Dielectric fan and dielectric antenna

Abstract

[Problem] The purpose of the present invention is to actualize a dielectric fan and a dielectric antenna that make it possible to achieve high gain of a beam in an arbitrary direction within an opening angle and to ensure a communication area without any holes in an antenna that can relatively reduce transmission line loss in an array antenna in the millimeter wave band or higher, increase gain, and handle arbitrary beam scanning. [Solution] This dielectric fan has a dielectric part having a dielectric constant greater than 1. The dielectric part is provided with a fan-shaped part in which a base-end part is substantially the center and a distal-end part is the outer peripheral part. The base part has an attachment part for attachment to an antenna serving as an excitation source.

Description

Dielectric Fan and Dielectric Antenna

[0001] The present invention relates to a dielectric antenna and a dielectric fan, and more particularly to a dielectric antenna and a dielectric fan used in a mobile communication base station antenna system.

[0002] At high frequencies, such as the millimeter wave band allocated for 5G, coverage is secured by scanning high-gain beams using array antennas. Beyond 5G / 6G is considering the use of high frequencies up to 300 GHz, increasing the need for high-gain beam scanning. The millimeter wave band (28 GHz) was allocated for 5G with the aim of achieving high speed and large capacity through wideband transmission. However, a drawback is the large free-space propagation loss due to communication distance. To compensate for this loss, high-gain beam scanning using array antennas is used to establish a link between each terminal and the base station. This tendency becomes more pronounced as the frequency increases. Array antennas in the 28 GHz band typically consist of 64 or more elements in an 8x8 array, or 8 rows and 8 columns, and often have a maximum antenna gain of 22 dBi or greater. The transmission lines of array antennas with 64 or more elements are generally very long, resulting in significant losses, such as losses of 4 dB or more. Therefore, reducing transmission line loss is a challenge. With 6G, which is expected to be used up to 300 GHz, there are concerns about increased transmission line loss. A different gain enhancement technology from array antennas is the dielectric rod antenna, in which a dielectric is extended in the axial direction. The dielectric rod can improve antenna gain without increasing transmission line loss. Patent Document 1 describes a beamforming device and a beamforming method. An amplifier and a phase shifter are arranged in each element to achieve beam scanning. A mixer is connected to each element, and a long transmission line is designed at an intermediate frequency, i.e., a frequency lower than the actual wireless communication frequency, thereby reducing loss. Patent Document 2 describes a dielectric rod antenna. In this dielectric rod antenna, the antenna gain is enhanced by extending the dielectric in the direction of radio wave propagation. Non-Patent Document 1 describes a dielectric rod antenna array in which a dielectric rod is provided for each antenna element.

[0003] Japanese Patent Publication No. 2021-16077 Japanese Patent Publication No. 2005-347936 Japanese Patent Application No. 2023-062604 Gabriel L. Saffold et al., "Dielectric Rod Antenna Array With Planar Folded Slot Antenna Excitation" IEEE Open Journal of Antennas and Propagation, Volume 2, 2021, pages 664-673

