JP6168904B2 - Waveguide planar line converter - Google Patents

Description

  The present invention relates to a waveguide planar line converter, and more particularly to an improvement of a waveguide planar line converter that transmits electromagnetic waves between a rectangular waveguide and a microstrip line.

  The microstrip antenna is a planar antenna that transmits and receives microwave and millimeter wave radio waves using an MSL (microstrip line) formed on a dielectric substrate. When feeding such a planar antenna using a waveguide, a waveguide planar line converter is used.

  For example, a waveguide planar line converter described in Patent Document 1 includes a ground plate in which a rectangular through-hole communicating with a rectangular waveguide is formed, a matching element disposed in the through-hole, a dielectric A body substrate, an MSL extending in a direction intersecting with the wide wall of the waveguide, and a short-circuit plate formed with a notch for arranging the MSL. In the dielectric substrate, one main surface closes the rectangular waveguide, and the MSL and the short-circuit plate are formed on the other main surface. The MSL faces the matching element across the dielectric substrate in a region on the dielectric substrate overlapping the through hole of the ground plate, and is electromagnetically coupled to the matching element. With such a configuration, the electromagnetic wave transmitted by the rectangular waveguide can be efficiently transmitted to the MSL, or conversely, the electromagnetic wave transmitted by the MSL can be efficiently transmitted to the rectangular waveguide.

  However, in the conventional waveguide planar line converter as described above, the through hole of the ground plate and the matching element are formed by patterning the conductor layer formed on the dielectric substrate by etching. For this reason, high accuracy is required for the etching process of the conductor layer, and if the patterning accuracy of the through hole of the ground plate and the matching element is low, there is a problem that transmission loss increases.

  Patent Documents 2 and 3 disclose a waveguide planar line converter that does not include a matching element and a short-circuit plate. These waveguide planar line converters described in Patent Documents 2 and 3 are slot excitation type converters, and a through hole having a long and narrow rectangular shape formed in the ground plate constitutes the slot exciter. However, this type of waveguide planar line converter has a problem in that the amount of reflection is large and transmission loss is large compared to a waveguide planar line converter including a matching element and a short-circuit plate.

JP 2011-223203 A JP 2002-76723 A Japanese Patent Laid-Open No. 2002-9512

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a waveguide planar line converter that can be easily manufactured while suppressing an increase in transmission loss. It is another object of the present invention to provide a waveguide plane line converter that can suppress the amount of reflection in a wider frequency band than the conventional waveguide plane line converter.

  A waveguide planar line converter according to a first aspect of the present invention has a waveguide communicating with a rectangular waveguide, and the wide end of the waveguide is inclined so that the tip opening is made wider than the cross section of the rectangular waveguide. A narrowed tapered waveguide, and a dielectric substrate in which one main surface closes the tapered waveguide and a microstrip line and a short-circuit plate are formed on the other main surface, and the short-circuit plate includes: The entire region covers a closed region on the dielectric substrate that overlaps the tip opening, and includes a continuous region in which a notch for arranging the microstrip line is formed. It is configured to straddle the long side of the region.

  According to such a configuration, since the amount of reflection can be suppressed by interposing the tapered waveguide having the inclined wide wall of the waveguide, compared with the case where the rectangular waveguide is directly closed by the dielectric substrate. An increase in the transmission loss of the waveguide planar line converter can be suppressed. The tapered waveguide has an opening at the tip that is narrower than the cross section of the rectangular waveguide. The tip of the tapered waveguide closed by a dielectric substrate functions as a slot exciter, and the entire tapered waveguide is grounded. Can function as. The microstrip line extends over the long side of the closed region on the dielectric substrate where the entire region overlaps the tip opening, and is electromagnetically coupled to the slot exciter across the dielectric substrate. This eliminates the need for a matching element that is electromagnetically coupled to the microstrip line, thereby facilitating the manufacture of the waveguide planar line converter.

  The waveguide plane line converter according to the second aspect of the present invention is, in addition to the above configuration, an elongated rectangular shape that is disposed between the tapered waveguide and the dielectric substrate, and the entire hole overlaps with the tip opening. A ground plate having a through hole is provided.

  According to such a configuration, the through hole of the ground plate disposed between the tapered waveguide and the dielectric substrate functions as a slot exciter. In other words, the overlapping region between the through hole of the ground plate and the dielectric substrate becomes a closed region, and the microstrip line is formed so as to straddle the long side of such a closed region, so that the matching element and the short-circuit plate are not provided. Transmission loss can be reduced compared to a waveguide planar line converter.

