JP2006081160A - Transmission line converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-yield transmission line converter that operates reliably at a design frequency even when characteristic variations due to processing variations occur.
A position at which a waveguide excitation antenna 18 connected to a feed line pattern 15 made of a microstrip line is separated from a short-circuited position of a waveguide whose one end is short-circuited by a predetermined interval s (≈λgw / 4). Insert into. Further, the feeder line pattern 15 is disposed at a position deviated in the Y-axis direction by a shift amount d from the center of the long-side direction (Y-axis direction) of the upper-surface substrate exposed portion 13. Is formed so that one boundary portion along the long side of the substrate exposed portion 13 protrudes toward the hollow portion of the waveguide by a protrusion amount p from the fixed portion of the waveguide. The protrusion amount p and the shift amount d are set to such a size that two resonance points are generated in the reflection characteristic of the MSL-WG converter and a wide operating frequency band is obtained.
[Selection] Figure 4

Description

  The present invention relates to a transmission line converter for connecting a planar line formed on a dielectric substrate and a waveguide.

  In recent years, various systems using millimeter waves have been developed for high-capacity high-speed communication and automobile radar. As one of the elemental technologies necessary for realizing such a millimeter wave system, the power transmitted through the waveguide is connected to the waveguide and a planar line formed on a dielectric substrate such as a microstrip line. There is known a transmission line converter that mutually converts power transmitted through a plane line.

Specifically, the waveguide is composed of a short-circuiting partial waveguide and a transmission partial waveguide that are integrally fixed with a dielectric substrate interposed therebetween, and both the partial waveguides are connected to the dielectric substrate. The strip line tip (open end) formed on the waveguide is arranged so that it is located inside the waveguide, and the tip of the strip line protruding into the waveguide is used as a waveguide excitation antenna. Is known (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 11-26312

  By the way, in a system that handles millimeter waves, each component constituting the system becomes very small, so the device can be miniaturized, but variations in characteristics occur due to processing variations during parts manufacturing and parts assembly. Cheap.

  Moreover, since the above-described transmission line converter generally has a narrow operating frequency band, if the operating frequency band varies due to processing variations during manufacturing or parts assembly, the frequency of the signal to be transmitted (design frequency) There is a problem that the required performance may not be obtained at the design frequency because the frequency band is deviated.

  On the other hand, it is conceivable to reduce the processing variation, but for that purpose, it is required to manufacture parts and assemble parts with very high processing accuracy, and there is a problem that enormous labor and cost are required. .

  In order to solve the above-described problems, an object of the present invention is to provide a transmission line converter that operates reliably at a design frequency at a high yield even if characteristic variations due to processing variations occur.

  In order to achieve the above object, a transmission line converter according to the present invention includes a planar line formed on a dielectric substrate, a waveguide whose one end is short-circuited, and a conductor connected to the planar line and the conductor. And a waveguide excitation antenna disposed at an antenna setting position inside the waveguide that is separated from a short-circuited end of the wave tube by a predetermined interval set in advance.

  Then, the internal space of the waveguide at the antenna setting position is set so that the distance between the front end portion of the waveguide excitation antenna and the inner wall of the waveguide facing the front end portion becomes a preset set length. A shaping ground plate for shaping the cross-sectional shape is provided, and the waveguide excitation antenna is disposed at a position deviated from the center of the waveguide by a preset deviation amount.

  In the transmission line converter of the present invention configured as described above, a standing wave is generated in the waveguide by reflecting the high frequency propagating through the waveguide at the short-circuited end. And by arranging the waveguide excitation antenna so that the antinode part of this standing wave becomes the antenna setting position, the power propagating through the waveguide is efficiently converted to the power propagating through the plane line, Similarly, the reverse is also performed efficiently.