[0004] The large-scale, multiple mixer circuits described in Patent Document 1 result in high costs and complicated wiring design. The structure described in Patent Document 2 does not increase transmission line loss, but does not enable beam scanning. In the dielectric rod antenna array described in Non-Patent Document 1, each rod faces the same direction, which can increase antenna gain but does not support beam scanning to create a wide-angle coverage area. Furthermore, the need for individual dielectrics, which not only increases manufacturing and assembly costs but also requires individual readjustment of antenna elements on-site due to misalignment caused by transportation, makes practical application impractical. As described above, in the millimeter-wave band (5 GHz and above), coverage is secured by scanning high-gain beams using array antennas. Beyond 5G and 6G, the use of high frequencies up to 300 GHz is being considered, increasing the need for high-gain beam scanning. In contrast, Patent Document 3 describes a low-cost dielectric rod antenna and dielectric rod that achieves relatively reduced transmission line loss, high gain, and beam scanning in array antennas at millimeter-wave bands and above. Specifically, an antenna is described that achieves low loss, high gain, and beam scanning using an array antenna with a small number of elements as an excitation source and rod-shaped dielectric rods equal in number to the number of beams used ( Figures 1 and 2 ). However, the configuration shown in Figure 1 of Patent Document 3 is compatible with four beams, which may result in reduced signal levels between beams and the creation of gaps in the communication area. In other words, the configuration shown in Figure 1 of Patent Document 3 uses discrete beams that can achieve high gain only in a certain direction of the dielectric rods. Therefore, the present invention aims to realize an antenna that can achieve relatively reduced transmission line loss in an array antenna at millimeter wave bands and above, high gain, and arbitrary beam scanning, and can achieve high gain in beams in any direction within the splay angle and ensure a communication area without gaps. Another objective of the present invention is to realize an antenna that can achieve relatively reduced transmission line loss in an array antenna at millimeter wave bands and above, high gain, and arbitrary beam scanning, and that can be manufactured more easily and at lower cost than a multiple-rod antenna.Other objects of the present invention are also explained in the detailed description of the invention.

[0005] A dielectric fan according to an embodiment of the present invention is a dielectric fan having a dielectric section with a dielectric constant greater than 1, the dielectric section including a sector-shaped section with a base approximately at its center and a tip at its outer periphery, the base including a portion for mounting an antenna serving as an excitation source. A dielectric fan according to an embodiment of the present invention is a dielectric fan as described above, including a plurality of sector-shaped sections arranged at predetermined intervals in a direction perpendicular to the direction of the opening angle of the sector-shaped sections. A dielectric fan according to an embodiment of the present invention is any of the dielectric fans described above, wherein the sector-shaped section has an opening angle of 360° and is disk-shaped with a gap on the base side. A dielectric fan according to an embodiment of the present invention is any of the dielectric fans described above, wherein the dielectric section has a shape that becomes thinner from the base to the tip. A dielectric fan according to an embodiment of the present invention is any of the dielectric fans described above, wherein the dielectric section includes a multilayer dielectric substrate having a plurality of dielectric layers, and wherein the lengths of the plurality of dielectric layers differ in the direction toward the tip, thereby causing the dielectric section to become thinner from the base to the tip. A dielectric antenna according to an embodiment of the present invention includes any one of the dielectric fans described above, and an array antenna with m rows and n columns as an excitation source, where m and n are natural numbers, and the row direction of the array antenna is the direction of the opening angle of the sector, and n is greater than m. A dielectric antenna according to an embodiment of the present invention includes any one of the dielectric fans described above, and an array antenna with m rows and n columns as an excitation source, where m and n are natural numbers, and the row direction of the array antenna is the direction of the opening angle of the sector, and n is greater than m. A dielectric antenna according to an embodiment of the present invention includes any one of the dielectric fans described above, a drive unit that drives the dielectric fan, and an antenna unit as an excitation source. A dielectric antenna according to an embodiment of the present invention includes an array antenna and any one of the dielectric fans described above, and the array antenna includes a plurality of unit arrays arranged in a regular polygonal shape from the center of the regular polygon toward the outside as an excitation source. A dielectric antenna according to an embodiment of the present invention is any one of the dielectric antennas described above, where the dielectric unit is shaped to become thinner from the base to the tip.A dielectric antenna according to one embodiment of the present invention is a dielectric antenna having an antenna portion and any one of the dielectric fans described above, the antenna portion being mounted on a multilayer dielectric substrate.

[0006] With the above-described configuration, the present invention can realize high gain of a beam in any direction within the opening angle of the fan-shaped dielectric, and can secure a communication area without holes. Furthermore, compared to a shape having multiple rods, the fan-shaped dielectric is easier to manufacture, and cost reductions can be expected. Other effects of the present invention will be explained in the description of the invention.

