Planar Line Waveguide Converter

Abstract

This invention provides a planar line-to-waveguide converter that prevents degradation of the frequency characteristics of signals passing through a waveguide by altering the characteristics of the radiating antenna through a dielectric film placed inside a conversion waveguide continuous with the waveguide. [Solution] The planar line-waveguide converter 1 comprises a conversion waveguide 30 having an insertion hole 39 that is short-circuited at one end by a short-circuiting wall 35 and open at the other end and communicates with an insertion space 38 into which a dielectric substrate 10 is inserted; a waveguide 20 connected to the conversion waveguide 30 and having an internal space 28 continuous with the insertion space 38, and arranged such that the direction of electromagnetic wave propagation is perpendicular or parallel to the dielectric substrate 10; a radiating antenna 14 provided on the dielectric substrate 10 and arranged in the insertion space 38; and a dielectric film 40 arranged in the vicinity of the radiating antenna 14 in the insertion space 38.

Description

[Technical Field]

[0001] The present invention relates to a planar line-to-waveguide converter, and more particularly to a planar line-to-waveguide converter for frequency bands from the microwave band to the terahertz band. [Background technology]

[0002] Conventionally, planar line-to-waveguide converters have been used as means to convert electrical signals transmitted through planar lines such as microstrip lines and coplanar lines formed on dielectric substrates into electromagnetic waves transmitted through waveguides, or to perform the reverse conversion (see, for example, Patent Document 1).

[0003] As shown in Figure 16, the planar line-waveguide converter 71 for substrates disclosed in Patent Document 1 comprises a dielectric substrate 72, a coplanar line 73 provided on the dielectric substrate 72, a back-surface grounding conductor 74 provided on the back surface of the dielectric substrate 72, a waveguide 75 erected on the dielectric substrate 72 and having the edge of the end opening on the dielectric substrate 72 side connected to the back-surface grounding conductor 74, a waveguide excitation antenna (radiating antenna) 77 formed by extending the end of the central conductor 76 into the interior of the waveguide 75, and a connecting projection 78 for connecting the waveguides 75.

[0004] Furthermore, in this substrate-type planar line / waveguide converter 71, the thickness of the dielectric substrate 72 is set to approximately 1 / 4 of the wavelength within the dielectric. Also, the size of the connecting protrusion 78 is set to a size that allows the lower end of the waveguide 75 to be fitted. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-261312 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, when the configuration disclosed in Patent Document 1 is used in the terahertz wave band, there is a problem in that the frequency characteristics of the signal passing through the planar line-waveguide converter change due to misalignment in the outer shape of the dielectric substrate on which the planar line is provided, or misalignment when mounting the dielectric substrate in the waveguide, making it impossible to achieve the desired signal propagation.

[0007] The present invention has been made to solve the above-mentioned conventional problems, and aims to provide a planar line-to-waveguide converter that can prevent deterioration of the frequency characteristics of signals passing through a waveguide by changing the characteristics of the radiating antenna by arranging a dielectric film in a conversion waveguide continuous with the waveguide. [Means for solving the problem]

[0008] To solve the above problems, the planar line-waveguide converter according to the present invention comprises a dielectric substrate (10), line conductors (13, 51) provided on the surface (10a) of the dielectric substrate, a ground conductor (15) provided below the line conductors on the back surface (10b) of the dielectric substrate, and a plug-in hole (39) having one end short-circuited by a short-circuit wall (35) and the other end open, communicating with a plug-in space (38) into which the dielectric substrate is inserted, and the edge (39a) of the plug-in hole is connected to the ground conductor. The configuration comprises a waveguide (30), a waveguide (20) connected to the conversion waveguide and having an internal space (28) continuous with the insertion space, and arranged such that the direction of electromagnetic wave propagation is perpendicular or parallel to the front and back surfaces of the dielectric substrate, a radiating antenna (14, 60) provided on the dielectric substrate and connected to the line conductor and placed in the insertion space, and dielectric films (40, 41, 42, 43) placed near the radiating antenna in the insertion space.

[0009] With this configuration, the planar line-waveguide converter according to the present invention has a dielectric film placed inside a conversion waveguide continuous with the waveguide, thereby changing the characteristics of the radiating antenna and preventing deterioration of the frequency characteristics of the signal passing through the waveguide 20, and enabling uniform transmission characteristics within the operating frequency bands of the millimeter wave and terahertz wave bands.

[0010] Furthermore, the planar line-waveguide converter according to the present invention may be configured such that the radiating antenna is a monopole antenna provided on the surface of the dielectric substrate and extending into the insertion space.

[0011] Furthermore, the planar line-waveguide converter according to the present invention may be configured such that the dielectric substrate is arranged such that its front and back surfaces are perpendicular to the propagation direction, and the extension direction of the radiating antenna is perpendicular to the propagation direction, and the dielectric film is arranged on the back surface side of the dielectric substrate.

[0012] Furthermore, the planar line-waveguide converter according to the present invention has a rectangular cross-sectional shape of the internal space and the insertion space perpendicular to the propagation direction, the converter waveguide has two wide tube walls (31, 32) that are in contact with the long side of the cross-sectional shape of the insertion space and two narrow tube walls (33, 34) that are in contact with the short side of the cross-sectional shape of the insertion space, and the dielectric film may be arranged below the radiating antenna, extending from one of the narrow tube walls of the converter waveguide to the other narrow tube wall.

[0013] Furthermore, the planar line-waveguide converter according to the present invention may be configured such that the dielectric film is attached to the back surface of the dielectric substrate below the radiating antenna.

