JP2011061290A - Microstrip line-waveguide converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microstrip line-waveguide converter which is thin and superior in mass-productivity. <P>SOLUTION: The microstrip line-waveguide converter for converting a transmission mode between a microstrip line and a waveguide is formed by stacking a waveguide 1, a metal spacer 2, a first conductor layer 6 consisting of a microstrip line 4 having a patch pattern 3 formed on a terminal end and a base conductor pattern 5 surrounding the periphery of the patch pattern, a dielectric substrate 7, a base conductor layer 8 sequentially from the top at a position where the center of an opening of the waveguide 1 is superimposed on the center of the patch pattern. In the microstrip line-waveguide converter, a plurality of via holes 9 for connecting the base conductor pattern formed on the first conductor layer to the base conductor layer are formed to surround the periphery of the opening of the waveguide 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a microstrip line-waveguide converter for converting a transmission mode between a microstrip line and a waveguide.

  As a microstrip line-waveguide converter, for example, a structure described in Patent Document 1 is generally known. FIG. 4 shows a microstrip line-waveguide converter 100 described in Patent Document 1 as a conventional technique. The microstrip line-waveguide converter 100 includes a dielectric substrate 101, a waveguide 102, and a short-circuited waveguide block 103. The dielectric substrate 101 has a microstrip line 104 formed on one surface thereof and is fixed so as to be sandwiched between the waveguide 102 and the short-circuited waveguide block 103.

  The distance between the shorted surface of the shorted waveguide block 103 and the microstrip line 104 is a highly efficient conversion between the transmission mode (quasi-TEM mode) of the microstrip line 104 and the transmission mode (TE mode) of the waveguide 102. Therefore, it is set to about λ / 4 (λ is the wavelength of the signal transmitted through the waveguide 102).

  FIG. 5 shows a microstrip line-waveguide converter 200 described in Patent Document 1. The microstrip line-waveguide converter 200 includes a dielectric substrate 201, dielectric substrates 202 and 203 stacked on the dielectric substrate 201, and a layer between the dielectric substrate 201 and the dielectric substrates 202 and 203. And a dielectric-filled waveguide 205a, 205b, 205c is formed from the dielectric substrate 201 and the dielectric substrates 202, 203, and the dielectric-filled waveguides 205a, 205b, 205c are formed. A back short circuit is formed.

JP 2008-193162 A

  The size of the short-circuit distance (depth direction) of the short-circuited waveguide block 103 described as the prior art in Patent Document 1 shown in FIG. 4 is determined by the cross-sectional size of the waveguide 102 and the wavelength λ described above. That is, the short-circuited waveguide block 103 has the same cross-sectional dimension as the waveguide 102 and a length of about λ / 4. The short-circuited waveguide block 103 occupies a relatively large volume as compared with other members constituting the high-frequency circuit, which is one factor that makes it difficult to reduce the size of the high-frequency circuit.

  Further, the structure shown in FIG. 4 leads to an increase in the number of assembling steps because the dielectric substrate 101 and the short-circuited waveguide block 103 are individually manufactured and then an operation of joining them is necessary. Furthermore, this joining work requires high accuracy particularly in a high-frequency band such as the millimeter wave band, which may lead to variations in characteristics during mass production, and there is room for improvement in terms of mass productivity.

  Moreover, the microstrip line-waveguide conversion structure according to Patent Document 1 shown in FIG. 5 utilizes the wavelength shortening effect of the dielectric in the dielectric-filled waveguide, and the metal described in Patent Document 1 is used. Although it can be made shorter than the back short length made of the short-circuited waveguide block made of metal, if the relative permittivity of the dielectric used is εr, only the shortening effect shown in the following formula (1) can be expected. There was a limit to reducing the thickness.

  An object of the present invention is to provide a microstrip line-waveguide converter that solves the above-described problems and is thin and excellent in mass productivity.

  The microstrip line-waveguide converter according to the present invention is a microstrip line-waveguide converter that performs transmission mode conversion between a microstrip line and a waveguide. The microstrip line 4 having the patch pattern 3 formed at the end, the first conductor layer 6 including the ground conductor pattern 5 surrounding the patch pattern, the dielectric substrate 7, and the ground conductor layer 8 are guided. A microstrip line-waveguide converter in which the center of the opening of the tube 1 and the center of the patch pattern overlap in order from above, and the ground conductor pattern formed on the first conductor layer and the ground A plurality of via holes 9 for connecting between conductor layers are formed so as to surround the periphery of the opening of the waveguide 1.