[0007] 1 shows an example of the configuration of a dielectric fan and a dielectric antenna according to an embodiment of the present invention. 2 shows an example of the configuration of a dielectric antenna according to an embodiment of the present invention. 3 shows an example of the configuration of a dielectric antenna according to an embodiment of the present invention. 4 shows an example of the characteristics of a dielectric antenna according to an embodiment of the present invention. 5 shows an example of the configuration of a dielectric fan according to an embodiment of the present invention. 6 shows an example of the configuration of a dielectric fan according to an embodiment of the present invention. 7 shows an example of the configuration of a dielectric antenna according to an embodiment of the present invention. 8 shows an example of the configuration of a dielectric fan according to an embodiment of the present invention. 9 shows an example of the configuration of a dielectric antenna according to an embodiment of the present invention. 10 shows an example of the configuration of a dielectric antenna according to an embodiment of the present invention. 11 shows an example of the configuration of a dielectric fan according to an embodiment of the present invention. 12 shows an example of the configuration of a dielectric antenna according to an embodiment of the present invention. 13 shows an example of the configuration of a dielectric antenna according to an embodiment of the present invention. 14 shows an example of the configuration of a dielectric antenna according to an embodiment of the present invention. 15 shows an example of the configuration of a dielectric fan according to an embodiment of the present invention. 16 shows an example of the configuration of a dielectric antenna according to an embodiment of the present invention. 17 shows an example of the configuration of a dielectric antenna according to an embodiment of the present invention.

[0008] FIG. 1 shows an example of a dielectric fan 2 and a dielectric antenna 1 according to an embodiment of the present invention. The dielectric fan 2 has a dielectric portion 20 having a dielectric constant greater than 1. The dielectric portion 20 includes a sector-shaped portion 200 having a base 210 at its approximate center and a tip 220 at its outer periphery. The base 210 has a mounting portion 211 for an external antenna that serves as an excitation source. The sector-shaped portion 200 can extend from the outer periphery, i.e., the tip 220, to the base 210, and the base 210 can include the mounting portion 211. While the sector-shaped portion has a dielectric constant greater than 1, it is desirable to keep it as small as possible to improve performance. This configuration, with the sector-shaped portion 200 and its sector-shaped configuration, solves the problem of the antenna communication area becoming too narrow even when directivity is high. Here, the sector-shaped portion 200 does not have a shape in which its thickness exceeds its width.

[0009] In the configuration described in Patent Document 3, for example, the level between beams decreases, which may result in holes in the communication area, and because the beams are discrete, high gain can only be achieved in a certain direction of the dielectric fan 2. In contrast, in this configuration, the dielectric has a fan-shaped portion 200, which makes it possible to achieve high gain in beams in any direction within the opening angle, and ensure a communication area without holes. Furthermore, compared to multiple fan-shaped dielectrics, fan-shaped dielectrics are easier to manufacture and are expected to reduce costs.

[0010] The dielectric antenna 1 in this embodiment includes the dielectric fan 2 described above. It also includes an array antenna 100 as an excitation source. In this embodiment, the frequency of transmission and reception of the array antenna 100 is 20 GHz or higher. In this specification, the excitation source antenna includes a single antenna and the array antenna 100, and these are sometimes collectively referred to as the "antenna." The array antenna 100 is used as the excitation source, and the dielectric fan 2 is designed to provide high gain for beamforming in any direction. Specifically, it is a fan-shaped dielectric, and preferably has a structure that tapers from the center to the tip of the fan. The beamforming method of the excitation source can be either analog or digital beamforming. Using the array antenna 100 with a small number of elements as the excitation source shortens the transmission line, resulting in a highly efficient antenna. Furthermore, the fan-shaped portion 200 enables high gain for beamforming in any direction within the opening angle.

[0011] The opening angle is adjusted to match the required area angle. For one planar array such as this embodiment, it is designed to be a maximum of 180 degrees. The excitation source shown in the figure is a four-element array, but it can be increased to eight or sixteen elements. Using eight or sixteen elements will increase the antenna gain. In this case, the structure of the dielectric fan 2 can be optimized.