[0014] With this configuration, the planar line-waveguide converter according to the present invention can modify the characteristics of the radiating antenna by attaching a dielectric film to the back surface of the protrusion, thereby preventing deterioration of the frequency characteristics of the signal passing through the waveguide and achieving uniform transmission characteristics within the operating frequency bands of the millimeter wave and terahertz wave bands.

[0015] Further, in the planar circuit - waveguide converter according to the present invention, the dielectric substrate is arranged such that the front surface and the back surface are parallel to the propagation direction, and the extending direction of the radiation antenna is perpendicular to the propagation direction. The dielectric film faces the other side surface (12c) opposite to one side surface (12b) of the dielectric substrate facing the short - circuit wall, and is arranged perpendicular to the front surface and the back surface of the dielectric substrate. This configuration may also be adopted.

[0016] With this configuration, in the planar circuit - waveguide converter according to the present invention, the dielectric film is arranged so as to cover at least a part of the cross - section of the insertion space of the conversion waveguide, thereby changing the characteristics of the radiation antenna and preventing deterioration of the frequency characteristics of the signal passing through the waveguide, and realizing uniform passing characteristics within the use frequency band of the millimeter - wave band or the terahertz - wave band.

[0017] Further, in the planar circuit - waveguide converter according to the present invention, the radiation antenna may be a dipole antenna having a first strip conductor (61) provided on the front surface of the dielectric substrate, connected to the circuit conductor, and extending into the insertion space, a first antenna element (63) provided on the front surface of the dielectric substrate and connected to the first strip conductor, a second strip conductor (62) provided on the back surface of the dielectric substrate, connected to the ground conductor, and extending into the insertion space, and a second antenna element (64) provided on the back surface of the dielectric substrate and connected to the second strip conductor.

[0018] With this configuration, in the planar circuit - waveguide converter according to the present invention, the dielectric film is arranged so as to cover at least a part of the cross - section of the insertion space of the conversion waveguide, thereby changing the characteristics of the radiation antenna and preventing deterioration of the frequency characteristics of the signal passing through the waveguide, and realizing uniform passing characteristics within the use frequency band of the millimeter - wave band or the terahertz - wave band.

Advantages of the Invention

[0019] This invention provides a planar line-to-waveguide converter that can prevent deterioration of the frequency characteristics of signals passing through a waveguide by changing the characteristics of the radiating antenna through a dielectric film placed inside a conversion waveguide continuous with the waveguide. [Brief explanation of the drawing]

[0020] [Figure 1] This is a cross-sectional view showing the configuration of a planar line-waveguide converter according to the first embodiment of the present invention. [Figure 2] This is a top perspective view showing the configuration of a planar line-waveguide converter according to the first embodiment of the present invention. [Figure 3] (a) is a cross-sectional view at the position of line AA in Figure 2, and (b) is a cross-sectional view at the position of line BB in Figure 2. [Figure 4] (a) is a graph showing the simulation results of the reflection characteristics S11 of a planar transmission line / waveguide converter model as designed, (b) is a graph showing the simulation results of the reflection characteristics S11 of a planar transmission line / waveguide converter model in which the distance from the tip of the radiating antenna to the end of the convex part is 0.01 mm further than the design value, and (c) is a graph showing the simulation results of the reflection characteristics S11 of a planar transmission line / waveguide converter model according to the first embodiment of the present invention. [Figure 5] This is a top perspective view showing the configuration of a planar line-waveguide converter according to a second embodiment of the present invention. [Figure 6] This is a cross-sectional view at the position of line AA in Figure 5. [Figure 7] (a) is a graph showing the simulation results of the reflection characteristics S11 of a planar transmission line / waveguide converter model as designed, (b) is a graph showing the simulation results of the reflection characteristics S11 of a planar transmission line / waveguide converter model in which the distance from the tip of the radiating antenna to the end of the convex part is 0.01 mm further than the design value, and (c) is a graph showing the simulation results of the reflection characteristics S11 of a planar transmission line / waveguide converter model according to the second embodiment of the present invention. [Figure 8] This is a side perspective view showing the configuration of a planar line-waveguide converter according to a third embodiment of the present invention. [Figure 9] This is a cross-sectional view showing the configuration of a planar line-waveguide converter according to a third embodiment of the present invention. [Figure 10] (a) is a cross-sectional view at the position of line AA in Figure 9, and (b) is a cross-sectional view at the position of line BB in Figure 9. [Figure 11] (a) is a graph showing the simulation results of the reflection characteristics S11 of a planar line-waveguide converter model as designed, (b) is a graph showing the simulation results of the reflection characteristics S11 of a planar line-waveguide converter model in which the back short length from the center position in the width direction of the radiating antenna in the convex portion to the short-circuit wall of the conversion waveguide is 0.01 mm shorter than the design value, and (c) is a graph showing the simulation results of the reflection characteristics S11 of a planar line-waveguide converter model according to the third embodiment of the present invention. [Figure 12] This is a cross-sectional view showing the configuration of a planar line-waveguide converter according to a fourth embodiment of the present invention. [Figure 13] This is a cross-sectional perspective view showing the configuration of a planar line-waveguide converter according to a fourth embodiment of the present invention. [Figure 14] (a) is a cross-sectional view at the position of line AA in Figure 13, (b) is a cross-sectional view at the position of line BB in Figure 13, and (c) is a cross-sectional view at the position of line CC in Figure 13. [Figure 15] (a) is a graph showing the simulation results of the reflection characteristics S11 of a planar line-waveguide converter model as designed, (b) is a graph showing the simulation results of the reflection characteristics S11 of a planar line-waveguide converter model in which the positions of the first and second strip conductors constituting the dipole antenna are shifted by 0.005 mm in the lateral direction perpendicular to the propagation direction of electromagnetic waves in the waveguide, and (c) is a graph showing the simulation results of the reflection characteristics S11 of a planar line-waveguide converter model according to the fourth embodiment of the present invention. [Figure 16] This is an exploded perspective view showing the configuration of a conventional planar line / waveguide converter for substrates. [Modes for carrying out the invention]

[0021] The following describes embodiments of the planar line-waveguide converter according to the present invention with reference to the drawings. The planar line-waveguide converter of the present invention is for converting high-frequency signals, such as those exceeding 200 GHz, into millimeter-wave or terahertz-wave electromagnetic waves, or conversely, converting millimeter-wave or terahertz-wave electromagnetic waves into high-frequency signals.

