Circularly polarized wave generator and method for manufacturing same

Abstract

This circularly polarized wave generator comprises: a hollow waveguide (10), one end of which is a first input / output terminal (11), the other end of which is a second input / output terminal (12), and which has a hollow part having a circular cross-section; and a pair of ridges (20), (30), each of which has a central axis parallel to the tube axis of the waveguide (10) and which is disposed so as to face each other on the inner wall surface of the waveguide (10). The pair of ridges (20), (30) each have a first input / output end section (21), (31) at one end section, a second input / output end section (22), (32) at the other end section, and an intermediate section (23), (33) between the first input / output end section (21), (31) and the second input / output end section (22), (32). The intermediate sections (23), (33) are periodically provided in the tube axial direction of the waveguide (10), and each have, in a first plane perpendicular to the tube axis of the waveguide (10), a plurality of protrusions (23a1) to (23aN), (33a1) to (33aN) protruding along a line orthogonal to a line connecting the pair of ridges (20), (30), and connecting parts (23b1) to (23bN-1), (33b1) to (33bN-1) connecting protrusions adjacent at the plurality of protrusions (23a1) to (23aN), (33a1) to (33aN).

Description

Circular polarizer and its manufacturing method

[0001] The present disclosure relates to a circular polarizer used primarily in the VHF band, UHF band, microwave band, and millimeter wave band, and a method for manufacturing the same.

[0002] Non-Patent Document 1 discloses a waveguide-based circular polarized wave generator that outputs a right-handed or left-handed circularly polarized signal depending on the input polarization signal when a vertically linearly polarized signal or a horizontally linearly polarized signal is input. The circular polarized wave generator disclosed in Non-Patent Document 1 has 14 corrugations and 5 matching steps in a square waveguide. The 14 corrugated portions formed in the waveguide are called ridges. The circular polarized wave generator disclosed in Non-Patent Document 1 is manufactured by using wire discharge milling on an aluminum block.

[0003] Angel Mediavilla etal. “Quasi-Octave Bandwidth Phase Matched K / Ka Antenna Feed Subsystem for dual RHCP / LHCP Polarization,” pp719-722, 2012 EuMA.

[0004] When the circular polarizer disclosed in Non-Patent Document 1 is connected to a horn antenna having a circular waveguide terminal, a converter from a square waveguide to a circular waveguide is required to connect to the horn antenna, which increases the number of components and the length in the tube axial direction.

[0005] The present disclosure has been made in consideration of the above points, and aims to provide a circular polarizer that has good reflection characteristics and axial ratio characteristics and does not increase in length in the tube axial direction even when connected to a horn antenna having a circular waveguide terminal.

[0006] A circular polarizer according to the present disclosure comprises a hollow waveguide having a hollow portion with a circular cross section, with one end serving as a first input / output terminal and the other end serving as a second input / output terminal, and a pair of ridges, each having a central axis parallel to the tube axis of the waveguide, and arranged opposite each other on the inner wall surface of the waveguide, each of the pair of ridges having a first input / output terminal at one end and a second input / output terminal at the other end, and an intermediate portion between the first input / output terminal and the second input / output terminal, the intermediate portions being periodically arranged in the tube axis direction of the waveguide, and each having a plurality of protrusions protruding in a direction along a line perpendicular to a line connecting the central axes of the pair of ridges in a first plane perpendicular to the tube axis of the waveguide, and connecting portions connecting adjacent protrusions among the plurality of protrusions.

[0007] According to the present disclosure, it is possible to connect to a horn antenna having a circular waveguide terminal while maintaining good reflection characteristics and axial ratio characteristics, without increasing the length in the tube axial direction.

[0008] 1 is a perspective view showing mainly a pair of ridges as seen through a waveguide in a circular polarizer according to a first embodiment. FIG. 2 is a side view showing mainly a pair of ridges as seen through a waveguide in the circular polarizer according to the first embodiment, viewed from the direction of a line connecting the central axes of the pair of ridges. FIG. 3 is a side view showing mainly a pair of ridges as seen through a waveguide in the circular polarizer according to the first embodiment, viewed from a direction orthogonal to the line connecting the central axes of the pair of ridges. FIG. 4 is a perspective view showing a pair of ridges in the circular polarizer according to the first embodiment. FIG. 5 is a side view showing a pair of ridges in the circular polarizer according to the first embodiment, viewed from the direction of a line connecting the central axes of the pair of ridges. FIG. 6 is a perspective view corresponding to FIG. 1 , showing the electric field directions when a horizontal linearly polarized signal (X-polarized signal) and a vertical linearly polarized signal (Y-polarized signal) are input to one of the waveguide input / output terminals in the circular polarizer according to the first embodiment. FIG. 7 is a side view showing a schematic view of a pair of ridges in the circular polarizer according to the first embodiment, viewed from the direction of a line connecting the central axes of the pair of ridges and a direction orthogonal to the direction. 8 is a cross-sectional view schematically showing the electric field directions of two linearly polarized signals at the A-A cross section and the B-B cross section in FIG. 7 in the circular polarizer according to the first embodiment. FIG. 9 is a perspective view showing a structure in which one protrusion is representatively shown on each of a pair of opposing ridges in the circular polarizer according to the first embodiment. FIG. 10 is a diagram showing phase characteristics in the circular polarizer according to the first embodiment. FIG. 11 is a diagram showing reflection characteristics in the circular polarizer according to the first embodiment. FIG. 12 is a side view schematically showing a pair of ridges in the circular polarizer according to the reference example, as viewed from the direction of a line connecting the central axes of the pair of ridges and a direction orthogonal to the line. FIG. 13 is a cross-sectional view schematically showing the electric field directions of two linearly polarized signals at the A-A cross section and the B-B cross section in FIG. 7 in the circular polarizer according to the reference example. FIG. 14 is a perspective view showing a structure in which one protrusion is representatively shown on each of a pair of opposing ridges in the circular polarizer according to the reference example. FIG. 15 is a diagram showing phase characteristics in the circular polarizer according to the reference example. FIG. 16 is a diagram showing reflection characteristics in the circular polarizer according to the reference example. FIG. 10 is a perspective view showing mainly a pair of ridges, seen through a waveguide, in a circular polarizer according to a second embodiment.1 is a side view of a circular polarizer according to a second embodiment, showing the pair of ridges mainly as viewed through the waveguide, as seen from a direction of a line connecting the central axes of the pair of ridges. FIG. 2 is a side view of the circular polarizer according to the second embodiment, showing the pair of ridges mainly as viewed through the waveguide, as seen from a direction perpendicular to the line connecting the central axes of the pair of ridges. FIG. 3 is a perspective view showing the pair of ridges in the circular polarizer according to the second embodiment. FIG. 4 is a side view of the pair of ridges in the circular polarizer according to the second embodiment, as seen from a direction of a line connecting the central axes of the pair of ridges. FIG. 5 is a perspective view of a circular polarizer according to a third embodiment, showing the pair of ridges mainly as viewed through the waveguide. FIG. 6 is a side view of the circular polarizer according to the third embodiment, showing the pair of ridges mainly as viewed through the waveguide, as seen from a direction of a line connecting the central axes of the pair of ridges. FIG. 7 is a side view of the circular polarizer according to the third embodiment, showing the pair of ridges mainly as viewed through the waveguide, as seen from a direction perpendicular to the line connecting the central axes of the pair of ridges. 1 is a side view showing a pair of ridges in a circular polarizer according to embodiment 3, viewed from the direction of a line connecting the central axes of the pair of ridges. FIG. 2 is a perspective view showing a pair of ridges mainly as viewed through a waveguide in a circular polarizer according to embodiment 4. FIG. 3 is a side view showing a pair of ridges mainly as viewed through a waveguide in a circular polarizer according to embodiment 4, viewed from the direction of a line connecting the central axes of the pair of ridges. FIG. 4 is a side view showing a pair of ridges mainly as viewed through a waveguide in a circular polarizer according to embodiment 4, viewed from a direction orthogonal to the line connecting the central axes of the pair of ridges. FIG. 5 is a perspective view showing a pair of ridges in a circular polarizer according to embodiment 4. FIG. 6 is a side view showing a pair of ridges in a circular polarizer according to embodiment 4, viewed from the direction of a line connecting the central axes of the pair of ridges. FIG. 7 is a perspective view showing a pair of ridges mainly as viewed through a waveguide in a circular polarizer according to embodiment 5. FIG. 8 is a side view showing a pair of ridges mainly as viewed through a waveguide in a circular polarizer according to embodiment 5, viewed from the direction of a line connecting the central axes of the pair of ridges.10 is a side view of a circular polarizer according to a fifth embodiment, showing mainly the pair of ridges as seen through the waveguide, from a direction orthogonal to a line connecting the central axes of the pair of ridges. FIG. 11 is a perspective view showing a pair of second ridges in the circular polarizer according to the fifth embodiment. FIG. 12 is a perspective view of a circular polarizer according to a sixth embodiment, showing mainly the pair of ridges as seen through the waveguide. FIG. 13 is a side view of a circular polarizer according to the sixth embodiment, showing mainly the pair of ridges as seen through the waveguide, from a direction of a line connecting the central axes of the pair of ridges. FIG. 14 is a side view of a circular polarizer according to the sixth embodiment, showing mainly the pair of ridges as seen through the waveguide, from a direction orthogonal to a line connecting the central axes of the pair of ridges as seen through the waveguide. FIG. 15 is a perspective view of a circular polarizer according to a seventh embodiment, showing mainly the pair of ridges as seen through the waveguide. FIG. 16 is a side view of a circular polarizer according to the seventh embodiment, showing mainly the pair of ridges as seen through the waveguide, from a direction of a line connecting the central axes of the pair of ridges. 10 is a side view of a circular polarizer according to a seventh embodiment, showing mainly a pair of ridges as seen through the waveguide, from a direction orthogonal to a line connecting the central axes of the pair of ridges. FIG. 11 is a perspective view of a circular polarizer according to an eighth embodiment, showing mainly a pair of ridges as seen through the waveguide. FIG. 12 is a side view of a circular polarizer according to an eighth embodiment, showing mainly a pair of ridges as seen through the waveguide, from a direction orthogonal to a line connecting the central axes of the pair of ridges. FIG. 13 is a perspective view of a pair of second ridges in the circular polarizer according to the eighth embodiment. FIG. 14 is a side view of a pair of second ridges in the circular polarizer according to the eighth embodiment, showing a pair of second ridges as seen from a direction orthogonal to a line connecting the central axes of the pair of second ridges.

[0009] Embodiment 1. A circular polarizer according to embodiment 1 will be described using Figures 1 to 11. The circular polarizer is used primarily in the VHF, UHF, microwave, and millimeter-wave bands, and is connected to a horn antenna having a circular waveguide terminal. When two orthogonal linearly polarized signals, i.e., a vertical linearly polarized signal and a horizontal linearly polarized signal, are input to the circular polarizer, the two orthogonal linearly polarized signals are output with a 90-degree phase difference between them.

[0010] Based on this principle, in a circular polarizer comprising a circular waveguide having a first input / output terminal at one end and a second input / output terminal at the other end, and a pair of ridges having a central axis parallel to the axis of the waveguide and arranged opposite each other on the inner wall surface of the waveguide, for example, when a linearly polarized signal tilted 45 degrees to the right with respect to the line segment connecting the pair of ridges is input, a right-handed circularly polarized signal is output from the second input / output terminal, and when a linearly polarized signal tilted 45 degrees to the left with respect to the line segment connecting the pair of ridges is input, a left-handed circularly polarized signal is output from the second input / output terminal.

[0011] The circular polarizer comprises a circular waveguide 10 and a pair of ridges 20, 30. The waveguide 10 is a hollow cylindrical waveguide having a circular first input / output terminal 11 at one end and a circular second input / output terminal 12 at the other end, and having a hollow portion 13 with a circular cross section. In the waveguide 10, the hollow portion 13 forms a waveguide for propagating electromagnetic waves, with one end of the waveguide forming the first input / output terminal 11 and the other end of the waveguide forming the second input / output terminal 12.

[0012] The second input / output terminal 12 is connected to a circular waveguide terminal of a horn antenna (not shown). A circularly polarized signal output from the second input / output terminal 12 is propagated to the horn antenna via the circular waveguide terminal of the horn antenna, and an electromagnetic wave signal is radiated from the horn antenna into the air.

[0013] In the following description, an axis parallel to the tube axis of the waveguide 10 is referred to as the Z-axis, a horizontal plane perpendicular to the tube axis of the waveguide 10 is referred to as the first plane, and two axes that intersect at right angles on the first plane are referred to as the X-axis and Y-axis. That is, in the first embodiment, the first plane is the X-Y plane centered on the tube axis of the waveguide 10.

