JPS60146504A - Rectangular-circular waveguide converter - Google Patents

Abstract

PURPOSE:To attain excellent matching over a broad band by inserting a rectangular waveguide near square form and a long elliptic waveguide for the conversion from the rectangular waveguide into the circular waveguide. CONSTITUTION:The shape of cross section of the long elliptic waveguide 5 is as shown in Fig. (b) and close to the shape of cross section of the rectangular waveguide 1 to be converted as shown in Fig. (a). On the other hand, the rectangular waveguide 6 connected to the circular waveguide 2 to be converted as shown in Fig. (d) has the shape of cross section close to a square in matching with the shape of cross section of the circular waveguide 2 as shown in Fig. (c). Thus, the conversion between both said waveguides is conducted very smoothly. Moreover, the long elliptic waveguide 5 and the rectangular waveguide 6 close to a square are in the relation of shape as shown in Figs. (b) and (c) and the conversion of both is conducted smoothly. As a result, the rectangular-circular waveguide converter constituted above has a broad band matching characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to line conversion of each microwave line in a microwave circuit, and is particularly commonly used in antennas and microwave receivers for satellite broadcast reception. Rectangular waveguide required for line conversion of two circular waveguides -
It concerns a circular waveguide conversion device.

Conventional configuration and its problems An example of a conventional rectangular-circular waveguide device is shown in FIG.

In the figure, a rectangular waveguide 1 is smoothly converted to a circular waveguide 2 by providing a taper from a circular shape to a rectangular shape. However, in this case, there is a drawback that the overall length is extremely long, which is inconvenient when attached to a receiver or the like.

FIG. 2 shows another conventional example. In FIG. 2, an elliptical waveguide 4 is inserted between a rectangular waveguide 1 and a circular waveguide 2 to perform rectangular-circular waveguide conversion. This method can shorten the total length compared to the taper type shown in Figure 1, but has the disadvantage of narrowing the bandwidth.In Figures 1 and 8, 1 is a rectangular waveguide, and 2 is a rectangular waveguide A circular waveguide, 3 is a tapered waveguide from a rectangular to a circular waveguide, and 4 is an elliptical waveguide.

OBJECTS OF THE INVENTION The present invention aims to eliminate such drawbacks and provide a rectangular to circular waveguide conversion device that has a wide band, has good matching impedance, and can have a short overall length.

Structure of the Invention The rectangular-circular waveguide conversion device according to the present invention connects an elongated waveguide to a first rectangular waveguide, and connects a second rectangular waveguide to the elongated waveguide. The first rectangular waveguide and the circular waveguide are connected by connecting the first rectangular waveguide and the circular waveguide to the second rectangular waveguide. It is possible to obtain a conversion device that can perform the conversion smoothly.

Description of examples An embodiment of the present invention is shown in FIGS. 3 and 4.

In FIG. 3, 1 is a rectangular waveguide, 2 is a circular waveguide, and 5.6 is an oblong waveguide connected between the rectangular waveguide 1 and the circular waveguide 2, and a square waveguide. It is a nearly rectangular waveguide.

FIG. 4 shows how this connection is made. Figure a shows a connection sectional view of each waveguide, and figures b and c show input front views seen from the input side of the rectangular waveguide 1 and the input side of the circular waveguide 2. In FIG. 4, the same reference numerals as in FIG. 3 indicate the same parts.

That is, in FIG. 4, the conversion from the rectangular waveguide 1 to the circular waveguide 2 is performed in two stages, and the rectangular waveguide 1 is first converted into the circular waveguide 2.
Two parallel sides having a width larger than the width of the E plane of the rectangular cross section are connected to an elongated elliptical waveguide 5, which is a first conversion waveguide and is surrounded by two circular arcs. In this case, the area of the arc of the long elliptical waveguide 5 cut by the E plane of the rectangular waveguide 1 in the connection cross section,
The areas of the two corners of the rectangular waveguide cut by the arc of the long elliptical waveguide 5 are made to be equal. The waveguide 6 is smoothly transformed by electric field coupling, as shown by the electric field distributions 1 and 5 in FIG.

Next, a fourth waveguide is placed between the long elliptical waveguide 5 and the circular waveguide
A rectangular waveguide 6 having a nearly square cross section as shown in 6 in the figure or FIG. 5 is connected, and then a circular waveguide 2 is connected. The rectangular waveguide 6 has a shorter width a2 (corresponding to the width of the H plane) and a longer vertical width b2 (corresponding to the width of the E plane) than the width a of the regular rectangular waveguide 10. It has a nearly square cross section that is slightly longer than the width (an aspect ratio of about 6:5), and each corner of the cross section has a slight curvature. However, the width of this rectangular waveguide 6 is approximately equal to the diameter of the circular waveguide 2.
The vertical width is slightly longer than this diameter.

By doing so, the circular waveguide 2 and the rectangular waveguide 6 are smoothly converted by electric field coupling as shown at 2 and 6 in FIG. On the other hand, as is clear from the electric field distribution at 5.6 in FIG. 6, the rectangular waveguide 6 and the oblong waveguide 50 are smoothly coupled.

Generally, a circular waveguide exhibits a higher characteristic impedance than a rectangular waveguide. In other words, the characteristic impedance Zw of a rectangular waveguide is, where λg□ is the wavelength inside the tube, zo is the characteristic impedance in free space, a, b are the long and short sides of the rectangular waveguide, and λ is the wavelength in free space. There is a wavelength of

Now, the rectangular waveguide is defined as W'Rγ5 (a = 19.05mm
.

b=a/2), the input signal frequency is 11.7GH
The characteristic impedance ZWR at z and 12.2 GHz is 509 (Q and 493 (g).