[0012] 2 and 3 show an example of a dielectric antenna 1 according to an embodiment of the present invention, and in particular, a configuration example of an array antenna 100. The dielectric antenna 1 in this configuration has the above-mentioned dielectric fan 2. It also has an array antenna 100 as an excitation source.

[0013] The array antenna 100 has a plurality of unit antennas 101. To achieve beam scanning, a high-frequency circuit 30 comprising an amplifier 33 and a phase shifter 34 is connected to each unit antenna 101. In this configuration, since the excitation source is the array antenna 100, if an amplifier 33 is connected to each unit antenna 101 and signals are transmitted and received by combining / dividing, power can be increased by parallel combining of the amplifiers. In this embodiment, the high-frequency circuit 30 includes amplifiers 33 connected to each unit antenna 101, phase shifters 34 connected to each amplifier 33, and a combiner / divider 32 connected to the phase shifter 34 and receiving input to the high-frequency circuit 30. The input to the high-frequency circuit 30 is combined / divided using the combiner / divider circuit 32, passes through the phase shifter 34, and is amplified by the amplifier 33, and the amplified signal is output to each unit antenna 101.

[0014] FIG. 4 shows the characteristics of a dielectric antenna 1 according to an embodiment of the present invention, particularly its directivity. FIG. 4 shows the intensity of a beam in a specific direction. Centered on the 0° beam indicated by the solid line, the antenna includes two beams at approximately +12° and approximately -12° indicated by the dashed lines, two beams at approximately +24° and approximately -24° indicated by the dotted lines, and two beams at approximately +36° and approximately -36° indicated by the dashed-dotted lines. This allows for a total of seven beams, enabling seamless transmission and reception in any direction. Of course, a configuration with seven or more beams can also be used, allowing for even more seamless beam formation. In this way, the fan-shaped dielectric allows for high gain in any beam direction. While the configuration shown in FIG. 1 of Patent Document 3 only allowed for the formation of four beams using four element excitation sources, this embodiment is not limited to four beams and allows for the formation of any number of beams without gaps.

[0015] 5 and 6 show a dielectric fan 2 according to an embodiment of the present invention, and FIGS. 7 and 8 show an example of a dielectric antenna 1 according to an embodiment of the present invention. The dielectric fan 2 includes a plurality of sectorial sections 200. The sectorial sections 200 are arranged at predetermined intervals in a direction DP perpendicular to the opening angle direction DO of the sectorial sections 200. In the configuration shown in FIG. 5, the sectorial sections 200 are independent of one another, but they may also be integrated at the base 210 side, as in the configuration shown in FIG. 6.

[0016] In this embodiment, the dielectric antenna 1 includes a switch circuit 31. The multiple sectorial sections 200 are arranged at different angles in a direction perpendicular to the sector plane. By switching between the sectorial sections 200 using the switch circuit 31, for example, beam selectivity in the orthogonal direction can be added. In this manner, multiple sectorial sections 200 can be arranged in the same direction. Furthermore, by applying a combining / dividing circuit 32 as shown in FIG. 8, further improvement in antenna gain is possible. Note that the solid line connecting the mounting section 211 and the combining / dividing circuit 32 in FIG. 8 is a schematic diagram showing the flow of signal transmission and reception. The solid line does not actually connect the mounting section 211 and the antenna; instead, the mounting section 211 and the antenna are arranged in close contact with each other or facing each other with a predetermined gap between them.

[0017] Fig. 9 shows an example of a dielectric fan 2 according to an embodiment of the present invention. Figs. 10, 11, 12, and 13 show an example of a dielectric antenna 1 according to an embodiment of the present invention. The dielectric part 20 has a sectorial portion 200 with an opening angle of 360°. The dielectric part 20 is disk-shaped with a gap 212 on the base 210 side.