[0014] The pair of ridges 20, 30 have central axes parallel to the tube axis of the waveguide 10 and are arranged opposite each other on the inner wall surface of the waveguide 10. The pair of ridges 20, 30 have a symmetrical structure with respect to a third plane, which is a vertical plane that passes through the tube axis, which is the central axis of the waveguide 10, and is parallel to the tube axis of the waveguide 10.

[0015] In the first embodiment, the third plane is the X-Z plane including the tube axis of the waveguide 10, and is a plane perpendicular to the line connecting the central axes of the pair of ridges 20, 30. In the first embodiment, the plane including the tube axis of the waveguide 10 and the line connecting the central axes of the pair of ridges 20, 30 is the Y-Z plane, which is the second plane.

[0016] The pair of ridges 20, 30 are integral with the waveguide 10. Each of the pair of ridges 20, 30 has a first input / output end 21, 31 at one end, a second input / output end 22, 32 at the other end, and an intermediate portion 23, 33 between the first input / output end 21, 31 and the second input / output end 22, 32.

[0017] The first input / output ends 21, 31 have a uniform length over their entire length in the direction (Y-axis direction) along the line connecting the central axes of the pair of ridges 20, 30, and a uniform length over their entire length in the direction (X-axis direction) along a line perpendicular to the line connecting the central axes of the pair of ridges 20, 30. Hereinafter, the length in the X-axis direction will be referred to as the width, the length in the Y-axis direction will be referred to as the height, and the length in the Z-axis direction will be referred to as the vertical width.

[0018] That is, the width and height of each of the first input / output terminals 21, 31 are the same along the entire length in the Z-axis direction. The boundary surface between each of the first input / output terminals 21, 31 and the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the X-Z plane. The opposing surface of each of the first input / output terminals 21, 31 that faces the boundary surface is rectangular and is a flat surface parallel to the X-Z plane. The first input / output terminals 21 and 31 have the same size and shape.

[0019] The second input / output end portions 22, 32 each have the same width along the entire length in the Z-axis direction, and the same height along the entire length in the Z-axis direction. The boundary surface between the second input / output end portions 22, 32 and the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the X-Z plane. The opposing surface facing the boundary surface of the second input / output end portions 22, 32 is rectangular and is a plane parallel to the X-Z plane. The second input / output end portions 22 and 32 have the same size and shape.

[0020] In the ridge 20, the opposing surfaces at the first input / output end 21 and the second input / output end 22 are on the same XZ plane. In the ridge 30, the opposing surfaces at the first input / output end 31 and the second input / output end 32 are on the same XZ plane.

[0021] The intermediate portions 23 and 33 are formed by a plurality of protrusions 23a that are periodically provided in the axial direction of the waveguide 10, i.e., in the Z-axis direction. １ ~23a Ｎ , 33a １ ~33a Ｎ and a plurality of protrusions 23a １ ~23a Ｎ , 33a １ ~33a Ｎ The connecting portion 23b connecting the adjacent protrusions in １ ~23b Ｎ－１ , 33b １ ~33b Ｎ－１ The plurality of protrusions 23a １ ~23a Ｎ , 33a １ ~33a Ｎ In a first plane perpendicular to the tube axis of the waveguide 10, i.e., in the XY plane, the connecting portion 23b extends in a direction perpendicular to the line connecting the central axes of the pair of ridges 20 and 30, i.e., in the X-axis direction. １ ~23b Ｎ , 33b １ ~33b Ｎ More prominent.

[0022] A plurality of protrusions 23a １ ~23a Ｎ , 33a １ ~33aＮ Each of the protrusions 23a has a rectangular cross section parallel to the third plane, which is the XZ plane. １ ~23a Ｎ In this configuration, the length in the direction (X-axis direction) along a line perpendicular to the line connecting the central axes of the pair of ridges 20, 30, i.e., the horizontal width W, becomes progressively shorter from the central protrusion on the central axis of the ridge 20 toward the first input / output end 21 and the second input / output end 22, respectively.

[0023] The central protrusion on the central axis of the ridge 20 is the protrusion 23a when N is an odd number. （Ｎ＋１）／２ If the number is even, it is 23a Ｎ／２ and 23a （Ｎ＋２）／２ In the following description, the central protrusion is referred to as protrusion 23a. Ｎ／２ The description will be given as follows. １ ~23a Ｎ Width W in ｎ (n is 1 to N) have the following relationship in the first embodiment: W １ <W ２ <...<W （Ｎ－２）／２ <W Ｎ／２ >W （Ｎ＋２）／２ >... >W Ｎ－１ >W Ｎ

[0024] A plurality of protrusions 23a １ ~23a Ｎ Width W in ｎ The relationship is shown by the dashed line W in FIG. Ｌｉｎｅ As shown in FIG. 1, the central protrusion 23a Ｎ／２ It is preferable that the protrusions 23a become shorter in a trigonometric function shape from the apex toward the first input / output end 21 and the second input / output end 22. １ ~23a Ｎ Width W in ｎ By changing the shape of the reflector in a trigonometric function manner, the shape changes gradually, thereby achieving better reflection characteristics.

[0025] A plurality of protrusions 23a １ ~23a Ｎ In the figure, the protrusion 23a at the center of the central axis of the ridge 20 Ｎ／２The length in the Z-axis direction, i.e., the vertical width L, of the plurality of protrusions 23a decreases sequentially from the first input / output end 23a to the first input / output end 21 and the second input / output end 22. １ ~23a Ｎ The vertical width L ｎ In the first embodiment, the relationship between L and L is as follows: １ <L ２ <...<L （Ｎ－２）／２ <L Ｎ／２ >L （Ｎ＋２）／２ > ... > L Ｎ－１ >L Ｎ In addition, the vertical width L ｎ may all be the same length.

[0026] A plurality of protrusions 23a １ ~23a Ｎ The length in the direction along the line connecting the central axes of the pair of ridges 20 and 30 (Y-axis direction), that is, the height H, is the same. １ ~23a Ｎ The boundary surface between the inner wall surface of the waveguide 10 and the protrusions 23a is an arcuate surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~23a Ｎ The surface facing the boundary surface in the ridge 20 is rectangular and is a plane parallel to the XZ plane. １ ~23a Ｎ The opposing surfaces at the first input / output end 21 and the second input / output end 22 are in the same XZ plane.

[0027] A plurality of protrusions 33a １ ~33a Ｎ The width W of each of the plurality of protrusions 33a is gradually reduced from the central protrusion 33a at the center of the central axis of the ridge 30 toward the first input / output end 31 and the second input / output end 32. １ ~33a Ｎ Width W in ｎ (n is 1 to N) have the following relationship: W １ <W ２ <...<W （Ｎ－２）／２ <W Ｎ／２ >W （Ｎ＋２）／２ >... >W Ｎ－１>W Ｎ

[0028] A plurality of protrusions 33a １ ~33a Ｎ Width W in ｎ The relationship is shown by the dashed line W in FIG. Ｌｉｎｅ As shown in FIG. 1, the central protrusion 33a Ｎ／２ It is preferable that the length of the first input / output terminal 31 and the second input / output terminal 3 become shorter in a trigonometric function fashion from the apex.

[0029] A plurality of protrusions 33a １ ~33a Ｎ In this case, the protrusion 33a at the center of the central axis of the ridge 30 Ｎ／２ The vertical width L gradually decreases from the first input / output end 31 to the second input / output end 32. １ ~33a Ｎ The vertical width L ｎ In the first embodiment, the relationship between L and L is as follows: １ <L ２ <...<L （Ｎ－２）／２ <L Ｎ／２ >L （Ｎ＋２）／２ > ... > L Ｎ－１ >L Ｎ In addition, the vertical width L ｎ may all be the same length.

[0030] A plurality of protrusions 33a １ ~33a Ｎ The height H of the plurality of protrusions 33a is the same. １ ~33a Ｎ The boundary surface between the inner wall surface of the waveguide 10 and the protrusions 33a is an arcuate surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~323a Ｎ The surface facing the boundary surface in the ridge 30 is rectangular and is a plane parallel to the XZ plane. １ ~33a Ｎ The opposing surfaces at the first input / output end 31 and the second input / output end 32 are in the same XZ plane.

[0031] Connecting part 23b １~23b Ｎ－１ , 33b １ ~33b Ｎ－１ Each of the connecting portions 23b has a rectangular cross section parallel to the third plane, which is the XZ plane. １ ~23b Ｎ－１ is the length in the X-axis direction, that is, the width W ０ are all the same, and the width W ０ is the protrusion 23a １ ~23a Ｎ The minimum width W １ and W Ｎ The connecting portion 23b is shorter than the first input / output end 31 and the second input / output end 32. １ ~23b Ｎ－１ is the length in the Z-axis direction, that is, the vertical width L ０ are all the same, and the protrusions 23a １ ~23a Ｎ are placed at equal intervals.

[0032] Connecting part 23b １ ~23b Ｎ－１ The boundary surface between each of the connecting portions 23b and the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~23b Ｎ－１ The opposing surface of each of the two surfaces facing the boundary surface is rectangular and is a plane parallel to the XZ plane.

[0033] In the ridge 20, the connecting portion 23b １ ~23b Ｎ－１ The opposing surfaces of the first input / output end 21, the second input / output end 22, and the plurality of protrusions 23a are １ ~23a Ｎ That is, the surface of the ridge 20 that faces the arcuate surface along the inner wall surface of the waveguide 10 is a flat surface that lies in the XZ plane.

[0034] Connecting portion 33b １ ~33b Ｎ－１ is the length in the X-axis direction, that is, the width W ０ are all the same, and the width W ０ is the protrusion 33a １ ~33a ＮThe minimum width W １ and W Ｎ The connecting portion 33b is shorter than the first input / output end portion 31 and the second input / output end portion 32. １ ~33b Ｎ－１ is the length in the Z-axis direction, that is, the vertical width L ０ are all the same, and the protrusions 33a １ ~33a Ｎ are placed at equal intervals.

[0035] Connecting portion 33b １ ~33b Ｎ－１ The boundary surface between each of the connecting portions 33b and the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~33b Ｎ－１ The opposing surface of each of the two surfaces facing the boundary surface is rectangular and is a plane parallel to the XZ plane.

[0036] In the ridge 30, the connecting portion 33b １ ~33b Ｎ－１ The opposing surfaces of the first input / output end 31, the second input / output end 32, and the plurality of protrusions 33a are １ ~33a Ｎ In other words, the opposing surface of the ridge 30 that faces the arcuate surface along the inner wall surface of the waveguide 10 is a flat surface that lies in the XZ plane. The opposing surface of the ridge 20 and the opposing surface of the ridge 30 face each other.

[0037] Next, a case will be described in which, in the circular polarizer according to embodiment 1, two orthogonal linearly polarized signals are input to first input / output terminal 11 of waveguide 10, as shown by the solid and dashed lines in Fig. 6. The linearly polarized signal shown by the dashed line is a horizontal linearly polarized signal indicating the direction of the electric field of the electromagnetic wave in the X-axis direction, and the linearly polarized signal shown by the solid line is a vertical linearly polarized signal indicating the direction of the electric field of the electromagnetic wave in the Y-axis direction.

[0038] Now, as shown in FIG. ｎ The protrusion 23a has ｎ , 33a ｎ B-B cross section of the X-Y plane and width W ０The connecting portion 23b has ｎ－１ , 33b ｎ－１ 8 shows the electric field of the electromagnetic wave at the A-A cross section of the X-Y plane in the above. The ridges 20, 30 in the circular polarizer according to the first embodiment are formed with their widths periodically changing in the axial direction of the waveguide 10. For example, the periodic structure in which the width is narrow at the A-A cross section and wide at the B-B cross section generates a phase difference in the electromagnetic wave propagating through the waveguide.

[0039] Moreover, the ridges 20 and 30 in the circular waveguide polarizer according to the first embodiment have protrusions 23a with different widths. １ ~23a Ｎ , 33a １ ~33a Ｎ In order to form a periodic structure in which the protrusions 23a are periodically arranged, １ ~23a Ｎ , 33a １ ~33a Ｎ By appropriately selecting the width W of the antenna, a desired phase difference can be obtained in a desired frequency band, and a desired axial ratio characteristic can be realized.

[0040] As a result, in the circular waveguide polarizer according to the first embodiment, the plurality of protrusions 23a on the ridges 20 and 30 １ ~23a Ｎ , 33a １ ~33a Ｎ By appropriately designing the shape, particularly the width W, of the antenna, a desired phase difference can be obtained in a selected frequency band, mainly in the VHF band, UHF band, microwave band, and millimeter wave band, and a circularly polarized signal with a desired axial ratio characteristic can be obtained.