  Furthermore, in the microstrip line-waveguide converter, the dimension L1 of the patch pattern 3 in the microstrip line direction is set to 0.3 to 0.5 times the effective wavelength λg of the frequency to be converted. To do.

  Further, in the microstrip line-waveguide converter, a via hole 9 connecting the ground conductor pattern formed in the first conductor layer and the ground conductor layer is formed so as to surround the opening of the waveguide 1. In this case, the interval between the adjacent via holes is arranged to be equal to or less than ¼ of the effective wavelength λg of the frequency to be used.

  According to the present invention, it is possible to provide a microstrip line-waveguide converter that is thin and excellent in mass productivity.

It is a disassembled perspective view of the microstrip line-waveguide converter which is one Example of this invention. It is sectional drawing explaining the conversion condition of the operation principle (excitation mode) of the microstrip line-waveguide converter which is one Example of this invention. It is a characteristic view which shows the relationship between the frequency of one Example of this invention, reflection loss, and transmission loss. It is a disassembled perspective view of the microstrip line-waveguide converter based on a prior art. It is sectional drawing of the microstrip line-waveguide converter based on another prior art. It is the schematic diagram which showed the shape of the patch pattern of a conversion part.

A microstrip line-waveguide converter according to the present invention includes a waveguide 1, a metal spacer 2, a microstrip line 4 having a patch pattern 3 formed at the end, and a ground conductor pattern 5 surrounding the patch pattern. A first conductor layer 6 made of the above, a dielectric substrate 7, and a ground conductor layer 8 are stacked in order from the top at a position where the center of the opening of the waveguide 1 and the center of the patch pattern overlap. It is a stripline-waveguide converter, and is converted from a mode (TE10) propagating in the waveguide to a mode (TM01) propagating the patch pattern due to the presence of the patch pattern 3 formed at the end of the microstripline 4. Then, mode conversion to a mode (quasi-TEM) propagating through the microstrip line becomes possible. The operating principle of the converter of the present invention is shown in FIG. Since the present invention uses TM01 mode conversion by the patch pattern, the back short length is made shorter than the wavelength shortening effect by the dielectric in the dielectric-filled waveguide described in Patent Document 1, The conversion part (conductor layer, dielectric substrate, ground conductor layer) can be thinned. Therefore, since there is no need for a joining step of the short-circuited waveguide block, the mass productivity is excellent.
In the microstrip line-waveguide converter according to the present invention, the metal spacer 2 has a hollow portion that matches the inner peripheral portion (shaded portion in FIG. 1) of the ground conductor pattern 5. The inner periphery of the ground conductor pattern 5 is a region having a width that is slightly larger than the line width of the patch pattern conversion region connected to the opening of the waveguide 1 and the microstrip line. Specifically, the patch pattern conversion region is the same as the opening size of the waveguide 1, and a region having a width slightly larger than the line width of the microstrip line is usually 0.3 mm on both sides of the microstrip line. It is a region having a width of ˜0.65 mm. The width of the ground conductor pattern 5 is such that the via holes 9 are arranged in a row, and is preferably 0.05 to 0.2 mm larger or 0.1 mm larger than the via hole diameter, for example. The metal spacer 2 may be larger than the ground conductor pattern 5.

Further, in the microstrip line-waveguide converter according to the present invention, the dimension L1 in the microstrip line direction of the patch pattern 3 is 0.3 to 0.5 times the effective wavelength λg of the frequency to be converted, TM01 mode conversion at a desired frequency can be efficiently realized, and as a result, conversion loss can be reduced.
For example, when the frequency to be used is 76.5 GHz, the effective wavelength λg of the frequency to be converted is about 2.5 mm. Therefore, the dimension L1 of the patch pattern 3 in the microstrip line direction is 0.75 to 1.25 mm. It is preferable that
The patch pattern of the conversion unit is preferably a square (rectangular), but may be any shape that can be converted into the TM01 mode, and may have an elliptical, circular, or polygonal structure (see FIG. 6).

Furthermore, the microstrip line-waveguide converter according to the present invention surrounds the via hole 9 connecting the ground conductor pattern formed in the first conductor layer and the ground conductor layer around the opening of the waveguide 1. When forming in this way, the conversion loss at a desired frequency can be reduced by arranging the interval between the adjacent via holes to be equal to or less than ¼ of the effective wavelength λg of the frequency to be used.
For example, when the frequency to be used is 76.5 GHz, the effective wavelength λg is 2.5 mm. Therefore, the interval between the adjacent via holes is preferably 0.63 mm or less.

