Antenna, omni antenna, and method for designing omni antenna

Abstract

To provide an omni-directional antenna with a simple configuration.SOLUTION: An antenna includes a main body. The main body includes: a reception unit; a first conversion unit; a second conversion unit; and a radiation unit. The reception unit receives an electromagnetic wave of a TE10. The first conversion unit is connected to the reception unit and converts a TE10 mode into a TE20 mode in a waveguide. The second conversion unit is connected to the first conversion unit and converts the TE20 mode into a TE01 mode in the waveguide. The radiation unit is connected to the second conversion unit. The reception unit, the first conversion unit, the second conversion unit, and the radiation unit are disposed along a predetermined radiation axis.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an antenna, an omnidirectional antenna having omnidirectionality, and a design method for an omnidirectional antenna. In particular, it relates to an antenna, an omnidirectional antenna, and a design method for an omnidirectional antenna used in the millimeter wave band, sub-terahertz band, and further in the terahertz band.

Background Art

[0002] In consideration of the utilization of the millimeter wave band and sub-terahertz band for 5G and 6G, the terahertz band has also attracted attention. At frequencies above the millimeter wave band, the loss of coaxial lines is large, and as one of the countermeasures, antenna technology using waveguide lines has become important. Currently, radio wave propagation experiments are actively carried out, and the demand for omnidirectional antennas is high and it is an important technology. Waveguide antennas include aperture antennas such as horn antennas and waveguide slot antennas, but all of them are single-directional antennas. As an omnidirectional antenna, an antenna that obtains omnidirectionality of vertically polarized waves, so-called V polarized waves, by reflecting the radio waves excited by the TM01 mode of the higher-order mode from a horn antenna with a conical reflector has been studied (Non-Patent Document 1), and it can be used as a vertically polarized omnidirectional antenna using a waveguide in the sub-terahertz band. In addition, as various mode converters, Non-Patent Document 2 shows the configuration of a mode converter that converts the fundamental TE10 mode to the higher-order TE20 mode. Non-Patent Document 3 describes the aspect ratios of rectangular waveguides when mode conversion is performed from the TE20 mode to a circular rectangular conversion, when it is converted to TE21, and when it is converted to TE01. In addition, Patent Document 1 (paragraph 0015, FIGS. 2 and 19) describes forming the TE01 mode via a sector from the TE20 mode in a microwave plasma processing apparatus.

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 5-74592 [Non-Patent Document]

[0004] [Non-Patent Document 1] "300 GHz Band Reflectorless Omnidirectional Antenna Using a TM01 Mode Converter with Cavity" by Keisuke Sato, Takayoshi Sasaki, Shunta Ichikawa, Ichiro Oshima, Transactions of the Institute of Electronics, Information and Communication Engineers, Part B, Vol J105-B, No. 4, pp. 405-413, issued on April 1, 2022 [Non-Patent Document 2] Antenna Engineering Handbook, 1st Edition, p. 263 [Non-Patent Document 3] Yan Wang, et al, “Wideband Circular TE21 and TE01 Mode Converters With Same Exciting Topologies,” IEEE Transactions on Electron Devices, Volume:63, Issue:10, p. 4088-4095. October 2016. [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] In Non-Patent Document 1, V polarization, that is, vertical polarization is used, but an H polarization, that is, a horizontal polarization omnidirectional antenna in the sub-terahertz band is not disclosed. Also, the omnidirectional antenna of Non-Patent Document 1 has a fractional bandwidth of about 5%. The technology described in Patent Document 1 is a plasma processing apparatus using microwaves, which is different from an omnidirectional antenna used for communication. Also, although it converts from the TE20 mode to the TE01 mode, it is a conversion via a sector, which increases the parameters for design and as a result, the design becomes complicated. Therefore, an object of the present invention is to provide an omnidirectional antenna for horizontally polarized waves in a waveguide system antenna. Another object of the present invention is to provide an omnidirectional antenna for H polarization as an antenna for millimeter wave band and sub-terahertz band in a waveguide system antenna. Furthermore, the present invention has broadband characteristics and good omnidirectional characteristics (low deviation characteristics) in a waveguide system antenna. Other objects of the present invention will be described in the embodiments for carrying out the invention.