[0041] The verification results of the transmission characteristics of linearly polarized signals, the phase characteristics which are the transmission phase difference between two linearly polarized signals, and the reflection characteristics obtained by electromagnetic field analysis of the circular polarizer according to embodiment 1 will be described using Figures 9 to 11. Figure 9 shows a structure in which one protrusion 23a, 33a is shown on each of a pair of opposing ridges 20A, 30A. In Figure 9, the dashed line indicates the direction of the electric field of the electromagnetic wave of the horizontal linearly polarized signal, and the solid line indicates the direction of the electric field of the electromagnetic wave of the vertical linearly polarized signal.

[0042] Fig. 10 shows the results of verification of phase characteristics, which are the transmission phase difference versus normalized frequency, obtained by electromagnetic field analysis using a structure in which one protrusion 23a, 33a shown in Fig. 9 is formed on each of a pair of ridges 20A, 30A. Fig. 11 shows the results of verification of reflection characteristics, which are the transmission line characteristics versus normalized frequency, obtained by electromagnetic field analysis. In Fig. 10, the horizontal axis represents normalized frequency, and the vertical axis represents phase difference. In Fig. 11, the horizontal axis represents normalized frequency, the vertical axis represents reflection coefficient, and the dashed line represents reflection characteristics for horizontal linearly polarized signals, while the solid line represents reflection characteristics for vertical linearly polarized signals.

[0043] When the phase difference between two orthogonal linearly polarized signals is set to about 10 degrees as shown in Fig. 10 due to a structure in which one protrusion 23a, 33a is formed on each of a pair of opposing ridges 20A, 30A, the reflection characteristics of the two orthogonal linearly polarized signals are approximately the same as shown in Fig. 11. Therefore, the difference in transmission loss between the two orthogonal linearly polarized signals is reduced.

[0044] By connecting a plurality of protrusions 23 a, 33 a to each of the pair of ridges 20 A, 30 A, it is possible to achieve a phase difference of 90° between the two orthogonal linearly polarized signals. Even when the phase difference between the two orthogonal linearly polarized signals is set to 90° by connecting a plurality of protrusions 23 a, 33 a, as can be seen from the reflection characteristics shown in Figure 1, the reflection characteristics for the two orthogonal linearly polarized signals are approximately the same, and the difference in transmission loss between the two orthogonal linearly polarized signals is reduced.

[0045] To achieve good axial ratio characteristics, it is desirable that the passing amplitudes of the two orthogonal linearly polarized signals are the same and that the passing phase difference is a desired value. As can be seen from Figures 10 and 11, the circular polarizer according to embodiment 1 achieves good axial ratio characteristics.

[0046] For comparison with the circularly polarized wave generator according to the first embodiment, the pair of opposing ridges 20' and 30' each have a groove 23a extending from the opposing surface toward the inner wall surface of the waveguide. １ ~23a Ｎ , 33a１ ~33a Ｎ A circular polarizer having a comb-like shape in which a circular polarizer having ...

[0047] As shown in FIG. 12, the pair of ridges 20′, 30′ in the reference example have a structure in which the opposing surfaces of the pair of ridges 20′, 30′ are positioned on a plane parallel to the XZ plane, and grooves 23′a extending from the opposing surfaces toward the inner wall surface of the waveguide are formed. １ ~23´a Ｎ , 33'a １ ~33'a Ｎ The depth D shown in FIG. ｎ Groove 23'a having ｎ , 33'a ｎ A groove 23'a having a height H and a cross section BB of the XY plane ｎ , 33'a ｎ The opposing surface 23'b adjacent to ｎ－１ , 33'b ｎ－１ The electric field of the electromagnetic wave at the AA cross section of the XY plane in Fig. 13 is shown. In Fig. 13, the dashed line indicates the direction of the electric field of the electromagnetic wave of the horizontal linearly polarized signal, and the solid line indicates the direction of the electric field of the electromagnetic wave of the vertical linearly polarized signal.

[0048] In the circularly polarized wave generator according to the reference example, the ridges 20' and 30' are also formed in the waveguide 10 in the axial direction by grooves 23'a. ｎ , 33'a ｎ Depth D ｎ By periodically changing the phase, for example, the phase is low at the BB cross section and high at the AA cross section, and a phase difference occurs in the electromagnetic wave propagating through the waveguide due to the periodic structure.

[0049] Fig. 14 shows the structure of one comb, in which one groove 23'a, 33'a is shown in each of a pair of opposing ridges 20'A, 30'A. In Fig. 14, the dashed line indicates the direction of the electric field of the electromagnetic wave of a horizontal linearly polarized signal, and the solid line indicates the direction of the electric field of the electromagnetic wave of a vertical linearly polarized signal.

[0050] Fig. 15 shows the results of verification of phase characteristics, which are the transmission phase difference versus normalized frequency, obtained by electromagnetic field analysis using a structure in which one groove 23'a, 33'a shown in Fig. 14 is formed in each of a pair of opposing ridges 20'A, 30'A. Fig. 16 shows the results of verification of reflection characteristics, which are the transmission line characteristics versus normalized frequency, obtained by electromagnetic field analysis. In Fig. 15, the horizontal axis represents normalized frequency, and the vertical axis represents phase difference. In Fig. 16, the horizontal axis represents normalized frequency, the vertical axis represents reflection coefficient, and the dashed line represents reflection characteristics for horizontal linearly polarized signals, while the solid line represents reflection characteristics for vertical linearly polarized signals.

[0051] When the phase difference between two orthogonal linearly polarized signals resulting from a structure in which one groove 23'a, 33'a is formed on each of a pair of ridges 20'A, 30'A is set to approximately 10 degrees as shown in Figure 15, similar to the phase difference between two orthogonal linearly polarized signals resulting from a structure in which one protrusion 23a, 33a is formed on each of a pair of ridges 20A, 30A as shown in Figure 9, the reflection characteristics of the two orthogonal linearly polarized signals exhibit significantly different reflection characteristics as shown in Figure 16.

[0052] As is clear from the reflection characteristics of the structure in which one protrusion 23 a, 33 a is formed on each of a pair of ridges 20A, 30A for the circular polarizer according to embodiment 1 shown in FIG. 11 and the reflection characteristics of the structure in which one groove 23 ' a, 33 ' a is formed on each of a pair of ridges 20 'A, 30 'A for the circular polarizer according to the reference example shown in FIG. 16 , the circular polarizer according to embodiment 1 achieves better axial ratio characteristics than the circular polarizer according to the reference example.

[0053] The following describes a method for manufacturing the circular polarizer according to embodiment 1. The circular polarizer according to embodiment 1 is manufactured by molding a waveguide 10 and a pair of ridges 20, 30 into two integral components separated by an X-Z plane including the axis of the waveguide 10, and then manufacturing each of the two integral components by aluminum die casting using an upper mold and a lower mold, and then joining the two integral components together.

[0054] The circular polarizer according to embodiment 1 may also be manufactured by additively manufacturing a tube body by resin injection molding, integrating the waveguide 10 and the pair of ridges 20, 30, and then metal plating the entire inner surface of the tube body to form a plating layer.

[0055] Furthermore, the circularly polarized wave generator according to the first embodiment may be manufactured by additive manufacturing using a metal 3D printer with additive manufacturing technology, integrating the waveguide 10 and the pair of ridges 20, 30 from the second input / output terminal 12 toward the first input / output terminal 11. When manufacturing using a metal 3D printer with additive manufacturing technology, additive manufacturing is preferably performed with the manufacturing direction tilted 45 degrees from the axial direction of the waveguide 10. By additive manufacturing with the manufacturing direction tilted 45 degrees from the axial direction of the waveguide 10, the connecting portion 23b １ ~23b Ｎ－１ , 33b １ ~33b Ｎ－１ The protrusions 23a １ ~23a Ｎ , 33a １ ~33a Ｎ This can prevent the protruding parts from collapsing during additive manufacturing.

[0056] Furthermore, the circular polarizer according to embodiment 1 may be manufactured by additive manufacturing using a resin 3D printer with additive manufacturing technology, similar to additive manufacturing using a metal 3D printer, by integrating the waveguide 10 and the pair of ridges 20, 30 from the second input / output terminal 12 toward the first input / output terminal 11 to form a tube body, and then metal plating the entire inner surface of the tube body to form a plating layer.

[0057] The circularly polarized wave generator according to the first embodiment has a pair of ridges 20, 30 arranged opposite to each other on the inner wall surface of a hollow waveguide 10 having a hollow portion with a circular cross section, and intermediate portions 23, 33 of each of the pair of ridges 20, 30 are periodically provided in the tube axis direction of the waveguide 10, and each of the intermediate portions 23, 33 has a plurality of protrusions 23a protruding in a direction along a line (line in the X direction) perpendicular to a line (line in the Y direction) connecting the central axes of the pair of ridges 20, 30 in a first plane (X-Y plane) perpendicular to the tube axis of the waveguide 10. １ ~23a Ｎ , 33a１ ~323a Ｎ , and a plurality of protrusions 23a １ ~23a Ｎ , 33a １ ~323a Ｎ The connecting portion 23b connecting the adjacent protrusions in １ ~23b Ｎ－１ , 33b １ ~33b Ｎ－１ Therefore, good reflection characteristics and axial ratio characteristics can be obtained.

[0058] Furthermore, when connecting to a horn antenna having a circular waveguide terminal, a converter from a square waveguide to a circular waveguide is not required for connecting to the horn antenna, and the length in the tube axial direction does not become long. １ ~23a Ｎ , 33a １ ~323a Ｎ By configuring the ridges 20, 30 so that their length (width) in the direction perpendicular to the line connecting the central axes of the pair of ridges 20, 30 shortens in a trigonometric function fashion from the central protrusion at the center of the central axis of the ridges 20, 30 as the apex toward the first input / output end 21, 31 and the second input / output end 22, 32, the shape changes gradually, thereby achieving better reflection characteristics.

[0059] Second Embodiment A circular polarizer according to a second embodiment will be described with reference to Figures 17 to 21. The circular polarizer according to the second embodiment differs from the circular polarizer according to the first embodiment in that it has a plurality of protrusions 23a at the intermediate portions 23, 33 of the pair of ridges 20, 30. １ ~23a Ｎ , 33a １ ~33a Ｎ The cross section of each of the ridges 201 and 301 parallel to the third plane, which is the XZ plane, is rectangular, whereas the plurality of protrusions 231a at the intermediate portions 231 and 331 of the pair of ridges 201 and 301 １ ~231a Ｎ , 331a １ ~331a Ｎ17 to 21, the same reference numerals as those in FIGS. 1 to 5 denote the same or corresponding parts, except that the cross section parallel to the third plane, which is the XZ plane, is a trapezoid.

[0060] The circular polarizer according to the second embodiment comprises a circular waveguide 10 and a pair of ridges 201, 301. The pair of ridges 201, 301 have central axes parallel to the tube axis of the waveguide 10 and are arranged opposite each other on the inner wall surface of the waveguide 10. The pair of ridges 201, 301 have a symmetrical structure with respect to a third plane passing through the tube axis of the waveguide 10. The waveguide 10 and the pair of ridges 201, 301 are integrally configured.

[0061] Each of the pair of ridges 201, 301 has a first input / output end portion 211, 311 at one end, a second input / output end portion 221, 321 at the other end, and an intermediate portion 231, 331 between the first input / output end portion 211, 311 and the second input / output end portion 221, 321. The first input / output end portions 211, 311 are the same as the first input / output end portions 21, 31 in the circular polarizer according to embodiment 1. The second input / output end portions 221, 321 are the same as the second input / output end portions 22, 32 in the circular polarizer according to embodiment 1.

[0062] The intermediate portions 231 and 331 are formed by a plurality of protrusions 231a that are periodically provided in the axial direction of the waveguide 10, i.e., in the Z-axis direction. １ ~231a Ｎ , 331a １ ~331a Ｎ and a plurality of protrusions 231a １ ~231a Ｎ , 331a １ ~331a Ｎ The connecting portion 231b connecting the adjacent protrusions in １ ~231b Ｎ－１ , 331b １ ~331b Ｎ－１ The plurality of protrusions 231a １ ~231a Ｎ , 331a １ ~331a ＮIn a first plane perpendicular to the tube axis of the waveguide 10, i.e., in the XY plane, the connecting portion 231b extends in a direction perpendicular to the line connecting the central axes of the pair of ridges 201 and 301, i.e., in the X-axis direction. １ ~231b Ｎ , 331b １ ~331b Ｎ More prominent.