  A waveguide planar line converter according to a third aspect of the present invention is configured so that, in addition to the above-described configuration, the short-circuit plate is substantially parallel to the long side of the closed region, and the wavelength from the long side of the closed region It has an outer edge formed on the outside by 1/4 times, and the microstrip line is inserted inward from the outer edge by a distance not less than 0.4 times and not more than 0.6 times the guide wavelength. Is done.

  According to such a configuration, since the short-circuit plate on the dielectric substrate has an outer edge formed outside the long side of the closed region by about 1/4 times the guide wavelength, the electromagnetic wave intersects with the long side of the closed region. When propagating through the dielectric substrate in the direction to be reflected, electromagnetic waves are reflected with the outer edge of the short-circuit plate as a boundary. Further, since the incident wave entering from the closed region cancels out with the reflected wave reflected by the outer edge of the short-circuit plate, it is possible to suppress the electromagnetic wave propagating in the dielectric substrate from leaking to the outside of the short-circuit plate.

  Furthermore, in the experiment of the transmission characteristics by the inventors of the present invention, in the waveguide plane line converter provided with the tapered waveguide, the microstrip line is 0.4 times or more and 0.6 times or less of the guide wavelength. Good transmission characteristics were obtained when it was inserted inward from the outer edge of the short-circuit plate by a distance. For example, the amount of reflection is suppressed in a wider frequency band than the conventional waveguide plane line converter. On the other hand, it was confirmed that if the insertion length of the microstrip line with respect to the outer edge is out of the range of 0.4 times or more and 0.6 times or less of the guide wavelength, the transmission loss is remarkably increased. Therefore, by adopting the above-described configuration, it is possible to suppress the amount of reflection in a wider frequency band than the conventional waveguide planar line converter.

  According to the present invention, it is possible to provide a waveguide planar line converter that can be easily manufactured while suppressing an increase in transmission loss. Moreover, the amount of reflection can be suppressed in a wider frequency band than the conventional waveguide planar line converter.

It is the perspective view which decomposed | disassembled and showed one structural example of the waveguide plane line converter 1 by Embodiment 1 of this invention. It is the figure which showed the structural example of the waveguide plane line converter 1 of FIG. 1, and the mode that the waveguide plane line converter 1 was seen from upper direction is shown. It is sectional drawing which showed the structural example of the waveguide plane line converter 1 of FIG. It is sectional drawing which showed the structural example of the waveguide plane line converter 1 of FIG. 2, and the cut surface at the time of cut | disconnecting the waveguide plane line converter 1 by a BB cutting line is shown. It is the figure which showed an example of the transmission characteristic of the waveguide plane line converter 1 of FIG. 2 compared with the prior art example. It is sectional drawing which showed the other structural example of the waveguide plane line converter 1 of FIG. 2, and the case where the length Lw of the taper waveguide 10 is varied is shown. It is the figure which showed an example of the transmission characteristic of the waveguide plane line converter 1 of FIG. It is sectional drawing which showed one structural example of the waveguide plane line converter 1 by Embodiment 2 of this invention, and the case where only one wide wall Ww1 of the waveguide 10a is inclined is shown.

Embodiment 1 FIG.
<Waveguide planar line converter 1>
FIG. 1 is an exploded perspective view showing a configuration example of a waveguide planar line converter 1 according to Embodiment 1 of the present invention. In the drawing, a waveguide plane line converter 1 connected to a rectangular waveguide 2 is drawn with the tube axis direction of the rectangular waveguide 2 being coincident with the vertical direction. Here, the directions orthogonal to the wide wall Ww and the narrow wall Wn of the rectangular waveguide 2 in the horizontal plane are referred to as the x direction and the y direction, respectively, and the vertical direction is referred to as the z direction.

  This waveguide plane line converter 1 is a slot excitation type converter, a tapered waveguide 10 communicating with a rectangular waveguide 2, a ground plate 11 in which an excitation slot 11a is formed, an MSL 13 and a short circuit. It is composed of a dielectric substrate 12 on which a plate 14 is formed.

