JPH02280503A - Microwave device - Google Patents

Abstract

PURPOSE:To attain a microwave device with excellent massproductivity, small size and light weight without deteriorating the characteristic of a square waveguide by constituting at least one guide wall among four guide walls forming a square waveguide with a printed circuit board whose rear side is made of a ground conductor. CONSTITUTION:A ground conductor 3 is provided to the entire face of the rear side of a circuit board 2, the ground conductor 3 is arranged in contact with a metallic member 1, and the circuit board 2 is fitted to the metallic member 1 with a machine screw 4. Through the constitution above, three guide walls of a square waveguide are formed by the metallic member 1 and the remaining one guide wall is made of the ground conductor 3. Since the circuit board is utilized as the guide wall of the square waveguide, a compact microwave device is obtained, in which the waveguide and the microwave circuit are integrated by forming the circuit pattern on the surface of the circuit board.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a microwave device used in a satellite broadcast receiving converter or a microwave communication device.

2. Description of the Related Art Conventionally, microwave devices of this type are made of metal materials.
A rectangular waveguide with two tube walls is used. A perspective view of this rectangular waveguide is shown in FIG. In FIG. 4, 19 is a flange, and 20 is a waveguide made of a metal material. When radio waves propagate within this waveguide, a high frequency current is generated on the wall of the waveguide, so the wall must have electrical conductivity. Such conventional waveguides are constructed by applying a metal plate to a metal member having a concave groove, and screwing or brazing the two together. Furthermore, in the case of mass-produced products, a mold is made in which a rectangular column is provided with a punched taper, and the waveguide is thereby constructed by the Guicasting method. The wall of the waveguide formed by either method is for constructing the waveguide itself.

Problems to be Solved by the Invention When manufacturing such a rectangular waveguide by die-casting, if the axial length of the rectangular waveguide is long, the characteristics of the rectangular waveguide will change due to the influence of the taber of the mold. It deteriorates compared to something without it. In addition, the method of attaching a metal plate to a concave metal member and fixing it with screws requires two waveguide parts,
The method of brazing a concave metal member and a metal plate is not suitable for mass production due to the time required for brazing and the working environment for brazing. Furthermore, in the case of a general microwave device, a rectangular waveguide is rarely used alone, and functions are often realized by combining this with a circuit board. In this case, since there is a shield case that houses the waveguide and the circuit board, there is a limit to how small and lightweight the microwave device can be made.

The present invention has been made in view of the problems in the conventional technology,
The purpose of this invention is to enable a small and lightweight microwave device that can be easily mass-produced without deteriorating the characteristics of the rectangular waveguide.

Means for Solving the Problems In order to solve the problems, the present invention provides a circuit board in which at least one of the four pipe walls constituting the rectangular waveguide is made of a circuit board whose back surface is a ground conductor. It is something.

In other words, a circuit board is placed on a metal member in which a concave groove is formed by removing one of the walls of a conventional waveguide, so as to cover the groove. In this case, a ground conductor is formed on the back surface of the circuit board, and the lid is placed so that the ground conductor and the concave metal member come into contact with each other.

Effect With this configuration, the ground conductor provided on the back side of the circuit board has conductivity, so it functions equivalently to the removed pipe wall, and the concave metal member and this ground conductor This means that a rectangular waveguide is formed. In addition, when manufacturing a rectangular waveguide with such a configuration by die-casting, when the dimensions of the opening surface of the rectangular waveguide are a and b, and the axial length of the rectangular waveguide is L, a, b Even when L is sufficiently large compared to , the direction in which the mold is extracted is perpendicular to the tube axis of the rectangular waveguide, so the extraction taper can be small.

Therefore, deterioration of waveguide characteristics can be suppressed. Furthermore, if a rectangular waveguide is constructed by processing a part of the inner surface of the shield case into a concave shape and storing the circuit board in this shield case, the concave part is covered. Since the tube and the shield case are integrated, and the circuit board itself also serves as the tube wall of the rectangular waveguide, it is possible to achieve a reduction in size and weight.