[0063] A plurality of protrusions 231a １ ~231a Ｎ , 331a １ ~331a Ｎ Each of the protrusions 231a has a trapezoidal cross section parallel to the third plane, which is the XZ plane. １ ~231a Ｎ In the trapezoidal cross section parallel to the third plane, the length of the lower base is equal to the length of the connecting portion 231b. １ ~231b Ｎ－１ Width W ０ The length of the upper base, that is, the width W, is the same as the length of the lower base W ０ The ridge 201 has an isosceles trapezoidal shape that is longer than the central protrusion on the central axis of the ridge 201 and that is successively shorter toward the first input / output end 211 and the second input / output end 221 .

[0064] A plurality of protrusions 231a １ ~231a Ｎ Width W in ｎ (n is 1 to N, and corresponds to the length W of the upper base) has the following relationship in the second embodiment, as in the first embodiment: W １ <W ２ <...<W （Ｎ－２）／２ <W Ｎ／２ >W （Ｎ＋２）／２ >... >W Ｎ－１ >W Ｎ A plurality of protrusions 231a １ ~231a Ｎ Width W in ｎ The relationship is shown by the dashed line W in FIG. Ｌｉｎｅ As shown in FIG. 1, the central protrusion 231a Ｎ／２ It is preferable that the protrusions 231a become shorter in a trigonometric function shape from the apex toward the first input / output end 211 and the second input / output end 221. １~231a Ｎ In the embodiment, the angle formed between the sole and the legs is θ as shown in Fig. 21. θ is preferably equal to or greater than 45 degrees and less than 90 degrees. In the second embodiment, the angle is set to 45 degrees.

[0065] , a plurality of protrusions 231a １ ~231a Ｎ In the figure, the protrusion 231a at the center of the central axis of the ridge 201 Ｎ／２ The length in the Z-axis direction, i.e., the vertical width L, of the plurality of protrusions 231a decreases sequentially from the first input / output end 211 to the second input / output end 221. １ ~231a Ｎ The vertical width L ｎ In the second embodiment, the relationship between L and L is as follows, similar to that in the first embodiment. １ <L ２ <...<L （Ｎ－２）／２ <L Ｎ／２ >L （Ｎ＋２）／２ > ... > L Ｎ－１ >L Ｎ In addition, the vertical width L ｎ may all be the same length.

[0066] A plurality of protrusions 231a １ ~231a Ｎ The height H of the plurality of protrusions 231a is the same. １ ~231a Ｎ The boundary surface between the inner wall surface of the waveguide 10 and the protrusions 231a is an arcuate surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~231a Ｎ The surface facing the boundary surface at 201 is an isosceles trapezoid and is a plane parallel to the XZ plane. １ ~231a Ｎ The opposing surfaces at the first input / output end 211 and the second input / output end 221 are on the same XZ plane.

[0067] A plurality of protrusions 331a １ ~331a Ｎ In the trapezoidal cross section parallel to the third plane, the length of the lower base is equal to the length of the connecting portion 331b. １ ~331bＮ－１ Width W ０ The length of the upper base, that is, the width W, is the same as the length of the lower base W ０ The ridge 301 has an isosceles trapezoidal shape that is longer from the central protrusion on the central axis of the ridge 301 and gradually shorter from the central protrusion towards the first input / output end 311 and the second input / output end 322 .

[0068] A plurality of protrusions 331a １ ~332a Ｎ Width W in ｎ (n is 1 to N, and corresponds to the length W of the upper base) has the following relationship in the second embodiment, as in the first embodiment: W １ <W ２ <...<W （Ｎ－２）／２ <W Ｎ／２ >W （Ｎ＋２）／２ >... >W Ｎ－１ >W Ｎ A plurality of protrusions 331a １ ~331a Ｎ Width W in ｎ The relationship is shown by the dashed line W in FIG. Ｌｉｎｅ As shown in FIG. 1, the central protrusion 331a Ｎ／２ It is preferable that the protrusions 331a are arranged in a trigonometric function pattern with the protrusions 331a at the apex and becoming shorter toward the first input / output end 311 and the second input / output end 321. １ ~331a Ｎ In the embodiment, the angle between the bottom and the leg is θ as shown in Fig. 21. θ is preferably 45 degrees or more and less than 90 degrees. In the second embodiment, it is set to 45 degrees.

[0069] A plurality of protrusions 331a １ ~331a Ｎ In this case, the protrusion 331a at the center of the central axis of the ridge 301 Ｎ／２ The length in the Z-axis direction, i.e., the vertical width L, of the plurality of protrusions 331a decreases sequentially from the first input / output end 311 to the second input / output end 321. １ ~331a Ｎ The vertical width L ｎ In the second embodiment, the relationship between L and L is as follows, similar to that in the first embodiment. １ <L ２ <...<L （Ｎ－２）／２ <LＮ／２ >L （Ｎ＋２）／２ > ... > L Ｎ－１ >L Ｎ In addition, the vertical width L ｎ may all be the same length.

[0070] A plurality of protrusions 331a １ ~331a Ｎ The height H is the same for all the protrusions 331a. １ ~331a Ｎ The boundary surface between the inner wall surface of the waveguide 10 and the protrusions 331a is an arcuate surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~331a Ｎ The surface facing the boundary surface at the ridge 301 is an isosceles trapezoid and is a plane parallel to the XZ plane. １ ~331a Ｎ The opposing surfaces at the first input / output end 311 and the second input / output end 32 1 are in the same XZ plane as the opposing surfaces at the first input / output end 311 and the second input / output end 32 1 .

[0071] Connecting part 231b １ ~231b Ｎ－１ , 331b １ ~331b Ｎ－１ Each of the connecting portions 231b has a rectangular cross section parallel to the third plane, which is the XZ plane. １ ~231b Ｎ－１ is the width W ０ are all the same. １ ~231b Ｎ－１ is the vertical width L ０ are all the same, and the protrusions 231a １ ~231a Ｎ are placed at equal intervals.

[0072] Connecting part 231b １ ~231b Ｎ－１ The boundary surface between each of the connecting portions 231 and the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~231b Ｎ－１ The opposing surface of each of the two surfaces facing the boundary surface is rectangular and is a plane parallel to the XZ plane.

[0073] In the ridge 201, the connecting portion 231b １ ~231b Ｎ－１ The opposing surfaces of the first input / output end 211, the second input / output end 221, and the plurality of protrusions 231a are １ ~231a Ｎ That is, the surface of the ridge 201 that faces the arcuate surface along the inner wall surface of the waveguide 10 is a flat surface that lies in the XZ plane.

[0074] Connecting part 331b １ ~331b Ｎ－１ is the width W ０ are all the same. １ ~331b Ｎ－１ is the vertical width L ０ are all the same, and the protrusions 331a １ ~331a Ｎ are arranged at equal intervals. １ ~331b Ｎ－１ The boundary surface between each of the connecting portions 331 and the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~331b Ｎ－１ The opposing surface of each of the two surfaces facing the boundary surface is rectangular and is a plane parallel to the XZ plane.

[0075] In the ridge 301, the connecting portion 331b １ ~331b Ｎ－１ The opposing surfaces of the first input / output end 311, the second input / output end 321, and the plurality of protrusions 331a are １ ~331a Ｎ In other words, the opposing surface of the ridge 301 that faces the arcuate surface along the inner wall surface of the waveguide 10 is a flat surface in the XZ plane. The opposing surface of the ridge 201 and the opposing surface of the ridge 301 face each other.

[0076] The ridges 201 and 301 in the circular waveguide polarizer according to the second embodiment have protrusions 231a with different upper base lengths, i.e., different widths. １ ~231a Ｎ , 331a１ ~331a Ｎ In order to form a periodic structure in which the protrusions 231a are periodically arranged, １ ~231a Ｎ , 331a １ ~331a Ｎ By appropriately selecting the width W of the antenna, a desired phase difference can be obtained in a desired frequency band, and a desired axial ratio characteristic can be achieved.

[0077] As a result, the circular waveguide polarizer according to the second embodiment has a plurality of protrusions 231a on the ridges 201 and 301. １ ~231a Ｎ , 331a １ ~331a Ｎ By appropriately designing the shape, particularly the width W, of the antenna, a desired phase difference can be obtained in a selected frequency band, mainly in the VHF band, UHF band, microwave band, and millimeter wave band, and a circularly polarized signal with a desired axial ratio characteristic can be obtained.

[0078] The following describes a manufacturing method for the circular polarizer according to embodiment 2. The circular polarizer according to embodiment 2 is manufactured by additive manufacturing using a metal 3D printer with additive manufacturing technology, integrating the waveguide 10 and the pair of ridges 20, 30 along the tube axis of the waveguide 10 from the second input / output terminal 12 toward the first input / output terminal 11.

[0079] A plurality of protrusions 231a on each of the pair of ridges 201 and 301 in the circular wave polarizer according to the second embodiment １ ~231a Ｎ , 331a １ ~331a Ｎ Each of them has an isosceles trapezoidal cross section parallel to the third plane, which is the XZ plane, and the length of the lower base is equal to the length of the connecting portion 231b. １ ~231b Ｎ－１ , 331b １ ~331b Ｎ－１ Width W ０ The angle between the bottom and the leg is θ (45≦θ<90), so the connecting part 23b １ ~23b Ｎ－１ , 33b １ ~33b Ｎ－１ The protrusions 23a １~23a Ｎ , 33a １ ~33a Ｎ The structure does not have a flat ceiling in the protruding part.

[0080] Therefore, even if metal powder is laid and solidified one layer at a time using a metal 3D printer to perform layer-by-layer manufacturing in the axial direction of the waveguide 10, the metal powder is layered at an angle θ on the side surface formed by the upper and lower bases in the axial direction of the waveguide 10, so that the connecting portion 231b １ ~231b Ｎ－１ , 331b １ ~331b Ｎ－１ The protrusions 231a １ ~231a Ｎ , 331a １ ~331a Ｎ The protruding portion does not collapse, and the accuracy of the circular shape of the waveguide 10 is not impaired, thereby improving the molding accuracy.

[0081] The circular polarizer according to the second embodiment may be manufactured by additive manufacturing using a metal 3D printer, using a resin 3D printer to integrate the waveguide 10 and the pair of ridges 201, 301 along the axis of the waveguide 10 from the second input / output terminal 12 toward the first input / output terminal 11 to form an additive manufacturing tube body, and then metal plating the entire inner surface of the tube body to form a plating layer, in the same manner as manufacturing using additive manufacturing using a metal 3D printer.

[0082] The circular polarizer according to embodiment 2 may also be manufactured by molding in the same way as the circular polarizer according to embodiment 1, by manufacturing two separate integrated components for the waveguide 10 and the pair of ridges 201, 301 by aluminum die casting using an upper mold and a lower mold, and then joining the two separate integrated components. Furthermore, the circular polarizer according to embodiment 2 may also be manufactured by additively manufacturing a tube body by integrating the waveguide 10 and the pair of ridges 201, 301 by resin injection molding, and then metal plating the entire inner surface of the tube to form a plating layer.

[0083] The circular polarizer according to the second embodiment has the same effect as the circular polarizer according to the first embodiment. Furthermore, the circular polarizer according to the second embodiment has the protrusions 231a on the ridges 201 and 301. １ ~231a Ｎ , 331a １ ~331a Ｎ Using a 3D printer with additive manufacturing technology, the waveguide 10 can be sequentially additively manufactured with high manufacturing accuracy in the axial direction without destroying the structure.

[0084] Third Embodiment A circular polarizer according to a third embodiment will be described with reference to Figures 22 to 26. The circular polarizer according to the third embodiment differs from the circular polarizer according to the first embodiment in that it has a plurality of protrusions 23a at the intermediate portions 23, 33 of the pair of ridges 20, 30. １ ~23a Ｎ , 33a １ ~33a Ｎ The cross section of each of the ridges 202 and 302 parallel to the third plane, which is the XZ plane, is rectangular, whereas the plurality of protrusions 232a at the intermediate portions 232 and 332 of the pair of ridges 202 and 302 １ ~232a Ｎ , 332a １ ~332a Ｎ 22 to 26, the same reference numerals as those in FIGS. 1 to 5 denote the same or corresponding parts, except that the cross section parallel to the third plane, which is the XZ plane, is a hexagon.

[0085] The circular polarizer according to the third embodiment comprises a circular waveguide 10 and a pair of ridges 202, 302. The pair of ridges 202, 302 have central axes parallel to the tube axis of the waveguide 10 and are arranged opposite each other on the inner wall surface of the waveguide 10. The pair of ridges 202, 302 have a symmetrical structure with respect to a third plane passing through the tube axis of the waveguide 10. The waveguide 10 and the pair of ridges 202, 302 are integrally configured.