  The rectangular waveguide 2 is a rectangular waveguide having a waveguide 2a extending in the z direction, and the cut surface when cut by a horizontal plane at an arbitrary position in the z direction has a rectangular shape. The waveguide 2a has a space surrounded by two wide walls Ww that are wide in the horizontal direction and that are opposed to each other and two narrow walls Wn that are narrow in the horizontal direction and are opposed to each other. In the rectangular waveguide 2, both the wide wall Ww and the narrow wall Wn are approximately equal in width in the z direction. The rectangular waveguide 2 is formed of a rectangular parallelepiped block body made of metal, for example, aluminum, and a hollow portion formed in the block body becomes a waveguide 2a.

  The tapered waveguide 10 has a waveguide 10 a that communicates with the waveguide 2 a of the rectangular waveguide 2, and the tip opening 10 b is formed from the cross section of the rectangular waveguide 2 by inclining the wide wall of the waveguide 10 a. It is a narrow waveguide. In other words, the cut surface when the waveguide 10a is cut by a horizontal plane has a smaller area as it extends upward. The lower end surface of the tapered waveguide 10 substantially coincides with the opening of the waveguide 2a. It consists of a rectangular shape elongated in the y direction. The tapered waveguide 10 is composed of an inclined surface in which two wide walls facing each other are inclined with respect to a vertical surface (yz surface).

  By interposing such a tapered waveguide 10, it is possible to reduce the amount of reflection compared to the case where the rectangular waveguide 2 is directly closed by the dielectric substrate 12. The tapered waveguide 10 is joined to the upper end surface of the rectangular waveguide 2. Similarly to the rectangular waveguide 2, the tapered waveguide 10 is also formed of a rectangular parallelepiped block body made of metal, for example, aluminum, and the hollow portion formed in the block body becomes the waveguide 10a. Note that the rectangular waveguide 2 and the tapered waveguide 10 are not separated and may be manufactured integrally.

  The ground plate 11 is a conductor plate that forms the ground of the MSL 13 and the short-circuit plate 14 with the dielectric substrate 12 interposed therebetween, and is disposed between the tapered waveguide 10 and the dielectric substrate 12. The excitation slot 11a is formed of an elongated rectangular through hole whose entire hole overlaps the tip opening 10b. The excitation slot 11a has substantially the same shape and size as the tip opening 10b.

  The dielectric substrate 12 is an insulating resin substrate made of a fluororesin having a relative dielectric constant smaller than that of a dielectric, for example, an epoxy resin. The lower surface closes the tapered waveguide 10 and the upper surface includes the MSL 13 and the dielectric substrate 12. A short-circuit plate 14 is formed.

  The short-circuit plate 14 is a conductor plate for terminating the rectangular waveguide 2, and includes a continuous region in which a cut 14 a for arranging the MSL 13 is formed. The notch 14a has a groove shape extending in the x direction with a substantially equal width, and is formed at the center of the short-circuit plate 14 in the y direction. The MSL 13 is a transmission line that transmits electromagnetic waves in the x direction, and includes a conductor pattern that extends from the inside of the cut 14 a in the x direction with a substantially equal width and reaches the side end face of the dielectric substrate 12. The MSL 13 is disposed at the center of the excitation slot 11a in the y direction.

  The ground plate 11, the short-circuit plate 14, and the MSL 13 are manufactured by pasting a metal thin film, for example, a copper foil on the dielectric substrate 12, and then patterning the metal thin film by etching. The waveguide planar line converter 1 is completed by bonding the dielectric substrate 12 on which the ground plate 11, the short-circuit plate 14 and the MSL 13 are formed to the upper end surface of the tapered waveguide 10.

  FIG. 2 is a diagram illustrating a configuration example of the waveguide planar line converter 1 of FIG. 1, and shows a state in which the waveguide planar line converter 1 is viewed from above. The short-circuit plate 14 covers the excitation slot 11a and is formed of a continuous region in which a cut 14a is formed. More specifically, the short-circuit plate 14 extends in the y direction and has an outer edge 14b substantially parallel to the long side of the excitation slot 11a, and an outer edge 14c extends in the x direction and substantially parallel to the short side of the excitation slot 11a. And consists of a continuous region.

  If the side end face of the dielectric substrate 12 where the MSL 13 is exposed is referred to as a front end face, and the opposite side end face is referred to as a rear end face, the outer edge 14b is connected to the front end face side of the excitation slot 11a and the excitation slot. It is formed on the rear end face side from 11a. These outer edges 14b are formed outside the long side of the excitation slot 11a by about 1/4 times the guide wavelength λg.

