matched, Era is 0, and considering that Y≠0, 1 +22
/ (1-Y2)=0 (10).

Therefore, by substituting the above equation 10 into the above equation 8.9, a linear equation is obtained.

Eo =EX Z2/ (1-Y2) =-EX (11) This is
When the electric field Ex passes through the polarization conversion grating, (2n+1)
This means that it undergoes a phase change of π (n: integer).

On the other hand, the amount of phase change of the electric field perpendicular to the lattice is 4φ(r
ad), a phase difference will occur between the two electric field components.

Therefore, by adjusting the polarization direction 0 of the incident electric field, the distance between the gratings, the incident electric field wavelength λ0 that determines the value of the susceptance B, and the grating wire diameter d9 interval a, linear polarization-circular polarization conversion can be performed. becomes possible.

Note that the explanation of the operation of the above embodiment is based on the case where the polarization grating is
Although the case where two or more polarization gratings are used is described, the present invention can also be applied to a case where three or more polarization gratings are used. In that case, a similar explanation can be made using a circuit in which the circuit a shown in FIG. 3 is cascaded in the number of polarization gratings.

<Modification of the embodiment> In the above embodiment, two polarization conversion gratings G are used.
In order to improve polarization conversion characteristics, three or more polarization gratings may be arranged at appropriate intervals with their grating directions aligned, and a low dielectric constant material may be inserted between each polarization grating.

In the above embodiment, non-metallic woven fabric N is used, but non-metallic cotton can also be used instead.

If necessary, both can be used in appropriate combination to enhance mechanical strength.

It is also possible to form a polarization grating by curing and molding only a woven fabric with susceptance element characteristics together with a synthetic resin, without combining it with a woven fabric made only of a non-metal mix or a cotton made only of non-metallic fibers. It is possible.

Further, in the above embodiment, the metal filaments are arranged in the warp direction, but they can also be arranged only in the weft direction to add susceptance element characteristics to the non-metallic woven fabric.

APPLICATIONS OF THE INVENTION The circularly polarized grating according to the present invention is lightweight and strong, and can be molded into any shape. For example, as shown in FIG. If the radar antenna A using a wave tube is used as the radome R, it can be easily changed to a circularly polarized radar antenna without changing the wave source. In this case, it also functions as a radome, so there is no need to provide a separate radome.
It is both economical and convenient.

[Effects of the Invention] As explained above, the present invention is easy to manufacture, can be formed at low cost, is lightweight, can be formed into any shape, has sufficient mechanical strength, and is environmentally resistant. This has the effect of realizing a circularly polarized grating with excellent properties.

[Brief explanation of drawings]

1A is a partially cutaway perspective view showing the configuration of an embodiment of a circularly polarized grating according to the present invention, FIG. 1B is a partially sectional view thereof, and FIG.
Fig. C is a partially enlarged perspective view of a woven fabric serving as a susceptance element used in the configuration of this embodiment, Fig. 2 is a perspective view showing a theoretical model for explaining the operation of the embodiment of the present invention, and Fig. 3 is a perspective view showing a theoretical model for explaining the operation of the embodiment of the present invention. A circuit diagram showing an equivalent circuit of the above theoretical model, FIG. 4 is a perspective view showing a marine antenna in which the circularly polarized grating of the present invention is applied to a radome, and FIG. 5 is a perspective view showing an example of a conventional circularly polarized grating. It is. H...Polarization grating T...Circular waveguide G...
・Polarization grating U...Foamable material C...Woven fabric that acts as a susceptance element for radio waves N...Non-metal woven fabric P...Synthetic resin material W...Conductive filament
Kl, Ni 2...Polarization grating 1...Warp
2...Weft 3...Warp

Claims (2)

[Claims] (1) Metallic filaments are arranged at predetermined intervals and woven into either the warp or weft of a woven fabric made of non-metallic fibers to form a woven fabric that acts as a susceptance element for radio waves. , and the woven fabric is cured and molded together with a synthetic resin to form a polarization grating, and the plurality of polarization gratings are aligned in the grating direction,
A circularly polarized grating characterized by being arranged at appropriate intervals and having a low dielectric constant material inserted or filled between each polarized grating. (2) The above-mentioned woven fabric is combined with a woven fabric made only of non-metallic fibers or cotton made only of non-metallic fibers, and these are cured and molded together with a synthetic resin to form a polarization grating, as claimed in claim 1. Circularly polarized grating as described.