JP3169972B2 - Waveguide-microstrip line converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide-microstrip line converter used for an input / output circuit of a microwave or millimeter-wave integrated circuit.

[0002]

2. Description of the Related Art As shown in FIG. 5A or 5B, a waveguide-to-microstrip line converter using a fin line has a tapered fin line 1 and a microstrip line 2 and a microstrip line 2 between them. The conversion unit 3 is formed on a single substrate 4 made of a dielectric material, and the substrate 4 is loaded in the waveguide 5. Specifically, it is configured to be converted into a microstrip line 2 from a waveguide 5 via a tapered fin line 1 and a low impedance conversion unit 3 also formed of a fin line. The fin lines used in the converter having such a configuration are called an antipodal type on the upper and lower surfaces of the substrate 4.
Conductor films A and B called fins as shown by solid lines and broken lines are formed and configured. The conductor films A and B are formed so that they do not overlap each other at all or only their edges overlap each other. One end of each of the conductor films A and B is connected by directly contacting the inner wall surface of the waveguide 5, or is connected so as to be short-circuited at a high frequency.

In the converter shown in FIG. 5A, in order to convert the tapered fin line 1 into a microstrip line 2, in the converter 3, the conductor film A on the upper surface becomes a strip and the conductor film B on the lower surface. Is deformed into a tapered shape so as to be a ground conductor as a whole.

FIG. 5 (b) shows another waveguide-microstrip line converter in which conductor films A and B are formed on both surfaces of a substrate 4 also made of a dielectric material.
Unlike FIG. 5A, the converter 3 between the tapered fin line 1 and the micro-cross line 2 is composed of two parallel lines composed of upper and lower strips.

However, any of the waveguide-to-microstrip line converters shown in FIGS. 5 (a) and 5 (b) is, for example, shown in FIGS. 6 (a) and 6 (b) in a commonly used frequency band.
As shown in (1), a structure in which two types of transmission waves are transmitted is obtained.
6 (a) and 6 (b) are cross-sectional views of the converter 3 of the converter shown in FIG. 5 (a), and both show the electromagnetic field distribution of a transmission wave propagating in the converter. The electric field E is a solid arrow,
The magnetic field H is indicated by a dotted arrow. FIG. 6 (a)
Indicates that the transmission wave is a transmission wave similar to the transmission wave of the microstrip line and contributes to the conversion.
(B) shows that an unnecessary wave completely different from this propagates. That is, the electromagnetic field distribution shown in FIG. 6B unnecessarily resonates in the conversion line (the conversion unit 3), and as shown in FIG. 7, an insertion loss occurs in the transmission band so that no conversion is performed at all. Appears. As described above, the conventional waveguide-microstrip line converter has a disadvantage that it cannot be used over the entire waveguide band (a range from the cut-off frequency of the fundamental mode to the cut-off frequency of the higher-order mode) due to unnecessary resonance. Occurs. Since the converter using the fin line itself has a simple configuration and low loss, it has been desired to widen the band in order to widen the range of use.

[0006]

The conventional waveguide-to-microstrip line converter has been required to be improved because the band used is narrow.

The present invention has been made in view of the above circumstances, and has as its object to provide a waveguide-to-microstrip line converter which does not generate unnecessary resonance in a waveguide band and realizes a wide band. And

[Structure of the Invention]

[0009]

According to the present invention, there is provided a waveguide-microstrip line converter having a tapered fin line, wherein a connecting portion between the fin line and the microstrip line is formed of an antipodal type line. Is
An approximately 1/4 wavelength short-circuit stub short- circuited to the waveguide wall is provided.
And wherein the digit.

[0010]

In the waveguide-microstrip line converter according to the present invention, a short-circuit stap of approximately 1/4 wavelength is provided between the fin line and the microstrip line so as to be open at the conversion part and to be balanced-unbalanced. Since the balanced conversion circuit is configured, conversion without unnecessary resonance is possible over a wide band.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a waveguide-microstrip line converter according to the present invention will be described below with reference to FIGS. The same components as those of the conventional configuration shown in FIGS. 5 to 7 are denoted by the same reference numerals, and detailed description is omitted.

FIG. 1 is a partially cutaway perspective view showing a first embodiment of a waveguide-microstrip line converter according to the present invention, in which a tapered fin line 1 and a microstrip line 2 are directly connected. In addition, the line for the conversion unit (3), which has been conventionally configured, is omitted. That is, the edge of the conductor film A on the upper surface of the substrate 4 and the edge of the conductor film B on the lower surface of the substrate 4 form an antipodal line stub 6 toward the wall surface on the right side of the illustrated waveguide 5. The stub 6 is short-circuited to the right wall of the waveguide 5 to form a short-circuit stub. The length of the stub 6 corresponds to the distance from the strip to the side wall of the waveguide. When the center frequency of the waveguide band is set to 1/4 wavelength, the stub 6 is opened, and the transmission wave is transmitted from the tapered fin line 1 to the microwave. It is converted to a strip line 2.