[0086] Each of the pair of ridges 202, 302 has a first input / output end portion 212, 312 at one end, a second input / output end portion 222, 322 at the other end, and an intermediate portion 232, 332 between the first input / output end portion 212, 312 and the second input / output end portion 222, 322. The first input / output end portions 212, 312 are the same as the first input / output end portions 21, 31 in the circular polarizer according to embodiment 1. The second input / output end portions 222, 322 are the same as the second input / output end portions 22, 32 in the circular polarizer according to embodiment 1.

[0087] The intermediate portions 232 and 332 are formed by a plurality of protrusions 232a that are periodically provided in the axial direction of the waveguide 10, i.e., in the Z-axis direction. １ ~232a Ｎ , 332a １ ~332a Ｎ and a plurality of protrusions 232a １ ~232a Ｎ , 332a １ ~332a Ｎ The connecting portion 232b connects adjacent protrusions in １ ~232b Ｎ－１ , 332b １ ~332b Ｎ－１ The plurality of protrusions 232a １ ~232a Ｎ , 332a １ ~332a Ｎ In a first plane perpendicular to the tube axis of the waveguide 10, i.e., in the XY plane, the connecting portion 232b is in a direction along a line perpendicular to the line connecting the central axes of the pair of ridges 202 and 302, i.e., in the X-axis direction. １ ~232b Ｎ , 332b １ ~332b Ｎ More prominent.

[0088] A plurality of protrusions 232a １ ~232a Ｎ , 332a １ ~332a Ｎ Each of the protrusions 232a has a hexagonal cross section parallel to the third plane, which is the XZ plane. １ ~232a ＮIn the hexagonal cross section parallel to the third plane, the length of a pair of opposite sides is equal to the length of the connecting portion 232b. １ ~232b Ｎ－１ Width W ０ and is symmetrical with respect to the YZ plane passing through the central axis of the ridge 202.

[0089] A plurality of protrusions 232a １ ~232a Ｎ , the hexagon is symmetrical with respect to the XY plane passing through the line connecting the left and right vertices of the hexagon. １ ~232a Ｎ In this case, the length connecting the left and right vertices of the hexagon, that is, the width W, is the length of the opposite side W. ０ The lengths are successively shorter from the central protrusion on the central axis of the ridge 202 to the first input / output end 212 and the second input / output end 222 .

[0090] A plurality of protrusions 232a １ ~232a Ｎ Width W in ｎ (n is 1 to N) in the third embodiment have the following relationship, similar to the first embodiment: W １ <W ２ <...<W （Ｎ－２）／２ <W Ｎ／２ >W （Ｎ＋２）／２ >... >W Ｎ－１ >W Ｎ A plurality of protrusions 232a １ ~232a Ｎ Width W in ｎ The relationship is shown by the dashed line W in FIG. Ｌｉｎｅ As shown in FIG. 1, the central protrusion 232a Ｎ／２ It is preferable that the length of the first input / output terminal 212 and the second input / output terminal 222 become shorter in a trigonometric function fashion from the apex.

[0091] A plurality of protrusions 232a １ ~232a Ｎ 26, the angle formed by each of the opposite sides of the ridge 202 and the oblique side on both sides in the central axis direction is θ. It is preferable that θ is 45 degrees or more and less than 90 degrees. １If the cross section parallel to the XZ plane at 232a is a regular hexagon, then θ is 60 degrees.

[0092] , a plurality of protrusions 232a １ ~232a Ｎ In this case, the protrusion 232a at the center of the central axis of the ridge 202 Ｎ／２ The length in the Z-axis direction, i.e., the vertical width L, of the plurality of protrusions 232a decreases sequentially from the first input / output end 212 to the second input / output end 222. １ ~232a Ｎ The vertical width L ｎ In the third embodiment, the relationship between L and L is as follows, similar to that in the first embodiment. １ <L ２ <...<L （Ｎ－２）／２ <L Ｎ／２ >L （Ｎ＋２）／２ > ... > L Ｎ－１ >L Ｎ In addition, the vertical width L ｎ may all be the same length.

[0093] A plurality of protrusions 232a １ ~232a Ｎ The height H is the same for all the protrusions 232a. １ ~232a Ｎ The boundary surface between the inner wall surface of the waveguide 10 and the protrusions 232a is an arcuate surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~232a Ｎ The surface facing the boundary surface at the ridge 202 is a hexagonal plane parallel to the XZ plane. １ ~232a Ｎ The opposing surfaces at the first input / output end 212 and the second input / output end 222 are in the same XZ plane.

[0094] A plurality of protrusions 332a １ ~332a Ｎ In the hexagonal cross section parallel to the third plane, the length of a pair of opposite sides is equal to the length of the connecting portion 232b. １ ~232b Ｎ－１ Width W ０and is symmetrical with respect to the YZ plane passing through the central axis of the ridge 302. １ ~332a Ｎ , the hexagon is symmetrical with respect to the XY plane passing through the line connecting the left and right vertices of the hexagon. １ ~332a Ｎ In this case, the length connecting the left and right vertices of the hexagon, that is, the width W, is the length of the opposite side W. ０ The lengths are longer from the central protrusion on the central axis of the ridge 302 toward the first input / output end 312 and the second input / output end 322, respectively.

[0095] A plurality of protrusions 332a １ ~332a Ｎ Width W in ｎ (n is 1 to N) in the third embodiment have the following relationship, similar to the first embodiment: W １ <W ２ <...<W （Ｎ－２）／２ <W Ｎ／２ >W （Ｎ＋２）／２ >... >W Ｎ－１ >W Ｎ A plurality of protrusions 332a １ ~332a Ｎ Width W in ｎ The relationship is shown by the dashed line W in FIG. Ｌｉｎｅ As shown in FIG. 1, the central protrusion 332a Ｎ／２ It is preferable that the length of the first input / output end 312 and the second input / output end 322 be shortened in a trigonometric function fashion from the apex.

[0096] A plurality of protrusions 332a １ ~332a Ｎ 26, the angle formed between each opposite side and the oblique side on both sides of the central axis of the ridge 302 is θ. θ is preferably 45 degrees or more and less than 90 degrees. １ ~332a Ｎ If the cross section parallel to the XZ plane is a regular hexagon, then θ is 60 degrees.

[0097] , a plurality of protrusions 332a １ ~332a ＮIn this case, the protrusion 332a at the center of the central axis of the ridge 302 Ｎ／２ The length in the Z-axis direction, i.e., the vertical width L, of the plurality of protrusions 332a decreases sequentially from the first input / output end 312 to the second input / output end 322. １ ~332a Ｎ The vertical width L ｎ In the third embodiment, the relationship between L and L is as follows, similar to that in the first embodiment. １ <L ２ <...<L （Ｎ－２）／２ <L Ｎ／２ >L （Ｎ＋２）／２ > ... > L Ｎ－１ >L Ｎ In addition, the vertical width L ｎ may all be the same length.

[0098] A plurality of protrusions 332a １ ~332a Ｎ The height H is the same for all the protrusions 332a. １ ~332a Ｎ The boundary surface between the inner wall surface of the waveguide 10 and the protrusions 332a is an arcuate surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~332a Ｎ The surface facing the boundary surface at the ridge 302 is a hexagonal plane parallel to the XZ plane. １ ~332a Ｎ The opposing surfaces at the first input / output end 312 and the second input / output end 322 are in the same XZ plane.

[0099] Connecting portion 232b １ ~232b Ｎ－１ , 332b １ ~332b Ｎ－１ Each of the connecting portions 232b has a rectangular cross section parallel to the third plane, which is the XZ plane. １ ~232b Ｎ－１ is the width W ０ are all the same. １ ~232b Ｎ－１ is the vertical width L ０ are all the same, and the protrusions 232a １~232a Ｎ are placed at equal intervals.

[0100] Connecting portion 232b １ ~232b Ｎ－１ The boundary surface between each of the connecting portions 232 and the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~232b Ｎ－１ The opposing surface of each of the two surfaces facing the boundary surface is rectangular and is a plane parallel to the XZ plane.

[0101] In the ridge 202, the connecting portion 232b １ ~232b Ｎ－１ The opposing surfaces of the first input / output end 212, the second input / output end 222, and the plurality of protrusions 232a are １ ~232a Ｎ That is, the surface of the ridge 202 that faces the arcuate surface along the inner wall surface of the waveguide 10 is a flat surface that lies in the XZ plane. Ｎ／２ The ridge 202 is vertically symmetrical with respect to the XY plane passing through the line connecting the left and right vertices of the hexagon.

[0102] Connecting portion 332b １ ~332b Ｎ－１ is the width W ０ are all the same. １ ~332b Ｎ－１ is the vertical width L ０ are all the same, and the protrusions 332a １ ~332a Ｎ are arranged at equal intervals. １ ~332b Ｎ－１ The boundary surface between each of the connecting portions 332 and the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. １ ~332b Ｎ－１ The opposing surface of each of the two surfaces facing the boundary surface is rectangular and is a plane parallel to the XZ plane.

[0103] In the ridge 302, the connecting portion 332b １ ~332b Ｎ－１The opposing surfaces of the first input / output end 312, the second input / output end 322, and the plurality of protrusions 332a are １ ~332a Ｎ That is, the surface of the ridge 302 that faces the arcuate surface along the inner wall surface of the waveguide 10 is a flat surface that lies in the XZ plane. Ｎ／２ The ridge 302 is vertically symmetrical with respect to the XY plane passing through the line connecting the left and right vertices of the hexagon in Fig. 1. The opposing surface of the ridge 202 and the opposing surface of the ridge 302 face each other.

[0104] The ridges 202 and 302 in the circular waveguide polarizer according to the third embodiment are formed by protruding portions 232a having different lengths connecting the left and right vertices of a hexagon, i.e., different widths. １ ~232a Ｎ , 332a １ ~332a Ｎ In order to form a periodic structure in which the protrusions 232a are periodically arranged, １ ~232a Ｎ , 332a １ ~332a Ｎ By appropriately selecting the width W of the antenna, a desired phase difference can be obtained in a desired frequency band, and a desired axial ratio characteristic can be realized.

[0105] As a result, the circular waveguide polarizer according to the third embodiment has a plurality of protrusions 232a on the ridges 202 and 302. １ ~232a Ｎ , 332a １ ~332a Ｎ By appropriately designing the shape, particularly the width W, of the antenna, a desired phase difference can be obtained in a selected frequency band, mainly in the VHF band, UHF band, microwave band, and millimeter wave band, and a circularly polarized signal with a desired axial ratio characteristic can be obtained.

[0106] As with the circular polarizer according to embodiment 2, the circular polarizer according to embodiment 3 is manufactured by additive manufacturing using a metal 3D printer with additive manufacturing technology to integrate the waveguide 10 and the pair of ridges 20, 30 along the tube axis of the waveguide 10 from the second input / output terminal 12 toward the first input / output terminal 11.

[0107] A plurality of protrusions 232a on each of the pair of ridges 202, 302 in the circular wave polarizer according to the third embodiment １ ~232a Ｎ , 332a １ ~332a Ｎ Each of the connecting portions 232b has a hexagonal cross section parallel to the third plane, which is the XZ plane, and the length of a pair of opposite sides is equal to １ ~232b Ｎ－１ , 332b １ ~332b Ｎ－１ Width W ０ The angle between the opposite side and the oblique side is θ (45≦θ<90). １ ~231b Ｎ－１ , 331b １ ~331b Ｎ－１ The protrusions 231a １ ~231a Ｎ , 331a １ ~331a Ｎ The structure does not have a flat ceiling in the protruding part.

[0108] Therefore, even if metal powder is laid and solidified one layer at a time using a metal 3D printer to be sequentially layer-by-layer manufactured in the axial direction of the waveguide 10, the metal powder is layered in the axial direction of the waveguide 10 at an angle θ on the side formed by the opposite side and the oblique side located on the lower side. １ ~231b Ｎ－１ , 331b １ ~331b Ｎ－１ The protrusions 231a １ ~231a Ｎ , 331a １ ~331a Ｎ The protruding portion does not collapse, and the accuracy of the circular shape of the waveguide 10 is not impaired, thereby improving the molding accuracy.

[0109] The circular polarizer according to embodiment 3 may be manufactured by additive manufacturing using a resin 3D printer, in the same way as manufacturing using additive manufacturing with a resin 3D printer, by integrating the waveguide 10 and the pair of ridges 202, 302 along the tube axis of the waveguide 10 from the second input / output terminal 12 toward the first input / output terminal 11 to form an additive manufacturing tube body, and then metal plating the entire inner surface of the tube body to form a plating layer.