[0018] In this embodiment, the dielectric antenna 1 includes an array antenna 100 and a dielectric fan 2. The array antenna 100 also includes, as an excitation source, a plurality of unit arrays 110 arranged in a regular polygonal shape from the center of the regular polygon toward the outside. The regular polygon, that is, a regular N-gon, where N is finite, naturally also includes a substantially circular shape when N is very large.

[0019] 10 and 11 show an example in which a plurality of unit arrays 110 are arranged in a square where N is 4, but as shown in FIGS. 12 and 13, N may be 3 or 6. In this configuration having a regular N-sided polygonal gap 212, the antenna and the dielectric fan 2 can be arranged in close contact with each other or facing each other with a gap of a predetermined distance or less. For ease of understanding, in FIG. 10, the dielectric fan 2 is shown as transparent, and the lower parts of the plurality of unit arrays 110 are also shown.

[0020] In this embodiment shown in Figures 10 and 11, the unit array 110 has four unit antennas 101 on the front surface side, which faces the dielectric fan 2. The unit array 110 also has wiring sections 102 on the back surface, opposite the front surface, and each wiring section 102 is connected to each unit antenna 101. This configuration allows the wiring to be concentrated in the center, making the structure more compact. In this embodiment, the air gap 212 on the base 210 side is a regular N-gon corresponding to each unit array 110, but it may also be circular as shown in Figure 13. If the air gap 212 is circular, and the antenna is planar, there will be areas where the dielectric fan 2 and the antenna are not in close contact, but they can be positioned within a predetermined distance. The fan-shaped dielectric is replaced with a cylindrical dielectric, and multiple excitation sources are located in the center of the cylinder. By switching between these multiple excitation sources, beamforming is possible in any direction within 360°.

[0021] 14 shows an example of a dielectric fan 2 and a dielectric antenna 1 according to an embodiment of the present invention. The dielectric portion 20 is tapered from the base 210 to the tip 220. The tapered shape may be either a smooth taper or a stepped structure. In this configuration, the fan gradually becomes thinner toward the tip.

[0022] 15 and 16 show an example of the dielectric antenna 1 according to an embodiment of the present invention, and in particular show a configuration example of an array antenna 100. The dielectric antenna 1 has any one of the dielectric fans 2 described above.

[0023] The dielectric antenna 1 also has an array antenna 100 with m rows and n columns as an excitation source, where m and n are natural numbers. The example shown in Fig. 15 has an array antenna 100 with 1 row and 4 columns, and the example shown in Fig. 16 has an array antenna 100 with 3 rows and 4 columns. The row direction of the array antenna 100 is the opening angle direction DO of the sector. The column direction is the direction DP orthogonal to the opening angle direction of the sector.

[0024] In addition, n is greater than m. Here, m may be plural, as in the example shown in Figure 16. With this configuration, the dielectric fan 2 having the sector-shaped portion 200 can be used effectively.

[0025] 17 and 18 show an example of a dielectric antenna 1 in an embodiment of the present invention. The dielectric antenna 1 has a dielectric fan 2, a drive unit 40 that drives the dielectric fan 2, and an antenna unit 10 as an excitation source. In this embodiment, as shown in FIG. 17, the drive unit 40 moves the dielectric fan 2 in a predetermined direction, but in one embodiment, as shown in FIG. 18, the drive unit 40 may be configured to rotate the dielectric fan 2. When the dielectric fan 2 is rotated, the direction of the radio waves can be controlled while maintaining the axis of the dielectric fan 2.

[0026] 19 shows an example of a dielectric fan 2 and a dielectric antenna 1 according to an embodiment of the present invention. In this embodiment, the dielectric section 20 has a multilayer dielectric substrate 230 having a plurality of dielectric layers 231, and the lengths of the plurality of dielectric layers 231 vary in the direction of the tip 220, resulting in a shape that becomes thinner from the base 210 toward the tip 220.