[0022] (First embodiment) First, the configuration of the planar line-waveguide converter according to the first embodiment of the present invention will be described with reference to the drawings.

[0023] Figure 1 is a cross-sectional view showing the configuration of the planar line-waveguide converter 1 of this embodiment. Figure 2 is a top perspective view showing the configuration of the planar line-waveguide converter 1 of this embodiment. Figure 3(a) is a cross-sectional view at the position of line AA in Figure 2, and Figure 3(b) is a cross-sectional view at the position of line BB in Figure 2.

[0024] As shown in Figures 1 and 2, the planar line-waveguide converter 1 comprises a dielectric substrate 10, a waveguide 20, a conversion waveguide 30, and a dielectric film 40.

[0025] The dielectric substrate 10 in this embodiment has a rectangular parallelepiped main body 11 and a rectangular parallelepiped protrusion 12 that is narrower than the main body 11. The protrusion 12 is integrated with the main body 11.

[0026] The dielectric substrate 10 can be any semiconductor material with a thickness of about 0.06 mm, such as GaAs, GaN, InP, or Si, or an alumina ceramic substrate, a resin substrate, or a quartz glass substrate. As for the resin substrate, for example, a fluororesin, liquid crystal polymer, or BT resin (bismaleimide-triazine resin) with a thickness of about 0.1 mm can be used.

[0027] Furthermore, the dielectric substrate 10 may be made by bonding together thin resin substrates of about 0.02 mm in thickness to a thickness of about 0.1 mm, or it may be a single layer resin substrate with a thickness of about 0.1 mm. Regardless of the material the dielectric substrate 10 is made of, it is sufficient that it has a thickness that will not be destroyed by the stress when it is mounted on the conversion waveguide 30, which will be described later.

[0028] Furthermore, a single-layer or multi-layer material with a relatively low dielectric constant and a thickness of about 0.03 mm, such as BCB (benzocyclobutene) or SiO2, may be laminated on the upper surface of the dielectric substrate 10.

[0029] The surface 10a of the dielectric substrate 10 is provided with a line conductor 13, which is a strip conductor, and a radiating antenna 14 electrically connected to the line conductor 13. The extension direction (Y-axis direction) of the radiating antenna 14 is parallel to one side surface 12b and the other side surface 12c of the protrusion 12.

[0030] A grounding conductor 15 is provided on the back surface 10b of the dielectric substrate 10, below the line conductor 13. The grounding conductor 15 may be at least a high-frequency ground (RF ground), and may be configured to have a bias voltage applied to it.

[0031] The dielectric substrate 10, the line conductor 13, and the ground conductor 15 constitute a planar line 17.

[0032] Furthermore, the dielectric substrate 10 has circuit components such as a monolithic microwave integrated circuit (MMIC) (not shown) mounted or integrated, and the transmission line conductor 13 is electrically connected to this circuit component. The MMIC is an integrated circuit that includes semiconductor components such as a field effect transistor (FET), and functions, for example, as an amplifier or frequency converter.

[0033] Waveguide 20 is a rectangular waveguide having two wide tube walls 21, 22 parallel to the XZ plane and two narrow tube walls 23, 24 parallel to the YZ plane. Waveguide 20 is, for example, a WR-3.4 rectangular waveguide with internal dimensions of 0.864 mm × 0.432 mm and a passband of 220 GHz to 330 GHz. Waveguide input / output 26, which is one opening of waveguide 20, is connected to an input / output section (not shown) such as a waveguide antenna. The other opening of waveguide 20 is connected to a conversion waveguide 30.

[0034] Hereafter, the space formed by the wide walls 21, 22 and narrow walls 23, 24 of the waveguide 20 will also be referred to as the "internal space 28". The cross-sectional shape of the internal space 28 perpendicular to the direction of electromagnetic wave propagation in the waveguide 20 is rectangular. The two wide walls 21, 22 are in contact with the long side of the cross-sectional shape of the internal space 28, and the two narrow walls 23, 24 are in contact with the short side of the cross-sectional shape of the internal space 28.

[0035] The conversion waveguide 30 has wide tube walls 31 and 32 parallel to the XZ plane, which are electrically connected to the wide tube walls 21 and 22 of the waveguide 20, respectively; narrow tube walls 33 and 34 parallel to the YZ plane, which are electrically connected to the narrow tube walls 23 and 24 of the waveguide 20, respectively; and a short-circuit wall 35 parallel to the XY plane. In other words, the conversion waveguide 30 is electrically connected to the waveguide 20. The wide tube walls 31 and 32 and the narrow tube walls 33 and 34 constitute a rectangular waveguide.

[0036] The conversion waveguide 30 is short-circuited at one end by a short-circuit wall 35 and open at the other end. The space 38 formed by the wide walls 31, 32 and the narrow walls 33, 34 (hereinafter also referred to as the "insertion space") is continuous with the internal space 28 of the waveguide 20. The insertion space 38 is, for example, a space with a width of 0.864 mm in the X-axis direction, a depth of 0.432 mm in the Y-axis direction, and a height of 0.39 mm in the Z-axis direction.