[0110] The circular polarizer according to embodiment 3 may also be manufactured by, similarly to the manufacturing method of the circular polarizer according to embodiment 1, manufacturing two separate integrated structures for the waveguide 10 and the pair of ridges 202, 302 by aluminum die casting using an upper mold and a lower mold, and then joining the two separate integrated structures. Furthermore, the circular polarizer according to embodiment 3 may also be manufactured by additively manufacturing a tube body by integrating the waveguide 10 and the pair of ridges 202, 302 by resin injection molding, and then metal plating the entire inner surface of the tube to form a plating layer.

[0111] The circular wave polarizer according to the third embodiment has the same effect as the circular wave polarizer according to the first embodiment. Ｎ／２ , 332a Ｎ／２ Since the ridges 202 and 302 are vertically symmetrical with respect to the XY plane passing through the line connecting the left and right vertices of the hexagon in FIG. 1, the symmetry in the tube axis direction is improved, and better reflection characteristics and axial ratio characteristics can be realized.

[0112] Furthermore, in the circular waveguide polarizer according to the third embodiment, the protrusions 231a on the ridges 202 and 302 are １ ~231a Ｎ , 331a １ ~331a Ｎ Using a 3D printer with additive manufacturing technology, the waveguide 10 can be sequentially additively manufactured with high manufacturing accuracy in the axial direction without destroying the structure.

[0113] 27 to 31, a circular polarizer according to a fourth embodiment will be described. The first input / output end portions 21, 31 and second input / output end portions 22, 32 of the pair of ridges 20, 30 in the circular polarizer according to the first embodiment have a uniform length along the line connecting the central axes of the pair of ridges 20, 30 over their entire length, and a uniform length along the line perpendicular to the line connecting the central axes of the pair of ridges 20, 30 over their entire length.

[0114] In contrast, the circular polarizer according to embodiment 4 differs from the circular polarizer according to embodiment 1 in that the first input / output end portions 21A, 31A of each of the pair of ridges 20A, 30A are tapered in length toward the first input / output terminal 11 in a second plane including the central axes of the pair of ridges 20A, 30A, and the second input / output end portions 22A, 32A of each of the pair of ridges 20A, 30A are tapered in length toward the second input / output terminal 12 in a second plane including the central axes of the pair of ridges 20A, 30A, but is otherwise the same. In Figures 27 to 31, the same reference numerals as those in Figures 1 to 5 indicate the same or corresponding parts.

[0115] Therefore, the following description will focus on the differences, namely the pair of ridges 20A, 30A, and in particular the first input / output end portions 21A, 31A and the second input / output end portions 22A, 32A. The circular polarizer according to embodiment 4 has an integrated configuration comprising a circular waveguide 10 and a pair of ridges 20A, 30A. The circular waveguide 10 is the same as the circular waveguide 10 in the circular polarizer according to embodiment 1, and therefore a description thereof will be omitted.

[0116] Each of the pair of ridges 20A, 30A has a first input / output end portion 21A, 31A at one end, a second input / output end portion 221, 321 at the other end, and an intermediate portion 23, 33 between the first input / output end portion 21A, 31A and the second input / output end portion 22A, 32A. The intermediate portions 23, 33 are the same as the intermediate portions 23, 33 in the circular polarizer according to embodiment 1, and therefore a description thereof will be omitted.

[0117] The height (length in the Y-axis direction) of the first input / output end portions 21A and 31A is １, 33a １ The height of the first input / output terminals 21A and 31A decreases gradually from the height of the first input / output terminal 11 toward the first input / output terminal 11. It is preferable that the height of the first input / output terminals 21A and 31A decreases in a trigonometric function manner, but it may decrease linearly. The width (length in the X-axis direction) of the first input / output terminals 21A and 31A is uniform over the entire length in the Z-axis direction, and the connecting portion 23b of the intermediate portions 23 and 33 １ ~23b Ｎ－１ , 33b １ ~33b Ｎ－１ Width W ０ is the same as

[0118] The boundary surface between the first input / output end portion 21A, 31A and the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. The opposing surface of the first input / output end portion 21A, 31A that faces the boundary surface is rectangular and is a flat surface that is inclined with respect to the XZ plane. The first input / output end portion 21A and the first input / output end portion 31A have the same size and shape.

[0119] The height of the second input / output end portions 22A and 32A is equal to the height of the projections 23a of the intermediate portions 23 and 33. Ｎ , 33a Ｎ The height of the second input / output terminals 22A and 32A is preferably decreased in a trigonometric function manner, but may be decreased in a linear manner. The width of the second input / output terminals 22A and 32A is uniform over the entire length in the Z-axis direction, and the connecting portion 23b of the intermediate portion 23 and 33 is １ ~23b Ｎ－１ , 33b １ ~33b Ｎ－１ Width W ０ is the same as

[0120] The boundary surface between the second input / output end portions 22A and 32A and the inner wall surface of the waveguide 10 is an arcuate surface that follows the inner wall surface of the waveguide 10 with respect to the XZ plane. The opposing surface of the second input / output end portions 22A and 32A that faces the boundary surface is rectangular and is a flat surface that is inclined with respect to the XZ plane. The second input / output end portions 22A and 32A have the same size and shape.

[0121] The circular polarizer according to embodiment 4 is manufactured by mold molding, similar to the manufacturing of the circular polarizer according to embodiment 1. Note that the circular polarizer according to embodiment 4 may be manufactured by a metal 3D printer with additive manufacturing technology, a resin 3D printer with additive manufacturing technology and metal plating, or resin injection molding and metal plating, as described for the circular polarizer according to embodiment 1.

[0122] The circular polarizer of embodiment 4 has the same effect as the circular polarizer of embodiment 1, and in addition, when viewed from the first input / output terminal 11 and the second input / output terminal 12, the heights of the ridges 20A and 30A change gradually, resulting in better reflection characteristics.

[0123] In the circular polarizer according to embodiment 2, the first input / output ends 211 and 311 of the ridges 201 and 301, respectively, may have the same shapes as the first input / output ends 21A and 31A of the ridges 20A and 30A, respectively, shown in the circular polarizer according to embodiment 4, and the second input / output ends 221 and 321 of the ridges 201 and 301, respectively, may have the same shapes as the second input / output ends 22A and 32A of the ridges 20A and 30A, respectively, shown in the circular polarizer according to embodiment 4.

[0124] That is, in the circular waveguide polarizer according to the second embodiment, the first input / output terminals 211 and 311 are provided with the projections 231a having intermediate heights 231 and 331, respectively. １ , 331a １ The second input / output terminals 221 and 321 have projections 231a at intermediate portions 231 and 331, respectively, which gradually become shorter from the first input / output terminal 11 to the second input / output terminals 221 and 321. Ｎ , 331a Ｎ Alternatively, the shape may be such that the length gradually decreases from the first input / output terminal 11 to the second input / output terminal 12.

[0125] In the circular polarizer according to embodiment 2, a circular polarizer in which the first input / output terminals 21A, 31A and the second input / output terminals 22A, 32A shown in the circular polarizer according to embodiment 4 are modified is manufactured by a metal 3D printer with additive manufacturing technology, as in the manufacturing of the circular polarizer according to embodiment 2, and may also be manufactured by a resin 3D printer with additive manufacturing technology and metal plating, mold forming processing, or resin injection molding and metal plating.

[0126] Furthermore, in the circular polarizer according to embodiment 3, the first input / output ends 212 and 312 of the ridges 202 and 302, respectively, may have the same shapes as the first input / output ends 21A and 31A of the ridges 20A and 30A, respectively, shown in the circular polarizer according to embodiment 4, and the second input / output ends 222 and 322 of the ridges 202 and 302, respectively, may have the same shapes as the second input / output ends 22A and 32A of the ridges 20A and 30A, respectively, shown in the circular polarizer according to embodiment 4.

[0127] That is, in the circular wave polarizer according to the third embodiment, the projections 232a at the intermediate portions 232 and 332 are spaced apart from the first input / output end portions 212 and 312, respectively. １ , 332a １ The second input / output terminals 222 and 322 have projections 232a with intermediate heights 232 and 332, respectively. Ｎ , 3321a Ｎ Alternatively, the shape may be such that the length gradually decreases from the first input / output terminal 11 to the second input / output terminal 12.

[0128] In the circular polarizer according to embodiment 3, a circular polarizer in which the first input / output terminals 21A, 31A and the second input / output terminals 22A, 32A shown in the circular polarizer according to embodiment 4 are changed is manufactured by a metal 3D printer with additive manufacturing technology, as in the manufacturing of the circular polarizer according to embodiment 3, and may also be manufactured by a resin 3D printer with additive manufacturing technology and metal plating, mold molding, or resin injection molding and metal plating.

[0129] Fifth Embodiment A circular polarizer according to a fifth embodiment will be described using Figures 32 to 35. The circular polarizer according to the fifth embodiment differs from the circular polarizer according to the first embodiment in that it is provided with a pair of second ridges 40, 50, but is otherwise the same. In Figures 32 to 35, the same reference numerals as those in Figures 1 to 5 indicate the same or corresponding parts.

[0130] Therefore, the following description will focus on the difference, the pair of second ridges 40, 50. The circular polarizer according to embodiment 5 comprises a circular waveguide 10, a pair of first ridges 20, 30, and a pair of second ridges 40, 50, and the waveguide 10, the pair of first ridges 20, 30, and the pair of second ridges 40, 50 are integrally configured. Each of the pair of second ridges 40, 50 has a central axis parallel to the tube axis of the waveguide 10, and is disposed opposite each other on the inner wall surface of the waveguide 10 rotated 90 degrees around the tube axis of the waveguide 10 with respect to the pair of first ridges 20, 30.

[0131] The pair of second ridges 40, 50 have a symmetrical structure with respect to a second plane (Y-Z plane) that passes through the tube axis, which is the central axis of the waveguide 10. The length of each of the pair of second ridges 40, 50 in the direction along a line connecting the central axes of the pair of second ridges 40, 50 is uniform over its entire length, and the length of each of the pair of second ridges 40, 50 in the direction perpendicular to the line connecting the central axes of the pair of second ridges 40, 50 is uniform over its entire length. Hereinafter, for the second ridges 40, 50, the length in the X-axis direction will be referred to as the height, the length in the Y-axis direction will be referred to as the width, and the length in the Z-axis direction will be referred to as the vertical width.

[0132] 35, the width and height of each of the second ridges 40, 50 are the same along the entire length in the Z-axis direction. The boundary surface between each of the second ridges 40, 50 and the inner wall surface of the waveguide 10 is an arcuate surface that follows the inner wall surface of the waveguide 10 with respect to the Y-Z plane. The opposing surface of each of the second ridges 40, 50 that faces the boundary surface is rectangular and is a flat surface parallel to the Y-Z plane. The second ridges 40 and 50 have the same size and shape.

[0133] From the viewpoint of design parameters, it is preferable that the width of each of the second ridges 40, 50 is the same as the width of the first input / output end portions 21, 31 and the width of the second input / output end portions 22, 32, but they may be different widths. Also, from the viewpoint of design parameters, it is preferable that the height of each of the second ridges 40, 50 is the same as the height of the first input / output end portions 21, 31 and the height of the second input / output end portions 22, 32, but they may be different heights. Making the widths and heights different increases the design parameters or provides better axial ratio characteristics and reflection characteristics.

[0134] The circular polarizer according to embodiment 5 is manufactured by mold forming, similar to the manufacturing of the circular polarizer according to embodiment 1. Note that the circular polarizer according to embodiment 5 may be manufactured by a metal 3D printer with additive manufacturing technology, a resin 3D printer with additive manufacturing technology and metal plating, or resin injection molding and metal plating, as described for the circular polarizer according to embodiment 1.

[0135] The circular polarizer according to embodiment 5 has the same effects as the circular polarizer according to embodiment 1, and in addition, it improves the symmetry of the cross section parallel to the XY plane (first plane) of waveguide 13, makes it easier to achieve a desired phase difference between two orthogonal linearly polarized signals, and obtains better axial ratio characteristics.

[0136] The pair of second ridges 40, 50 in the circular polarizer according to embodiment 5 may have the following shape, similar to the pair of ridges 20, 30 in the circular polarizer according to embodiment 1. That is, the pair of second ridges 40, 50 have one end, the other end, and an intermediate portion between the one end and the other end.

[0137] The intermediate portions of each of the pair of second ridges 40, 50 are arranged periodically in the axial direction of the waveguide 10, similar to the intermediate portions of each of the pair of ridges 20, 30 in the circular polarizer according to embodiment 1, and each has a plurality of protrusions that protrude in the X-Y plane (first plane) in a direction along a line connecting the central axes of the pair of first ridges 20, 30, and connecting portions that connect adjacent protrusions among the plurality of protrusions.