When viewed from the transmission form of the transmission wave, the tapered fin line 1 is a balanced transmission line, and the microstrip line 2 is an unbalanced transmission line. The stripline converter realizes balanced-unbalanced conversion by providing the stub 6 as described above. Further, since the conventional line for the converter (3) is not used, unnecessary conversion does not occur in the waveguide band, and normal conversion can be performed over a wide band as shown in FIG. Was. Note that the length of the stub 6 needs to be approximately 1/4 wavelength of the center frequency, but the shape of the conductor films A and B must be corrected even when the length of the stub 6 is short or too long. Can be adapted.

FIG. 3A is a partially cutaway perspective view showing a waveguide-microstrip line converter according to a second embodiment of the present invention. A slit (cut) 6a is formed in the part,
The electric length of the stub 6 can be increased, and the electric length of the stub 6 of the antipodal type line can be adapted to the length of １ ／ wavelength of the center frequency. Similarly, stub 6
In the case where the electrical length is less than a quarter wavelength of the center frequency, a similar correction effect can be obtained by forming a slit 6b in the conductive film B on the lower surface as shown in FIG. Can be

FIG. 4 is a view showing a third embodiment of the waveguide-microstrip line converter according to the present invention, in which a conductor film A on the upper surface and a conductor film B on the lower surface are stubs 6 at edges of each other. The intermediate portion of the overlapping portion is short-circuited by a through hole 6c.

This is a stub 6 of an antipodal type line.
Is adopted when the electrical length of the stub 6 is longer than １ ／ wavelength of the center frequency, and the length of the stub 6 can be substantially shortened so that the stub 6 can be adjusted to approximately 波長 wavelength of the center frequency.

As described above, the waveguide-to-microstrip line converter according to the present invention provides a fin line by providing a short-circuit stub composed of an anti-podal type line on the connection surface between the tapered fin line and the microstrip line. And the conversion characteristics of the microstrip line are improved.

Although the present invention has been described with respect to a waveguide-to-microstrip line converter, it can be used as a converter between a general fin line and a microstrip line except for the waveguide.

[0019]

The waveguide-to-microstrip line converter according to the present invention realizes wide-band conversion capable of covering the entire waveguide band without unnecessary resonance, which is a large effect obtained in practical use. The short stub of about 1/4 wavelength
Easy to manufacture.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a first embodiment of a waveguide-microstrip line converter according to the present invention.

FIG. 2 is a graph showing characteristics of insertion loss and reflection loss of the converter shown in FIG. 1;

FIGS. 3 (a) and 3 (b) are partially cutaway perspective views showing a second embodiment of the converter according to the present invention.

FIG. 4 is a partially cutaway perspective view showing a third embodiment of the converter according to the present invention.

FIGS. 5A and 5B are partially cutaway perspective views showing a conventional waveguide-microstrip line converter.

6 (a) and 6 (b) are electromagnetic field distribution diagrams of main transmission waves in the conversion line portion of the waveguide-microstrip line converter shown in FIG. 5 (a).

FIG. 7 is a graph showing insertion loss and reflection loss characteristics of the converter shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Tapered fin line A, B ... Conductive film 2 ... Microstrip line 3 ... Conversion part 4 ... Substrate 5 ... Waveguide 6 ... Stub

Continuation of the front page (56) References JP-A-53-33031 (JP, A) JP-A-50-120753 (JP, A) 1987 IEEE MTT Symp. Dig. pp. 353-356 (58) Field surveyed (Int.Cl. ⁷ , DB name) H01P 5/107 H01P 5/10 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A waveguide-microstrip line converter via a tapered fin line, wherein a connecting portion between the fin line and the microstrip line is formed of an anti-podal type line, and is connected to a wall of the waveguide of the waveguide. Approximately 1 short-circuited
/ 4 waveguide, characterized in that a short stub of the wavelength - microstrip line converters. 2. A waveguide through a tapered fin line.
-In the microstrip line converter, the fin
Anti-Position at the connection between the line and the microstrip line
The conductor film on the upper surface of the substrate is composed of
An approximately 1/4 wavelength short-circuit stub short-circuited to the conductor film on the bottom
Waveguide-microstrip line characterized by radiating
converter.