  Further, in the transmission line converter of the present invention, the impedance of the waveguide excitation antenna and the waveguide is changed by adjusting the set length and the deviation amount. As a result, conversion between the waveguide and the planar line is performed. Characteristics (especially reflection characteristics) change. Specifically, it is possible to generate two resonance points in the reflection characteristic and to adjust the frequency width between the two resonance points as appropriate.

  In other words, in the transmission line converter, since the frequency region where the amount of reflection is equal to or less than a preset threshold value is set as the operating frequency region around the resonance point appearing in the reflection characteristics, two resonance points are generated, and the resonance point A wide operating frequency band can be realized by adjusting the set length and the shift amount so as to obtain a reflection characteristic in which two operating frequency regions centering on are integrated. The reflection characteristic referred to here represents the input / output power ratio between the high frequency input toward the short-circuited end of the waveguide and the reflected wave.

  Since the transmission path converter has a wide operating frequency band, the allowable range of the reflection characteristic variation based on the shift of the operating frequency region with respect to the design frequency, that is, the processing variation, etc. is widened, so that the processing accuracy is improved. Even without using a laborious and costly technique, a transmission line converter that operates reliably at the design frequency can be provided at a high yield.

  In other words, when it is possible to manufacture with high processing accuracy so that the operating frequency region does not shift, the design frequency band can be set wide, so that it is suitable for high-speed communication using a wide band. A transmission line converter can be provided.

  By the way, when a rectangular waveguide having a rectangular cross section is used as the waveguide, the waveguide is guided from one side into the waveguide among a pair of waveguide wall surfaces forming the long side of the rectangle. It is desirable to insert the tube excitation antenna, extend the shaping ground plate from the other side, and dispose the waveguide excitation antenna so as to deviate from the center in the long side direction of the waveguide.

In this case, the set length (the distance between the front end of the waveguide excitation antenna and the inner wall of the waveguide facing the front end) can be adjusted by adjusting the protruding amount of the shaping ground plate.
Here, FIG. 6A and FIG. 7A are graphs showing the results of calculating the resonance frequency in the reflection characteristics by calculation (simulation) and experiment. However, as shown in FIGS. 6 (b) and 7 (b), the long side of the rectangular waveguide is 3 as long as the projecting amount of the shaping ground plate is p and the shift amount of the waveguide excitation antenna is d. 1 mm, 1.55 mm short side (EIA standard WR-12) was used, and the length of the waveguide-excited antenna (projection from the wall along the long side) l was 0.7 mm. It is.

  As shown in FIG. 6, when the deviation amount is fixed at d = 0.45 mm and the protrusion amount p is changed, if the protrusion amount p is increased to some extent (that is, the set length is reduced to some extent), the two resonance points are obtained. When the protrusion amount p is further increased, the frequency width between the two resonance points is increased. Also, as shown in FIG. 7, when the amount of protrusion is fixed at p = 0.5 mm and the amount of deviation d is changed, two resonance points are generated only by slightly shifting, and the amount of deviation d is further increased. As it goes on, it can be seen that the frequency width between the two resonance points becomes narrower and the resonance point becomes one.

  As can be seen from these measurement results, the projecting amount p of the shaping ground plate is in the range of 0.48 mm to 0.56 mm, that is, about 30 to 40% of the inner dimension in the short side direction of the waveguide. Further, the shift amount d of the waveguide excitation antenna is preferably in the range of 0.30 mm to 0.45 mm, that is, about 10 to 15% of the inner dimension in the long side direction of the waveguide.

  Also, the frequency width between the two resonance points can be adjusted more finely by adjusting the deviation amount d because the rate of change is smaller than by adjusting the protrusion amount p. First, it is conceivable to optimize the frequency width between the two resonance points by adjusting the protrusion amount p so that two resonance points are generated, and then adjusting the deviation amount d.

  Next, since the predetermined interval that defines the antenna setting position may be a position that becomes an antinode of the standing wave, λ / 4 + n × λ / 2 may be set, where λ is the wavelength in the waveguide. However, in order to reduce the size of the transmission line converter, it is desirable that the waveguide has the minimum necessary size, that is, the predetermined interval is 1/4 of the wavelength in the waveguide of the transmission signal. However, it is not always necessary to be exactly 1/4.