  The excitation slot 11a of the ground plate 11 disposed between the tapered waveguide 10 and the dielectric substrate 12 has the entire hole overlapping the tip opening 10b of the tapered waveguide 10, and functions as a slot exciter. That is, the overlapping region with the excitation slot 11a on the dielectric substrate 12 becomes a closed region Rc (shown in FIGS. 3 and 4) that closes the waveguide 10a.

  In general, the effective dielectric constant of a dielectric substrate varies depending on the surface state of the dielectric substrate even if the material or the like is uniform. Further, when an electromagnetic wave propagates through the dielectric substrate, the electromagnetic wave is reflected at the change point of the effective dielectric constant. For this reason, in the dielectric substrate 12 on which the short-circuit plate 14 is formed, the effective dielectric constant changes with the outer edges 14b and 14c of the short-circuit plate 14 as a boundary, and electromagnetic waves are reflected.

  When the electromagnetic wave propagates in the dielectric substrate 12 in a direction intersecting with the long side of the closed region Rc, the electromagnetic wave is reflected with the outer edge 14b as a boundary. Further, the incident wave entering from the closed region Rc cancels the reflected wave reflected by the outer edge 14b because the distance to the outer edge 14b is λg / 4. For this reason, the electromagnetic wave propagating in the x direction in the dielectric substrate 12 can be prevented from leaking to the outside of the short-circuit plate 14, and the electromagnetic wave can be efficiently transmitted to the MSL 13.

  The reason why leakage of electromagnetic waves can be suppressed will be described from another viewpoint. By providing an open stub having a stub length of λg / 4 as a stub connected to the end face of the tapered waveguide 10, the tapered waveguide 10 is provided. This is equivalent to the case where all the end faces of are electrically short-circuited and there are through holes. For this reason, leakage of electromagnetic waves into the dielectric substrate 12 can be suppressed by the same principle as when the tapered waveguide 10 is surrounded by through holes.

  On the other hand, the outer edge 14c is formed on the left end surface side of the excitation slot 11a and on the right end surface side of the excitation slot 11a. These outer edges 14c are all formed outside the short side of the excitation slot 11a by approximately 1/4 times the guide wavelength λg. When the electromagnetic wave propagates in the dielectric substrate 12 in the direction intersecting the short side of the closed region Rc, the electromagnetic wave is reflected with the outer edge 14c of the short-circuit plate 14 as a boundary. Further, the incident wave entering from the closed region Rc cancels the reflected wave reflected by the outer edge 14c because the distance to the outer edge 14c is λg / 4. For this reason, electromagnetic waves propagating in the y direction in the dielectric substrate 12 can be prevented from leaking outside the short-circuit plate 14.

  Since the rate at which electromagnetic waves propagate in the dielectric substrate 12 in the y direction and leak to the outside of the short-circuit plate 14 is very small, the distance from the short side of the excitation slot 11a to the outer edge 14c is not λg / 4. May be.

  The MSL 13 extends from the front end face of the dielectric substrate 12 in the x direction, straddles the long side of the excitation slot 11a, and is electromagnetically coupled to the excitation slot 11a with the dielectric substrate 12 interposed therebetween. This eliminates the need for a matching element that is electromagnetically coupled to the MSL 13, thereby facilitating the manufacture of the waveguide planar line converter 1.

  The excitation slot 11a of the ground plate 11 disposed between the tapered waveguide 10 and the dielectric substrate 12 has the entire hole overlapping the tip opening 10b of the tapered waveguide 10, and functions as a slot exciter. That is, the overlapping region of the excitation slot 11a and the dielectric substrate 12 becomes the closed region Rc, and the MSL 13 is formed so as to straddle the long side of such a closed region Rc, so that the matching element and the short-circuit plate 14 are not provided. Transmission loss can be reduced compared to a waveguide planar line converter.

  More specifically, the MSL 13 is inserted inward from the outer edge 14b by a distance not less than 0.4 times and not more than 0.6 times the guide wavelength λg. That is, the insertion length Lm of the MSL 13 with respect to the outer edge 14b satisfies the relationship of 0.4λg ≦ Lm ≦ 0.6λg.