[0037] The cross-sectional shape of the insertion space 38 perpendicular to the direction of electromagnetic wave propagation in the waveguide 20 is rectangular. Two wide tube walls 31 and 32 are in contact with the long side of the cross-sectional shape of the insertion space 38, and two narrow tube walls 33 and 34 are in contact with the short side of the cross-sectional shape of the insertion space 38. The wide tube wall 31 is provided with an insertion hole 39 that communicates with the insertion space 38.

[0038] The dielectric substrate 10 is inserted into the insertion space 38 through the insertion hole 39, and is mounted on the conversion waveguide 30 when the protrusion 12 is inserted into the insertion hole 39. In this state, the ground conductor 15 is electrically connected to the conversion waveguide 30 and the waveguide 20 via the edge 39a of the insertion hole 39. The electrical connection between the ground conductor 15 and the edge 39a can be achieved, for example, by attaching the end of the ground conductor 15 to the edge 39a with a conductive adhesive.

[0039] For example, the insertion hole 39 is formed near the center of the broad tube wall 31 of the conversion waveguide 30. For impedance matching between the radiating antenna 14 and the conversion waveguide 30 and waveguide 20, the position of the insertion hole 39 in the X-axis direction may be offset from the central axis of waveguide 20.

[0040] Furthermore, to prevent the transmission line conductor 13 and radiating antenna 14 from being electrically connected to the conversion waveguide 30 and waveguide 20, a gap of 0.28 mm in the X-axis direction and 0.1 mm in the Z-axis direction is provided above the transmission line conductor 13 and radiating antenna 14 in the insertion hole 39. In addition, a gap of approximately 0.02 mm in the lateral direction (X-axis direction) is provided between the protrusion 12 and the insertion hole 39, taking into account the machining accuracy of both.

[0041] With the dielectric substrate 10 inserted into the insertion hole 39 of the conversion waveguide 30, the radiating antenna 14 is positioned within the insertion space 38 of the conversion waveguide 30, and the planar line 17 is positioned on the edge 39a of the insertion hole 39 and outside the conversion waveguide 30. When the dielectric substrate 10 is inserted into the insertion hole 39, the height from the inner wall surface 35a of the short-circuit wall 35 to the surface of the radiating antenna 14, i.e., the back short (BS) length, is, for example, 0.275 mm. This is approximately 1 / 4 wavelength of the center frequency of 275 GHz in the operating frequency band of the planar line-waveguide converter 1, which is 220 GHz to 330 GHz.

[0042] Furthermore, the distance between the tip of the radiating antenna 14 and the wide tube wall 32 of the conversion waveguide 30 facing the tip of the radiating antenna 14 is approximately half the depth (0.432 mm) of the internal space 28 of the waveguide 20 and the insertion space 38 of the conversion waveguide 30.

[0043] The waveguide 20 is positioned such that the direction of electromagnetic wave propagation is perpendicular to the front surface 10a and back surface 10b of the dielectric substrate 10 inserted into the insertion hole 39. As a result, the planar line-waveguide converter 1 of this embodiment has better transmission characteristics S when the millimeter wave band or terahertz wave band is used as the operating frequency band, compared to a configuration in which the direction of electromagnetic wave propagation of the waveguide 20 is parallel to the front surface 10a of the dielectric substrate 10. 21 You can obtain this.

[0044] Waveguides 20 and conversion waveguides 30 are made of metal materials such as brass, aluminum, copper, or gold. Of these metal materials, aluminum is particularly preferred because it is easy to process, inexpensive, and allows for a low surface roughness. Waveguides 20 and conversion waveguides 30 may be integrally formed from the same material.

[0045] The radiating antenna 14 is provided on the surface 10a of the dielectric substrate 10, is integrally formed with the line conductor 13, and is a strip conductor that extends into the insertion space 38 of the conversion waveguide 30. The radiating antenna 14 functions as a monopole antenna that excites the waveguide 20. For this reason, as shown in Figure 1, etc., the ground conductor 15 is not provided on the back surface 10b of the dielectric substrate 10 below the radiating antenna 14.

[0046] The dielectric substrate 10 is placed in the conversion waveguide 30 such that the extension direction of the radiating antenna 14 is perpendicular to the direction of electromagnetic wave propagation in the waveguide 20.

[0047] The length of the radiating antenna 14 in the Y-axis direction is approximately one-quarter of the wavelength λs on the dielectric substrate 10 for the frequency band used in the planar transmission line / waveguide converter 1. Here, the wavelength λs on the dielectric substrate 10 refers to the effective wavelength, taking into account the wavelength shortening effect due to the dielectric properties of the dielectric substrate 10.

[0048] The distance from the tip of the radiating antenna 14 to the end of the protrusion 12 and the width of the radiating antenna 14 should preferably be such that impedance matching can be achieved with the planar transmission line 17.

[0049] With the above configuration, the high-frequency signal transmitted from the circuit section is transmitted through the planar line 17, radiated from the radiating antenna 14 in the conversion waveguide 30, propagates through the waveguide 20, and is output from the waveguide input / output 26. Conversely, the electromagnetic wave input to the waveguide input / output 26 propagates through the waveguide 20, is received by the radiating antenna 14 in the conversion waveguide 30, transmitted through the planar line 17, and received by the circuit section.