  Further, the planar line may be anything as long as it is formed on a dielectric substrate, such as a slot line, a coplanar line, a strip line, a microstrip line, or a triplate type line. A microstrip line is desirable.

  By the way, when the waveguide excitation antenna is formed on the dielectric substrate together with the planar line, the waveguide is composed of a short-circuited partial waveguide and a transmission partial waveguide fixed together with the dielectric substrate interposed therebetween. One partial waveguide that is composed of a wave tube and is fixed to the plane of the plane line is formed with a notch for passing the plane line at the fixed end to the dielectric substrate. On both surfaces of the body substrate, a pair of ground plates that are electrically connected to each other are provided at portions where the short-circuit waveguide and the transmission waveguide are fixed, and the waveguide excitation antenna is formed on the surface of the pair of ground plates. The formed ground plate may also serve as a shaping ground plate.

  In other words, the conversion characteristics (reflection characteristics and hence the operating frequency band) of the transmission line converter are as shown in FIG. 6 from the amount of protrusion of the shaping ground plate, in other words, from the tip of the waveguide excitation antenna to the shaping ground plate. In order to obtain stable conversion characteristics, the partial waveguide has a constant cross-sectional shape in the internal space of the waveguide at the antenna setting position. Must be assembled to the dielectric substrate with high accuracy.

  On the other hand, according to the transmission line converter of the present invention, since the ground plate also serves as the shaping ground plate, the fixing position (part assembly accuracy) of the partial waveguide varies, and thus the shaping ground plate. Even if the position of the partial waveguide is fixed slightly shifted to the internal space side on the protruding side, the interval (set length) between the waveguide excitation antenna and the shaping ground plate does not change at all. Stable conversion characteristics can be obtained.

  In addition, it is desirable that the pair of ground plates formed on both surfaces of the dielectric substrate are electrically connected through a plurality of through holes arranged so as to surround a portion forming the internal space of the waveguide.

In this case, since leakage of the electromagnetic field from the dielectric substrate sandwiched between the partial waveguides can be suppressed, it is possible to prevent the conversion efficiency of the transmission line converter from being lowered.
In the above invention, the shaping ground plate is provided and the waveguide excitation antenna is disposed at a position off the center of the waveguide. However, the present invention introduces the waveguide excitation antenna. It may be characterized in that it is arranged only at the center of the wave tube (the amount of displacement is zero), that is, only by providing a shaping ground plate.

  That is, even if the amount of deviation of the waveguide excitation antenna is zero, the gap between the tip of the waveguide excitation antenna and the inner wall of the waveguide facing the tip is adjusted by the shaping ground plate. Thus, two resonance points can be generated in the reflection characteristic, and the frequency width between the resonance points can be adjusted, so that a wide operating frequency band can be realized as in the case of the above invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing a structure of a microstrip line-waveguide converter (hereinafter referred to as “MSL-WG converter”) to which the present invention is applied, and FIG. 2 is a dotted line in FIG. FIG. 3 is a cross-sectional view taken along the A-Z plane in FIG. 2, and FIG. 3 is a cross-sectional view taken along the A-Z plane in FIG. However, in FIGS. 2 and 3, the thickness of the dielectric substrate and the thickness of the pattern formed on the dielectric substrate are emphasized (thicker) than the actual one in order to make the drawings easy to see and understand the structure. As shown.

  As shown in FIGS. 1 to 3, the MSL-WG converter 1 is fixed with a dielectric substrate 10 on both sides of which a pattern made of a conductive material (for example, a metal thin film) is formed, and the dielectric substrate interposed therebetween. A short-circuiting partial waveguide 20a and a transmission partial waveguide 20b.