  In this waveguide planar line converter 1, the width of the wide wall Ww of the rectangular waveguide 2 is a, the width of the narrow wall Wn is b, and the relationship of a = 2b is generally satisfied. The length of the excitation slot 11a in the y direction, that is, the slot length is approximately the same as the width a of the wide wall Ww, and the width in the x direction, that is, the slot width Ws is larger than the width b of the narrow wall Wn. narrow. Further, the width of the MSL 13, that is, the line width Wm, is sufficiently narrower than the width a of the wide wall Ww.

  FIG. 3 is a cross-sectional view showing a configuration example of the waveguide planar line converter 1 of FIG. (A) in the figure shows a cut surface when the waveguide plane line converter 1 is cut along the A1-A1 cutting line, and (b) shows the waveguide plane line converter 1 in A2 The cut surface when cut by the A2 cutting line is shown.

  In the tapered waveguide 10, both the wide walls Ww <b> 1 of the waveguide 10 a are inclined so that the width of the tip opening 10 b in the x direction is narrower than the width b of the narrow wall Wn of the rectangular waveguide 2. The wide wall Ww1 is composed of an inclined surface having a constant inclination. The excitation slot 11a of the ground plate 11 is a through hole communicating with the waveguide 10a.

  The short-circuit plate 14 covers the closed region Rc on the dielectric substrate 12 where the entire region overlaps the excitation slot 11a, and the distance D1 from the long side of the excitation slot 11a to the outer edge 14b is approximately λg / 4. is there.

  FIG. 4 is a cross-sectional view showing a configuration example of the waveguide planar line converter 1 of FIG. 2, and shows a cut surface when the waveguide planar line converter 1 is cut along a BB cutting line. ing. Both narrow walls Wn1 of the waveguide 10a are wall surfaces perpendicular to the horizontal plane, and the length of the tip opening 10b in the y direction is about the same as the width a of the wide wall Ww of the rectangular waveguide 2.

  The short-circuit plate 14 covers the closed region Rc on the dielectric substrate 12 where the entire region overlaps the excitation slot 11a, and the distance D2 from the short side of the excitation slot 11a to the outer edge 14c is approximately λg / 4. is there.

FIG. 5 is a diagram showing an example of transmission characteristics of the waveguide planar line converter 1 of FIG. 2 in comparison with a conventional example. In the figure, characteristic curves RL1, RL2, IL1, and IL2 showing these correspondences are drawn with the horizontal axis as the normalized frequency and the vertical axis as the reflection amount RL and the transmission amount IL. The normalized frequency is a frequency f / f ₀ normalized using the target frequency f ₀ . For example, f ₀ = 76.5 GHz.

  The reflection amount RL indicates a reflection loss (return loss) in dB. The transmission amount IL indicates insertion loss (insertion loss) in dB. Characteristic curves RL1 and IL1 respectively represent the reflection amount RL and the transmission amount IL when the waveguide plane line converter 1 according to the present invention is used. Further, characteristic curves RL2 and IL2 represent the reflection amount RL and the transmission amount IL, respectively, when a conventional waveguide plane line converter having a matching element and a short-circuit plate is used.

  According to the transmission characteristic simulation experiment by the inventors of the present invention, good transmission characteristics were obtained when the insertion length Lm of the MSL 13 was in the range of 0.4λg to 0.6λg. On the other hand, it was confirmed that the transmission loss significantly increases when the insertion length Lm of the MSL 13 is out of the above range.

  The characteristic curves RL1 and IL1 shown in FIG. 5 indicate that the inclination angle of the wide wall Ww1 = 5 ° with respect to the rectangular waveguide 2 having the wide wall Ww width a = 3.2 mm and the narrow wall Wn width b = 1.55 mm. Simulation using a tapered waveguide 10 having a width of the tip opening 10b (corresponding to the slot width Ws) = 0.2 mm and an insertion length Lm of the MSL 13 being Lm = 0.47λg (corresponding to 1.33 mm) It is a result. The insertion length Lm = 0.47λg is an optimum value when other parameters are fixed.

  The characteristic curve IL1 is substantially constant with a peak near the normalized frequency = 1 in the range of 0.9 to 1.1. The peak value of the transmission amount IL is -0.5 dB. The characteristic curve IL2 shows a tendency that is approximately similar to the characteristic curve IL1, but the transmission amount IL slightly falls on the low frequency side. Therefore, it can be seen that the waveguide plane line converter 1 has the same or higher performance as the conventional waveguide plane line converter in the transmission amount IL.