[0138] Furthermore, the pair of second ridges 40, 50 in the circular polarizer according to embodiment 5 may have the following shape, similar to the description of the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4. That is, the pair of second ridges 40, 50 have one end, the other end, and an intermediate portion between the one end and the other end.

[0139] One end of each of the pair of second ridges 40, 50 is tapered in length toward the first input / output terminal 11 in the X-Z plane (third plane) including the central axis of the pair of second ridges 40, 50, similar to the first input / output terminals 21A, 31A of each of the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4. The other end of each of the pair of second ridges 40, 50 is tapered in length toward the second input / output terminal 12 in the X-Z plane including the central axis of the pair of second ridges 40, 50, similar to the second input / output terminals 22A, 32A of each of the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4.

[0140] Furthermore, the pair of first ridges 20, 30 in the circular polarizer according to embodiment 5 may each have the following shapes, similar to the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4.

[0141] That is, the first input / output terminals 21 and 31 of the first ridges 20 and 30, respectively, are provided with projections 231a having intermediate heights 231 and 331, respectively, which are similar in shape to the first input / output terminals 21A and 31A of the ridges 20A and 30A shown in the circular waveguide polarizer according to the fourth embodiment. １, 331a １ The second input / output terminals 22 and 32 of the first ridges 20 and 30, respectively, are shaped similarly to the second input / output terminals 22A and 32A of the ridges 20A and 30A shown in the circularly polarized wave generator according to the fourth embodiment, that is, the height of the projections 231a at the intermediate portions 231 and 331 is gradually reduced. Ｎ , 331a Ｎ The shape of the terminal gradually becomes shorter from the first terminal 11 to the second input / output terminal 12.

[0142] Sixth Embodiment A circular polarizer according to the sixth embodiment will be described using Figures 36 to 38. The circular polarizer according to the sixth embodiment differs from the circular polarizer according to the second embodiment in that it is provided with a pair of second ridges 40, 50, but is otherwise the same. In Figures 36 to 38, the same reference numerals as those in Figures 1 to 5 and Figures 17 to 21 indicate the same or corresponding parts.

[0143] Therefore, the following description will focus on the difference, the pair of second ridges 40, 50. The circular polarizer according to embodiment 6 comprises a circular waveguide 10, a pair of first ridges 201, 301, and a pair of second ridges 40, 50, and the waveguide 10, the pair of first ridges 201, 301, and the pair of second ridges 40, 50 are integrally configured. Each of the pair of second ridges 40, 50 has a central axis parallel to the tube axis of the waveguide 10, and is disposed opposite each other on the inner wall surface of the waveguide 10 rotated 90 degrees around the tube axis of the waveguide 10 with respect to the pair of first ridges 201, 301.

[0144] The pair of second ridges 40, 50 have a symmetrical structure with respect to a second plane (Y-Z plane) that passes through the tube axis, which is the central axis of the waveguide 10. The length of each of the pair of second ridges 40, 50 in the direction along a line connecting the central axes of the pair of second ridges 40, 50 is uniform over its entire length, and the length of each of the pair of second ridges 40, 50 in the direction perpendicular to the line connecting the central axes of the pair of second ridges 40, 50 is uniform over its entire length. Hereinafter, for the second ridges 40, 50, the length in the X-axis direction will be referred to as the height, the length in the Y-axis direction will be referred to as the width, and the length in the Z-axis direction will be referred to as the vertical width.

[0145] That is, in each of the second ridges 40, 50, the width is the same over the entire length in the Z-axis direction, and the height is the same over the entire length in the Z-axis direction, as in the fifth embodiment shown in Figure 35. The boundary surface between each of the second ridges 40, 50 and the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the Y-Z plane. The opposing surface of each of the second ridges 40, 50 that faces the boundary surface is rectangular and is a flat surface parallel to the Y-Z plane. The second ridges 40 and 50 have the same size and shape.

[0146] From the viewpoint of design parameters, it is preferable that the width of each of the second ridges 40, 50 is the same as the width of the first input / output end portions 211, 311 and the width of the second input / output end portions 221, 321, but they may be different widths. Also, from the viewpoint of design parameters, it is preferable that the height of each of the second ridges 40, 50 is the same as the height of the first input / output end portions 211, 311 and the height of the second input / output end portions 221, 321, but they may be different heights. Making the widths and heights different increases the design parameters or provides better axial ratio characteristics and reflection characteristics.

[0147] The circular polarizer according to embodiment 6 may be manufactured using a metal 3D printer with additive manufacturing technology, a resin 3D printer with additive manufacturing technology and metal plating, mold forming processing, or resin injection molding and metal plating, as in the case of the circular polarizer according to embodiment 2.

[0148] The circular polarizer according to the sixth embodiment has the same effects as the circular polarizer according to the second embodiment, and in addition, it has improved symmetry in a cross section parallel to the XY plane (first plane) of the waveguide 13, and it is easier to achieve a desired phase difference between two orthogonal linearly polarized signals, resulting in better axial ratio characteristics.

[0149] The pair of second ridges 40, 50 in the circular polarizer according to embodiment 6 may have the following shape, similar to the pair of ridges 201, 301 in the circular polarizer according to embodiment 2. That is, the pair of second ridges 40, 50 have one end, the other end, and an intermediate portion between the one end and the other end.

[0150] The intermediate portions of each of the pair of second ridges 40, 50 are arranged periodically in the axial direction of the waveguide 10, similar to the intermediate portions of each of the pair of ridges 201, 301 in the circular polarizer according to embodiment 2, and each has a plurality of protrusions that protrude in the X-Y plane (first plane) in a direction along a line connecting the central axes of the pair of first ridges 201, 301, and connecting portions that connect adjacent protrusions among the plurality of protrusions.

[0151] Furthermore, the pair of second ridges 40, 50 in the circular polarizer according to embodiment 6 may have the following shape, similar to the description of the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4. That is, the pair of second ridges 40, 50 have one end, the other end, and an intermediate portion between the one end and the other end.

[0152] One end of each of the pair of second ridges 40, 50 is tapered in length toward the first input / output terminal 11 in the X-Z plane (third plane) including the central axis of the pair of second ridges 40, 50, similar to the first input / output terminals 21A, 31A of each of the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4. The other end of each of the pair of second ridges 40, 50 is tapered in length toward the second input / output terminal 12 in the X-Z plane including the central axis of the pair of second ridges 40, 50, similar to the second input / output terminals 22A, 32A of each of the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4.

[0153] Furthermore, the pair of first ridges 201, 301 in the circular polarizer according to embodiment 6 may each have the following shapes, similar to the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4.

[0154] That is, the first input / output terminals 211 and 311 of the first ridges 201 and 301, respectively, are provided with projections 231a having intermediate heights 231 and 331, respectively, which are similar in shape to the first input / output terminals 21A and 31A of the ridges 20A and 30A shown in the circular waveguide polarizer according to the fourth embodiment. １ , 331a １ The second input / output terminals 221 and 321 of the first ridges 201 and 301, respectively, are formed to have the same shape as the second input / output terminals 22A and 32A of the ridges 20A and 30A shown in the circular waveguide polarizer according to the fourth embodiment, that is, the projections 231a at the intermediate portions 231 and 331 are formed to have the same height as the second input / output terminals 22A and 32A of the ridges 20A and 30A shown in the circular waveguide polarizer according to the fourth embodiment. Ｎ , 331a Ｎ The shape of the terminal gradually becomes shorter from the first terminal 11 to the second input / output terminal 12.

[0155] Seventh Embodiment A circular polarizer according to a seventh embodiment will be described using Figures 39 to 41. The circular polarizer according to the seventh embodiment differs from the circular polarizer according to the third embodiment in that it is provided with a pair of second ridges 40, 50, but is otherwise the same. In Figures 39 to 41, the same reference numerals as those in Figures 1 to 5 and Figures 22 to 26 indicate the same or corresponding parts.

[0156] Therefore, the following description will focus on the difference, the pair of second ridges 40, 50. The circular polarizer according to embodiment 7 comprises a circular waveguide 10, a pair of first ridges 202, 302, and a pair of second ridges 40, 50, and the waveguide 10, the pair of first ridges 202, 302, and the pair of second ridges 40, 50 are integrally configured. Each of the pair of second ridges 40, 50 has a central axis parallel to the tube axis of the waveguide 10, and is disposed opposite each other on the inner wall surface of the waveguide 10 rotated 90 degrees around the tube axis of the waveguide 10 with respect to the pair of first ridges 202, 302.

[0157] The pair of second ridges 40, 50 have a symmetrical structure with respect to a second plane (Y-Z plane) that passes through the tube axis, which is the central axis of the waveguide 10. The length of each of the pair of second ridges 40, 50 in the direction along a line connecting the central axes of the pair of second ridges 40, 50 is uniform over its entire length, and the length of each of the pair of second ridges 40, 50 in the direction perpendicular to the line connecting the central axes of the pair of second ridges 40, 50 is uniform over its entire length. Hereinafter, for the second ridges 40, 50, the length in the X-axis direction will be referred to as the height, the length in the Y-axis direction will be referred to as the width, and the length in the Z-axis direction will be referred to as the vertical width.

[0158] That is, in each of the second ridges 40, 50, the width is the same over the entire length in the Z-axis direction, and the height is the same over the entire length in the Z-axis direction, as in the fifth embodiment shown in Figure 35. The boundary surface between each of the second ridges 40, 50 and the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the Y-Z plane. The opposing surface of each of the second ridges 40, 50 that faces the boundary surface is rectangular and is a flat surface parallel to the Y-Z plane. The second ridges 40 and 50 have the same size and shape.

[0159] From a design parameter perspective, it is preferable that the lateral width of each of the second ridges 40, 50 be the same as the lateral width of the first input / output end portions 212, 312 and the lateral width of the second input / output end portions 222, 322, but they may be different widths. Also, from a design parameter perspective, it is preferable that the height of each of the second ridges 40, 50 be the same as the height of the first input / output end portions 212, 312 and the height of the second input / output end portions 222, 322, but they may be different heights. Making the lateral widths and heights different increases the design parameters or provides better axial ratio characteristics and reflection characteristics.

[0160] The circular polarizer according to embodiment 7 may be manufactured using a metal 3D printer with additive manufacturing technology, a resin 3D printer with additive manufacturing technology and metal plating, mold forming processing, or resin injection molding and metal plating, as in the case of the circular polarizer according to embodiment 3.

[0161] The circular polarizer according to embodiment 7 has the same effects as the circular polarizer according to embodiment 3, and in addition, it improves the symmetry of the cross section parallel to the XY plane (first plane) of waveguide 13, and makes it easier to achieve a desired phase difference between two orthogonal linearly polarized signals, resulting in better axial ratio characteristics.

[0162] The pair of second ridges 40, 50 in the circular polarizer according to embodiment 7 may have the following shape, similar to the pair of ridges 202, 302 in the circular polarizer according to embodiment 3. That is, the pair of second ridges 40, 50 have one end, the other end, and an intermediate portion between the one end and the other end.

[0163] The intermediate portions of each of the pair of second ridges 40, 50 are arranged periodically in the axial direction of the waveguide 10, similar to the intermediate portions of each of the pair of ridges 202, 302 in the circular polarizer according to embodiment 3, and each has a plurality of protrusions that protrude in the X-Y plane (first plane) in a direction along a line connecting the central axes of the pair of first ridges 202, 302, and connecting portions that connect adjacent protrusions among the plurality of protrusions.

[0164] Furthermore, the pair of second ridges 40, 50 in the circular polarizer according to embodiment 7 may have the following shape, similar to the description of the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4. That is, the pair of second ridges 40, 50 have one end, the other end, and an intermediate portion between the one end and the other end.

[0165] One end of each of the pair of second ridges 40, 50 is tapered in length toward the first input / output terminal 11 in the X-Z plane (third plane) including the central axis of the pair of second ridges 40, 50, similar to the first input / output terminals 21A, 31A of each of the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4. The other end of each of the pair of second ridges 40, 50 is tapered in length toward the second input / output terminal 12 in the X-Z plane including the central axis of the pair of second ridges 40, 50, similar to the second input / output terminals 22A, 32A of each of the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4.

[0166] Furthermore, the pair of first ridges 202, 302 in the circular polarizer according to embodiment 7 may each have the following shapes, similar to the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4.

[0167] That is, the first input / output terminals 212 and 312 of the first ridges 202 and 302, respectively, are provided with projections 231a having intermediate portions 231 and 331 in height, respectively, which are similar in shape to the first input / output terminals 21A and 31A of the ridges 20A and 30A shown in the circular waveguide polarizer according to the fourth embodiment. １ , 331a １ The second input / output terminals 222 and 322 of the first ridges 202 and 302, respectively, are shaped similarly to the second input / output terminals 22A and 32A of the ridges 20A and 30A shown in the circular waveguide polarizer according to the fourth embodiment, that is, the height of the projections 231a at the intermediate portions 231 and 331 is gradually reduced. Ｎ , 331aＮ The shape of the terminal gradually becomes shorter from the first terminal 11 to the second input / output terminal 12.