On the other hand, the characteristic impedance ZWo and the guide wavelength λ9o of the circular waveguide are expressed by the following equation.

r: radius of circular waveguide, x (m, m): Beso cell function Tm (x (m, +n))
= root of 0, In TE11 mode, TI(x(i, 1))-〇, and x(1,1)=, 1.841.

Input signal frequency is 11.7GHz and 12.2GHz
When the circular waveguide is CR62 (r≠8) at the time of z, the characteristic impedance is Zwo1 = 1249 (
wealth).

Zwo2≠930 (, Q, and the characteristic impedance is about twice that of the rectangular waveguide described above. Therefore, waveguide conversion between a rectangular waveguide and a circular waveguide can be performed with a short waveguide length. It is not easy to configure them so that they can be combined smoothly.

Therefore, in this device, as shown in FIG. 4 and FIG. A tube 6 is provided, and the width a1 of the long elliptical waveguide 5 is the same as the width a of the rectangular waveguide 1. , and the height bl is the height of the rectangular waveguide 1. The characteristic impedance of the elongated elliptical waveguide 6 is increased by increasing the width a2 of the rectangular waveguide 1. Narrower and taller elongated waveguide 5
By increasing the height bl of the circular waveguide 2, the characteristic impedance becomes larger from the equations
The characteristic impedance is close to that of , and smooth waveguide conversion is obtained. Further, the length of the rectangular waveguide 6 is made approximately 1.5 times longer than the length of the oblong waveguide 5, thereby making the coupling from the circular waveguide 2 smoother.

In FIG. 5, the rectangular waveguide 1 is a. -19.05 hours.

If bo -9, 5tnm (WR75) and circular waveguide 20 radius r # 8 mm (CR62), elongated elliptical waveguide 5 has b1 13 mm and arc radius R #1.
0 mm, the waveguide length is about 81 mm, and the square type rectangular waveguide 6 has a wave length of 15 rnm and a waveguide length of 18 ran for both a and b.
, especially at 12 GHz by setting the waveguide length to about 12 mm.
It is possible to construct a broadband matched rectangular-to-circular waveguide converter in the band (approximately 11.7 to 12 GHz, 7 GHz). Therefore, as shown in FIG. A simple rectangular-circular waveguide converter is constructed by attaching flanges of a rectangular waveguide (WR75) and a circular 4-wave tube (CR62) to both ends of an integrated rectangular waveguide 6 similar to the one shown in FIG. Furthermore, as shown in FIG. 6, by attaching flanges to the elongated waveguide 5 and the rectangular waveguide 6, a very small rectangular-circular conversion adapter with a total length of about 2 saws can be created. It can be configured as

In addition, in FIG. 6, 7 and 8 indicate flanges, and 9 indicates a fastening hole of the flange.

Effects of the Invention As described above, according to the present invention, conversion between a circular waveguide and a rectangular waveguide can be performed with good matching over a wide range and with low loss (0,01
dB or less) and can be configured with a very short structure, making it possible to provide a small and inexpensive rectangular-circular waveguide converter and conversion device.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional tapered rectangular-circular waveguide converter, and FIG. 2 is a perspective view of another conventional rectangular-circular waveguide converter via an elliptical waveguide. FIG. 3 is a diagram showing the opening surface of each rectangular waveguide in one embodiment of the present invention, and FIG. 6 is a cross-sectional view of a main part showing an example of a rectangular to circular waveguide conversion adapter in another embodiment of the present invention. It is a diagram. 1... Rectangular waveguide, 2... Circular waveguide, 5... Long elliptical waveguide, 6... Rectangular waveguide, 7, 8...Flange. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
month, 3

Claims (6)

[Claims] (1) Connect an elongated waveguide to the first rectangular waveguide, connect a second rectangular waveguide to the elongated waveguide, and connect the second rectangular waveguide to the elongated waveguide.
A rectangular-circular waveguide characterized in that the first rectangular waveguide and the circular waveguide are coupled by connecting the circular waveguide to the rectangular waveguide. conversion device. (2) The long elliptical waveguide is connected so that the longitudinal direction of the cross section of the second rectangular waveguide is orthogonal to the longitudinal direction of the cross section of the second rectangular waveguide. Rectangular-circular waveguide conversion device. (3) The width ratio of the H-plane and E-plane of the first rectangular waveguide is 2:1.
and the H plane of the first rectangular waveguide of the second rectangular waveguide, E
2. The rectangular-to-circular waveguide conversion device according to claim 1, wherein the horizontal to vertical ratio corresponding to the plane is 2:1 or less. (4) The rectangular-circular waveguide conversion device according to claim 1 or 3, characterized in that each corner of the inner wall of the second rectangular waveguide has a constant curvature. . (5) The two long sides of the cross section of the long elliptical waveguide are parallel and the distance between them is larger than the width of the E plane of the first rectangular waveguide, and the other two sides are formed by circular arcs. The diameter of the arc is the first
The length must be equal to or greater than the width of the H-plane of the rectangular waveguide, and the E
2. The rectangular-circular waveguide conversion device according to claim 1, wherein the length is shorter than the diagonal length of the H-plane. (6) The length of one set of two parallel sides of the second rectangular waveguide cross section is equal to or less than the diameter of the circular waveguide, and the length of the other two parallel sides is set to the diameter of the circular waveguide. Claim 1, item 2, characterized in that the length is longer. The rectangular-circular waveguide conversion device according to item 3 or 4.