  Among these, the waveguide 20 has a shape obtained by cutting a rectangular waveguide having a rectangular cross section, one end of which is short-circuited and the other end of which is opened, at a position separated by a predetermined interval s. Of these two partial waveguides, the side including the short-circuit end is the short-circuiting partial waveguide 20a, and the other side is the transmission partial waveguide 20b. Further, in the present embodiment, the predetermined interval s is set so that s≈λgw / 4, where λgw is the wavelength in the waveguide of the transmission signal (design frequency) (hereinafter simply referred to as “intrawavelength”). ing.

  Further, the short-circuiting partial waveguide 20a is formed with a notch 21 at a fixed end to the dielectric substrate 10 so as not to come into contact with a later-described feeder line pattern 15 formed on the dielectric substrate 10. Has been.

  4A is a top view of the dielectric substrate 10 as viewed from the fixing side of the short-circuiting partial waveguide 20a, and FIG. 4B is a fixing of the dielectric substrate 10 to the transmission partial waveguide 20b. It is the bottom view seen from the side.

  As shown in FIG. 4B, on the lower surface of the dielectric substrate 10, the lower surface ground as a ground plate is formed on the entire surface except the rectangular portion (lower surface substrate exposed portion) 11 corresponding to the hollow portion of the waveguide 20. A pattern 12 is formed.

  Further, as shown in FIG. 4A, a waveguide is provided around a portion of the upper surface of the dielectric substrate 10 where the waveguide 20 is fixed (hereinafter referred to as “waveguide fixing portion”) 10a. An upper surface ground pattern 14 as a ground plate is formed on almost the entire surface excluding a rectangular portion (upper surface substrate exposed portion) 13 corresponding to the hollow portion of the tube 20, and a portion other than the waveguide fixing portion 10 a (hereinafter, “ 10b, which forms a microstrip line together with the lower surface ground pattern 12, is wired along the short side direction of the upper surface substrate exposed portion 13 (hereinafter also referred to as "Z-axis direction"). The feeder line pattern 15 is formed.

  When the short-circuiting partial waveguide 20a is fixed to the dielectric substrate 10, the upper substrate exposed portion 13 and the portion on the dielectric substrate 10 corresponding to the notch 21 of the short-circuiting partial waveguide 20a are provided. A communication portion 17 having no upper surface ground pattern 14 is provided so that the substrate exposed portion 16 of the feeder line wiring portion 10 b communicates with the upper surface ground pattern 14 without being blocked by the upper surface ground pattern 14. The feeder line pattern 15 is wired so as to reach the upper surface substrate exposed portion 13. The leading end portion of the feeder line pattern 15 protruding into the upper surface substrate exposed portion 13 forms the waveguide excitation antenna 18.

  However, the feeder line pattern 15 is not located at the center in the long side direction (Y-axis direction) of the upper surface substrate exposed portion 13 but at a position deviated from the center in the Y-axis direction by a preset deviation amount d. ing.

  In the upper surface ground pattern 14, a portion of the portion along the long side of the upper surface substrate exposed portion 13 that is opposite to the side where the communication portion 17 is formed is set in advance from the fixing portion of the waveguide 20. The protrusion p is formed so as to protrude toward the hollow portion of the waveguide 20. Hereinafter, this projecting portion, that is, a part of the upper surface ground pattern 14 divided by a dotted line in the drawing is also referred to as a ground protruding portion 14a.

  The ground protruding portion 14a shapes (limits) the cross-sectional shape of the hollow portion of the waveguide 20 on the upper surface of the dielectric substrate 10 (hereinafter also referred to as “antenna setting position”), and the ground protruding portion 14a is provided. Thus, the set length g between the tip of the waveguide excitation antenna 18 and the upper surface ground pattern 14 is shortened.

  Note that the protrusion amount p of the ground protrusion 14a and the shift amount d of the waveguide excitation antenna 18 cause two resonance points in the reflection characteristics of the MSL-WG converter 1, and each resonance point is centered. The frequency region with good reflection characteristics (frequency region where the amount of reflection is equal to or less than a preset threshold value) is set to be integrated, that is, set so as to obtain a wide operating frequency band. .