Means for Solving the Problems

[0006] The antenna according to claim 1 of the present invention includes a main body portion. The main body portion A receiving portion that receives TE10 electromagnetic waves, A first conversion portion that is connected to the receiving portion and converts the TE10 mode into the TE20 mode in the waveguide, A second conversion portion that is connected to the first conversion portion and converts the TE20 mode into the TE01 mode in the waveguide, and A radiation portion connected to the second conversion portion, and is an antenna in which the receiving portion, the first conversion portion, the second conversion portion, and the radiation portion are arranged along a predetermined radiation axis. The antenna according to claim 1, wherein the second conversion portion The antenna according to claim 2 of the present invention The second conversion portion A TE20 taper conversion portion that converts the aspect ratio of the TE20 rectangle, and The antenna according to claim 1, which has a TE20-TE01 conversion portion connected to the TE20 taper conversion portion and in which the cross section of the waveguide changes from a TE20 rectangle to a TE01 circle. The antenna according to claim 3 of the present invention The TE20 taper conversion portion has a structure that converts the aspect ratio of the TE20 rectangle at a predetermined TE20 taper conversion angle with respect to the radiation axis. The TE20TE01 conversion section has a structure in which the cross-section of the waveguide changes from a TE20 rectangle to a TE01 circle at a predetermined TE20TE01 conversion angle with respect to the radiation axis. The antenna according to claim 2, wherein the length of the second conversion section is a predetermined second conversion length. The antenna according to claim 4 of the present invention is The first conversion section is a rectangular T-shaped conversion section in which the cross-section of the waveguide changes from a TE10 rectangle to a T shape, and The antenna according to claim 2, further comprising a T-shaped rectangular conversion section connected to the rectangular T-shaped conversion section and configured to change the cross-section of the waveguide from a T shape to a TE20 rectangle. The antenna according to claim 5 of the present invention is the antenna according to claim 2, wherein the frequency of the electromagnetic wave radiated from the antenna is 110 GHz or higher. The antenna according to claim 6 of the present invention is the antenna according to claim 2, wherein the radiation section has a configuration in which the opening widens in the direction in which the electromagnetic wave is radiated. The antenna according to claim 7 of the present invention is the antenna according to claim 6, wherein the main body portion has a substantially conical shape that tapers toward the tip where the electromagnetic wave is radiated. The omnidirectional antenna according to claim 8 of the present invention is an omnidirectional antenna, comprising the antenna according to claim 1 and a reflector section, The omnidirectional antenna according to any one of claims 1 to 7, wherein the reflector section reflects the electromagnetic wave from the radiation section and radiates it 360 degrees. The omnidirectional antenna according to claim 9 of the present invention is the omnidirectional antenna according to claim 8, wherein the reflector section has a conical shape obtained by rotating a straight line in the xy plane about the y axis from the reflector tip closest to the antenna, with the radiation axis as the y axis and the direction perpendicular to the radiation axis as the x axis. The antenna according to claim 10 of the present invention is the omnidirectional antenna according to claim 8, wherein the reflecting mirror portion has a shape obtained by rotating the curve y = p*sqrt(x + q) in the xy plane about the y-axis, with the radiation axis being the y-axis and the direction perpendicular to the radiation axis being the x-axis, and both p and q being greater than 0, starting from the reflecting mirror tip closest to the antenna. The omnidirectional antenna according to claim 11 of the present invention includes the antenna according to claim 3 or more, and a reflecting mirror portion. The three or more antennas are omnidirectional antennas that emit electromagnetic waves in different frequency bands, with at least one of the TE20 taper conversion angle, the TE20TE01 conversion angle, and the second conversion length being different from each other. The design method of the omnidirectional antenna according to claim 12 of the present invention is as follows. It is a design method of an omnidirectional antenna including the antenna according to claim 3 and a reflecting mirror portion, where the reflecting mirror reflects the electromagnetic wave from the radiation portion and emits it omnidirectionally. A setting step of setting a predetermined antenna performance value. A TE20 taper design step of determining the TE20 taper conversion angle with respect to the radiation axis by converting the aspect ratio of the TE20 rectangle in the TE20 taper conversion section. A TE20TE01 design step of determining the TE20TE01 conversion angle with respect to the radiation axis by changing the cross-section of the waveguide from a TE20 rectangle to a TE01 circle in the TE20TE01 conversion section, and A conversion length design step of determining the second conversion length, which is the length of the second conversion section. The design method of the omnidirectional antenna includes these steps. Other effects of the present invention are also described in the embodiments for carrying out the invention.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0008] Figures 1 and 2 show a configuration example of the antenna 1 in one embodiment of the present invention. The antenna 1 includes a main body 100.