  On the other hand, the characteristic curve RL1 rapidly decreases around the normalized frequency = 1 within the range of 0.9 to 1.1, and the minimum value of the reflection amount RL is about −27 dB. Further, the bandwidth Wb1 of the frequency band in which the reflection amount RL is −10 dB or less is 14%. On the other hand, the minimum value of the characteristic curve RL2 is about −22 dB, and the bandwidth Wb2 of the frequency band in which the reflection amount RL is −10 dB or less is 4.6%. That is, it can be seen that the waveguide plane line converter 1 suppresses the reflection amount RL in a wider frequency band than the conventional waveguide plane line converter.

  According to the present embodiment, since the amount of reflection RL can be suppressed by interposing the tapered waveguide 10 in which the wide wall Ww1 of the waveguide 10a is inclined, the rectangular waveguide 2 is directly connected to the dielectric substrate 12 by the dielectric substrate 12. It is possible to suppress an increase in the transmission loss of the waveguide planar line converter 1 as compared with the case where it is closed. Further, the MSL 13 straddles the long side of the closed region Rc on the dielectric substrate 12 where the entire region overlaps the tip opening 10b, and is electromagnetically coupled to the excitation slot 11a with the dielectric substrate 12 interposed therebetween. This eliminates the need for a matching element that is electromagnetically coupled to the MSL 13, thereby facilitating the manufacture of the waveguide planar line converter 1.

  FIG. 6 is a cross-sectional view showing another configuration example of the waveguide planar line converter 1 of FIG. 2, and shows a case where the length Lw of the tapered waveguide 10 is varied. 3A shows a case where the length Lw of the tapered waveguide 10 is about ½ of the tapered waveguide 10 shown in FIG. 3, and FIG. The case where it is set to about 1/3 of the tapered waveguide 10 is shown. The length Lw is the tube length in the z direction.

  In the tapered waveguide 10, both the wide walls Ww <b> 1 of the waveguide 10 a are inclined to make the width of the tip opening 10 b in the x direction narrower than the width b of the narrow wall Wn of the rectangular waveguide 2. The inclination angle of the wide wall Ww1 is approximately the same as that of the tapered waveguide 10 of FIG. The distance D1 from the long side of the excitation slot 11a to the outer edge 14b is approximately λg / 4.

  In the case of the tapered waveguide 10 of FIG. 6A, the width of the tip opening 10b, that is, the slot width Ws is 0.75 mm, and the insertion length Lm of the MSL 13 is 0.48λg (corresponding to 1.37 mm). It is.

  In the case of the tapered waveguide 10 of FIG. 6B, the width of the tip opening 10b, that is, the slot width Ws is 1.25 mm, and the insertion length Lm of the MSL 13 is 0.49λg (corresponding to 1.40 mm). It is.

  FIG. 7 is a diagram showing an example of transmission characteristics of the waveguide planar line converter 1 of FIG. FIG. 6A shows the case of the tapered waveguide 10 shown in FIG. Characteristic curves RL3 and IL3 represent the reflection amount RL and the transmission amount IL, respectively.

  The characteristic curve IL3 has a peak in the vicinity of the normalized frequency = 1 within the range of 0.9 to 1.1, and gradually increases within the range up to the normalized frequency 1, while rapidly exceeding 1 is decreasing. The peak value of the transmission amount IL is -1.6 dB. The characteristic curve RL3 is the minimum near the normalized frequency = 1 within the range of 0.9 to 1.1, and the minimum value of the reflection amount RL is about −8 dB.

  FIG. 6B shows the case of the tapered waveguide 10 shown in FIG. Characteristic curves RL4 and IL4 represent the reflection amount RL and the transmission amount IL, respectively. The characteristic curve IL4 has a peak near the normalized frequency = 1 within the range of 0.9 to 1.1 and gradually increases within the range up to the normalized frequency 1. On the other hand, when it exceeds 1, the characteristic curve IL4 increases rapidly. is decreasing. The peak value of the transmission amount IL is -2.6 dB. The characteristic curve RL4 is minimum in the vicinity of the normalized frequency = 1 within the range of 0.9 to 1.1, and the minimum value of the reflection amount RL is about −6 dB.

  From these simulation results, even when the length Lw of the tapered waveguide 10 is changed and the slot width Ws is changed, the insertion length Lm of the MSL 13 is within the range of 0.4λg to 0.6λg. If so, it can be seen that generally good transmission characteristics are obtained.