  In the waveguide 20, the ratio of the local electric field to the magnetic field at the position (antenna setting position) in the X-axis direction of the waveguide excitation antenna 18 is high at the center in the Y-axis direction. It gets lower as you move away from. That is, when the waveguide excitation antenna 18 is shifted from the center in the Y-axis direction, the characteristic impedance of the waveguide 20 is greater than that when the waveguide excitation antenna 18 is disposed in the center in the Y-axis direction (about several hundred Ω). Therefore, matching with the feeder line pattern 15 having the characteristic impedance (59.5Ω) of the microstrip line can be easily obtained.

  Further, the lower surface ground pattern 12 and the upper surface ground pattern 14 are electrically connected to each other by a plurality of through holes 19 arranged so as to surround the lower surface substrate exposed portion 11 and the upper surface substrate exposed portion 13 and the ground protruding portion 14a. Is configured to do.

  The interval between the through holes 19 is such that the wavelength in the substrate of the transmission signal is λp so that leakage of the electromagnetic field from between the upper surface ground pattern 14 and the lower surface ground pattern 12 is effectively suppressed. It is set to be λp / 2 or less at which radio waves are cut off.

  The short-circuiting partial waveguide 20a is fixed on the upper surface ground pattern 14 by soldering or the like so that the hollow portion thereof coincides with the rectangular portion including the upper surface substrate exposed portion 13 and the ground protruding portion 14a. The transmission partial waveguide 20b is fixed to the lower surface ground pattern 12 by soldering or the like so that the hollow portion thereof coincides with the lower surface substrate exposed portion 11.

  4A indicates the position of the outer periphery of the short-circuiting partial waveguide 20a fixed to the dielectric substrate 10, and the alternate long and short dash line in FIG. The position of the outer periphery of the partial waveguide for transmission 20b fixed to the dielectric substrate 10 is shown.

  The MSL-WG converter 1 configured as described above is configured such that the waveguide excitation antenna 18 connected to the feeder line pattern 15 made of a microstrip line (MSL) is short-circuited in the waveguide 20 whose one end is short-circuited. Thus, a structure is inserted at a position (antenna setting position) that is a predetermined distance s (≈λgw / 4) away from the center.

  For this reason, the high frequency wave propagated through the waveguide 20 and reflected at the short-circuit end generates a standing wave in the waveguide 20, and the waveguide excitation antenna 18 is located in the antinode portion thereof. The power propagating through the wave tube is efficiently converted to the power propagating through the plane line, and vice versa.

  Further, in the MSL-WG converter 1, the protrusion amount p of the ground protrusion 14a and the shift amount d of the waveguide excitation antenna 18 are set to such a size that a wide operating frequency band can be obtained. By having such a wide operating frequency band, the shift of the operating frequency region with respect to the design frequency, that is, the tolerance range of the reflection characteristic variation based on the processing variation, etc. is widened, so enormous labor and cost of improving the processing accuracy Even without using a technique requiring a high frequency, the MSL-WG converter 1 that operates reliably at the design frequency can be provided at a high yield.

  In addition, when it is possible to manufacture with high processing accuracy so that the operating frequency region does not shift, a wide design frequency band can be set, so that MSL-WG suitable for high-speed communication using a wide band. A converter 1 can be provided.

  Further, in the MSL-WG converter 1, the ground protrusion 14 a is formed in advance on the dielectric substrate 10 together with the waveguide excitation antenna 18. For this reason, even if the fixed positions of the partial waveguides 20a and 20b are slightly shifted and fixed to the internal space side on the ground protruding portion 14a side, the distance (setting between the waveguide excitation antenna 18 and the ground protruding portion 14a is set. (Long) g does not change at all, that is, the conversion characteristics (reflection characteristics) are not greatly deteriorated due to processing variations, so that stable conversion characteristics can be obtained.