[0009] The main body 100 includes a receiving unit 110, a first conversion unit 120, a second conversion unit 130, and a radiating unit 140. The receiving unit 110 receives the electromagnetic wave of TE10. The first conversion unit 120 is connected to the receiving unit 110 and converts the TE10 mode into the TE20 mode in the waveguide. The second conversion unit 130 is connected to the first conversion unit 120 and converts the TE20 mode into the TE01 mode in the waveguide.

[0010] The radiating unit 140 is connected to the second conversion unit 130. The first conversion unit 120, the second conversion unit 130, and the radiating unit 140 are arranged along a predetermined radiation axis RA. In this embodiment, due to the structure of the first conversion unit 120, the center of the receiving unit 110 is arranged slightly deviated from the radiation axis RA. Note that the solid line of the radiation axis RA in FIG. 1 does not indicate that there is actually a linear structure, but is a diagram for easy understanding. With this configuration, an antenna 1 for the omnidirectional antenna 2 that operates in a wide band with a small deviation in horizontal polarization can be obtained.

[0011] FIGS. 3 to 11 show cross-sections of the inside of the waveguide at the receiving unit 110, the first conversion unit 120, and the second conversion unit 130 in this embodiment. The first conversion unit 120 has a rectangular T-shaped conversion unit 121 and a T-shaped rectangular conversion unit 122 connected to the rectangular T-shaped conversion unit 121. In the rectangular T-shaped conversion unit 121, the cross-section of the waveguide changes from a TE10 rectangle to a T shape. Also, the T-shaped rectangular conversion unit 122 has a T-shaped rectangular conversion unit 122 in which the cross-section of the waveguide changes from a T shape to a TE20 rectangle.

[0012] The second conversion unit 130 has a TE20 taper conversion unit 131 and a TE20TE01 conversion unit 132 connected to the TE10TE20 conversion unit 131. In the TE20 taper conversion unit 131, the aspect ratio of the TE20 rectangle is converted. In the TE20-TE01 conversion unit 132 connected to the TE20 taper conversion unit 131, the cross-section of the waveguide changes from a TE20 rectangle to a TE01 circle.

[0013] FIG. 12 shows a configuration example of the antenna 1 in one embodiment of the present invention. The second conversion unit 130 includes a TE20 taper conversion unit 131 and a TE20-TE01 conversion unit 132 connected to the TE10-TE20 conversion unit 131.

[0014] The TE20 taper conversion unit 131 is configured to convert the aspect ratio of the TE20 rectangle. In the TE20-TE01 conversion unit 132 connected to the TE10-TE20 conversion unit 131, the cross-section of the waveguide changes from a TE20 rectangle to a TE01 circle.

[0015] FIG. 13 shows a configuration example of the antenna 1 in one embodiment of the present invention. The TE20 taper conversion unit 131 has a structure that converts the aspect ratio of the TE20 rectangle at a predetermined TE20 taper conversion angle Θ1 with respect to the radiation axis RA. The TE20-TE01 conversion unit 132 has a structure in which the cross-section of the waveguide changes from a TE20 rectangle to a TE01 circle at a predetermined TE20-TE01 conversion angle Θ2 with respect to the radiation axis RA.