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

FIG. 1(a) is a perspective view showing a first embodiment of the present invention. In the figure, 1 is a concave metal member, and 2 is a circuit board. A ground conductor 3 is provided on the back side of this circuit board 2.
is provided on the entire surface of the board, and this ground conductor 3 is connected to the metal member 1.
The circuit board 2 is attached to the metal member 1 with screws 4. With this configuration, three tube walls of the rectangular waveguide are constituted by the metal member 1, and the remaining tube wall is constituted by the ground conductor 3. In this example, as the ground conductor 3, the copper provided on the front surface of a double-sided steel-clad board is removed by etching, and the copper on the back surface is left as is. The opening dimensions of the waveguide are 19.05 x 9.525 m
This is the one used in 12 GHz band satellite broadcasting. Considering the skin effect at the operating frequency, it is important for the thickness of the ground conductor 3 to be sufficiently thicker than the skin depth in order to reduce loss, and in this embodiment, it is set to 18 μm. If the thickness of the circuit board 2 is too thin, the circuit board 2 will become wavy when fixed, which is not preferable. In other words, it is necessary for the tube wall to have a certain degree of hardness, and in this embodiment, a 0.8 mm thick Teflon laminated base material is used as the circuit board. If the number of screws 4 for attaching the circuit board 2 to the metal member 1 is too small, a gap will be created between the metal member and the ground conductor 3, and the characteristics of the rectangular waveguide will deteriorate.

4 in the frequency used to suppress radio wave leakage.
It is important to fasten with screws at intervals of one-tenth of a wavelength or less.

Although this embodiment shows an example in which a circuit pattern is not configured on the back side of the circuit board 2, it is possible to provide a circuit pattern on the front side and configure a circuit with the functions shown here. . Since a circuit board is used as the tube wall of the rectangular waveguide, a compact microwave device in which the waveguide and microwave circuit are integrated is possible by configuring a circuit pattern on one surface of the circuit board. . This example is the first example.
Shown in Figure (b). FIG. 1(b) shows a perspective view of an amplifier constructed by a circuit pattern 5 and a transistor 6 on the surface of the circuit board 2 shown in FIG. 1(a').

In this embodiment, one opening of the rectangular waveguide is short-circuited, and a probe 7 is installed perpendicular to the magnetic interface at a position about a quarter wavelength away from the opening in the tube axis direction. One end is connected to the circuit pattern 5. therefore,
The radio waves incident on the opening surface of the rectangular waveguide shown in FIG. 1(b) are picked up by the probe 7, guided to the circuit pattern 5, and amplified by the transistor 6. In the figure, reference numeral 8 denotes a ground pattern for grounding the ground electrode of the transistor, which is connected to the ground conductor on the back surface through a through hole. In this case, the inner diameter of the through hole is selected to be sufficiently smaller than the wavelength of the incident radio wave. By doing so, leakage of radio waves from the through holes can be suppressed.

Next, a second embodiment of the present invention will be described using FIG. 2. FIG. 2(a) is a top view when the circuit board 2 is housed in the shield case 9, and FIG. 2(b) is a sectional view taken along the line AA' in FIG. 2(a'). A concave portion 10 is provided on a part of the inner surface of the shield case 9. A ground conductor 3 is provided over the entire back surface of the circuit board 2, and a microstrip line 11 is provided on the back surface. A probe 7 is installed at the tip of the microstrip line.
It is set up in the same way as Figure 1 ■. With this configuration, a rectangular waveguide with both openings short-circuited at the recess 10 is constructed by the shield case 9 and the circuit board 2. When the input end 12 is excited, the signal propagating through the microstrip line 11 is guided to the probe 7, and further propagates through the recess 10, which is a rectangular waveguide, to the probe 7 on the right side.
It is picked up at the output terminal 13 and guided to the output terminal 13. Since the rectangular waveguide passes frequencies higher than the cutoff frequency, the microwave device according to this embodiment realizes a bypass filter. The longer the length of the recess 10, the greater the amount of attenuation below the cutoff frequency.

Further, as a matter of course, a desired value of the cutoff frequency can be obtained by setting the width a of the recess 10. Forming a concave groove in advance on the inner surface of the shield case housing the circuit board as shown in this embodiment can be easily done by the Guicasting method, and is extremely convenient for mass production.