  Further, in the MSL-WG converter 1, a plurality of through holes 19 for conducting the upper surface ground pattern 14 and the lower surface ground pattern 12 are portions corresponding to the hollow portions of the waveguide 20, that is, the upper surface substrate exposed portion 13. It is arranged so as to surround a rectangular portion composed of the ground protruding portion 14 a and a rectangular portion composed of the lower surface substrate exposed portion 11. For this reason, it is possible to prevent the electromagnetic field from leaking through the dielectric substrate 10 and, consequently, the conversion efficiency in the MSL-WG converter 1 from being reduced due to leakage loss.

  In the present embodiment, the feeder line pattern 15 constituting the microstrip line together with the lower surface ground pattern 12 is a planar line, the ground protruding portion 14a is a shaping ground plate, and the lower surface ground pattern 12 and the upper surface ground pattern 14 are a pair of ground plates. It corresponds to.

Examples will be described below.
A rectangular waveguide (long side inner dimension a = 3.099 mm, short side inner dimension b = 1.550 mm) of EIA standard WR-12 is used as the waveguide 20, and εγ = 2 as the dielectric substrate 10. .2 was used.

  Further, assuming that the design frequency is 76.5 GHz, the protruding amount of the ground protrusion 14a is p = 0.5 mm, the antenna length l of the waveguide excitation antenna 18, and the predetermined distance from the short-circuited end of the waveguide 20 to the antenna setting position s and the three parameters d of the displacement of the waveguide-excited antenna 18 are as large as possible in the bandwidth where the reflection amount is -20 dB or less, and the design frequency is located near the center of the bandwidth. In this way, optimization was performed by calculation (simulation). As a result, l = 0.70 mm, s = 0.50 mm, and d = 0.45 mm were obtained.

  For the MSL-WG converter 1 to which the parameters optimized in this way are applied, the calculation result (displayed with a broken line) for obtaining the reflection characteristic S11 and the transmission characteristic S21, and the measurement result using the real object (displayed with a solid line) ) Is shown in FIG.

As shown in the figure, the loss (transmission characteristic) at the design frequency was 0.35 dB in the measurement result (0.24 dB in the calculation), and a low loss characteristic was obtained.
Further, the bandwidth having a reflection amount (reflection characteristic) of −20 dB or less was 19.4 GHz (66.8 GHz to 87.0 GHz, calculated to be 19.1 GHz), and a wide band characteristic was obtained.
[Other Embodiments]
In the above embodiment, the short-circuiting partial waveguide 20 a is fixed to the upper surface of the dielectric substrate 10 on which the waveguide excitation antenna 18 is formed, and the transmission partial waveguide 20 b is fixed to the lower surface of the dielectric substrate 10. However, the partial waveguides 20a and 20b may be fixed by switching the upper and lower surfaces. However, in this case, it is necessary to set the predetermined interval s in consideration of the thickness of the dielectric substrate 10.

  In the above embodiment, the ground protruding portion 14a is provided, and the waveguide excitation antenna 18 is disposed at a position deviated from the center in the Y-axis direction by the shift amount d, but the waveguide excitation antenna 18 is centered (ie, shifted). The amount of protrusion p of the ground protrusion 14a is set as follows (in some cases, the antenna length I of the waveguide excitation antenna 18 and the predetermined interval s from the short-circuited end of the waveguide 20 to the antenna setting position). Also, by optimizing, two resonance points may be generated in the reflection characteristics of the MSL-WG converter 1 to obtain a wide operating frequency band.