[0016] Here, the TE20 taper conversion angle Θ1 and the TE20-TE01 conversion angle Θ2 indicate the rate of change of the cross-section along the radiation axis RA. In this embodiment, they are parameters obtained by dividing 100% by the length of the TE20 taper conversion unit 131 and the length of the TE20-TE01 conversion unit 132 along the radiation axis RA, respectively. The length of the second conversion unit 130 is a predetermined second conversion length L.

[0017] With this configuration, there are three design parameters for antenna 1, making the design easier. When the omnidirectional antenna 2 is used, by appropriately designing the angle and length of the conversion section, an omnidirectional pattern with small deviation operating in a wide band can be obtained. The ratio bandwidth of the antenna 1 described in Non-Patent Document 1 is about 5%, while in the present invention, the ratio bandwidth is extended to about 15%.

[0018] FIG. 14 shows a configuration example of antenna 1 in an embodiment of the present invention. The first conversion section 120 has a rectangular T-shaped conversion section 121 and a T-shaped rectangular conversion section 122 connected to the rectangular T-shaped conversion section 121.

[0019] In the rectangular T-shaped conversion section 121, the cross-section of the waveguide changes from a TE10 rectangle to a T shape. Also, the T-shaped rectangular conversion section 122 has a T-shaped rectangular conversion section 122 in which the cross-section of the waveguide changes from a T shape to a TE20 rectangle. With this configuration, the TE10 mode can be converted to the TE20 mode with a simple configuration.

[0020] In one embodiment, the frequency of the electromagnetic wave radiated from antenna 1 is 110 GHz or higher. With this configuration, it is possible to support from the millimeter wave band to the sub-terahertz band and the terahertz band.

[0021] In one embodiment, as shown in FIG. 2, the radiation section 140 has a configuration in which the opening widens in the direction in which the electromagnetic wave is radiated. Also, it can be configured to have a tip portion that becomes thinner toward the tip where the electromagnetic wave is radiated. With this configuration, the directivity of the electromagnetic wave can be adjusted.

[0022] FIG. 15 shows a configuration example of antenna 1 in an embodiment of the present invention. The main body portion 100 has a substantially conical shape that becomes thinner toward the tip where the electromagnetic wave is radiated. Antenna 1 can also be configured to be connected to a flange. With this configuration, efficient manufacturing is possible, and the strength of the main body portion 100 is also improved.

[0023] FIG. 16 shows a configuration example of the omnidirectional antenna 2 in an embodiment of the present invention. The omnidirectional antenna 2 includes the above-described antenna 1 and a reflector unit 200. The reflector unit 200 reflects the electromagnetic wave from the radiating unit 140 and radiates it 360 degrees. For example, with the radiation axis RA in the vertical direction and by providing the reflector unit 200 in the radiation direction, the omnidirectional antenna 2 that radiates electromagnetic waves 360° around the antenna 1 can be obtained.

[0024] With this configuration, the propagation mode of the waveguide is excited to be the TE01 mode, which is a higher-order mode, the radio wave is radiated by the horn antenna 1, and is reflected by the conical reflector, so that an omnidirectional characteristic of horizontally polarized waves can be obtained. In addition, by appropriately designing the dimensions of the conversion structure, that is, the angle and length, an omnidirectional characteristic with small deviation operating in a wide band can be obtained. In one embodiment, as shown in FIG. 16, with the radiation axis RA as the y-axis and the direction perpendicular to the radiation axis RA as the x-axis, the straight line in the xy plane from the reflector tip closest to the antenna 1 is rotated about the y-axis to form a conical shape.

[0025] FIG. 17 shows a configuration example of the omnidirectional antenna 2 in an embodiment of the present invention. The reflector unit 200 has the radiation axis RA as the y-axis and the direction perpendicular to the radiation axis RA as the x-axis. Assuming that both p and q are greater than 0, from the reflector tip closest to the antenna 1, the curve y = p * sqrt(x + q) in the xy plane is rotated about the y-axis. Here, sqrt represents the square root. In other words, it is a shape obtained by rotating one of the curves obtained by cutting a predetermined range from the vertex of a parabolic shape about the y-axis. The gain can be increased by making the reflector a parabola instead of the above-described cone. Optimize the center of the horn antenna 1 to be the focus of the parabola.