[0168] Eighth Embodiment A circular polarizer according to eighth embodiment will be described using Figures 42 to 46. The circular polarizer according to eighth embodiment differs from the circular polarizer according to embodiment 4 in that it is provided with a pair of second ridges 40A, 50A, but is otherwise the same. In Figures 42 to 46, the same reference numerals as those in Figures 1 to 5 and Figures 27 to 31 indicate the same or corresponding parts.

[0169] Therefore, the following description will focus on the difference, that is, the pair of second ridges 40A, 50A. The circular polarizer according to embodiment 8 comprises a circular waveguide 10, a pair of first ridges 20A, 30A, and a pair of second ridges 40A, 50A, and the waveguide 10, the pair of first ridges 20A, 30A, and the pair of second ridges 40A, 50A are integrally configured. Each of the pair of second ridges 40A, 50A has a central axis parallel to the tube axis of the waveguide 10, and is disposed opposite each other on the inner wall surface of the waveguide 10 rotated 90 degrees around the tube axis of the waveguide 10 with respect to the pair of first ridges 20A, 30A.

[0170] The pair of second ridges 40A, 50A have a symmetrical structure with respect to a second plane (Y-Z plane) that passes through the tube axis, which is the central axis of the waveguide 10. Each of the pair of second ridges 40A, 50A has one end 41A, 51A, the other end 42A, 52A, and an intermediate portion 43A, 53A between the one end 41A, 51A and the other end 42A, 52A. In each of the pair of second ridges 40A, 50A, the one end 41A, 51A serves as a first input / output end, and the other end 42A, 52A serves as a twenty-first input / output end. Hereinafter, in the second ridges 40A, 50A, the length in the X-axis direction will be referred to as the height, the length in the Y-axis direction will be referred to as the width, and the length in the Z-axis direction will be referred to as the vertical width.

[0171] 45 and 46, each of the second ridges 40A, 50A has the following shape: That is, one end portion 41A, 51A of each of the second ridges 40A, 50A is tapered in a third plane (X-Z plane) including the central axes of the pair of second ridges 40A, 50A, with the length, i.e., height, decreasing from one end of the intermediate portion 43A, 53A toward the first input / output terminal 11, and the length, i.e., width, in the direction along the line connecting the central axes of the pair of second ridges 40A, 50A is uniform.

[0172] The other end portions 42A, 52A of the second ridges 40A, 50A, respectively, are tapered so that the height decreases from the other end of the intermediate portions 43A, 53A toward the second input / output terminals 12, and the width is uniform. The intermediate portions 43A, 53A of the second ridges 40A, 50A, respectively, have the same width over the entire length in the Z-axis direction, and the same height over the entire length in the Z-axis direction.

[0173] The boundary surface of each of the second ridges 40A, 50A with the inner wall surface of the waveguide 10 is an arc surface that follows the inner wall surface of the waveguide 10 with respect to the YZ plane. The opposing surface of each of the second ridges 40A, 50A that faces the boundary surface is rectangular and is a continuous plane from one end 41A, 51A to intermediate portions 43A, 53A and the other end 42A, 52A.

[0174] The widths of the one end portions 41A, 51A, the intermediate portions 43A, 53A, and the other end portions 42A, 52A are the same. The second ridges 40A and 50A have the same size and shape. The heights of the second ridges 40A and 50A change gradually when viewed from the first input / output terminal 11 and the second input / output terminal 12, thereby achieving better reflection characteristics.

[0175] From a design parameter perspective, it is preferable that the width of each of the second ridges 40A and 50A be the same as the width of the first input / output end portions 21A and 31A and the width of the second input / output end portions 22A and 32A of the first ridges 20A and 30A, respectively, but these widths may be different. Furthermore, from a design parameter perspective, it is preferable that the height of the intermediate portions 43A and 53A of each of the second ridges 40A and 50A be the same as the height of the first input / output end portions 21A and 31A and the height of the second input / output end portions 22A and 32A of the first ridges 20A and 30A, respectively, but these heights may be different. Making the widths and heights different increases the design parameters or provides better axial ratio characteristics and reflection characteristics.

[0176] The circular polarizer according to embodiment 8 is manufactured by mold molding, similar to the manufacturing of the circular polarizer according to embodiment 4. Note that the circular polarizer according to embodiment 8 may be manufactured by a metal 3D printer with additive manufacturing technology, a resin 3D printer with additive manufacturing technology and metal plating, or resin injection molding and metal plating, as described for the circular polarizer according to embodiment 4.

[0177] The circular polarizer according to embodiment 8 has the same effects as the circular polarizer according to embodiment 4. In addition, by tapering one end 41A, 51A and the other end 42A, 52A of each of second ridges 40A, 50A, the height changes gradually when viewed from each of first input / output terminal 11 and second input / output terminal 12. This improves the symmetry of waveguide 13 in a cross section parallel to the X-Y plane (first plane), makes it easier to achieve a desired phase difference between two orthogonal linearly polarized signals, and results in better axial ratio characteristics.

[0178] Note that the intermediate portions 43A, 53A of the pair of second ridges 40A, 50A in the circular polarizer according to embodiment 8 may have the following shapes, similar to the configurations described for the intermediate portions 23, 33 of the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4.

[0179] That is, the intermediate portions 43A, 53A in each of the pair of second ridges 40A, 50A are arranged periodically in the tube axis direction of the waveguide 10, similar to the intermediate portions 23, 33 in each of the pair of ridges 20A, 30A in the circular polarizer according to embodiment 4, and each has a plurality of protrusions that protrude in the X-Y plane (first plane) in a direction along a line connecting the central axes of the pair of first ridges 20A, 30A, and connecting portions that connect adjacent protrusions among the plurality of protrusions.

[0180] Furthermore, in the circular wave polarizer according to the eighth embodiment, the plurality of protrusions 23a in the intermediate portions 23 and 33 of the pair of first ridges 20A and 30A are １ ~23a Ｎ , 33a １ ~33a Ｎ The plurality of protrusions 231a at the intermediate portions 231 and 331 of the pair of ridges 201 and 301 in the circular wave polarizer according to the second embodiment are １ ~231a Ｎ , 331a １ ~331a Ｎ Similarly, the cross section parallel to the third plane (XZ plane) may be trapezoidal.

[0181] Furthermore, in the circular waveguide polarizer according to the eighth embodiment, the plurality of protrusions 23a in the intermediate portions 23 and 33 of the pair of first ridges 20A and 30A are １ ~23a Ｎ , 33a １ ~33a Ｎ The plurality of protrusions 232a at the intermediate portions 232, 332 of the pair of ridges 202, 302 in the circular waveguide polarizer according to the third embodiment are １ ~232a Ｎ , 332a １ ~332a Ｎ Similarly, the cross section parallel to the XZ plane may be hexagonal.

[0182] It should be noted that the embodiments may be freely combined, or any of the components in each embodiment may be modified, or any of the components in each embodiment may be omitted.

[0183] The circular polarizer according to the present disclosure is primarily applicable to circular polarizers used in the VHF band, UHF band, microwave band, and millimeter wave band, and is suitable for use as a circular polarizer connected to a horn antenna having a circular waveguide terminal.

[0184] 10 Waveguide, 11 First input / output terminal, 12 Second input / output terminal, 13 Hollow portion, 20, 201 to 203, 30, 301 to 303, 20A, 30A Ridge, 21, 211 to 213, 31, 311 to 313, 21A, 31A First input / output end portion, 22, 221 to 223, 32, 321 to 323, 22A, 32A Second input / output end portion, 23, 231 to 233, 33, 331 to 333 Intermediate portion, 23a １ ~23a Ｎ , 231a １ ~231a Ｎ ~233a １ ~233a Ｎ , 33a １ ~33a Ｎ , 331a １ ~331a Ｎ ~333a １ ~333a Ｎ Projection, 23b １ ~23b Ｎ－１ , 231b １ ~231b Ｎ－１ ~233b １ ~233b Ｎ－１ , 33b １ ~33b Ｎ－１ , 331b １ ~331b Ｎ－１ ~33b １ ~333b Ｎ－１ Connection, 40, 50, 40A, 50A Second ridge.

Claims

1. A circular polarizer comprising: a hollow waveguide having a hollow portion with a circular cross section, one end of which is a first input / output terminal and the other end of which is a second input / output terminal; and a pair of ridges, each of which has a central axis parallel to the tube axis of the waveguide and is arranged opposite each other on the inner wall surface of the waveguide, each of the pair of ridges having a first input / output end at one end and a second input / output end at the other end, and an intermediate portion between the first input / output end and the second input / output end, the intermediate portions being periodically arranged in the tube axis direction of the waveguide, and each of the intermediate portions having a plurality of protrusions protruding in a direction along a line perpendicular to a line connecting the central axes of the pair of ridges in a first plane perpendicular to the tube axis of the waveguide, and a connecting portion connecting adjacent protrusions among the plurality of protrusions.

2. A circular polarizer according to claim 1, wherein each of said plurality of protrusions has a rectangular cross section parallel to a third plane perpendicular to the second plane containing the central axes of said pair of ridges.

3. A circular polarizer according to claim 1, wherein each of said plurality of protrusions has a trapezoidal cross section parallel to a third plane perpendicular to the second plane containing the central axes of said pair of ridges.

4. A circular polarizer according to claim 1, wherein each of said plurality of protrusions has a hexagonal cross section parallel to a third plane perpendicular to the second plane containing the central axes of said pair of ridges.

5. A circular polarizer according to any one of claims 1 to 4, wherein the length of the plurality of protrusions is short in a direction along a line perpendicular to a line connecting the central axes of the pair of ridges from a central protrusion on the central axis of the ridge toward each of the first input / output end and the second input / output end.

6. A circular polarizer according to any one of claims 1 to 4, wherein the lengths of the plurality of protrusions in a direction perpendicular to a line connecting the central axes of the pair of ridges decrease in a trigonometric function fashion from a central protrusion on the central axis of the ridge as an apex toward the first input / output end and the second input / output end.

7. A circular polarizer according to any one of claims 1 to 4, wherein the length of the plurality of protrusions in the direction along the central axis of the ridge is short from the central protrusion on the central axis of the ridge toward the first input / output end and the second input / output end.

8. A circular polarizer according to any one of claims 1 to 4, wherein the first input / output end of each of the pair of ridges is shorter in length toward the first input / output terminal in a second plane including the central axes of the pair of ridges, and the second input / output end of each of the pair of ridges is shorter in length toward the second input / output terminal in a second plane including the central axes of the pair of ridges.

9. A circular polarizer as claimed in any one of claims 1 to 4, further comprising a pair of second ridges, each having a central axis parallel to the axis of the waveguide, and arranged opposite each other on the inner wall surface of the waveguide rotated 90 degrees around the axis of the waveguide relative to the pair of ridges.

10. A circular polarizer according to claim 9, wherein the length of each of the pair of second ridges in a direction along a line connecting the central axes of the pair of second ridges is uniform over its entire length, and the length of each of the pair of second ridges in a direction perpendicular to the line connecting the central axes of the pair of second ridges is uniform over its entire length.

11. A circular polarizer according to claim 9, wherein each of the pair of second ridges has one end, the other end, and an intermediate portion between the one end and the other end, the intermediate portions of each of the pair of second ridges being periodically arranged in the axial direction of the waveguide, and each having a plurality of protrusions protruding in the first plane in a direction along a line connecting the central axes of the pair of ridges, and a connecting portion connecting adjacent protrusions among the plurality of protrusions.

12. The circular polarizer according to claim 9, wherein each of the pair of second ridges has one end, the other end, and an intermediate portion between the one end and the other end, wherein the intermediate portion has a uniform length along a line connecting the central axes of the pair of second ridges over its entire length and a uniform length along a line perpendicular to the line connecting the central axes of the pair of second ridges, wherein the one end has a length along the line perpendicular to the line connecting the central axes of the pair of second ridges that is shorter toward the first input / output terminal and a uniform length along the line connecting the central axes of the pair of second ridges, and wherein the other end has a length along the line perpendicular to the line connecting the central axes of the pair of second ridges that is shorter toward the second input / output terminal and a uniform length along the line connecting the central axes of the pair of second ridges.

13. A method for manufacturing a circular polarizer according to any one of claims 1 to 4, wherein the circular polarizer is integrally formed from the second input / output terminal to the first input / output terminal using a 3D printer.

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