Next, a third embodiment of the present invention will be described using FIG. 3. FIG. 3 shows a top view when the circuit board 2 is housed in the shield case 9, similar to FIG. 2(a). In the case of this implementation as well, in the same manner as the second example,
A concave groove is formed on the inner surface of the shield case.
This and the ground conductor provided on the back surface of the circuit board 2 form a rectangular waveguide with both openings short-circuited. The probe 7 is also provided in the same manner as in the second embodiment, and this rectangular waveguide portion forms a bypass filter. A circuit pattern of a microwave mixer using a diode 14 is formed on the surface of the circuit board. One electrode of the diode is grounded through a through hole 15.

In the figure, 16, 17, and 18 respectively indicate an RF input terminal, a single station oscillation input terminal, and an IF output terminal. The signal frequency relationship of the mixer shown in this embodiment is f IF = J RF - f LQ·fRF>fL.

Suppose that Here, 51p*5Rv and fto are the IF frequency, RF frequency, and LO frequency, respectively.

The mixer shown in this embodiment has a configuration in which an RF boat is provided with the bypass filter described in the second embodiment, and an image signal (j + m =
2 fto -far, f IN is the image frequency)
This is an attempt to remove the . The width a of the recess 10 is set so as to provide a cutoff for the image signal. Furthermore, if it is desired to suppress the leakage of the local signal to the RF input terminal, the width a of the recess 10 should be further narrowed and jLo
What is necessary is to set the cut-off to .

Effects of the Invention As described above, according to the present invention, in order to configure at least one of the four walls of the rectangular waveguide with a circuit board, the waveguide part and the microwave circuit part are This makes it possible to integrate the waveguide into one piece, making it possible to downsize the microwave device.Furthermore, even if the tube axis of the rectangular waveguide is long, the concave metal member can be easily manufactured by die-casting. It is possible to reduce the cutting bar of the mold, and there is an effect that waveguides in excellent condition can be manufactured with good mass production.

In addition, a circuit pattern such as a mixer is formed on the circuit board that makes up the tube wall, a shield is used to house the pattern, and a filter is constructed using a rectangular waveguide in the case.By combining these, a microwave device with excellent characteristics can be achieved. can be realized.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are perspective views of a microwave device according to a first embodiment of the present invention, and FIGS. 2(a) and (b) are
) are a top view and a sectional view of a microwave device according to a second embodiment of the present invention, FIG. 3 is a top view of a microwave device according to a third embodiment of the present invention, and FIG. 4 is a conventional rectangular waveguide. FIG. 3 is a perspective view of the tube. DESCRIPTION OF SYMBOLS 1...Concave metal member, 2...Circuit board, 3...Grounding conductor provided on the back side of the circuit board, 4
...screw, 5... circuit pattern, 6.
...Transistor, 7...Probe, 8
...Grounding pattern, 9...Shield case, 10...Recess, 11...Microstrip line, 12...Input end, 13・・・
...Output end, 14...Diode, 15.
...Through hole, 16...RF input terminal, 17...Local oscillator input terminal, 18...I
F output terminal. Name of agent: Patent attorney Shigetaka Kurino and 1 other person 5-11 times 1 sipeder> δ--41 Kaggukun Tomi 11!1 Figure (α) <b) Now-do-sp-up U-de 9- Nno L booth 10-Ikkoha I4- Diode 15--S A/Hose υ

Claims (4)

[Claims] (1) A microwave device characterized in that at least one of the tube walls of a rectangular waveguide is constituted by a circuit board provided with a ground conductor on the back surface. (2) A shield case with a part of the inner surface processed into a concave shape and a circuit board with a ground conductor on the back surface are provided, and the back surface of the circuit board is applied to the concave part of the shield case to form a rectangular waveguide. A microwave device according to claim (1) comprising: (3) The cutoff frequency of the rectangular waveguide according to claim (2) is set higher than the local oscillation frequency, and the rectangular waveguide is provided at the input end of the RF signal of the mixer. microwave equipment. (4) Claims (3) for the output stage of low-noise preamplification
A microwave device comprising the microwave device described above.