[0050] The dielectric film 40 is positioned in the insertion space 38 of the conversion waveguide 30, near the radiating antenna 14. As shown in Figures 2 and 3(b), the dielectric film 40 is positioned below the radiating antenna 14 in a portion of the conversion waveguide 30, for example, from the narrow tube wall 33 to the narrow tube wall 34. The dielectric film 40 may be held by, for example, a holding part (not shown) such as a mounting shelf or groove provided in the narrow tube wall 33 and the narrow tube wall 34, or it may be positioned in contact with the back surface 10b of the dielectric substrate 10.

[0051] The dielectric film 40 may be an alumina ceramic substrate, a resin substrate, or a quartz glass substrate. For example, as the resin substrate, a fluororesin, liquid crystal polymer, or BT resin with a thickness of about 0.02 mm to 0.1 mm can be used. Alternatively, the dielectric film 40 may be made by laminating thin resin substrates, for example, about 0.02 mm thick.

[0052] By placing the dielectric film 40 inside the conversion waveguide 30, the effective length of the back short length can be adjusted by the wavelength shortening effect due to the dielectric properties of the dielectric film 40, thereby changing the characteristics of the radiating antenna 14. The dielectric constant of the dielectric film 40 is not particularly limited, but it is preferable that it is lower than the dielectric constant of the dielectric substrate 10, as this makes it easier to fine-tune the characteristics of the radiating antenna 14.

[0053] Furthermore, in addition to the dielectric film 40, a dielectric film (not shown) may be arranged to cover the entire cross-section of the insertion space 38 of the conversion waveguide 30.

[0054] Figure 4(a) shows the reflection characteristics S of a planar line-waveguide converter model that is manufactured exactly as designed, without any external machining deviations of the dielectric substrate 10 or positional deviations when mounted on the conversion waveguide 30. 11 This graph shows the simulation results. This model does not use the dielectric film 40, and the reflection characteristics S 11 It is designed to be less than -10dB in the frequency range of 220GHz to 330GHz.

[0055] FIG. 4(b) is a graph showing the reflection characteristic S of the model of the planar circuit - waveguide converter when the distance from the tip of the radiating antenna 14 shown in FIG. 2 to the end of the convex portion 12 is 0.01 mm farther than the design value. 11 This model has no dielectric film 40, and the reflection characteristic S 11 exceeds -10 dB around 280 GHz and around 330 GHz.

[0056] FIG. 4(c) is a graph showing the reflection characteristic S of the model of the planar circuit - waveguide converter 1 of the present embodiment in which the dielectric film 40 is added to the configuration of the model of FIG. 4(b). 11 The dielectric film 40 here is alumina ceramic with a relative dielectric constant ε r of 9.4, a width in the depth direction of the insertion space 38 of 0.08 mm, and a thickness of 0.035 mm. By adding the dielectric film 40, the reflection characteristic S 11 is adjusted, and the reflection characteristic S 11 becomes -10 dB or less in the frequency range of 220 GHz to 330 GHz.

[0057] As described above, in the planar circuit - waveguide converter 1 according to the present embodiment, since the dielectric film 40 is disposed in the conversion waveguide 30 continuous with the waveguide 20, the characteristics of the radiating antenna 14 are changed, and the deterioration of the frequency characteristics of the signal passing through the waveguide 20 can be prevented, and uniform passing characteristics can be realized within the operating frequency band in the millimeter - wave band and the terahertz - wave band.

[0058] For example, according to the planar circuit - waveguide converter 1 according to the present embodiment, when characteristic changes occur due to the processing accuracy of the dielectric substrate 10 or the positional deviation during mounting after the dielectric substrate 10 is mounted on the conversion waveguide 30, by disposing the dielectric film 40 in the conversion waveguide 30 later, the characteristics of the radiating antenna 14 can be improved.

[0059] (Second Embodiment) Next, a planar line-waveguide converter 2 according to a second embodiment of the present invention will be described with reference to the drawings. Components similar to those in the first embodiment will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate. The main points to be described will be the differences from the first embodiment.

[0060] Figure 5 is a top perspective view showing the configuration of the planar line-waveguide converter 2 of this embodiment. Figure 6 is a cross-sectional view at the position of line AA in Figure 5.

[0061] In the first embodiment, an example was shown in which the dielectric film 40 is arranged in a part of the conversion waveguide 30, extending from one narrow tube wall 33 to the other narrow tube wall 34. As shown in Figures 5 and 6, in this embodiment, the dielectric film 41 is attached to a part of the back surface 10b of the protrusion 12 below the radiating antenna 14. As a result, the dielectric film 41 is positioned in the vicinity of the radiating antenna 14 in the insertion space 38 of the conversion waveguide 30. For example, a resin-based adhesive can be used to adhere the dielectric film 41 to the back surface 10b of the protrusion 12.

[0062] The dielectric film 41 may have notches spaced, for example, about 50 μm apart, in the width direction (X-axis direction). After the dielectric film 41 configured in this way is attached to the back surface 10b of the protrusion 12, a portion of it can be peeled off from the back surface 10b of the protrusion 12 as needed, thereby making it possible to fine-tune the frequency characteristics of the planar line-waveguide converter 2.

[0063] Furthermore, in addition to the dielectric film 41, a dielectric film (not shown) may be arranged to cover the entire cross-section of the insertion space 38 of the conversion waveguide 30.

[0064] Figure 7(a) is the same graph as Figure 4(a), showing the reflection characteristics S of a planar line-waveguide converter model that is exactly as designed, without any deviations in the outer shape of the dielectric substrate 10 or positional deviations when mounted on the conversion waveguide 30. 11 This graph shows the simulation results.

[0065] Figure 7(b) is the same graph as Figure 4(b), and shows the reflection characteristics S of the planar transmission-waveguide converter model when the distance from the tip of the radiating antenna 14 to the end of the convex portion 12 shown in Figure 5 is 0.01 mm further than the design value. 11 This is a graph showing that.