[0027] The dielectric fan 2 can also be realized using a multilayer dielectric substrate 230, which is inexpensive and easy to manufacture. By configuring the dielectric fan 2 as a multilayer substrate as shown in the figure, it is possible to mount an antenna as an excitation source, an IC 232 for beamforming, and other components on the same substrate. In this embodiment, each layer of the multilayer substrate has a dielectric layer 231 and a bonding sheet 234, but other configurations are also possible. Furthermore, while this embodiment uses a shape in which the thickness gradually decreases layer by layer, a configuration in which the thickness gradually decreases by two or more layers may also be used. Furthermore, the tip 220 side of the multilayer dielectric substrate 230 may be cut in a curved shape to achieve a continuous thickness.

[0028] The dielectric antenna 1 has an antenna section 10 and the dielectric fan 2, and the antenna section 10 is mounted on a multilayer dielectric substrate 230. With this configuration, not only the dielectric fan 2 but also the dielectric antenna 1 can be realized on a multilayer substrate, which makes processing easier, reduces costs, and makes it easier to make the antenna smaller.

[0029] The present invention is not limited to the above-described embodiments, and it goes without saying that various embodiments are included within the scope of the present invention.

[0030] REFERENCE SIGNS LIST 1 Inductive antenna 10 Antenna section 100 Array antenna 101 Unit antenna 102 Wiring section 110 Unit array 2 Inductive fan 20 Dielectric section 200 Fan-shaped section 210 Base section 211 Mounting section 212 Air gap section 220 Tip section 230 Multilayer dielectric substrate 231 Dielectric layer 232 IC 233 Via 234 Bonding sheet 30 High-frequency circuit 31 Switch circuit 32 Combiner / divider circuit 33 Amplifier 34 Phase shifter 40 Driver section

Claims

1. A dielectric fan having a dielectric part with a dielectric constant greater than 1, the dielectric part having a fan-shaped part with the base approximately at the center and the tip at the outer periphery, and the base having an attachment part for an antenna that serves as an excitation source.

2. A dielectric fan according to claim 1, comprising a plurality of sectorial sections, the sectorial sections being arranged at predetermined intervals in a direction perpendicular to the opening angle direction of the sectorial sections.

3. The dielectric fan according to claim 1, wherein the sectorial portion of the dielectric portion has an opening angle of 360° and is disk-shaped with a gap on the base side.

4. The dielectric fan according to any one of claims 1 to 3, wherein the dielectric portion is shaped so as to become thinner from the base portion toward the tip portion.

5. A dielectric fan as described in claim 4, wherein the dielectric portion has a multilayer dielectric substrate having a plurality of dielectric layers, and the lengths of the plurality of dielectric layers in the direction of the tip are different, so that the dielectric portion has a shape that becomes thinner from the base toward the tip.

6. A dielectric antenna comprising the dielectric fan according to claim 1, an array antenna with m rows and n columns as an excitation source, where m and n are natural numbers, the row direction of the array antenna being the opening angle direction of the fan shape, and n being greater than m.

7. A dielectric antenna comprising the dielectric fan according to claim 2, an array antenna with m rows and n columns as an excitation source, where m and n are natural numbers, the row direction of the array antenna being the opening angle direction of the fan shape, and n being greater than m.

8. A dielectric antenna comprising: a dielectric fan according to claim 1; a drive unit for driving said dielectric fan; and an antenna unit as an excitation source.

9. A dielectric antenna comprising an array antenna and the dielectric fan according to claim 3, wherein the array antenna has a plurality of unit arrays arranged in a regular polygonal shape from the center of the regular polygon toward the outside as an excitation source.

10. A dielectric antenna according to any one of claims 6 to 9, wherein the dielectric portion is shaped so as to become thinner from the base portion to the tip portion.

11. A dielectric antenna comprising an antenna section and the dielectric fan according to claim 5, wherein the antenna section is mounted on the multilayer dielectric substrate.

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