JPS6324561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to the structure of a waveguide orthogonal section for microwave and millimeter wave bands.

(b) Background of the technology Hollow waveguides have good attenuation loss for the propagation of electromagnetic waves in the microwave band, and rectangular waveguides with a rectangular cross section are the most commonly used in practical use. Generally, a 1:2 rectangular cross section is standard. Furthermore, the cutoff frequency that can be propagated is determined by this rectangular size. For this reason, as the frequency moves to a higher region, the rectangular cross section of the waveguide is also becoming smaller. In a practical structure using a waveguide, the rectangular direction cannot be fixed, and a twisted waveguide (twist) is used to change the polarization plane in some cases. However, if the transmission direction is suddenly changed, reflected waves are generated, and due to processing limitations, the length of the twisted portion must be at least twice the wavelength.

(c) Conventional technology and problems Figure 1 is a perspective view of a conventional torsion waveguide.
The figure shows a rectangular section twisted 90 degrees. Note that the mounting structures at both ends are omitted. Twisted waveguides are processed by filling a rectangular tube with filler, softening it by heating, and twisting it, or by using complicated handicraft processing techniques such as electroforming, which requires skill and is expensive. .
Moreover, it occupies space and becomes a constraint from a design standpoint.

The lengths A and B of the sides of the rectangular dimension of the torsion waveguide are limited by the wavelength as well as the torsion length L.

As a means of solving this problem, a waveguide transmission element was invented in which two waveguides with polarization planes different by 90° are joined at their connection surfaces with an extremely thin metal (Japanese Patent Application No. 52-115106). ).

FIG. 2 is an exploded perspective view of a conventional waveguide transmission element. The rectangular hole 11a of the waveguide 11 and the rectangular hole 12a of the waveguide 12 differ in direction by 90 degrees. An extremely thin metal plate 13 is interposed between the two waveguides 11 and 12, and the metal plate 13 has an L-shaped conductor in the overlapped part of the two opposing rectangular holes 11a and 12a. A section 13a is configured. In reality, the waveguide 11, metal plate 13, and waveguide 12 are integrally coupled in the directions of arrows A and B.

FIG. 3 is an enlarged view of an L-shaped conductor portion of a metal plate of a conventional waveguide transmission element. A rectangle 14 indicated by a two-dot chain line indicates a rectangular hole 11a of the waveguide 11, and a rectangle 14
5 indicates a rectangular hole 12a of the waveguide 12. With respect to the side B of the square 16 where the two rectangles overlap, the two sides C of the center line of the L shape shown by the dashed line have a relationship of C=1/2B. This L-shaped conductor exhibits magnetic induction on the side perpendicular to the magnetic field with respect to the waveguides 11 and 12, and exhibits electrical capacitance on the side perpendicular to the electric field. Therefore, the L-shaped conductor as a whole corresponds to a low frequency LC resonant circuit. Since the relationship between the waveguide 11 and the waveguide 12 is completely opposite, the polarization direction of the electromagnetic field is changed by 90 degrees due to the interposition of the L-shaped conductor. That is, induction and capacitance conversion using an L-shaped conductor.

The invention described above has made it possible to convert the polarization direction with a simple structure instead of using a twisted waveguide.

(d) Object of the Invention The present invention is intended to further improve the efficiency and degree of freedom of the above-mentioned coupling method.

(e) Structure of the Invention The present invention involves interposing an extremely thin metal plate between the bonding surfaces of first and second waveguides in which the planes of polarization of electromagnetic waves to be transmitted differ by 90 degrees. A first slot parallel to the H-plane of the first waveguide is provided, and the first slot is parallel to the H-plane of the first waveguide.
One end of a second slot provided parallel to the H-plane of the second waveguide is connected to one end of the slot, and the other end of the second slot is connected to the H-plane of the first waveguide. The process of connecting one end of the third slot provided in parallel to the slot is repeated N times (N is 1, 2, etc.) to form a slot part, and the integrated total length in the vertical direction and the integrated total length in the horizontal direction of the slot part are The above object is achieved by a waveguide circuit element characterized in that the waveguide circuit elements are the same and the sum thereof is n/2 (n is a positive integer) of the internal wavelength of the electromagnetic waves.

(f) Embodiments of the Invention FIG. 4 is a plan view of a slit portion for slit mode coupling of a waveguide according to the present invention, in which the left side is a metal plate and the right side is an enlarged view of the slit. Diagram A shows a Z-shape, diagram B shows a staircase shape, and diagram C shows a key shape.

The common point in all three figures is that the cumulative total length D of the slit in the horizontal direction and the cumulative total length E of the slit in the vertical direction are equal. There is a constant proportional relationship with the wavelength being propagated. Thickness of slit
It is processed using the etching method on a 50μm copper plate.

In the present invention, the slit is used as a slot coupling to confine the resonant electromagnetic energy within the slit, and use this resonant energy as an intermediary to convert it into polarized waves with a 90° phase difference. be. That is, in all three figures, the slits are equal in both the vertical and horizontal directions, and the total length is 2D or 2E.

The principle of the present invention is a method of forming an excitation state of an electromagnetic field in the space of the slit portion in accordance with the length and wavelength of the slit, and is a well-known principle applied to slot antennas. In this state, a symmetrical electromagnetic field is formed as a mirror surface, as if the slit itself were a virtual transmitter. In the present invention, two orthogonal
Because of the slits spanning the sides, propagation is possible even with a 90° phase difference.

The shape of the slit is not limited to the shape shown in FIG. 4, and any slit configured symmetrically on two orthogonal sides can provide the same effect. Further, as the metal plate, a copper plate is generally used, but there are no particular restrictions, and the thickness should be selected depending on the characteristics and processing method.

(g) Effect of the invention According to the present invention, the conventional invention
115106), it has a smaller and simpler structure than a twisted waveguide, and can be used for more efficient polarization direction conversion.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a conventional torsion waveguide, Figure 2 is an exploded perspective view of a conventional waveguide transmission element, and Figure 3 is an L of a metal plate of a conventional waveguide transmission element.
FIG. 4 is an enlarged view of the letter-shaped conductor portion and a plan view of the slit portion of the slit mode coupling of the waveguide according to the present invention. In the figure, 11, 12 are waveguides, 23, 33,
43 is a metal plate.

Claims (1)

[Claims] 1 First, the polarization plane of the electromagnetic waves to be transmitted differs by 90°.
An extremely thin metal plate is interposed between the bonding surfaces of the first waveguide and the second waveguide, a first slot parallel to the H-plane of the first waveguide is provided in the metal plate, and a first slot is provided in the metal plate parallel to the H-plane of the first waveguide. One end of a second slot provided parallel to the H-plane of the second waveguide is connected to one end of the slot, and the other end of the second slot is connected to the H-plane of the first waveguide. Connecting one end of the third slot provided in parallel to N
A slot portion is formed by repeating the process several times (N is 1, 2, etc.), and the cumulative total length of the slot portion in the vertical direction and the cumulative total length in the horizontal direction are the same, and the sum is n/2 ( A waveguide circuit element characterized in that n is a positive integer.