[0066] Figure 7(c) shows the reflection characteristics S of the planar line-waveguide converter 2 model of this embodiment, in which a dielectric film 41 is added to the configuration of the model in Figure 7(b). 11 This is a graph showing the dielectric film 41, where the relative permittivity ε r The material is an alumina ceramic with a thickness of 0.08 mm and a depth of 0.035 mm in the insertion space 38. The addition of the dielectric film 41 improves the reflection characteristics S 11 The reflection characteristics S are adjusted in the frequency range of 220GHz to 330GHz. 11 The level dropped to below -10dB.

[0067] As described above, in this embodiment, the planar line-waveguide converter 2 has a dielectric film 41 attached to the back surface 10b of the protrusion 12, which changes the characteristics of the radiating antenna 14 and prevents deterioration of the frequency characteristics of the signal passing through the waveguide 20, thereby achieving uniform transmission characteristics within the operating frequency bands of the millimeter wave and terahertz wave.

[0068] For example, according to the planar line-waveguide converter 2 of this embodiment, if a change in characteristics occurs due to the processing accuracy of the dielectric substrate 10 or misalignment during mounting after the dielectric substrate 10 has been mounted onto the conversion waveguide 30, the characteristics of the radiating antenna 14 can be improved by later attaching a dielectric film 41 to the back surface 10b of the protrusion 12.

[0069] (Third embodiment) Next, a planar line-waveguide converter according to a third embodiment of the present invention will be described with reference to the drawings. Components similar to those in the first or second embodiment will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate. The differences from the first or second embodiment will be described primarily.

[0070] Figure 8 is a side perspective view showing the configuration of the planar line-waveguide converter 3 of this embodiment. Figure 9 is a cross-sectional view of the planar line-waveguide converter 3. Figure 10(a) is a cross-sectional view at the position of line AA in Figure 9, and Figure 10(b) is a cross-sectional view at the position of line BB in Figure 9.

[0071] In the planar line-waveguide converters 1 and 2 of the first and second embodiments, the front surface 10a and back surface 10b of the dielectric substrate 10 were perpendicular to the direction of electromagnetic wave propagation in the waveguide 20. In contrast, in the planar line-waveguide converter 3 of this embodiment, the waveguide 20 is arranged so that the direction of electromagnetic wave propagation is parallel to the front surface 10a and back surface 10b of the dielectric substrate 10 inserted into the insertion hole 39.

[0072] Similar to the first and second embodiments, the dielectric substrate 10 is positioned in the conversion waveguide 30 such that the extension direction of the radiating antenna 14 is perpendicular to the propagation direction of electromagnetic waves in the waveguide 20.

[0073] In the planar line-waveguide converter 3 of this embodiment, the dielectric film 42 is positioned perpendicular to the front surface 10a and back surface 10b of the dielectric substrate 10, facing one side surface 12b and the other side surface 12c of the convex portion 12 of the dielectric substrate 10 that faces the short-circuit wall 35. As a result, the dielectric film 42 is positioned near the radiating antenna 14 in the insertion space 38 of the conversion waveguide 30. The dielectric film 42 may be held by, for example, a holding portion (not shown) such as a groove provided in the wide tube walls 31, 32 and the narrow tube walls 33, 34.

[0074] For example, as shown in Figure 8, the dielectric film 42 may be arranged to cover the entire cross-section of the insertion space 38 of the conversion waveguide 30, or it may be arranged to cover a part of the cross-section of the insertion space 38.

[0075] Furthermore, a dielectric film (not shown) may be disposed on the surface 10a or back surface 10b of the protrusion 12 of the dielectric substrate 10.

[0076] Figure 11(a) shows the reflection characteristics S of a planar line-waveguide converter model that is manufactured exactly as designed, without any external machining deviations of the dielectric substrate 10 or positional deviations when mounted on the conversion waveguide 30. 11 This graph shows the simulation results. This model does not use the dielectric film 42, and the reflection characteristics S 11 It is designed to be less than -10dB in the frequency range of 220GHz to 330GHz.

[0077] Figure 11(b) shows the reflection characteristics S of the planar line-waveguide converter model when the back short (BS) length from the center position of the radiating antenna 14 in the width direction (Z-axis direction in Figure 9) on the protrusion 12 to the short-circuit wall 35 of the conversion waveguide 30 is 0.01 mm shorter than the design value. 11 This graph shows the reflection characteristics S without the dielectric film 42. 11 The level is above -10dB around 220GHz and 290GHz.

[0078] Figure 11(c) shows the reflection characteristics S of the planar line-waveguide converter 3 model of this embodiment, in which a dielectric film 42 is added to the configuration of the model in Figure 11(b). 11 This is a graph showing the dielectric film 42 having a relative permittivity ε. r The material is an alumina ceramic with a ratio of 9.4, a height in the X-axis direction of 0.864 mm, a width in the Y-axis direction of 0.432 mm, and a thickness in the Z-axis direction of 0.035 mm. The addition of the dielectric film 42 improves the reflection characteristics S 11 The reflection characteristics S are adjusted in the frequency range of 220GHz to 330GHz. 11 The level dropped to below -10dB.

[0079] As described above, in this embodiment, the planar line-waveguide converter 3 has a dielectric film 42 arranged so as to cover at least a portion of the cross-section of the insertion space 38 of the conversion waveguide 30, thereby changing the characteristics of the radiating antenna 14 and preventing deterioration of the frequency characteristics of the signal passing through the waveguide 20, and enabling uniform transmission characteristics within the operating frequency bands of the millimeter wave and terahertz wave bands.