[0026] FIG. 18 shows a configuration example of the omnidirectional antenna 2 in an embodiment of the present invention. In this embodiment, the omnidirectional antenna 1 includes three or more of the above-described antennas 1A, 1B, 1C, and the reflector unit 200. Among the three or more antennas 1, at least one of the TE20 taper conversion angle Θ1, the TE20TE01 conversion angle Θ2, and the second conversion length L is different from each other, and electromagnetic waves in different frequency bands are radiated. Here, the "different frequency bands" includes cases where a part of the bands overlap. With this configuration, it becomes possible to cover a wider band.

[0027] In this configuration, it is also possible to configure the entire band of the waveguide to be covered by three antennas with different parameters, that is, three antennas 1A, 1B, 1C with different bands. For example, in the standard frequency band of an arbitrary waveguide, by changing the parameters of the TE20 taper conversion angle, the TE20TE10 conversion angle, and the second conversion length, the frequency range can be arbitrarily designed in a ratio band of approximately 15%. Also in this configuration, a horizontally polarized omnidirectional antenna can be realized in the waveguide antennas 1A, 1B, 1C. Further, the omnidirectional antenna 2 in this embodiment has broadband characteristics and good omnidirectional characteristics, that is, low deviation characteristics.

[0028] FIG. 19 shows a design method of the omnidirectional antenna 2 in an embodiment of the present invention. The omnidirectional antenna 2 includes any one of the above-described antennas 1 and the above-described reflector unit 200, and the reflector reflects the electromagnetic wave from the radiation unit 140 and radiates it 360 degrees.

[0029] The design method of the omnidirectional antenna 2 has a setting step S10, a TE20 taper design step S20, a TE20TE01 design step S30, and a conversion length design step S40. In the setting step S10, a predetermined antenna performance value is set. The antenna performance value is, for example, the maximum deviation, the radiation intensity, etc., and may be one or a plurality.

[0030] In the TE20 taper design step S20, in the TE20 taper conversion unit 131, the TE10-TE20 conversion angle Θ1 with respect to the radiation axis RA is determined to convert the aspect ratio of the TE20 rectangle. In the TE20-TE01 design step S30, in the TE20-TE01 conversion unit 132, the TE20-TE01 conversion angle Θ2 with respect to the radiation axis RA is determined such that the cross-section of the waveguide changes from a TE20 rectangle to a TE01 circle.

[0031] In the conversion length design step S40, the second conversion length L, which is the length of the second conversion unit 130, is determined. The TE10-TE20 design step S20, the TE20-TE01 design step S30, and the conversion length design step S40 may be performed individually, or the optimization of the three variables of the TE10-TE20 conversion angle Θ1, the TE20-TE01 conversion angle Θ2, and the second conversion length L may be performed simultaneously.

[0032] FIG. 20 and FIG. 21 show the voltage standing wave ratio (VSWR) in one embodiment of the present invention and a conventional comparative example, respectively. In a conventional comparative example to which the configuration of the present invention is not applied, the range in which the VSWR is 2 or less is from about 285 GHz to about 304 GHz, whereas in this embodiment, the VSWR can be 2 or less in a wide range of about 285 GHz or more.