Embodiment 2. FIG.
In the first embodiment, an example in which the waveguide planar line converter 1 includes the tapered waveguide 10 in which both the wide walls Ww1 of the waveguide 10a are inclined has been described. In contrast, in the present embodiment, a case will be described in which a tapered waveguide 10 is provided in which only one wide wall Ww1 of the waveguide 10a is inclined.

  FIG. 8 is a cross-sectional view showing a configuration example of the waveguide planar line converter 1 according to the second embodiment of the present invention, and is a tapered waveguide in which only one wide wall Ww1 of the waveguide 10a is inclined. The case with 10 is shown. In the tapered waveguide 10, the front wide wall Ww1 is a wall surface perpendicular to the horizontal plane, while the rear wide wall Ww1 is inclined forward.

  The inclination angle of the wide wall Ww1 is about the same as the wide wall Ww1 of the tapered waveguide 10 shown in FIG. 3, and the length Lw is about twice that of the tapered waveguide 10 of FIG. With this configuration, it is possible to obtain the tapered waveguide 10 having the width of the tip opening 10b, that is, the slot width Ws of 0.2 mm.

  The excitation slot 11a of the ground plate 11 is a through hole communicating with the waveguide 10a. A distance D1 from the long side of the excitation slot 11a to the outer edge 14b in the short-circuit plate 14 is approximately λg / 4. Even with such a configuration, it is possible to provide the waveguide planar line converter 1 that can be easily manufactured while suppressing an increase in transmission loss.

  In the first and second embodiments, an example in which the waveguide planar line converter 1 includes the ground plate 11 having the excitation slot 11a has been described. However, the present invention does not include such a ground plate 11. It can also be applied to things. For example, by sticking the dielectric substrate 12 to the upper end surface of the tapered waveguide 10 and closing the waveguide 10a, the tip of the tapered waveguide 10 functions as a slot exciter, and the entire tapered waveguide 10 Can function as a ground. In this case, the region on the dielectric substrate 12 facing the tip opening 10b of the tapered waveguide 10 becomes the closed region Rc. The short-circuit plate 14 covers the tip opening 10b of the tapered waveguide 10, and the MSL 13 is formed so as to straddle the long side of the tip opening 10b.

  In the first and second embodiments, the example in which the excitation slot 11a has substantially the same shape and size as the tip opening 10b of the tapered waveguide 10 has been described. However, the present invention has the configuration of the excitation slot 11a. It is not limited to. For example, the slot length and slot width Ws of the excitation slot 11a may be shorter than the length and width of the tip opening 10b.

DESCRIPTION OF SYMBOLS 1 Waveguide planar line converter 10 Tapered waveguide 10a Waveguide 10b End opening 11 Grounding plate 11a Excitation slot 12 Dielectric substrate 13 MSL
14 Short-circuit plate 14a Notches 14b, 14c Outer edge 2 Rectangular waveguide Rc Closed region Wn Narrow wall Ww of rectangular waveguide 2 Wide wall Wn1 of rectangular waveguide 2 Narrow wall Ww1 of tapered waveguide 10 Taper waveguide 10 Wide wall

Claims (3)

A tapered waveguide having a waveguide communicating with a rectangular waveguide, wherein the waveguide is formed of a hollow portion, and a wide wall of the waveguide is inclined so that a tip opening is narrower than a section of the rectangular waveguide. When,
One main surface closes the tapered waveguide, and includes a dielectric substrate having a microstrip line and a short-circuit plate formed on the other main surface,
The short-circuit plate comprises a continuous region in which a cutout for arranging the microstrip line is formed while covering a closed region on the dielectric substrate where the entire region overlaps the tip opening.
The waveguide planar line converter, wherein the microstrip line straddles the long side of the closed region.   The ground plate according to claim 1, further comprising a ground plate disposed between the tapered waveguide and the dielectric substrate, and having an elongated rectangular through-hole having the entire hole overlapping the tip opening. Waveguide planar line converter. The short-circuit plate has an outer edge that is substantially parallel to the long side of the closed region and is formed on the outer side of the long side of the closed region by about 1/4 times the guide wavelength;
3. The waveguide planar line according to claim 1, wherein the microstrip line is inserted inward from the outer edge by a distance not less than 0.4 times and not more than 0.6 times an in-tube wavelength. 4. converter.

Images