[0080] For example, according to the planar line-waveguide converter 3 of this embodiment, if a change in characteristics occurs due to the processing accuracy of the dielectric substrate 10 or misalignment during mounting after the dielectric substrate 10 has been mounted onto the conversion waveguide 30, the characteristics of the radiating antenna 14 can be improved by later placing the dielectric film 42 inside the conversion waveguide 30.

[0081] (Fourth embodiment)

[0082] Next, a planar line-waveguide converter according to the fourth embodiment of the present invention will be described with reference to the drawings. Components similar to those in the first to third embodiments will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate. The differences from the first to third embodiments will be described primarily.

[0083] Figure 12 is a cross-sectional view showing the configuration of the planar line-waveguide converter 4 of this embodiment. Figure 13 is a cross-sectional perspective view showing the configuration of the planar line-waveguide converter 4. Figure 14(a) is a cross-sectional view at the position of line AA in Figure 13, Figure 14(b) is a cross-sectional view at the position of line BB in Figure 13, and Figure 14(c) is a cross-sectional view at the position of line CC in Figure 13.

[0084] In the planar line-waveguide converters 1 to 3 of the first to third embodiments, the radiating antenna was a monopole antenna. In contrast, the planar line-waveguide converter 4 of this embodiment is configured to use a dipole antenna as the radiating antenna.

[0085] As shown in Figure 12, the surface 10a of the dielectric substrate 10 is provided with an antenna feed line 51 as a transmission line conductor and mounting lands 52 which are surface ground conductors for mounting semiconductor ICs 50 such as MMICs. The ground conductor (not shown) of the semiconductor IC 50 is electrically connected to the mounting lands 52 by being attached to the mounting lands 52 with a conductive adhesive 53.

[0086] Furthermore, the mounting land 52 is electrically connected to the ground conductor 15 provided on the back surface 10b of the dielectric substrate 10 via interlayer connections through via holes 54.

[0087] The pad 55 of the semiconductor IC 50 is electrically connected to a line conductor (not shown) within the semiconductor IC 50, allowing high-frequency signals to be input and output. Furthermore, the pad 55 is electrically connected to the antenna feed line 51 by a wire 56.

[0088] In this embodiment, the radiating antenna 60 has a first strip conductor 61, a second strip conductor 62, a first antenna element 63, and a second antenna element 64, and constitutes a dipole antenna.

[0089] The first strip conductor 61 is provided on the surface 10a of the dielectric substrate 10, electrically connected to the antenna feed line 51, and extends into the insertion space 38 of the conversion waveguide 30. The first strip conductor 61 may be integrally formed with the antenna feed line 51.

[0090] The second strip conductor 62 is provided on the back surface 10b of the dielectric substrate 10, is electrically connected to the ground conductor 15, and extends into the insertion space 38 of the conversion waveguide 30. The second strip conductor 62 may be integrally formed with the ground conductor 15.

[0091] The first antenna element 63 is provided on the surface 10a of the dielectric substrate 10 and is electrically connected to the first strip conductor 61. The extension direction of the first antenna element 63 is perpendicular to the extension directions of the first strip conductor 61 and the second strip conductor 62. The first antenna element 63 may be integrally formed with the first strip conductor 61.

[0092] The second antenna element 64 is provided on the back surface 10b of the dielectric substrate 10 and is electrically connected to the second strip conductor 62. The extension direction of the second antenna element 64 is perpendicular to the extension directions of the first strip conductor 61 and the second strip conductor 62. The second antenna element 64 may be integrally formed with the second strip conductor 62.

[0093] In this embodiment, the insertion hole 39 is formed in the short-circuit wall 35. The dielectric substrate 10 on which the dipole antenna is formed is inserted into the insertion hole 39, thereby electrically connecting the ground conductor 15 to the conversion waveguide 30 and the waveguide 20 via the edge 39a of the insertion hole 39. Furthermore, the front surface 10a and the back surface 10b are arranged to be parallel to the direction of electromagnetic wave propagation in the waveguide 20, and the extension directions of the first strip conductor 61 and the second strip conductor 62 are arranged to be parallel to the direction of electromagnetic wave propagation in the waveguide 20.

[0094] In the planar line-waveguide converter 4 of this embodiment, the dielectric film 43 is positioned opposite the end face 10c of the dielectric substrate 10 on the tip side of the radiating antenna 60, and perpendicular to the front surface 10a and back surface 10b of the dielectric substrate 10. That is, the dielectric film 43 is positioned perpendicular to the radiation direction of the radiating antenna 60 within the conversion waveguide 30. As a result, the dielectric film 43 is positioned near the radiating antenna 60 in the insertion space 38 of the conversion waveguide 30. The dielectric film 43 may be held by, for example, a holding part (not shown) such as a groove provided in the wide tube walls 31, 32 and the narrow tube walls 33, 34.

[0095] For example, as shown in Figure 14(c), the dielectric film 43 may be arranged to cover the entire cross-section of the insertion space 38 of the conversion waveguide 30, or it may be arranged to cover a part of the cross-section of the insertion space 38.

[0096] Furthermore, a dielectric film (not shown) may be disposed on the front surface 10a or back surface 10b of the dielectric substrate 10.

[0097] Figure 15(a) shows the reflection characteristics S of a planar line-waveguide converter model that is manufactured exactly as designed, without any external machining deviations of the dielectric substrate 10 or positional deviations when mounted on the conversion waveguide 30. 11 This graph shows the simulation results. This model does not use the dielectric film 43, and the reflection characteristics S 11 It is designed to be less than -10dB in the frequency range of 220GHz to 330GHz.

