JPS605605Y2 - Submillimeter wave band low loss transmission line - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a broadband, low-loss submillimeter waveband transmission line.

Conventionally, this type of transmission line is shown in Fig. 1a.

The one using the circular waveguide TEo1 mode shown in b, the second
There was one that used a focused beam transmission system using a dielectric lens as shown in the figure.

However, since the circular waveguide TEo1 mode is a high-order mode, in order to perform low-loss transmission, the waveguide has to be oversized, resulting in an increase in mode conversion loss due to bending, etc.

In addition, in a focused beam transmission system using a dielectric lens, there is reflection loss and absorption loss of the dielectric lens, and these losses become large in an ultra-high frequency band such as a submillimeter wave band.

Furthermore, there is a drawback that transmission loss increases due to a slight deviation in the set position of the lens.

In order to solve these drawbacks, the present invention is a submillimeter wave band low-loss transmission line using a focused beam transmission system using a spheroidal mirror, and will be described in detail below with reference to the drawings.

FIG. 3 shows an embodiment of the present invention, which has a structure in which a spheroidal mirror 2 having a focal point 1 is gradually shifted in the axial direction, and the principle of transmission operation can be explained in FIG. 4.

In FIG. 4, spheroidal mirrors 2 having a focal point 1 are successively arranged so that one of the focal points of adjacent identical spheroidal mirrors coincides with the focal point 1.

Now, when a radio wave enters from 3, it is reflected by the spheroidal mirror 2,
It is focused and reaches the next spheroidal mirror, and is similarly transmitted and can be taken out from 5.

Even if the light is incident from 4, it can be taken out from 6 in exactly the same way.

Loss in such a transmission path is thought to be due to diffraction loss due to spillover from the mirror surface and heat loss from the mirror surface.

Diffraction loss is shown in Figure 5. It depends on the Fresnel number N given by .

The larger N becomes, the smaller the diffraction loss becomes.

Therefore, diffraction loss can be reduced by appropriately selecting the size d of the mirror surfaces and the interval a between them.

Similarly, the ratio of the major axis (B/2) and minor axis (b/2) of the ellipse is c
It is related to l, that is, a, and is related to diffraction loss.

That is, if the focal length is e, then e=27(B/2)
2- (b/2) 2, and from the relationship of thorn = fraud, c =
e=2 (B 2) 2 (b 2) 2.

Also, due to the relationship between the pitch C and the length of the arc of the ellipse, c=2d
In the case of , the mirror surfaces 2 can be arranged without any gaps, and in the case of c>2d, there will be gaps, but this has nothing to do with achieving the objective of the present invention.

Therefore, the values of these parameters can be set arbitrarily within a range that satisfies the transmission path design conditions.

The heat loss varies depending on the polarization, but if we consider the case where the electric field is perpendicular to the plane of the paper as shown in FIG. 4, the heat loss is given by the following equation.

Here, f is the frequency, σ is the conductivity of the mirror surface, EQ=8.8
54×10 −2 (F/m).

Heat loss can be reduced by selecting a metal with a high electrical conductivity for the mirror surface.

Furthermore, multiplex transmission is possible on this transmission path.

That is, in FIG. 4, one transmission line can function equivalently to two transmission lines due to the incident radio waves from 3 and 4.

Furthermore, as shown in FIG. 4, even in a plane perpendicular to the plane of the paper, the same function as two transmission lines can be performed, which can be said to have a great economical advantage.

In the present invention, a spheroidal mirror is formed from a part of an ellipse having two focal points 1 with the axis passing through the two focal points continuously shifted in the axial direction. It will look like the figure.

Therefore, its operation is exactly the same as the principle explained in FIGS. 4 and 5.

That is, since the adjacent mirror surfaces on the opposite side share focal point 1,
The incident wave is reflected by the mirror surface and reaches the adjacent mirror surface on the opposite side.

By repeating this, the incident wave will be transmitted in the same manner as in FIGS. 4 and 5, and the same effect as in FIGS. 4 and 5 will be achieved.

Further, the transmission line of the present invention can be realized by winding it around a round bar having an elliptical curvature, and has the advantage that it is extremely easy to manufacture a long-distance transmission line and can be manufactured with high precision.

[Brief explanation of drawings]

1a and 1b are cross-sectional views and vertical sectional views showing an example of a conventional transmission line, FIG. 2 is a sectional view showing another example of a conventional transmission line, and FIG. 3 is a cross-sectional view showing an example of the conventional transmission line. 4 is a sectional view for explaining the principle of the transmission line, and FIG. 5 is a sectional view for explaining the operation of the transmission line in FIG. 4. 1...focal point, 2-spheroidal mirror, 3, 4...
...Input radio waves, 5, 6... Output radio waves.

Claims (1)

[Scope of utility model registration request] Two focal points F1. A spheroidal mirror obtained by rotating a part of an ellipse with F2 around an axis passing through two focal points,
A submillimeter wave band low-loss transmission line, characterized in that the focal point is formed continuously in the axial direction as it rotates, and the mirror surface is formed in a spiral shape.