Hereinafter, the present invention will be specifically described with reference to examples.
An embodiment of the present invention is shown in FIG. In this configuration, WR-10 (inside tube size: 2.54 mm × 1.27 mm) defined by EIA (American Electronics Industry Association) standard was used as the waveguide 1.
An aluminum plate having a thickness of 0.3 mm is used as the metal spacer 2, and the aluminum plate in a region having a width slightly larger than the line width of the patch pattern conversion region connected to the opening of the waveguide WR-10 and the corresponding microstrip line Was removed. As the first conductor layer 6, the dielectric substrate 7, and the ground conductor layer 8, a 0.1 mm thick copper clad laminate MCL-FX-2 (trade name, manufactured by Hitachi Chemical Co., Ltd.) is used. The microstrip line 4 and the ground conductor pattern 5 are formed, and the via hole 9 connecting the ground conductor pattern 5 and the ground conductor layer 8 is formed so as to surround the periphery of the waveguide WR-10 (dimensions of the patch pattern L1). : 1.0 mm, microstrip line width: 0.2 mm, via hole diameter: 0.3 mm in diameter). The interval between adjacent via holes was 0.6 mm.
The operating frequency was 76 to 77 GHz. Therefore, the effective wavelength λg of the frequency to be converted was 2.52 to 2.49 mm.

FIG. 3 shows transmission characteristics and reflection characteristics of the converter shown in the embodiment. FIG. 3 is a simulation result by a three-dimensional electromagnetic field simulator (manufactured by Ansoft, HFSS), and is a characteristic diagram when designed to be used at a frequency of 76.5 GHz (effective wavelength λg: 2.5 mm). Thus, the reflection loss in the frequency band to be used was -20 dB or less, and the transmission loss was less than -1 dB, showing good characteristics.
Therefore, when the reflection loss is minimal, the L1 dimension (direction of the width of the microstrip line) of the patch pattern is 0.4 times the effective wavelength λg, and the interval between via holes is 4.17 of the effective wavelength λg. A fraction of a minute.

  As described above, in the prior art, the back-short distance of the waveguide is 0.8 mm and about 1/4 of the wavelength λ in the waveguide, whereas in the present invention, mode conversion using a patch pattern is used. By using a copper clad laminate MCL-FX-2 (trade name, manufactured by Hitachi Chemical Co., Ltd.) having a thickness of 0.1 mm, the waveguide back-short is set to 0.1 mm and the wavelength λ within the waveguide. Therefore, it was confirmed that the microstrip line-waveguide conversion structure can be thinned.

1. 1. Waveguide 2. Metal spacer Patch pattern4. 4. Microstrip line 5. Ground conductor pattern Conductor layer 7. Dielectric substrate 8. Ground conductor layer9. Via hole 100. Microstrip line-waveguide converter 101 according to the prior art. Dielectric substrate 102. Waveguide 103. Shorted waveguide block 104. Microstrip line 200. Other prior art microstrip line-waveguide converters 201.202.203. Dielectric substrate 204. Microstrip line 205a. 205b. 205c. Dielectric filled waveguide 206. Waveguide 207. Via hole L1. Dimensions of patch pattern in microstrip line direction

Claims (3)

  In the microstrip line-waveguide converter for converting the transmission mode between the microstrip line and the waveguide, the waveguide (1), the metal spacer (2), and the patch pattern (3) are formed at the end. A first conductor layer (6) comprising a microstrip line (4) and a ground conductor pattern (5) surrounding the patch pattern, a dielectric substrate (7), and a ground conductor layer (8) are guided. A microstrip line-waveguide converter in which the center of the opening of the wave tube (1) and the patch pattern center overlap each other in order from above, and is formed in the first conductor layer (6). A microstrip line-conductor characterized in that a plurality of via holes (9) connecting the ground conductor pattern (5) and the ground conductor layer (8) are formed so as to surround the periphery of the opening of the waveguide (1). Wave tube converter.   The microstrip line according to claim 1, wherein the dimension (L1) in the microstrip line direction of the patch pattern (3) is 0.3 to 0.5 times the effective wavelength λg of the frequency to be converted. Waveguide converter.   When the via hole (9) for connecting the ground conductor pattern formed in the first conductor layer and the ground conductor layer is formed so as to surround the opening of the waveguide (1), the space between the adjacent via holes is formed. The microstrip line-waveguide converter according to claim 1 or 2, characterized in that they are arranged at a quarter or less of an effective wavelength λg of a frequency to be used.

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