[0098] Figure 15(b) shows the reflection characteristics S of a planar line-waveguide converter model when the positions of the first strip conductor 61 and the second strip conductor 62 constituting the dipole antenna shown in Figure 13, etc., are shifted by 0.005 mm in the lateral direction (X-axis direction) perpendicular to the electromagnetic wave propagation direction of the waveguide 20. 11 This graph shows the reflection characteristics S without the dielectric film 43. 11 It is above -10dB around 330GHz.

[0099] Figure 15(c) shows the reflection characteristics S of the planar line-waveguide converter 4 model of this embodiment, in which a dielectric film 43 is added to the configuration of the model in Figure 15(b). 11 This is a graph showing the dielectric film 43, where the relative permittivity ε r The alumina ceramic has a ratio of 9.4, a height in the Y-axis direction of 0.432 mm, a width in the X-axis direction of 0.864 mm, and a thickness in the Z-axis direction of 0.035 mm. The addition of the dielectric film 43 improves the reflection characteristics S 11 The reflection characteristics S are adjusted in the frequency range of 220GHz to 330GHz. 11 The level dropped to below -10dB.

[0100] As described above, in this embodiment, the planar line-waveguide converter 4 has a dielectric film 43 arranged so as to cover at least a portion of the cross-section of the insertion space 38 of the conversion waveguide 30, thereby changing the characteristics of the radiating antenna 60 and preventing deterioration of the frequency characteristics of the signal passing through the waveguide 20, and enabling uniform transmission characteristics within the operating frequency bands of the millimeter wave band and terahertz wave band.

[0101] For example, according to the planar line-waveguide converter 4 of this embodiment, if a change in characteristics occurs due to the processing accuracy of the dielectric substrate 10 or positional misalignment during mounting after the dielectric substrate 10 has been mounted onto the conversion waveguide 30, the characteristics of the radiating antenna 60 can be improved by later placing the dielectric film 43 inside the conversion waveguide 30. [Explanation of symbols]

[0102] 1-4 Planar Line / Waveguide Converter 10 Dielectric substrate 10a surface 10b back side 10c,12a end face 11 Main body 12 Convex part 12b,12c side 13 Track conductors 14,60 Radiating antenna 15 Ground conductor 17 Plane track 20 Waveguide 28 Interior space 30 Waveguides for Conversion 21, 22, 31, 32 Wide tube wall 23,24,33,34 narrow tube wall 35 Short-circuit wall 38 Insertion space 39 insertion holes 39a Edge 40, 41, 42, 43 Dielectric film 51 Antenna feed line (line conductor) 61 First strip conductor 62 Second strip conductor 63 First Antenna Element 64 Second antenna element

Claims

1. Dielectric substrate (10) and A line conductor (13, 51) is provided on the surface (10a) of the dielectric substrate, A grounding conductor (15) is provided below the line conductor on the back surface (10b) of the dielectric substrate, A conversion waveguide (30) having an insertion hole (39) that is short-circuited at one end by a short-circuiting wall (35) and open at the other end, and communicating with an insertion space (38) into which the dielectric substrate is inserted, and the edge (39a) of the insertion hole is connected to the ground conductor, A waveguide (20) connected to the conversion waveguide, having an internal space (28) continuous with the insertion space, and arranged such that the direction of electromagnetic wave propagation is perpendicular or parallel to the surface and back surface of the dielectric substrate, A radiating antenna (14, 60) is provided on the dielectric substrate, connected to the line conductor, and positioned in the insertion space, A planar line / waveguide converter comprising dielectric films (40, 41, 42, 43) arranged in the vicinity of the radiating antenna in the aforementioned insertion space.

2. The planar line / waveguide converter according to claim 1, characterized in that the radiating antenna is a monopole antenna provided on the surface of the dielectric substrate and extending into the insertion space.

3. The dielectric substrate is arranged such that its front and back surfaces are perpendicular to the propagation direction, and the extension direction of the radiating antenna is perpendicular to the propagation direction. The planar line / waveguide converter according to claim 1 or 2, characterized in that the dielectric film is disposed on the back side of the dielectric substrate.

4. The cross-sectional shape of the internal space and the insertion space perpendicular to the propagation direction is rectangular. The conversion waveguide has two wide tube walls (31, 32) that are in contact with the long side of the cross-sectional shape of the insertion space, and two narrow tube walls (33, 34) that are in contact with the short side of the cross-sectional shape of the insertion space. The planar line-waveguide converter according to claim 3, characterized in that the dielectric film is arranged below the radiating antenna, extending from one narrow tube wall to the other narrow tube wall of the conversion waveguide.

5. The planar line / waveguide converter according to claim 3, characterized in that the dielectric film is attached to the back surface of the dielectric substrate below the radiating antenna.

6. The dielectric substrate is arranged such that its front and back surfaces are parallel to the propagation direction, and the extension direction of the radiating antenna is perpendicular to the propagation direction. The dielectric film is positioned opposite one side surface (12b) of the dielectric substrate that faces the short-circuit wall and the other side surface (12c) opposite to it, and is arranged perpendicular to the front and back surfaces of the dielectric substrate, as described in claim 1 or 2.

7. The aforementioned radiating antenna is A first strip conductor (61) is provided on the surface of the dielectric substrate, connected to the line conductor, and extends into the insertion space, A first antenna element (63) is provided on the surface of the dielectric substrate and connected to the first strip conductor, A second strip conductor (62) is provided on the back surface of the dielectric substrate, connected to the ground conductor, and extends into the insertion space, The planar line / waveguide converter according to claim 1, characterized in that it is a dipole antenna having a second antenna element (64) provided on the back surface of the dielectric substrate and connected to the second strip conductor.

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