[0033] The present invention is not limited to the above embodiments, and it goes without saying that the present invention includes various embodiments without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0034] 1, 1A, 1B, 1C Antenna 100 Main Body 110 Receiving Unit 120 First Conversion Unit 121 Rectangular T-Conversion Unit 122 T-Rectangular Conversion Unit 130 Second Conversion Unit 131 TE20 Taper Conversion Unit 132 TE20-TE01 Conversion Unit 140 Radiation section 2 Omnidirectional antenna 200 Mirror section RA Radiation axis θ1 TE20 taper conversion angle θ2 TE20-TE01 conversion angle L Second conversion length

Claims

1. An antenna, comprising a main body portion, wherein the main body portion has a receiving portion for receiving electromagnetic waves in the TE10 mode, a first conversion portion connected to the receiving portion for converting the TE10 mode into the TE20 mode in a waveguide, a second conversion portion connected to the first conversion portion for converting the TE20 mode into the TE01 mode in the waveguide, and a radiation portion connected to the second conversion portion, wherein the first conversion portion, the second conversion portion, and the radiation portion are arranged along a predetermined radiation axis. The antenna.

2. The second conversion portion has a TE20 taper conversion portion for converting the aspect ratio of a TE20 rectangle, and a TE20TE01 conversion portion connected to the TE20 taper conversion portion, wherein the cross-section of the waveguide changes from a TE20 rectangle to a TE01 circle. The antenna according to claim 1.

3. The TE20 taper conversion portion has a structure for converting the aspect ratio of a TE20 rectangle at a predetermined TE20 taper conversion angle with respect to the radiation axis, the TE20TE01 conversion portion has a structure for changing the cross-section of the waveguide from a TE20 rectangle to a TE01 circle at a predetermined TE20TE01 conversion angle with respect to the radiation axis, and the length of the second conversion portion is a predetermined second conversion length. The antenna according to claim 2.

4. The first conversion portion has a rectangular T-shaped conversion portion where the cross-section of the waveguide changes from a TE10 rectangle to a T shape, and a T-shaped rectangle conversion portion connected to the rectangular T-shaped conversion portion, where the cross-section of the waveguide changes from a T shape to a TE20 rectangle. The antenna according to claim 2.

5. The frequency of the electromagnetic wave radiated from the antenna is 110 GHz or higher. The antenna according to claim 2.

6. The radiation portion has a configuration in which the opening widens in the direction in which the electromagnetic wave is radiated. The antenna according to claim 2.

7. The main body portion has a substantially conical shape that becomes thinner toward the tip where the electromagnetic wave is radiated. The antenna according to claim 6.

8. An omnidirectional antenna, comprising the antenna according to claim 1 and a reflector portion, wherein the reflector portion reflects the electromagnetic wave from the radiation portion and radiates it 360 degrees. The omnidirectional antenna according to any one of claims 1 to 7.

9. The reflector portion has a conical shape obtained by rotating a straight line in the xy plane from the reflector tip closest to the antenna about the y axis, with the radiation axis as the y axis and the direction perpendicular to the radiation axis as the x axis. The omnidirectional antenna according to claim 8.

10. In the mirror section, with the radiation axis as the y-axis and the direction perpendicular to the radiation axis as the x-axis, and assuming that both p and q are greater than 0, from the mirror tip closest to the antenna, the curve y = p*sqrt(x + q) in the xy plane is rotated about the y-axis. The omnidirectional antenna according to Claim 8, which has a shape obtained by rotation.

11. An omnidirectional antenna comprising three or more antennas according to Claim 3 and the mirror section. In three or more of the antennas, at least one of the TE20 taper conversion angle, the TE20-TE01 conversion angle, and the second conversion length is different from each other, and the antennas radiate electromagnetic waves in different frequency bands. The omnidirectional antenna.

12. A design method for an omnidirectional antenna comprising the antenna according to Claim 3 and the mirror section, wherein the mirror reflects the electromagnetic wave from the radiation section and radiates it 360 degrees, comprising: A setting step of setting a predetermined antenna performance value; A TE20 taper design step of determining the TE20 taper conversion angle with respect to the radiation axis, which converts the aspect ratio of the TE20 rectangle in the TE20 taper conversion section; A TE20-TE01 design step of determining the TE20-TE01 conversion angle with respect to the radiation axis, in which the cross section of the waveguide changes from a TE20 rectangle to a TE01 circle in the TE20-TE01 conversion section, and A conversion length design step of determining the second conversion length, which is the length of the second conversion section. The design method for an omnidirectional antenna includes these steps.

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