It is a perspective view which shows the structure of the MSL-WG converter of embodiment. It is sectional drawing which looked at the yz plane shown with the dotted line in FIG. 1 from the near side in the figure. It is AA sectional drawing in FIG. (A) is the top view which looked at the dielectric substrate from the fixed side of the partial waveguide for short circuit, (b) is the bottom view which looked at the dielectric substrate from the fixed side of the partial waveguide for transmission. It is a graph which shows the calculation result and measurement result which calculated | required the reflection characteristic and the permeation | transmission characteristic about the MSL-WG conversion shown in the Example. It is a graph which shows the relationship between the protrusion amount of the shaping ground board, and the resonance point. It is a graph which shows the relationship between the deviation | shift amount of a waveguide excitation antenna, and a resonance point.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... MSL-WG converter, 10 ... Dielectric substrate, 10a ... Waveguide fixing | fixed part, 10b ... Feed line wiring part, 11 ... Lower surface board exposed part, 12 ... Lower surface ground pattern, 13 ... Upper surface board exposed part, 14 ... upper surface ground pattern, 14a ... ground protruding part, 15 ... feeder line pattern, 16 ... substrate exposed part, 17 ... communication part, 18 ... waveguide excitation antenna, 19 ... through hole, 20 ... waveguide, 20a ... short circuit Partial waveguide for transmission, 20b... Partial waveguide for transmission, 21.

Claims (7)

A planar line formed on a dielectric substrate;
A waveguide with one end short-circuited;
A waveguide-excited antenna connected to the planar line and disposed at an antenna setting position inside the waveguide separated from a short-circuited end of the waveguide by a predetermined interval;
In a transmission line converter for mutually converting power transmitted by the waveguide and power transmitted by the feeder line,
The internal space of the waveguide at the antenna setting position so that the distance between the distal end portion of the waveguide excitation antenna and the inner wall of the waveguide facing the distal end portion has a preset set length. While providing a shaping ground plate to shape the cross-sectional shape of
A transmission line converter characterized in that the waveguide excitation antenna is disposed at a position deviated by a preset deviation amount from the center of the waveguide.   The waveguide is a rectangular waveguide having a rectangular cross-sectional shape, and the waveguide excitation is performed from one side of the pair of waveguide walls forming the long side of the rectangle toward the inside of the waveguide. An antenna is inserted, the shaping ground plate is extended from the other side, and the arrangement of the waveguide excitation antenna is deviated from the center in the long side direction of the waveguide. The transmission line converter according to claim 1.   The transmission line converter according to claim 1 or 2, wherein the predetermined interval is ¼ of a wavelength in a waveguide of a transmission signal.   The transmission line converter according to any one of claims 1 to 3, wherein the planar line is a microstrip line. Forming the waveguide excitation antenna on the dielectric substrate together with the planar line;
The waveguide is composed of a short-circuiting partial waveguide and a transmission partial waveguide fixed together with the dielectric substrate interposed therebetween, and one partial waveguide fixed to the plane of the planar line. In the tube, a notch for passing the planar line is formed at a fixed end to the dielectric substrate,
Furthermore, on both surfaces of the dielectric substrate, a pair of ground plates that are electrically connected to each other are provided at portions that fix the short-circuit waveguide and the transmission waveguide,
The transmission line converter according to any one of claims 1 to 4, wherein a ground plate on a side formed on a formation surface of the waveguide excitation antenna also serves as the shaping ground plate. .   6. The transmission line conversion according to claim 5, wherein the pair of ground plates are electrically connected through a plurality of through holes arranged so as to surround a portion forming an internal space of the waveguide. vessel. A planar line formed on a dielectric substrate;
A waveguide with one end short-circuited;
A waveguide-excited antenna connected to the planar line and disposed at an antenna setting position inside the waveguide separated from a short-circuited end of the waveguide by a predetermined interval;
In a transmission line converter for mutually converting power transmitted by the waveguide and power transmitted by the feeder line,
The internal space of the waveguide at the antenna setting position so that the distance between the distal end portion of the waveguide excitation antenna and the inner wall of the waveguide facing the distal end portion has a preset set length. A transmission line converter comprising a shaping ground plate for shaping the cross-sectional shape of the wire.